Arsenic removal from water using calcined Mg–Al layered double hydroxide

Arsenic (As) in drinking water and its related toxicology are serious concerns nowadays. Development of better techniques related to removal of As from drinking water is an urgent need. Layered double hydroxide (LDH) or hydrotalcite-like compound with the general formula [M 1− x 2+ M x 3+ (OH) 2 ] x + A x − · n H 2 O can be considered as a good adsorbent for the removal of toxic As from water. Due to large surface area and high anion exchange capacity of LDH, the compound may be a good adsorbent for the removal of As from contaminated water. In this study, the removal of As in aqueous solution by adsorption method based on the calcination–rehydration reaction was investigated in batch experiment at (30 ± 1)°C. Results showed the removal of 99.99% As from a solution of 0.1 ppm of As; the adsorbent required at saturation was 0.10 g/20 ml As solution with 90 min of exposure at (30 ± 1)°C. Factors like pH, adsorbent dose and shaking time influenced the rate of As removal. Experiment showed that the adsorption process follows the Freundlich-type adsorption isotherm. The explanation of adsorption phenomenon is supported by X-ray diffraction pattern.