Calcined Mg–Al Layered Double Hydroxides for Uptake of Trace Levels of Bromate from Aqueous Solution

Abstract

Layered double hydroxides of Mg and Al (Mg–Al LDH) were synthesized with OH–, Cl–, or CO32– as charge compensating anions. The materials were calcined at 500 °C in air. The bromate uptakes of calcined and uncalcined LDH materials were investigated from 0.78 μmol/dm3 bromate solution. Results show that uncalcined LDH exhibited no bromate uptake, although calcined LDH exhibited bromate uptake: the initial bromate concentration of 0.78 μmol/dm3 decreased to less than 0.078 μmol/dm3, the maximum contaminant level established for bromate in drinking water. The rate of bromate uptake of calcined LDH was slow to attain equilibrium in 48 h. The bromate uptake data of calcined LDH agreed well with the Freundlich model.