Adsorption Equilibrium of Selenium Oxyanions Using FeY Mixed Oxides

Selenium oxyanions (Se(IV) and Se(VI)) in wastewater are of concern as serious pollutants due to their easy bioaccumulation and toxicity to living organisms.In this study, mixed oxides with various Y/Fe molar composition ratios (x=0.5, 1, 2) were investigated in the adsorption properties of selenium oxyanions, and were studied their adsorption mechanism.The experimental data best fits the Langmuir adsorption model, which is characteristic of monolayer adsorption (r 2 >0.991).The maximum adsorption capacity (qmax) of Se(IV) and Se(VI) increased in the order of FeY2 > FeY1 > FeY0.5 and of Fe2 > FeY1, respectively.It was suggested that FeY2 adsorbed Se(IV) by formation of inner-sphere complexes and outer-sphere complexes, and adsorbed Se(VI) by outer-sphere complexes.