A DBD method has been developed to decompose sulphur hexafluoride (SF₆) nearly 100% under conditions close to the exhaust gas in industries with energy efficiency of 0.015–0.15 GJ/ton carbon dioxide (CO₂) equivalent, 1–2 orders of magnitude higher than CO₂ capture and sequestration from power generation boilers. A typical test condition was SF₆: 820 ppm; CO₂/air: 50/50; gas flow rate: 623 mL/m at 25°C; AC voltage: 17–23 kV p–p; AC frequency: 7 kHz. The success of this project was due to the development of highly effective star-shaped discharge elements and an improved design of the DBD system, that is mode of applying voltage, the physical aspects of the reactor. © 2013 Canadian Society for Chemical Engineering

This paper demonstrates the influence of low Rayleigh vibration on thermodiffusion measurement in microgravity environment. The goal is to show how the variation of certain parameters such as frequency and amplitude of translational vibrations would impact the results obtained from the ISS experiment. Precisely, impact of change in low Rayleigh vibration on the separation of a component is studied for each experimental run.

ISS experimental data are obtained based on optical digital interferometry in a reduced gravity environment. The experiment is done in a cubic cell containing an aqueous solution exposed to a lateral temperature gradient. A mixture of water and isopropanol of different initial concentrations with positive and negative Soret coefficient is chosen as the test fluid. Collected data are analysed by image processing. Results show maximum separation of components for the case without any forced vibration. Moreover, an increase in Rayleigh number corresponds to decrease in the separation of components. © 2013 Canadian Society for Chemical Engineering

The integrity and robustness of Pd-based composite membranes depend heavily on the quality of the metallic substrate. This paper presents an improved method for pre-treating the substrate. Detailed pre-treatment steps of these porous stainless steel substrates included washing, polishing, etching, coating the first alumina layer, calcining the first alumina layer, coating the second alumina layer, calcining the second alumina layer and repair. The repair cycle was the most helpful step, greatly improving the membrane reproducibility and stability. Repeat coating with dilute suspensions of alumina particles of 0.3 µm mean diameter can repair defects on the top alumina layer. The hydrogen permeation flux was 268 × 10⁻⁴ N m³/(m² h Pa) after one repair cycle, decreasing by 14% after an additional repair cycle. The hydrogen permeation flux of the pre-treated porous stainless steel substrate was thus maintained at a level comparable with previous work. Surface topography revealed that the average roughness was reduced from 1.15 to 0.47 µm, and the surface Maximum Peak to Valley decreased from 17.5 to 6.0 µm/mm² as a result of the pre-treatment. © 2013 Canadian Society for Chemical Engineering

In the present work, usual statistical process control (SPC) definitions are reformulated to allow for long-term analyses, giving rise to extended statistical process control (ESPC) procedures. In order to allow for implementation of the ESPC approach, t- and F-control charts and monitoring indexes (NEPM, EPY and OEP) are designed in this work and are used to monitor the performance of a real industrial poly(ethylene terephthalate) (PET) site based on six process outputs (intrinsic viscosity, crystallinity, acetaldehyde concentration and colours a, b and L). As shown in this manuscript, ESPC tools allow for proper and systematic analysis of huge amounts of industrial data, using simple, fast and efficient statistical techniques, which can be used to improve the quality of the process operation in most industrial polymerisation plants. © 2013 Canadian Society for Chemical Engineering

This work concerns a fundamental understanding of how heterogeneities induced by flow barriers and connate water affect the displacement efficiency of polymer floods, which has rarely been studied in the available literature. Here, a series of water/polymer injection experiments to heavy oil performed on five-spot glass micromodels containing randomly distributed shale structures is presented. It has been found that macroscopic efficiency of polymer flooding majorly depends on flow barriers distribution/configuration; shale content and geometrical characteristics; presence of connate water and wettability of medium. Microscopic pictures revealed that the main parts of connate water were trapped in some pores/throats near and especially behind the shale streaks; also, presence of connate water causes a reduction of sweep efficiency due to premature breakthrough of displacing fluid in an oil-wet media. In absence of connate water, polymer solution could linger and stick to the pore walls to delay the time for a polymer to channel to the production site. Results of this work disclose requirements for a detailed geologic study of barrier size and distribution for successful design of EOR processes in heterogeneous reservoirs. © 2013 Canadian Society for Chemical Engineering

Ethanol steam reforming is a promising method for hydrogen production. Kinetic studies are carried out over a nickel-based catalyst from 200 to 600°C. A simplified Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetic model was proposed with nine parameters, where the surface decomposition of methane is assumed as the rate determining step (RDS), and while all other reaction steps are set as reversible. It is postulated that the velocity of the backward reaction step of the dissociative methane adsorption is similar to all other equilibrium reactions proposed, while the forward reaction step is set as the RDS. In addition, the formation of adsorbed carbon species is excluded due to the fact that SRE experiments were performed with excess water, suggesting that OH species, excluding O species formation, stick better on active Ni surface than methane. In addition, a power law kinetic model was used for analysis; the activation energy was 31.8 kJ/mol, and the reaction order of ethanol pressure was 1.52. Experimental results were successfully demonstrated by both kinetic models. The purpose of this work was to develop a simplified mechanistic model to replace empirical models (power rate model) and other proposed kinetic models that are too complex for an applied kinetic process. It was found that the simplified LHHW kinetic model has a better fit than that of the power law model. The proposed kinetic model works well over a wide temperature range (200–600°C). © 2013 Canadian Society for Chemical Engineering

Pressure swirl atomisers are widely used in both industry and daily life. It is critical to understand the spray transient behaviour for better design of these systems. This paper presents an experimental study of conical liquid sheets breakup from a swirl atomiser nozzle in trigger sprayers. Spray and atomisation characteristics were measured and analysed. Water–ethanol mixtures were used to simulate different fluids on the breakup and atomisation quality of the spray development process with a wide range of surface tension while maintaining relatively small changes in fluid viscosity and density. The spray images were taken by a high speed digital camera and post-processed to analyse the global spray structure, spray cone angle, and breakup length. The droplet size and its distribution were measured using a laser diffraction technique. It was observed that the surface waves grow rapidly on the cone-shaped liquid sheets and breakup into liquid ligaments and droplets during the initial stage of fluid dispensing. Then the spray transitions into the developed stage. Near the end of the dispensing process, the liquid cone collapses with poor atomisation (large droplets) due to momentum loss. The comparison between different fluids showed that the spray cone angle and liquid breakup length decreased with the increase of ethanol percentage ratio. The percentiles parameters, Sauter mean diameter (SMD) and particle size distribution were measured and compared for different locations. High surface tension fluids produce larger droplets than lower surface tension fluids, which have the same trend as the percentiles parameters and SMD. Results also show that droplet size and its distribution depend on the location of the measurement. Generally speaking, smaller droplet size is found for a location away from the nozzle axis in the vertical direction. In the horizontal direction, larger droplet sizes are found for a location closer to the nozzle exit. © 2013 Canadian Society for Chemical Engineering

In paraffinic froth treatment, tailings from the tailings solvent recovery unit (TSRU) contain a significant fraction of asphaltenes. In current commercial practice, the TSRU tailings are disposed of in a tailings pond where the large asphaltene particles and coarse tailings settle and the fines form mature fine tailings (MFT). With increasing public concern about the environmental impact of tailings ponds and stricter government regulations on tailings disposal, the oil sand industry has increased efforts to find alternatives that eliminate or reduce the use of tailings ponds. In collaboration with Total E&P Canada (TEPCA), CanmetENERGY conducted an extensive research program to explore alternatives for TSRU tailings disposal. TSRU tailings were produced from TEPCA's froth treatment pilot tests conducted at the CanmetENERGY froth treatment facility. Various processes were investigated, including flocculation and thickening, filtration, and centrifugation. A large number of bench-scale flocculation-thickening and filtration tests were conducted, followed by numerous pilot-scale flocculation-thickening tests and centrifugation tests. The experimental results demonstrate that TSRU tailings can be flocculated and thickened to produce paste-like sediment, and the hot water can be recovered and recycled. The thickened TSRU tailings have good water drainage and deposition of the sediment on a beach would result in further dewatering. Centrifugation of the TSRU tailings or filtration of the thickener underflow can produce a cake that appears to be very dry and suitable for disposal without pond containment. © 2013 Canadian Society for Chemical Engineering

Prediction of particle velocity in a dilute turbulent gas–particle flow nearby a flat solid boundary is investigated numerically using a fully Eulerian two-fluid model. The particulate phase model is based on the kinetic theory of granular flow. The turbulence in both phases is modelled. Inter-particle and particle-wall inelastic collisions are considered. Effects of presence/absence of particulate phase turbulence modelling on velocity of particles are investigated. Results indicate that turbulence modelling is necessary for particulate phase, but conventional models should be modified to consider particulate flow nature. Effects of free stream velocity and particle diameter on turbulence modelling results have been discussed. © 2013 Canadian Society for Chemical Engineering

In this study, a series of crosslinked N-vinyl-2-pyrrolidone–itaconic acid (NVP-IA) hydrogels was prepared by free radical polymerisation in aqueous solution. Swelling, mechanical and adsorption properties for the removal of Cu²⁺ and Pb²⁺ ions from aqueous solutions of these hydrogels were investigated. Metal ion adsorption capacities of hydrogels for Cu²⁺ and Pb²⁺ ions were determined as 2.1 and 0.6 mmol g⁻¹, respectively. Adsorption processes of metal ions onto the NVP-IA hydrogels follow pseudo-second-order type adsorption kinetics. The equilibrium adsorption data have been evaluated using Freundlich and Langmuir isotherm models. The results illustrated that the adsorption follows Freundlich isotherm. © 2013 Canadian Society for Chemical Engineering

The present study focuses on the process optimisation of porous carbon preparation from date seed pits. The response surface methodology (RSM) technique with Box–Behnken method (BBM) was utilised with the response variables being the yield and BET surface area. The influencing parameters selected were activation temperature, impregnation ratio (IR) and activation time. The optimum conditions were identified to be an activation temperature of 500°C, IR of 2 and activation time of 75 min, with the resulting yield and BET surface area being 46% and 838 m²/g. The average pore volume and average pore diameter were 1.07 cm³/g and 1.69 nm, respectively. In order to assess the suitability of the carbon for adsorption of macromolecules, the kinetics of methylene blue (MB) adsorption were assessed by varying the initial concentration and the adsorption temperature. The kinetic parameters were evaluated applying the pseudo-second-order kinetic model by minimising the error between the experimental data and the model prediction; it was found to represent the experimental data more aptly. © 2013 Canadian Society for Chemical Engineering

High purity titanium dioxide (TiO₂) nanoparticles were synthesised via a modified sol–gel method using titanium tetraisopropoxide (TTIP). XRD analysis showed that the synthesised product was TiO₂ powder in anatase form. The sample possessed a relatively high surface area of 75.64 m²/g. The typical TEM images suggested that the crystalline phase product was composed of fine particles with dimensions between 17 and 20 nm. The synthesised material was used as a photocatalyst for the removal of mercaptans from gas–oil. The result showed that up to 78% of the mercaptans in gas–oil was removed using the synthesised TiO₂ photocatalyst. © 2013 Canadian Society for Chemical Engineering

The flow structures around continuous cryogenic Taylor bubbles in the concentric glass tube with different diameters were investigated using particle image velocimetry (PIV) technique under various inclination angles. Optical distortions produced by tube curvature and the refractive index differences between tube and fluid were corrected using ray tracing method. Based on the PIV results, the proper orthogonal decomposition (POD) method was used to investigate the effect of flow structure on the interaction of Taylor bubbles through the large-scale turbulent structures of POD modes. Four best-fitted curves for Taylor bubble interaction for different inclination angles were represented. A correlation for Taylor bubble formation was developed with the consideration of turbulence suppression, tube inner diameter, fluid properties, inclination angle, etc. The results demonstrate that the minimum stable distance attains the smallest value at θ = 60°. The correlation for Taylor bubble formation shows good agreement with the experimental data both in the present study and from its references. © 2013 Canadian Society for Chemical Engineering

A numerical simulation has been conducted to investigate the thermodiffusion phenomenon in a porous layer sandwiched between two liquid layers that are wetted with water alcohol mixtures at different water concentrations. Two different binary mixtures with different Soret coefficients have been used in the entire system, one with a negative Soret coefficient and the other one with a positive sign. The results show that the direction of the component migration in a porous layer depends on the sign of the Soret coefficient. For a binary mixture with a negative Soret coefficient, such as 10% isopropanol and 90% water, the heavier species move in the direction of the hot surface, while for a mixture with a positive Soret effect, such as 50% isopropanol and 50% water, the heavier species migrate toward the colder surface. To reduce the gravity effect, the cavity was heated from the top with different temperatures ranging from 5 to 20 K. © 2013 Canadian Society for Chemical Engineering

Surfactant flooding aims at lowering the interfacial tensions between the oil and water phases to improve the displacement efficiency during oil recovery. However, surfactant losses due to adsorption on the reservoir rock impairs performance of the chemical flooding, consequently renders the process impractical economically. This article presents adsorption equilibrium and kinetics of Zizyphus Spina Christi (ZSC), a new non-ionic surfactant, onto carbonate rocks. The adsorption tests were conducted at a temperature range of 28–75°C. A conductivity method was employed in this study to measure CMC parameter and surfactant concentration in the aqueous solutions. The equilibrium conditions for the crushed rock samples were obtained after about 2 days. According to the experimental results, the equilibrium data were well-fitted by the Freundlich isotherm for carbonate samples. Furthermore, the adsorption process is exothermic and obeys the second-order kinetic model. Such a systematic investigation is very helpful to select a proper surfactant for EOR application and reservoir stimulation in the petroleum industry. © 2013 Canadian Society for Chemical Engineering

Detailed study of the gas–solid flow in FCC reactor was performed using Euler–Euler two-fluid model. Two distinct regions were identified in the reactor vessel based on differences in catalyst void fraction and fluid flow: the dilute phase congested disengager region and dense phase congested stripper region. Velocity profile revealed an inert yet random flow pattern in the disengager and a counter-current type of flow with a pronounced radial unevenness in the stripper. Residence time distribution proved that a small portion of oil vapour could linger over 5 min before exiting despite that the apparatus may have a significantly shorter average residence time. © 2013 Canadian Society for Chemical Engineering

Direct coal liquefaction (DCL) is a process for converting coal to synthetic oils, which can be refined to make transportation fuels. Residue from this process contains inorganic material such as mineral matter originating from the coal and catalysts, and organic matter such as unconverted coal, heavy oils, pre-asphaltenes and asphaltenes. The conversion of these DCL residues to lighter, high-value products is an important step in helping to make this technology both commercially viable and environmentally acceptable. This paper provides an overview of the physico-chemical characteristics and processing options available for coal liquefaction residues and compares and contrasts them to those of petroleum residues.

Residue properties vary considerably, since they are highly dependent on feed coal, process configuration and operating conditions. Determination of composition and structural parameters of products derived from residue conversion can help determine their stability, coking and solvent hydrogen donating ability. Thermal conversion processes such as visbreaking and gasification offer the greatest promise for handling these heavy materials. The conversion chemistry, reactivity and kinetics of residue gasification are not well-understood but are important in optimising hydrogen production for the process.

The literature has been comprehensively reviewed to provide characteristics and properties of residues and their potential for conversion. In addition, the potential for producing high-value carbon products from residues is briefly discussed. © 2013 Canadian Society for Chemical Engineering

Adsorption of reactive blue (RB) 21 dye in the aqueous solution has been carried out on TiO₂ alone and in combination with rare earth ions [La³⁺, Ce⁴⁺, Pr³⁺ and Gd³⁺] in the presence and absence of ultrasound. The formation of adsorbent (TiO₂) from tetra n-butyl orthotitanate and its characterisation has been done through X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), Raman spectroscopy and N₂ adsorption techniques. Complete decolourisation was achieved in 5 min in the presence of US + TiO₂ + Ce. The effects of initial concentration of dye, adsorbent dose and contact time on the decolourisation of dye have been examined under different experimental conditions. The removal of dye in the presence of ultrasound was (88–99%) compared to conventional stirring (62–69%).

Adsorption behaviour has been analysed using Langmuir, Freundlich, Dubinin–Radushkevich and Temkin isotherm models. RE–TiO₂ combination had higher adsorption equilibrium constant (K_c) and better adsorption capacity (q_max) than TiO₂ alone, both in the absence and presence of ultrasound, indicating the formation of Dye-RE complex before sorption. This is confirmed from the shift in λ_max from 626 to 616 cm⁻¹. The kinetic data fit well with the pseudo-second order kinetic model, and the adsorption process was spontaneous in the presence of rare earths. The mechanism of adsorption has been explained with the help of Weber–Morris intraparticle diffusion and Boyd kinetic models. A batch adsorber has been proposed for different TiO₂ dose to effluent volume ratios using the Langmuir equation. © 2013 Canadian Society for Chemical Engineering

Ore blending is a strategy developed in the oil sands industry to enhance bitumen recovery from low grade oil sands ores. It involves blending low grade ores with high grade ores at a certain ratio, resulting in a higher overall bitumen recovery from the mixture than the simple recovery summation of the two extracted separately. To understand the underlying mechanisms, both bitumen-coated glass beads (−150 + 125 µm) and raw coal particles (−500 + 300, −300 + 150 and −150 µm) were used as carrier materials in this study to simulate bitumen droplets from high grade ores. Experimental results revealed that coal particles were more efficient than hydrophobised bitumen-coated glass beads in accelerating bitumen recovery and that better bitumen extraction performance was obtained by using smaller sizes of coal. This was attributed to the gravitational effect of larger, heavier particles on the detachment of bitumen-particle aggregates from bubbles. For smaller sizes of coal (−150 µm), a faster bitumen flotation recovery was achieved with more coal added. An increase in bitumen recovery up to 20–30% (absolute) was obtained by adding coal into the oil sands slurry. The interaction of bitumen with coal particles or bitumen-coated glass beads during oil sands slurry conditioning and flotation was visually verified from simple coagulation tests. The similarity of ore blending in oil sands extraction to carrier flotation in minerals flotation and the potential application of carrier flotation principles to oil sands extraction were discussed. © 2013 Canadian Society for Chemical Engineering

The full Brinkman equation coupled with the heat and mass transfer equations was solved numerically using the finite element technique. A square cavity filled with hydrocarbon nanofluid of fullerene–toluene with different concentration values of fullerene was subject to various heating conditions. Results have confirmed that in the presence of nanofluid a heat transfer enhancement is present until a certain amount of initial concentration of the nanofluids. The heat convection coefficient was found to be 16% higher when nanofluid is used as the wetting fluid. In addition, it was determined that the concentration of fullerene in toluene has its limitation in heat removal enhancement. In fact, beyond 5% of fullerene, there is no noticeable enhancement of the heat removal in the system. The model was also used to study thermodiffusion effects in the cavity. Despite the small value and negligible effects of thermodiffusion in general heat and mass transfer problems, which is <5% in the case of studying nanofluids, a maximum value of 20% variation of fullerene concentration has been detected. Moreover, fullerene separation was investigated for different heating intensities. As the Rayleigh number increases, the mixing was found to reduce the separation, which diminishes the Soret effect in the system. © 2013 Canadian Society for Chemical Engineering

Miscible gas injection (MGI) processes such as miscible CO₂ flooding have been in use as attractive EOR options, especially in conventional oil reserves. Optimal design of MGI is strongly dependent on parameters such as gas–oil minimum miscibility pressure (MMP), which is normally determined through expensive and time-consuming laboratory tests. Thus, developing a fast and reliable technique to predict gas–oil MMP is inevitable. To address this issue, a smart model is developed in this paper to forecast gas–oil MMP on the basis of a feed-forward artificial neural network (FF-ANN) combined with particle swarm optimisation (PSO). The MMP of a reservoir fluid was considered as a function of reservoir temperature and the compositions of oil and injected gas in the proposed model. Results of this study indicate that reservoir temperature among the input parameters selected for the PSO–ANN has the greatest impact on MMP value. The developed PSO–ANN model was examined using experimental data, and a reasonable match was attained showing a good potential for the proposed predictive tools in estimation of gas–oil MMP. Compared with other available methods, the proposed model is capable of forecasting oil–gas MMP more accurately in wide ranges of thermodynamic and process conditions. All predictive models used other than the PSO–ANN model failed in providing a good estimate of the oil–gas MMP of the hydrocarbon mixtures in Azadegan oilfield, Iran. © 2013 Canadian Society for Chemical Engineering

Due to increasing energy demands, energy crises and strict environmental regulations, the eco-efficiency of all industrial processes and plants has become vitally important. Control loop configuration or control system structure determination is a major and vitally important activity in the complex task of process control because a poorly structured control strategy can lose much energy from the process or plant when implemented. To save this loss of energy due to a poorly structured control strategy, engineers need to find a way to integrate control loop configuration and measurements of eco-efficiency. In this paper, we present the relative exergy-destroyed array (REDA), a new tool to measure the relative eco-efficiency of a process. The REDA is a means to compare the eco-efficiency of multi-input multi-output processes for different combinations of control structures. Based on steady state information, it is a simple tool for comparing eco-efficiency. The results obtained from the REDA are interpreted and explained with the help of case studies involving a whole monochlorobenzene (MCB) plant and a heat exchanger network (HEN). The REDA may help guide the process designer to quickly find a control design with low operating costs and high eco-efficiency. © 2013 Canadian Society for Chemical Engineering

A new application of hybrid emulsion liquid membrane, in which an O/W emulsion phase is placed between two supporting membranes, is applied in the present research for removal of cadmium from aqueous phase. The new setting has advantages such as higher stability of the emulsion phase, lower pollution of feed and stripping phases due to contacting with the membrane phase and higher removal capacity. Trioctylamine has been used as a carrier in the organic phase of the emulsion, while the applied surfactant is nonyl phenol ethoxylate. The effect of different parameters is investigated, such as pHs of aqueous and dispersed phases, organic to aqueous volume ratio in the emulsion, carrier concentration, temperature, stirring intensity and cadmium concentration in the feed phase on the performance of the system. The appropriate values of pH for stripping phase and the emulsion's aqueous phase are found to be about 13 and 7, respectively. The optimum organic to aqueous phase volume ratio in emulsion is found to be about 1. The removal efficiency increases approximately twice when the emulsion is stirred more rigorously. Applying the new setup can enhance the removal capacity comparing to the ultimate capacity obtained from the hybrid liquid membrane system. © 2013 Canadian Society for Chemical Engineering

Mass- and mole-based pellet models have been solved using least-squares formulation to describe the evolution of species composition, pressure, velocity, total concentration and mass diffusion fluxes in porous pellets for the steam methane reforming (SMR) process. The objective of this work has been to compare the mass- and mole-based diffusion flux models, convection and fluid velocity for the SMR process using the least-squares spectral element method (LS-SEM). The diffusion–reaction problems are computationally intensive, requiring efficient numerical methods for dealing with them. This paper presents formulation and algorithm of LS-SEM for solving multicomponent mass diffusion pellet models. The mass diffusion flux is described according to the rigorous Maxwell Stefan model. This flux may be defined either with molar- or mass-averaged velocities. The effectiveness factors have been calculated for the SMR process and compared with the literature data.

The model evaluations revealed that:

• The least-squares method is well-suited for solving the multicomponent mass diffusion pellet models for the SMR process, achieving exponential convergence.

• Molar- and mass-based pellet models do not give fully identical results for the SMR process, since the pellet model is not completely consistent.

© 2013 Canadian Society for Chemical Engineering

Dehydration of methanol to dimethyl ether (DME) over a commercial γ-Al₂O₃ catalyst was studied at the temperature interval 513–613 K, liquid hourly space velocity (LHSV) of 0.9–6.0 h⁻¹ and pressures between 0.1 and 1.0 MPa. The effect of different operation conditions on the dehydration of methanol was investigated in an isothermal fixed bed reactor. A kinetic equation which describes a Langmuir–Hinshelwood surface controlled reaction with dissociative adsorption of methanol was found to fit the experimental results quite well. An activation energy of 62.4 kJ/mol was obtained for the catalyst. A two-dimensional reaction–diffusion model was established for a cylindrical-shaped methanol dehydration catalyst. The internal effectiveness factor and the concentration distribution of methanol in the catalyst were obtained by the finite element method in MATLAB. The reaction–diffusion model was verified by the global kinetics data. The calculation data agreed well with the experimental data, so the model can be used to describe the processes of reaction and diffusion in the cylindrical-shaped catalyst. © 2013 Canadian Society for Chemical Engineering

The main aim of this study was to determine the optimal operational parameters for a biological nitrification process. For this reason, a batch mode biological nitrification filled with acclimated sludge was used to remove ammonium from synthetic wastewater. Increasing the initial ammonium concentration from 50 to 300 mg NH₄-N/L within 67 days led to a decrease in the removal efficiency of ammonium from 97.2% to 57.3%, which is equivalent to increasing the specific ammonium oxidation from 1.09 to 3.85 mg NH₄-N/g MLVSS/h. Response surface methodology (RSM) based on central composite design (CCD) was used to evaluate the interactive effects of the three main parameters, including the sodium bicarbonate/ammonium chloride ratio, air flow rate and the reaction time, on the removal of ammonium. For the highest ammonium removal of 98.7%, the optimum sodium bicarbonate/ammonium chloride ratio, air flow rate and reaction time were identified to be 3.48, 3.44 vvm (volume air per volume reactor per minute) and 24.65 h, respectively, based on an initial ammonium concentration of 200 mg NH₄-N/L. © 2013 Canadian Society for Chemical Engineering

The effect of liquid viscosity on hydrodynamics and bubble behaviour of an external-loop airlift reactor within air–water system were studied by an electrical conductivity probe. Carboxyl methyl cellulose (CMC) was used to change liquid viscosity (1.00–51.25 cP). Gas holdup increased with superficial gas velocity increasing, as well as bubble Sauter diameter and bubble rise velocity. With liquid viscosity increasing, average gas holdup increased first then decreased, while bubble Sauter diameter was opposite, with critical viscosity µ_l ≈ 3.7 cP. The cross-sectional average bubble Sauter diameter increased obviously after µ_l > 3.7 cP, and its size distribution was wider within the higher viscosity. Bubble rise velocity increased significantly and nearly unchanged after µ_l > 10.3 cP. Gas holdup first increased then remained unchanged with the axial height increasing. The radial profile of local gas holdup presented a central peak distribution, and the value at inlet was smaller than that at the higher position. Average gas holdup was correlated greatly with superficial gas velocity and liquid viscosity. © 2013 Canadian Society for Chemical Engineering

A modified method for the design of multi-stream plate-fin heat exchangers that considers variable physical properties is proposed in this paper. The new method, based on Pinch Technology, exploits the dependency of physical properties (heat capacity, viscosity, density and thermal conductivity) on temperature variations. A set of temperature correction factors based on variable physical properties is derived for the hot and cold streams of a multi-stream heat exchanger. This allows calculation of effective stream pressure drops, which can lead to a valid trade-off between operating and capital cost in the targeting stage. Accordingly, composite curves are constructed; based on the enthalpy intervals, the multi-stream heat exchanger is subdivided into a number of block sections. A plate-fin heat exchanger is then designed for each section by maximising the allowable effective pressure drops. Next, using a Genetic Algorithm, the method is completed in order to optimise the pressure drop of streams. Therefore, fin types for each individual stream are considered as optimising variables. By taking the variable physical properties of each stream into account and using the best fin selection, one can achieve accurate results in the design stage. © 2013 Canadian Society for Chemical Engineering

The available methods for the selection of controlled variables (CVs), using the concept of self-optimising control (SOC), focus on finding CVs, which are held at constant setpoints using a feedback controller. In this paper, it is shown that better self-optimising properties can be achieved by incorporating feedforward action using measured disturbances in the SOC policies. The resulting operational policy allows the setpoints for CVs to be varied with measured disturbances, allowing for near-optimal operation in the presence of disturbances and uncertainties. The effectiveness of the proposed approach is demonstrated through its application to an exothermic reactor and a forced-circulation evaporator. © 2013 Canadian Society for Chemical Engineering

This communication reports the effects of Mn/Cr on the reducibility and catalytic activity of Cu–Fe–Mn and Cu–Fe–Cr mixed oxide catalysts for the water gas shift reaction (WGSR). The reduction kinetics of the mixed oxide catalysts is investigated using TPR data, nucleation/nuclei growth models, and a power law model. Based on the statistical indicators, it is concluded that a second-order power law model describes the reduction of all catalysts adequately. The estimated activation energy for the reduction of the Cu–Fe–Mn catalyst is low compared to the Cu–Fe–Cr catalyst. The TPR analysis of the catalysts reveals that the addition of Mn significantly improved the reducibility of Cu-oxide species, which is consistent with the low activation energy for reduction of the Cu–Fe–Mn catalyst. In a flow type reactor, the Cu–Fe–Mn catalyst showed highest CO conversion at around 220°C, achieving a high specific reaction rate compared to the Cu–Fe–Cr catalyst. The enhanced reducibility of Cu–Fe–Mn catalyst played the key role in the high conversion of CO. These results are comparable with the results obtained for a commercial Cu–ZnO/Al₂O₃ catalyst, which was evaluated under the same reaction conditions. © 2013 Canadian Society for Chemical Engineering

Activated carbon (AC) is well-known for its unique properties; hence, the search for new precursors and the investigation of new methods for the preparation of AC is still drawing attention of many researchers. In the present work, microporous AC was prepared from Aegle marmelos fruit shell (AMFS) by potassium hydroxide (KOH) activation. The effect of process parameters such as impregnation ratio, carbonisation temperature and holding time on porous characteristics was investigated. The porous characteristics of prepared AC samples were analysed by N₂ adsorption–desorption isotherms, and it was found that the isotherms obtained resemble typical microporous solids (Type-I). The Langmuir surface area and total pore volume of the sample prepared at optimum conditions were found to be 937 m²/g and 0.33 cm³/g, respectively. The contribution of micropores to the porous characteristics of the prepared AC is very much appreciable, and about 97% of the total surface area and pore volume is attained by micropores. Pore size distribution (PSD) by Dubinin–Astakhov (DA) and micro-pore (MP) methods confirmed the presence of micropores to a great extent with insignificant mesoporosity. © 2013 Canadian Society for Chemical Engineering

The present study was aimed to compare different mathematical models used to simulate process of supercritical extraction from commercially important Lamiaceae herbs. Supercritical extractions with carbon dioxide from rosemary, sage, thyme and lavender originated from the southern Balkan region were performed at 10 MPa and 40°C. Obtained extraction curves were simulated by the model based on the heat transfer analogy, Sovova's model and the model on the micro-scale. The models were used to analyse mass transfer phenomena and to quantify mass transfer parameters in the fluid and/or solid phase as well as the solubility of the solute in supercritical phase. © 2013 Canadian Society for Chemical Engineering

A three-phase bubbling fluidised bed model has been developed to simulate and predict the performance of a methane catalytic cracking fluidised bed reactor, using Ni/(porous and non-porous) Al₂O₃ catalysts, under relevant conditions. The model includes the chemistry and hydrodynamics occurring within the fluidised bed reactor. Methane cracking kinetics, developed in a previous work using a thermo balance, was used in the model. The model predictions were compared to the results from an experimental study carried out in a lab-scale fluidised bed. Good fit between experimental data and the model was obtained under a wide range of reaction conditions. © 2013 Canadian Society for Chemical Engineering

A stabilised meshless local Petrov–Galerkin (MLPG) method with unity as the test function is extended to simulate the buoyancy-driven fluid flow and heat transfer in a right-angled, triangular enclosure filled with a nanofluid composed of a mixture of Al₂O₃ spherical nanoparticles in water. A cold source with a constant temperature T_c and a hot source with a constant temperature T_h are placed along the left and bottom walls of the cavity, respectively, with a differential temperature difference between T_c and T_h so that T_h > T_c. The simulations performed in this study are based on the stream function–vorticity formulation. The moving least-squares interpolations of the field variables are employed in these MLPG numerical calculations. A streamline upwind technique is employed to obtain stable solutions for high Rayleigh numbers. A parametric study is performed, and the effects of the Rayleigh number, the locations of the cold and hot sources on the respective cavity walls, and the volume fraction of the nanoparticles on the fluid flow and heat transfer inside the cavity are investigated. The results show that the average Nusselt number is generally an increasing function of the volume fraction of the nanoparticles. Moreover, it is concluded from the results that the locations of the cold and hot sources on the respective cavity walls have a significant effect on the flow and temperature fields inside the enclosure. In general, the maximum average Nusselt number occurs when the centres of the cold and hot sources are at Y_s = 0.167 and X_s = 0.167, respectively, while the average Nusselt number is minimum for Y_s = 0.833 and X_s = 0.833. © 2013 Canadian Society for Chemical Engineering

The removal of Pb(II) ions from aqueous solution by chemically surface modified Strychnos potatorum seeds (SMSP) was investigated. The surface modification of the adsorbent was confirmed by the FTIR and SEM analyses. The Freundlich adsorption isotherm model provides a better fit to the adsorption isotherm data. The maximum adsorption capacity of SMSP for Pb(II) ions was found to be 166.67 mg/g at optimum conditions of pH 5.0, contact time of 30 min, SMSP dosage of 2 g/L and temperature of 30°C. The adsorption kinetics for Pb(II) ions removal by the SMSP follows the pseudo-second order kinetic model. Adsorption mechanism of Pb(II) ions onto the SMSP was explained with the intraparticle diffusion, Boyd kinetic and Shrinking core models (SCM). The effective diffusivity values were calculated from the Boyd kinetic model: 7.723 × 10⁻¹², 8.464 × 10⁻¹², 6.877 × 10⁻¹², 8.358 × 10⁻¹² and 6.983 × 10⁻¹² m²/s for the initial Pb(II) ions concentration from 100 to 500 mg/L, respectively. The diffusivity values were estimated from the SCM: 8.901 × 10⁻⁹, 8.586 × 10⁻⁹, 8.359 × 10⁻⁹, 5.368 × 10⁻⁹ and 4.318 × 10⁻⁹ m²/s for the initial Pb(II) ions concentration from 100 to 500 mg/L, respectively. The results suggest that SMSP can be used as an effective low-cost adsorbent for the Pb(II) ions removal. © 2013 Canadian Society for Chemical Engineering

A re-circulating fluidised bed (RCFB) reactor is proposed here for gaseous fuel combustion using chemical-looping combustion (CLC). A single RCFB reactor was operated in alternate oxidation and reduction cycles for simulating the interconnected reactors arrangement for CLC. For this, a Perspex made transparent, concentric, semicircular cold model of RCFB reactor was used with three grades of Indian Standard sand. Operational parameters like bed inventory, pressure drop, particle size, suspension density, solid circulation rate, bed voidage and fluidisation gas velocity were studied to how they affect the performance of the RCFB reactor. The solid circulation rate has been found to increase with the increase in the bed inventory. Proper solid circulation rate is very much required for proper heat and mass transfer in an interconnected fluidised bed reactors system. The bed voidage is observed to be high during the aeration cycle and low during the reduction cycle. A high bed voidage during the oxidation cycle is appropriate for the fast oxidation reaction of the metal oxides. However, a low bed voidage is required for proper heat transfer for an endothermic reduction reaction in the fuel reactor. Suspension density in the downcomer of the RCFB reactor has been found to be increasing with bed inventory for both the oxidation and reduction cycles, which is good for the bed-to-wall heat transfer. A good observed solid circulation rate, operating voidage and suspension density add to the capability of RCFB to run CLC. © 2013 Canadian Society for Chemical Engineering

This study investigates heavy water enrichment using the Frazier scheme of flat-plate thermal diffusion columns with the column number adjusted and the column heights varied at a constant ratio with the total sum of column heights fixed. The equations for predicting the best number of columns and the best column-height ratio for maximum separation are derived. Considerable improvement in performance is obtainable if the column-height ratio and/or column number in a modified Frazier scheme are properly assigned, instead of using the conventional Frazier scheme of uniform column height with the same total sum of column heights. © 2013 Canadian Society for Chemical Engineering

For binary solid mixtures, the mixture just-suspended speed is predicted with reasonable accuracy from the sum of powers to suspend the solids individually. Exceptions to this behaviour occur for mixtures of low-density solids and for mixtures involving a small, high-density solid. For these systems, summing the powers required to individually suspend the solids over-predicts the mixture just-suspended speed. Limited testing of ternary solid mixtures indicates that summing the powers required to individually suspend the solids also predicts the just-suspended speed in these more complex systems. © 2013 Canadian Society for Chemical Engineering

Oil sands coke was activated with CO₂ at 900°C in a tubular fixed bed reactor. Samples activated in a CO₂ stream with 50% air contained a significant number of functional groups. Some activated samples were post-oxidised in air at 350°C to increase their surface functionality. Post-oxidation was necessary for the adsorption of ferric cations by the coke samples activated, except for the sample activated with 50% air. However, non-oxidised samples were also able to adsorb molybdate anions. Both organic and inorganic constituents of oil sands tailings water were successfully removed, but some inorganic species leached into water. © 2012 Canadian Society for Chemical Engineering

Removal of Cr(III) from aqueous solution using Spirulina biomass was studied in a batch experiment. Spirulina biomass was characterised before and after Cr(III) sorption using FTIR, SEM and potentiometric titration. The effects of experimental parameters such as solution pH, contact time, biomass dose, initial Cr(III) concentration and temperature were studied. pH had significant influence on Cr(III) uptake capacity of biomass. The optimum equilibrium solution pH was found as 6.2. Biosorption efficiency decreased at higher temperature. A simple proton binding model was investigated for the quantitative determination of acid–base characteristics of Spirulina. The dissociation constants (pK_a) of 1.19, 2.87 and 8.07 mol L⁻¹ were estimated, which correspond to carboxylic, phosphatic and amine groups, respectively. A modified metal binding model was then tested, and Cr(III) binding constants (K_θ) of 80.9, 3.9 × 10³ and 3.5 × 10⁴ L mol⁻¹ were found for carboxylic, phosphatic and amine groups, respectively. © 2012 Canadian Society for Chemical Engineering

Oil sands coke is a byproduct of oil sands upgrading, which potentially can be used for the production of low cost activated carbons. Activation of oil sands delayed coke was performed by partial CO₂-gasification in a tubular fixed bed reactor at 900°C. Pore development during activation initially proceeded almost exclusively by micro-pore formation, and the reaction appeared to follow a shrinking core model. Surface areas up to 646 m²/g were obtained, and coarser particles reached lower maximum surface areas at lower levels of burn-off than finer particles. Pre-oxidation in air at 270°C resulted in higher maximum surface areas. © 2012 Canadian Society for Chemical Engineering

A proper knowledge of the osmotic pressure and thermodynamic behaviour of protein solutions is vital for designing an efficient protein separation process. It is also of great importance to develop a rapid and inexpensive technique to accurately estimate the protein osmotic pressure. A connectionist model to estimate the osmotic pressure of bovine serum albumin (BSA) in terms of pH, ionic strength and BSA concentration is proposed in this paper. Osmotic pressure of BSA is also modelled through the application of a colloidal interaction approach. Molecular interaction forces such as electrostatic, London–van der Waals and hydration along with entropy pressure are considered in the colloidal model to predict the BSA osmotic pressure. The advantages and disadvantages of both modelling approaches are discussed, and a hybrid modelling scheme is proposed for further investigations. © 2012 Canadian Society for Chemical Engineering

Multi-period planning models result in solutions which are feasible at the boundaries of the periods but may be infeasible within the periods. The composite algorithm presented here (i) solves coarse multi-period MILP model structure for production planning; (ii) sequences operations via a genetic algorithm to minimise switching; (iii) verifies schedule feasibility via agent-based simulation and local logical decision making; and (iv) if infeasible, re-partitions the time horizon into multi-periods and resolves from (i) until feasible. Application of the algorithm to gasoline blending illustrates its effectiveness in computing feasible plans and schedules for such systems. © 2012 Canadian Society for Chemical Engineering

As one of the key parts of discharging system in the diluted zone at the bottom of high consistency bleaching tower, the spraying water pipe would be used to dilute the pulp uniformly while it was rotating, with a range from 0 to 90 rpm. Fluid dynamics of the three kinds of spraying water pipes such as straight-shaped, spindle-shaped and waist-shaped were studied by performing computational fluid dynamics (CFD) simulations and particle image velocimetry (PIV) measurements. Simulated velocity fields were compared with experiment PIV data. The results from the simulations and experiments are in good agreement. The works show that CFD simulations using the Realisable κ–ε model combined with the MRF technique can predict the hydrodynamic characteristics in industrial scales spraying water pipes. Spindle-shaped spraying water pipe would be better finished equal consistency spraying water. © 2012 Canadian Society for Chemical Engineering

In order to purify phosphoric acid hemihydrate (H₃PO₄·0.5H₂O) crystal further, the effects of sweating time and sweating temperature on purification are investigated in a dry-sweating process. Experimental results indicate the content of Mg, As, Sb and Pb in the H₃PO₄·0.5H₂O crystal decreases with increasing sweating time and sweating temperature during sweating process and show the same tendency to decrease with time at different sweating temperatures. The purification rate coefficients of H₃PO₄·0.5H₂O crystals for Mg, As, Sb and Pb are determined. They increase with an increase in sweating temperature. The Arrhenius equation can be successfully used to describe the relationship between the purification rate coefficient and the absolute sweating temperature. The activation energy of sweating for Mg, As, Sb and Pb in the H₃PO₄·0.5H₂O crystal are calculated using these experimental data. These values for Mg, As, Sb and Pb are 130.13, 193.59, 98.51 and 102.29 kJ mol⁻¹, respectively. © 2012 Canadian Society for Chemical Engineering

Invert emulsions are used to drill for oil and gas when good wellbore stability and high temperature tolerance are required. These drilling fluids contain a solid phase and two immiscible liquid phases stabilised with a polymeric surfactant. In ultra deep drilling, due to high temperature, the surfactant degrades causing phase separation. However, fine particles can be used as stabilisers, and the result is a Pickering emulsion. Here, we demonstrate that the use of a combination of hydrophobic nanoparticles and organically modified nanoclay results in stable water-in-oil invert emulsions model drilling fluids. These gel-like model fluids have the desired plastic viscosity and yield stress suitable for drilling fluid applications that can be modified by adjusting the nanoparticle-content. Aging experiments at 225°C showed that they also have high-temperature stability for demanding drilling operations. © 2012 Canadian Society for Chemical Engineering

In Bingham plastic fluids, a central pre-yield or plug region exists in the middle of the concentric annular flow. In this region, the local shear stress is less than the dynamic yield stress, so the plug behaves like a rigid solid. This is the main feature that distinguishes the flow of a Bingham plastic fluid from that of a power law fluid. In this work, a simple-to-use correlation is developed to predict the boundaries of the plug of Bingham plastic fluids for laminar flow through annulus as a function of dimensionless yield stress and aspect ratio parameters for given values of the rheological constants, pressure gradient and the dimensions of the annulus. The results are found to be in excellent agreement with reported data in the literature with an average absolute deviation of less than 1.7%.

The predictive tool is simple and straightforward and can be readily implemented in a standard spreadsheet program. The prime application of the method is as a quick-and-easy evaluation tool in engineering studies where plug boundaries of Bingham plastic fluids for laminar flow through annulus are being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies. © 2012 Canadian Society for Chemical Engineering

Data taken with six solids at numerous Zwietering loadings ranging from near zero to 67 have been used to determine the just-suspended speed Zwietering loading exponent (N_js ∝ Xⁿ where n is the Zwietering solids loading exponent). When only the loadings range similar to that studied by Zwietering [Zwietering, Chem. Eng. Sci. 1958, 8, 244] is considered (0 < X < 18), the solids loading exponent averaged over all solids is equal to 0.12, essentially the same as the 0.13 reported by Zwietering. However, when the entire loading range is considered (0 < X ≤ 67), a higher average exponent of 0.17 is found and a single power-law correlation does not accurately describe the experimental data. A piecewise fit of the data indicates that the solids loading exponent increases from an average value of 0.097 at low solids loadings (0 < X ≤ 5) to 0.22 at intermediate loadings (5 ≤ X ≤ 25) and 0.34 for the highest loadings (25 ≤ X ≤ 67). © 2012 Canadian Society for Chemical Engineering

The thermal decomposition of pure perspex and a mixture of 50% perspex and 50% poly(ethylene terephthalate; PET) was carried out between 295 and 325°C using a thermogravimetric analyser (TGA) in air and nitrogen (N₂) atmosphere. The weight losses of decomposition products were measured during these experiments. The thermal degradation process is slower in inert atmosphere than air, where oxidation reaction expedites the decomposition process. Kinetic rate constants (k), pre-exponential factor (A) and activation energy (E) for both pure prespex and a blend of perspex/PET were calculated for both air and N₂ conditions. The thermal degradation process followed a third-order reaction in air and second-order in N₂. A second-order (n = 2) model for the pyrolytic process based on simultaneous reactions was developed using experimental data for pure and blend. The pyrolytic products are gases, liquids, waxes, aromatics and char, which can be ultimately used as raw material and fuel in various applications. It is important to note that the addition of PET to perspex was found to suppress/inhibit the decomposition of perspex compared with pure perspex. Pre-exponential factor (A) and activation energy (E) values support such an observation. © 2012 Canadian Society for Chemical Engineering

A problem of laminar film condensation from steam–gas mixtures between two coaxial cylinders is numerically analysed. A set of complete boundary layer equations is used to model simultaneous momentum, heat and mass transfer in the liquid film and the vapour–gas mixture. In order to locate accurately the liquid–mixture interface, a relevant change of coordinates is performed. Equations are solved using an implicit finite difference scheme. The liquid film thickness is determined from an iterative procedure based on the secant method. An analytical solution of the momentum equations of both phases at the end of condensation is also developed. Results presented include evolutions of field profiles and flow parameters from the inlet until the end of condensation. We also analyse the effects of the wall properties, the inlet conditions, the type of non-condensable gas, the size of the annular space and the convective cooling coefficient. © 2012 Canadian Society for Chemical Engineering

In the present work, the effect of dilute acid pretreatment was studied on the composition of liquid hydrolysate obtained after pretreatment by employing different combinations of process variables (temperature, time and acid concentration). The effect of pretreatment was also studied on subsequent enzymatic saccharification of remaining solids to obtain maximum yield of sugars. The efficiency of pretreatment was measured in terms of high-xylose and low-glucose yields, which was found most suitable at pretreatment conditions of 120°C, 120 min and 2% (v/v) acid concentration. With increased severity of pretreatment, xylose yield decreased with concomitant increase in glucose yield. The decrease in xylose yield was attributed to conversion into degradation products such as 5-hydroxylmethyl furfural (HMF) and acetic acid. The percentage of enzymatic saccharification increased with increased pretreatment severity. Saccharification of biomass pretreated at 180°C, 7 min and 0.5% (v/v) acid concentration produced the maximum glucose yield of saccharification of 352 g/kg dry matter, compared to just 97 g glucose/kg dry matter in the case of untreated biomass. The same pretreatment conditions resulted in maximum total sugar yield of pretreatment and saccharification of 459 g/kg dry matter, which was more than 67% of the total potential sugars in biomass. © 2012 Canadian Society for Chemical Engineering

This study examined the effects of aromatic cores and spacer lengths of chromophore structures on photoreactivity and mesomorphic properties of a series of azobenzene- and stilbene-based chromophores bearing electron-withdrawing (NO₂) terminal groups caused by esterification reactions. The chromophores were composed of liquid crystalline mesophases with six or 11 methylene segments as spacers and with azobenzene (NN) and stilbene (CC) aromatic cores. The target compounds were further characterised using nuclear magnetic resonance spectroscopy, differential scanning calorimetry, polarising optical microscopy, absorption and photoluminescence spectroscopies. All of the azobenzene and stilbene derivatives with six or 11 methylene segments showed enantiotropic mesophases and revealed chiral nematic phases (cholesteric, exhibiting oily streaks textures). S6 and S11 with stilbene cores showed broader phase transition temperature ranges than A6 and A11 with azobenzene cores because of the molecular interaction enhancement of the planar stilbene structure. We investigated the effects of these photochromic compounds' structures on E/Z photoisomerisation under UV irradiation. UV irradiation caused E/Z photoisomerisation at NN and CC segments of the chromophores, leading to reversible and irreversible isomerisation respectively. These synthesised chromophores with functionally photoisomerised groups might have potential application for photoinduced alignments in liquid crystal industries. © 2012 Canadian Society for Chemical Engineering

In order to improve the selectivity of the AMX membrane, a polyethyleneimine (PEI) layer was adsorbed on its surface. Ion exchange isotherms of (Cl⁻/NO), (Cl⁻/SO) and (NO/SO), using a modified AMX membrane, were established at different temperatures (from 283 to 313 K), with a constant total concentration of 0.3 mol/L and neutral pH. The results obtained with the modified membrane in this range of temperature show that chloride was the most sorbed and the selectivity order was Cl⁻ > NO > SO. Selectivity coefficients and thermodynamic equilibrium constants, determined for the three binary systems, increased with increasing temperature. These results were compared with those obtained with the unmodified membrane. It was observed that for the modified membrane, the selectivity towards sulphate ion decreased and the modified membrane became more selective towards monovalent anions. Ion exchange equilibrium at temperatures 283, 298 and 313 K of the studied binary systems were found to be endothermic processes. © 2012 Canadian Society for Chemical Engineering

The local parameters for kerosene–water upward flow are measured in a vertical pipe of 77.8 mm inner diameter at 4200 mm from the inlet (L/D = 54) using hot-film and dual optical probes. The effect of superficial water velocity and volumetric quality on radial distribution of two-phase flow parameters is investigated. The results show the following: (i) the profiles of volume fraction and drop frequency are very similar, and increasing superficial water velocity at low volumetric qualities (<18.6%) change the profile from a convex shape with peak at the pipe centreline to uniform then to concave shape with peak near the wall; (ii) the profiles of drop cut chord change from a parabolic shape with peak at centreline for low superficial water velocities to a flat shape at higher superficial water velocity, and the area-averaged drop diameter decreases with higher superficial water velocities for all volumetric qualities; (iii) velocity profiles for both phases have shapes similar to single phase flow, flatter at higher values of superficial water velocity and volumetric quality and centreline peaked at low superficial water velocities and volumetric qualities; (iv) the slip velocity decreases with radial distance having a peak at centreline and zero values near the wall; (v) introducing kerosene drops into single phase water flow results in a sharp increase in turbulent intensity, particularly at low water velocity, and the difference between the single phase and two-phase flow turbulence intensities decreases with higher superficial water velocities and (vi) the results show that interfacial area concentration increased with higher volumetric quality and higher number of bubbles thereby increases the contact area between the two phases. © 2012 Canadian Society for Chemical Engineering

This work describes the use of Co(II) and Ni(II) impregnated SBA-15 as catalysts for the oxidative degradation of a few persistent chlorinated phenols in an aqueous medium: 2-chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4,6-trichlorophenol (2,4,6-TCP). The catalysts were characterised in terms of their crystallographic features, surface topography, functional groups, thermal stability, etc. The oxidation reactions were carried out using the reaction time, concentration of chlorophenol, amount of catalyst and pH of the reaction mixture as the process variables with or without hydrogen peroxide as the chemical oxidising agent. The conversion achieved with Co/SBA-15 for 2-CP, 4-CP and 2,4,6-TCP was respectively 84.7%, 78.4% and 64.8% with H₂O₂ and 86.3%, 80.2% and 70.3% in the absence of H₂O₂. The conversion with Ni/SBA-15 also at 353 K for 2-CP, 4-CP and 2,4,6-TCP was, respectively, 82.3%, 81.9% and 64.0% at 5 h with H₂O₂ and 89.5%, 82.9% and 65.6% without H₂O₂. The reactions followed pseudo-first-order kinetics. The leachability study indicated that the catalysts release very little Co and Ni to water. Therefore, the possibility of water contamination through metal leaching was almost negligible. Oxidative degradation was confirmed by measuring the total organic carbon. © 2012 Canadian Society for Chemical Engineering

Interest is increasing in plastic compounding plants that offer tailor-made resins. Such plants produce a wide range of products in small quantities and with frequent changeovers. The underlying scheduling problem has been extensively researched; however, the concept of incorporating qualities of the finished product in the problem of plastics compounding has not been considered.

We express product qualities as an additional problem constraint so that the production schedule ensures product quality. The additional constraint makes this mixed integer nonlinear program (MINLP) problem more difficult to solve. Several case studies are solved to illustrate the utility of the proposed approach.

Experiments demonstrated that qualities of the finished product can be ensured a priori if the appropriate relations are developed and integrated in the optimisation model. As well, this paper provides insight into the economic aspects of the scheduling problem under consideration. Experiments showed that none of the cost components (operation, raw material, inventory, penalty or utilities) can alone play the role of the optimisation criterion. © 2012 Canadian Society for Chemical Engineering

The continuous catalytic regeneration (CCR) reforming process optimisation leads to nonlinear programming with nonlinear quality constraints such as octane number and coke concentration on the catalytic particles. A typical CCR reforming process consists of four reactors with recycle. The reaction patterns and reactors have been mathematically modelled on a base of 12-lumped kinetics reaction network derived from literature. The bee colony optimisation (BCO) algorithm is one of the most recent and efficient swarm intelligence-based algorithms which simulates the foraging behaviour of honey bee colonies. The performance of the BCO algorithm in the process optimisation was compared with the genetic algorithm (GA). In the present work, BCO algorithm was used for optimising the CCR reforming process. The results show that the BCO algorithm reaches a better optimum point in a lower evaluation time and higher convergence rate with respect to the GA. © 2012 Canadian Society for Chemical Engineering

In this study, the performance of a proton exchange membrane fuel cell at different channel geometries is investigated experimentally. Three PEM fuel cells with different channel geometries with 25 cm² active area and Nafion 117 as membrane with 0.004 g/cm² platinum for the anode and cathode are employed as a membrane electrode assembly. Some parameters such as input oxygen temperature , input hydrogen temperature , cell temperature (45°C ≤ T_cell ≤ 65°C), input pressure (1.905 bar ≤ P ≤ 4.905 bar), oxygen flow rate , hydrogen flow rate and geometry of channels (1 ≤ Z ≤ 3) affect the performance of the cell. A series of experiments are carried out to investigate the influence of the above parameters on the polarisation curve under the above conditions. A semi empirical equation is offered to correlate the data for the polarisation curve. The results show that when the geometry of channel is rectangular, the performance of the cell is better than the triangular and elliptical channel. Also, results show that increase in the operating temperature and pressure can enhance the cell performance and they are compared with the results of the correlated equation and a good agreement exists. © 2011 Canadian Society for Chemical Engineering

The catalytic oxidation of 2-propanol over a series of Pt/γ-Al₂O₃, Co/Pt/γ-Al₂O₃, and Cu/Pt/γ-Al₂O₃ catalysts was investigated in a fixed bed reactor under atmospheric pressure and different temperatures. Among them, Co/Pt/γ-Al₂O₃ was found to be the most promising catalyst based on activity. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ICP-AES techniques were used to characterise a series of catalysts. The influence of reaction temperature, calcination temperature, and content of metal loading on conversion efficiency was studied. Cobalt loadings on Pt/γ-Al₂O₃ had a great effect on catalytic activity and 3.74 wt.% Co/Pt/γ-Al₂O₃ bimetallic catalyst at calcination temperature of 300°C was observed to be the most active. An artificial neural networks (ANN) model was developed to predict the performance of catalytic oxidation process over bimetallic catalysts based on experimental data. Levenberg–Marquardt (LM) learning algorithm was employed to train the model by using laboratory experimental data. A comparison between the predicted results of the designed ANN model and experimental data was also conducted. ANN predicted the content of metal loading is the most effective factor. The developed model can describe the catalytic oxidation over bimetallic catalysts under different conditions.

On a étudié l'oxydation catalytique du propan-2-ol sur une série de catalyseurs Pt/γ-Al₂O₃, Co/Pt/γ-Al₂O₃ et Cu/Pt/γ-Al2O3 dans un réacteur à lit fixe sous une pression atmosphérique et différentes températures. Parmi eux, on a déterminé que le Co/Pt/γ-Al₂O₃ était le catalyseur le plus prometteur selon l'activité. La diffraction des rayons X, la microscopie électronique à balayage (MEB), la microscopie électronique à transmission (MET), la spectroscopie de photoélectrons X et les techniques de spectrométrie d'émission ICP-AES ont été utilisées pour caractériser une série de catalyseurs. On a étudié l'influence de la température de réaction, la température de calcination et la teneur en charge de métal sur le rendement de conversion. Les charges de cobalt sur le Pt/γ-Al₂O₃ ont eu un effet considérable sur l'activité catalytique et on a observé que le catalyseur bimétallique Co/Pt/γ-Al₂O₃ de 3,74% d'équivalent en poids à une température de calcination de 300°C était le plus actif. Un modèle de réseaux de neurones artificiels (RNA) a été créé dans le but de prédire le rendement du processus d'oxydation catalytique sur les catalyseurs bimétalliques fondé sur les données expérimentales. L'algorithme d'apprentissage Levenberg–Marquardt (LM) a été utilisé pour former le modèle au moyen de données expérimentales de laboratoire. On a également procédé à une comparaison entre les résultats prédits du modèle de RNA conçu et les données expérimentales. Les RNA ont prédit que la teneur en charge de métal constitue le facteur le plus efficace. Le modèle créé peut décrire l'oxydation catalytique sur les catalyseurs bimétalliques dans différentes conditions. © 2011 Canadian Society for Chemical Engineering

The following article from the Canadian Journal of Chemical Engineering, “Carbonaceous degradation of endocrine disruption chemicals (EDCs) using ozonolysis - studied with sparger effect for minimum ozone consumption” by M. S. Islam, et al., published online on February 9, 2011 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor-in-Chief, Joao B. P. Soares, and Wiley Periodicals, Inc. The retraction has been agreed because the co-authors did not approve the inclusion of their names in the article.

A ternary semicontinuous system for the separation of bio-dimethyl ether from methanol and water is presented. The performance of eight potential control configurations, including the application of temperature inferential control, is evaluated. Dynamic simulations of the semicontinuous system and associated control scheme demonstrate that the temperature inferential control configuration is effective in achieving the separation objectives while remaining within operational limits. The semicontinuous system using the inferential temperature control scheme is simulated and shown to be economically preferable to the traditional continuous process for a range of production rates. © 2013 Canadian Society for Chemical Engineering

The kinetics and equilibrium of cadmium biosorption from aqueous solutions were investigated using fresh tissues of Hydrilla verticillata. The biosorptive characteristics of cadmium ions were studied with respect to well-established effective parameters, including pH, temperature and contact time. The biosorptive capacity of H. verticillata for cadmium increased with increasing pH. In addition, the resulting isotherms were well-described by Langmuir and extended Langmuir models (R² = 0.9794–0.9957 and 0.9880, respectively). The comparison between calculated and experimental q_e values showed that the extended Langmuir model had a better simulation for the cadmium biosorption by H. verticillata than the Langmuir isotherm model. The equilibrium biosorption data at a constant temperature were well-interpreted by the Langmuir model. The maximum biosorptive capacity increased from 33.54 to 37.46 mg/g when the solution temperature was increased from 278 to 298 K. Other various thermodynamic parameters were also estimated. Biosorptive equilibrium was established within approximately 20 min. Moreover, the pseudo-second-order equation was more appropriate in predicting biosorptive capacity than the pseudo-first-order equation. In practical viewpoints, the abundant and inexpensive plant biomass H. verticillata can be used as an effective and environmentally friendly biosorbent for the detoxification of cadmium from aqueous solutions. © 2012 Canadian Society for Chemical Engineering

In this study, adsorption separation of main components of landfill gas, methane (CH₄) and carbon dioxide (CO₂) was carried out. Henry's law constants, limiting heat of adsorption values, pure and binary isotherms for CO₂ and CH₄ were determined for CaX zeolite adsorbent. Pure isotherm data were compared to those for NaX zeolite from previous studies. The CO₂ adsorption capacity of CaX was greater than that of NaX; however, NaX's separation factor was higher. The heat of adsorption for CO₂ for CaX was higher than those for NaX. © 2013 Canadian Society for Chemical Engineering

This work provides preliminary data on the effect of torrefaction on the apparent density of biomass. It also examines how the shape of wood is affected by torrefaction. Experiments conducted on cylinders of poplar wood showed that torrefaction reduced both density and volume of the wood, and the extent of reduction increased with increase in severity of torrefaction. The shape of the wood appears to have some effect on the extent of density change. The shrinkage in radial direction was 3–4%, while reduction in longitudinal direction was 6.5–8.8%. The mass yield decreased with torrefaction severity. © 2013 Canadian Society for Chemical Engineering

Rapid industrialisation and urbanisation releases numerous toxic compounds into natural water bodies, polluting these pristine fresh water resources. This is a subject of great concern, and the attention of environmentalists around the world has been increased towards this problem in recent years. Several techniques have been proposed for efficient wastewater treatment, most of them presenting some limitations, such as poor capacity, the generation of waste products, incomplete mineralisation and a high operating cost. Currently, aerobic granulation treatments are considered to be the most effective and economic alternative. Aerobic granulation is a process of microbial self-immobilisation that results into a cell-structured shape, characterised by dense biomass. Aerobic granules have a number of advantages over conventional bioflocs, such as a round and compact structure, good settling ability, high biomass retention and the ability to withstand high organic loading rates. Aerobic granulation technology has been demonstrated to be useful for a wide variety of wastewaters, including industrial, nutrient-rich and toxic. This paper presents a state-of-the-art review of effective aerobic granulation technology for wastewater treatment selected from the point-of-view of basic concepts of aerobic granulation, characterisation and factors that affect aerobic granulation, demonstrating the effectiveness of the cell-immobilisation (aerobic granulation) technique. © 2012 Canadian Society for Chemical Engineering

Liquid degassing using mono-dispersed and poly-dispersed micron droplets (148.6 and 264.8 µm) falling in an inert gas was studied experimentally and analytically in a laboratory setting. The system using poly-dispersed droplets revealed an upper degassing limit of 93% when the inert gas to liquid flow ratio was above 15 and a fog-type nozzle was used. Linear correlations of the Sherwood number to the Peclet number were derived for both systems of medium Reynolds numbers (10–100). The correlation for the mono-dispersed droplets agreed well with the steady state mass transfer correlations that are available in literature, especially at small Peclet number situations. © 2012 Canadian Society for Chemical Engineering

Activated carbon fibre is investigated for adsorption of organic pollutants from wastewater generated from refined cotton production. UV–Vis spectroscopy and FTIR are used to evaluate the chemical changes. Results indicate that the main organic components of refined cotton production wastewater are guaiacyl (G-) and hydroxyphenyl (H-) lignin. It is found that 85% of COD can be removed at 40°C with ACF dosage of 90 g L⁻¹. The adsorption process is described by the Redlich–Peterson isotherm model. The kinetic data follows a pseudo-second-order equation. Over 99% of acute toxicity for Refined Cotton Production (RCP) wastewater has been reduced after adsorption using ACF. © 2012 Canadian Society for Chemical Engineering

In this paper, an optimisation approach is proposed to increase the profit of a commercial hydrocracking unit called Isomax. To represent the system, a full-lump kinetic model incorporating the flow rate of fresh vacuum gas oil (VGO), bed temperatures, recycle flow rate and the catalyst life is developed. This model is capable of predicting the yield of all products, and it improves with respect to the previous works by considering LPG and light gases, fresh VGO and recycle streams as separate lumps. After developing and validating the model, the profit function of the plant, including the value of the products, fresh feed and hydrogen, as well as energy expenses, is optimised by manipulating the bed temperatures, flow rate of fresh VGO and combined feed ratio (CFR) whilst all process limitations and operating constraints are taken into account. During two years of study and considering all mechanical and operational constraints, the results confirm that the decision variables, generated by the optimisation package, can increase the gross profit of the Isomax process to about 8.17%, which is equal to $5.6 million of net profit annually. © 2012 Canadian Society for Chemical Engineering

A mathematical model for the dynamic performance of gas separation with high flux, asymmetric hollow fibre membranes was developed considering the permeate pressure build-up inside the fibre bore and cross flow pattern with respect to the membrane skin. The solution technique provides reliable examination of pressure and concentration profiles along the permeator length (both residue/permeate streams) with minimal effort. The proposed simulation model and scheme were validated with experimental data of gas separation from literature. The model and solution technique were applied to investigate dynamic performance of several membrane module configurations for methane recovery from biogas (landfill gas or digester gas), considering biogas as a mixture of CO₂, N₂ and CH₄. Recycle ratio plays a crucial role, and optimum recycle ratio vital for the retentate recycle to permeate and permeate recycle to feed operation was found. From the concept of two recycle operations, complexities involved in the design and operation of continuous membrane column were simplified. Membrane permselectivity required for a targeted separation to produce pipeline quality natural gas by methane-selective or nitrogen-selective membranes was calculated. © 2012 Canadian Society for Chemical Engineering

In this article, a novel internal model control (IMC) approach based on singular value decomposition (SVD) is proposed for the control of multiple-input–multiple-output (MIMO) systems with multiple time delays. This approach achieves decoupling using a compensation term and improves the robustness using SVD in the inverse of the steady-state gain matrix of process. Meanwhile, a novel filter is designed for decoupling and fast response speed of multivariable systems with multiple delays. The design of the controller can be extended to non-square systems where there are more inputs than outputs. Examples are included to illustrate the effectiveness of the method. © 2012 Canadian Society for Chemical Engineering

Supersonic nozzles have been applied in various jet-induced fluidised bed attrition processes such as jet milling and Fluid Coking. In jet-induced particle attrition, the penetration length into the bed of the jet issuing from the supersonic nozzle is a critical property that affects the attrition mechanisms. A numerical model was developed to predict the penetration length of jets issuing from a horizontal supersonic nozzle in high temperature fluidised beds, based on an Eulerian–Eulerian multiphase model and Granular kinetic theory. The predicted jet penetration lengths are in very good agreement with the experimental data and the predictions of Li's empirical correlation [Li, “Penetration of High Velocity Horizontal Gas Jets Into a Fluidized Bed at High Temperature”, in Fluidization XIII, S. D. Kim, Y. Kang, J. K. Lee, Y. C. Seo, Eds., Gyeong-ju, Korea 2010; Engineering Conferences International, Gyeong-ju, Korea 2010, pp. 893–900.]. The simulation results have also demonstrated that the fluidisation velocity and bed temperature have little influence on jet penetration length. © 2013 Canadian Society for Chemical Engineering

Imidazole and 2-chloropyridine were used as model molecules to investigate the acid hydrolysis kinetics of agrochemicals in high-temperature water in a batch reactor system at 28 MPa. Pseudo-first-order hydrolysis reaction rate constants for the acid hydrolysis of Imidazole and 2-chloropyridine were determined in the temperature ranges 200–600 and 400–575°C, respectively, at 28 MPa. Rate constants for both compounds increased with temperature with a local maximum observed at around 400°C due to changes in the physical properties of the solvent. Imidazole and 2-chloropyridine conversions of 0.95 and 0.99999 were respectively attained at the highest temperature after 30 min of reaction. © 2012 Canadian Society for Chemical Engineering

Transport of Pb²⁺ was carried from acidic solution into alkaline stripping phase through tri-n-octylamine-xylene-polypropylene supported liquid membrane. The transport of Pb²⁺ through the membrane was studied by varying the concentration of Pb²⁺ and HNO₃ in feed solution, NaOH concentration in strip solution and TOA concentration in membrane phase. The flux data obtained has been used to study the stoichiometry of complex Pb(NO₃)_n+2(HNR₃)_n. The supported liquid membrane (SLM) has been found stable for 10 runs with 24 h between each run. This SLM has been used effectively to extract lead ions along with chromium, copper and zinc ions from aqueous acidic leached solution of paint and industrial effluents. © 2012 Canadian Society for Chemical Engineering

Non-aqueous extraction of bitumen from oil sands has the potential to reduce fresh water demand of the extraction process and eliminate tailings ponds. In this study, different light hydrocarbon solvents, including aromatics, cycloalkanes, biologically derived solvents and mixtures of solvents were compared for extraction of bitumen from Alberta oil sands at room temperature and ambient pressure. The solvents are compared based on bitumen recovery, the amount of residual solvent in the extracted oil sands tailings and the content of fine solids in the extracted bitumen. The extraction experiments were carried out in a multistage process with agitation in rotary mixers and vibration sieving. The oil sands tailings were dried under ambient conditions, and their residual solvent contents were measured by a purge and trap system followed by gas chromatography. The elemental compositions of the extraction tailings were measured to calculate bitumen recovery. Supernatants from the extraction tests were centrifuged to separate and measure the contents of fine solid particles. Except for limonene and isoprene, the tested solvents showed good bitumen recoveries of around 95%. The solvent drying rates and residual solvent contents in the extracted oil sands tailings correlated to solvent vapour pressure. The contents of fine solids in the extracted bitumen (supernatant) were below 2.9% for all solvents except n-heptane-rich ones. Based on these findings, cyclohexane is the best candidate solvent for bitumen extraction, with 94.4% bitumen recovery, 5 mg of residual solvent per kilogram of extraction tailings and 1.4 wt% fine solids in the recovered bitumen. © 2012 Canadian Society for Chemical Engineering

The effect of non-mechanically induced nozzle pulsations was investigated in the current work, and it was found that appropriately tailored spray nozzles pulsations resulted in the dramatic improvement of the liquid feed spray distribution on particles of a fluidised bed. Non-mechanically induced pulsations were imposed on the liquid spray, using liquid and gas circuits that favour the development of beneficial pulsations. The resulting effect on liquid dispersion on the fluidised bed particles was determined with a conductance method. © 2013 Canadian Society for Chemical Engineering

Following a detailed analysis of the experimental data on thermodiffusion coefficients of numerous binary hydrocarbon mixtures from over 90 experiments, four new algebraic expressions are proposed. As per these formulations, the thermodiffusion coefficient of binary n-alkane mixtures can be expressed as a function of the chemical composition of the mixture and the mixture properties such as density and viscosity. Detailed experimental validation is presented using four n-alkane series containing a wide range of combinations of n-alkanes. Additionally, comparison with recently proposed neural network model and a model based on the principles of non-equilibrium thermodynamics is also presented. It has been found that the proposed algebraic models are simple in formulations, are evaluated with least computational effort and yet have a very high accuracy in predicting the thermodiffusion coefficients. © 2012 Canadian Society for Chemical Engineering

The stripper section of a fluid-coker consists of a system of baffles (sheds) that enhances the removal efficiency of entrained and adsorbed hydrocarbons from the fluidised coke-particles. If the particles contain a thin liquid film layer of heavy hydrocarbons, making them excessively ‘wet’ or ‘sticky’, and if they stay in contact with sheds for too long, solid deposits are formed that lead to stripper fouling. Extensive fouling decreases stripping efficiency and liquid product yield and can shorten run-times between shutdowns. Because of the fouling, the shape of sheds mostly changes by increasing their surfaces thickness. An early indication of that fouling and the ability to follow its development are essential for choosing optimal parameters of the process. The radioactive particle tracking (RPT) method has been tested to determine its applicability to indicate the change in the shape of internals within a fluidised bed reactor when direct observation is impossible. A single radioactive tracer-particle has been traced in experiments lasting from 2 to 6 h. The experiments were conducted in a lab-scale, cold-flow fluidised bed into which a single shed with walls of different thickness was incorporated. This experimental fluidised bed provides intensive solid phase mixing that allows a single tracer-particle to be located in any place within the reactor. By registering the frequency of the tracer-particle appearance within a defined internal space surrounding the shed, the shape of shed was reconstructed. The conducted experiments suggest that RPT technique allows for tracking internals' fouling within a fluidised bed reactor. © 2012 Canadian Society for Chemical Engineering

Accurate value determination of natural gas viscosity plays a key role in its management as it is one of the most important parameters in natural gas engineering calculations. In this study, a comprehensive model is suggested for prediction of natural gas viscosity in a wide range of pressures, temperatures, densities and compositions. The new model can be applicable for gases containing heptane plus and non-hydrocarbon components. It is validated by the 2011 viscosity data from 18 different gas mixtures. Compared to existing similar models and correlations, its results are quite satisfactory. © 2012 Canadian Society for Chemical Engineering

Mass transfer in the continuous phase around a small eccentricity prolate spheroidal drop in an axisymmetric extensional creeping flow and at large Peclet numbers was investigated theoretically. The results show that, at very short times, the total quantity of solute transferred to or from the drop represents, at O(Ca¹), mass transfer by diffusion only around a sphere. For long times, or at steady-state, the total quantity of solute transferred is, at O(Ca¹), slightly smaller than that of a spherical drop, and it decreases with an increase of the capillary number or the viscosity ratio. © 2012 Canadian Society for Chemical Engineering