Phosphate uptake studies on different types of lanthanum-loaded polymeric materials



Three different polymeric materials loaded with La(III) were prepared such as La(III)-loaded silica-chitosan composite (LSCC), an inorganic-organic hybrid material; La(III)-loaded cross-linked chitosan beads (LCB), a biopolymer; La(III)-loaded Duolite C 466 (LDR), a commercially available styrene divinyl benzene co polymer with imino diacetic acid and the adsorption behavior of phosphate on these three adsorbents were investigated in batch mode. The effects of contact time, temperature of solution, adsorbent dosage, initial pH of solutions, and coexistent anions were analyzed. The adsorption capacities of LSCC, LCB, and LDR from 1000 mg L−1 of phosphate solution were 155.4, 84.2, and 74.2 mg/g, respectively. Regenerations of the LSCC, LCB, and LDR were carried out with 0.25 M NaOH solution. All the three adsorbents were selective toward the phosphate ion in the presence of common ions like Cl, NO3, SO42−, and HCO3 present in natural water. The Freundlich isotherm model seems to be a better fit than the Langmuir and Dubinin-Radushkevich isotherm models. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated in order to understand the nature of adsorption process. The adsorption kinetics data were best described by the pseudo-second-order rate equation. The adsorbents were characterized using SEM with EDX, FTIR and BET surface area. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 146–154, 2015