Removal of vanadate anion by calcined Mg/Al-CO3 layered double hydroxide in aqueous solution

Mg/Al-CO3 layered double hydroxide (LDH2) with Mg(II): Al(III) molar ratio of 2:1 was synthesized by co-precipitation method and its calcined product Mg2Al-CLDH(CLDH2) was prepared by heating Mg2Al-LDH at 773 K for 6 h. Removal of vanadate anion (VO43−) from aqueous solution on CLDH2 was studied. Batch studies were carried out to address various experimental parameters such as Mg/Al molar ratio, adsorbent dosage, initial concentration of solution, contact time and temperature. Vanadate was removed effectively at the optimized experimental conditions. The adsorption kinetics data fitted the pseudo-first-order model. Isotherms for adsorption vanadate by CLDH2 at different solution temperatures were well described using the Langmuir and Freundlich equations, and the isotherm parameters were calculated using linear regression analysis. The adsorption data fitted the langmuir model with good values of the correlation coefficient (R2>0.999). The negative value of ΔGΘ and the positive value of ΔHΘ indicate that the adsorption processes are spontaneous endothermic in nature. The mechanism of adsorption suggests that the surface adsorption is the main process.