Abstract
Hydroxyethylcellulose succinate (HEC-Suc) was utilized for the removal of As(III) and As(V) from aqueous solution. HEC-Suc was characterized by FTIR and scanning electron microscope-energy dispersive spectroscopic analysis (SEM-EDS) before and after arsenic uptake. Effect of initial arsenic concentration, sorbent dose, pH, contact time and temperature on the uptake of arsenic was studied. Isothermal equilibrium sorption data were subjected to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models which provided better fit suggesting monolayer formation on the sorbent surface. The maximum sorption capacity was 151.5 and 204.10 mg(-1) for As(III) and As(V), respectively, as calculated by Langmuir model. Values of mean sorption energy (E) calculated by D-R model suggested that chemisorption appeared to be the mechanism of removal of both As(III) and As(V). Negative values for thermodynamic parameters (Delta G degrees and Delta H degrees) revealed the feasible, spontaneous and exothermic nature of sorption process. Contact time experiment data were subjected to pseudo-second order, pseudo-first order, intraparticle diffusion and Elovich models. Pseudo-second order model provided the best fit to the experimental data. HEC-Suc appeared an efficient and super-sorbent in removing As(III) and As(V) from aqueous solution as compared with other sorbents already used for the removal of arsenic. Regeneration studies were also carried out.