The contamination of arsenic groundwater is the most serious global concern and responsibility for the death rate per year. Complete removal of arsenic through the conventional method is very difficult and cost consuming. We have synthesized the starch thiomer, sulfonium starch and iron immobilized starch derivatives for the removal of As (III) and As (V) from the aqueous system. The batch experiments were performed as a function of initial As (III) and As (V) concentrations, contact time and pH values. The results supported a little preferential sorption for As (V) (95%) in comparison to As (III) (92%) via thiomer, while sulfonium structure showed similar affinity for As (III) and As (V) sorption (92.7% for As (III) and 93% for As (V)) at pH 5.0. The present study also supported that synthesized thiomer and sulfonium structure are selective to arsenic and only marginal effect has been observed with competitive anions except for phosphate. The SEM-EDX studies confirmed the arsenic sorption mechanism of synthesized starch derivatives. Isotherm studies indicated that the Langmuir model is preferential, while in kinetics pseudo-second-order kinetic model is superior in describing the adsorption process for As (III) and As (V) adsorption through synthesized starch derivatives. The results of arsenic equilibrium adsorption at 35°C showed the endothermic nature of As (III) adsorption indicated by the positive ΔH° value support the result that As (III) adsorption decreased with temperature. The temperature effect on the intrinsic kinetics of As (V) adsorption for the present adsorbent is likely to surpass the endothermic effect on the adsorption reaction. Therefore, it is recommended that the excellent adsorption for As (III) and As (V) by thiomer and sulfonium structure would be a better solution and can be explored for commercialization in arsenic contaminated water for arsenic removal.
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