Perchlorate Uptake from Aqueous Solutions by Calcined Mg-Al Layered Double Hydroxides

The calcined layered double hydroxides (CLDHs) with 3:1 Mg/Al molar ratio were observed to acquire a high removal efficiency of perchlorate. And they were applied into perchlorate adsorption process with the initial 100 mg/L perchlorate solution in order to analyze removal efficiencies of perchlorate on various influential factors. The results represented that 1.5 g/L CLDHs could achieve ideal adsorption efficiencies of perchlorate at the pH range of 7-9 and at the temperature of 25 degrees C. The removal efficiencies of perchlorate increased up to a maximum efficiency with the increasing dose of CLDHs. Acidic or highly alkaline environment adversely affected perchlorate adsorption. The adsorption process was found to be endothermic due to the higher adsorption capacity in CLDHs with the increasing temperature. The removal of perchlorate was best represented by the pseudo second-order kinetics model and Langmuir isotherm model. Co-existing anions tests showed that the anions of higher valence had a more significant effect than the monovalent anions during the adsorption process. Finally, the adsorption process was further validated by the X-ray patterns and Fourier-transform Infrared spectra of CLDHs. Results demonstrated potential utility of CLDHs that could be developed into a viable technology for perchlorate removal from water.