Calcined Mg–Fe–CO3 LDH as an adsorbent for the removal of selenite

Abstract: Mg–Fe–CO3 layered double hydroxide (LDH) with a Mg/Fe molar ratio of 2.0 was synthesized by co-precipitation method and its calcined product (CLDH) was obtained by heating Mg/Fe-LDH at 500 °C. Sorption of SeO2− 3 on CLDHs was studied and the results indicate that the sorption capacity of CLDHs was higher than that of uncalcined LDHs. Isotherms for SeO2− 3 sorption by CLDHs were well described using the Freundlich and Langmuir equations. The thermodynamic parameters, viz. , , were calculated to predict the nature of adsorption. The negative and positive values of and indicate that the adsorption process is spontaneous and endothermic in nature, respectively. The adsorption process followed first-order kinetics. [Copyright &y& Elsevier]