Adsorption of sulfate from natural water on calcined Mg–Fe layered double hydroxides

The calcined Mg–Fe layered double hydroxides (Mg–Fe–CLDHs) with the Mg–Fe molar ratio of 3 were used as adsorbents to remove sulfate in natural water. The Mg–Fe–CLDHs were synthesized by the co-precipitation method. The influences of initial adsorbent concentration, temperature, and pH on the adsorption of sulfate on Mg–Fe–CLDHs were evaluated. Three kinetic models and two isotherms were used to fit the experimental data, and it was found that the pseudo-second order kinetics model and Langmuir isotherm model could be used to describe the uptake process appropriately. Characteristics of the adsorbents and adsorption mechanism were analyzed by XRD, FT-IR, BET, TG-DSC, and SEM.