Chemical Engineering & Technology

Modeling a packed-bed reactor in one dimension using the assumption of pseudo-homogeneity requires the application of an effective conductivity correlation. Available literature models are summarized for this parameter while describing a methodology to generate chemical kinetic results based only on chemical constituents and not reactor design.

Oleylamine ethoxylate is examined as a substitute for the surfactant perfluorooctane sulfonate in decorative chromium plating. Mist suppression and plating quality are retained, but oleylamine ethoxylate is degraded and must be replenished. It also leads to increased corrosion of the Pb anodes. The influence of the plating bath components was examined and some of the degradation products were identified.

The influence of emulsifiers in high-pressure homog-enization as an emulsification technique and for the production of solid lipid nanoparticles is described exemplarily for Polysorbate 20 and sodium caseinate. For the emulsification process, Polysorbate 20 was found to be better suited whereas in crystallization sodium caseinate was more advantageous.

For calculation of forces and stresses in bulk cargos by the discrete elements method, a new mode for calibration of the simulation parameters is developed. By significant simplifications of the parameters and the calibration it is even possible to apply this method to simulate the processes in large bulk cargo silos with several millions of particles.

The effect of various technological parameters on glycerol hydrogenolysis to 1,2-propanediol over a Cu/Al₂O₃ catalyst prepared by coprecipitation was determined. Temperature, amount of catalyst, and reaction time influenced the process most significantly. A catalyst recycle study indicates that the Cu/Al₂O₃ catalyst loses its activity gradually.

In order to reduce salt concentrations in wastewater streams for recycling purposes, reverse osmosis is applied as an interception separation technology. Options for reducing wastewater volumes by regeneration and recycling routes in the pulp and paper industry are evaluated. A preliminary cost estimate provides economic incentives by installation of reverse osmosis units.

The influence of conventional stabilizers and buffers on the solubility of three nonsteroidal anti-inflammatory drugs (NSAIDs) and phytosterol in aqueous solutions is analyzed and discussed. These experimental data are crucial for e.g. solubilization processes which can be applied to overcome the poor solubility of drugs in aqueous media.

The oxidative desulfurization process of fuels using ionic liquids (ILs) was studied. Lewis acidic ILs acted as both extractant and catalyst in the removal of dibenzothio-phene and benzothiophene with 30 wt % hydrogen peroxide aqueous solution as oxidant. The effects of different reaction parameters such as Lewis acidity, cation structure, and reaction temperature on the sulfur removal were investigated.

The effect of two sizes of glass beads on micromixing has been investigated using the competitive iodide/iodate reaction system. Different feeding locations and its relation with the total energy dissipation have been explored. Experimental results showed that the presence of the particles could have a negative effect on micromixing. Also, distributed feeding of reactants is beneficial to the overall selectivity towards the desired products.

Since the atomization effect of spray nozzles plays a key role in wet flue gas desulfurization processes, an innovative gas-around-liquid spray nozzle was designed. The two-phase flow fluid field in this nozzle was simulated numerically and the flow characteristics were determined with different structural parameters to find the optimum conditions.

Liquefaction of cornstalk in sub-/supercritical cyclohexane catalyzed by a zeolite was investigated. The reaction system was divided into four fractions: lumps gas, water-soluble fraction, ethanol-soluble fraction, and residue. The effects of different reaction parameters on the lump yields were studied and the main secondary reaction pathways of bio-oil generation are proposed.

Regeneration of fibrous filter media by backflushing is a challenging task. Generally, reliance on hydrodynamic properties of the fluid action is reported as the mechanism of action. This postulate could be experimentally proven for the case of an engine lube oil filtration task. More so, superposed ultrasonification could be shown as a means to enhance the hydrodynamic backflushing effect.

Computational fluid dynamics-based models were applied to consider the effect of cavitation on fuel atomization in nozzles of different length-to-width ratios. The results indicated that cavitation has a strong impact on fuel injection and spray quality, i.e., cavitation generated in the nozzle enhances the fuel atomization characteristics.

A group contribution method based on UNIFAC groups was developed to estimate the vapor pressures of pure hydrocarbons at reduced temperatures. Experimental vapor pressures for 456 hydrocarbons were collected and used to calculate model parameters. Model finding showed that taking both the molecular structure and the Gibbs free energy into account significantly decreases the prediction error.

Processes based on the use of black-light radiation and ozone were applied to a mixture of nine emerging contaminants in water. The influence of municipal wastewater was investigated at different initial contam-inants concentration. A TiO₂-coated activated carbon was lab-prepared and evaluated in photo-catalytic tests. The theoretical contaminants' evolution was simulated in different aqueous matrixes for ozonation experiments.

Conceptual combination of a theoretical kinetic model with a set of experimental data, which were designed by the response surface method, enabled a semi-empirical kinetic model for reactive absorption of CO₂ with NaOH in a laboratory-scale spray-dryer absorber. Optimum operating conditions for maximum absorption efficiency were determined.

Modeling and numerical simulation of membrane-based solvent extraction by computational fluid dynamics of mass transfer for removal of priority organic pollutants from wastewaters by membrane contactors are established and performed. A comprehensive mathematical model is developed to predict the transport of pollutants through nanoporous media.

The effect of operating variables on the oxygen mass transfer process was tested in a pilot plant using a membrane diffuser as intensive gas-liquid contactor. Tests simulated the conditions of biofiltration of H₂S at high loads for biogas sweetening. Interesting effects were observed with higher solution ion concentration and additional nonliquid phase.

The performance of pressure swing adsorption (PSA), membrane separation, and gas absorption systems for hydrogen recovery from refinery off-gas streams was investigated by simulation-based data. The membrane process enables high recoveries and high purity simultaneously unlike the PSA process and higher hydrogen recovery compared to the other processes.