Abstract
Cross-linked branched polyethylenimine (CPEI) was sulfonated by reaction with 3-chloropropanesulfonyl chloride. The functionalized polymer was used as an adsorbent for the removal of SeO32− from aqueous solutions, particularly mining wastewaters. The binding affinity of the synthesized polymer to abstract SeO32– from synthetic solutions and wastewater samples has been assessed as well as its ability to be regenerated for reuse. The process demonstrated that sulfonated cross-linked polyethylenimine (SCPEI) exhibited good affinity to SeO32– with removal efficiency up to 81%. The kinetic rates were modeled using pseudo first-order and pseudo second-order equations. The pseudo second-order equation was found to explain the adsorption kinetics most effectively implying chemisorption. The Langmuir and Freundlich isotherms were used to interpret the adsorption of SeO32– onto the modified polymer. The Freundlich isotherm was found to best fit and describe the experimental data. The thermodynamic study of the adsorption process revealed high activation energies >41 kJ mole−1 which confirm chemisorption as a mechanism of interaction between the adsorbate (SeO32−) and adsorbent (SCPEI).