Nitrate sorption by thermally activated Mg/Al chloride hydrotalcite-like compound

A laboratory study was conducted to investigate the ability of Mg-Al-Cl hydrotalcite-like compound for the removal of nitrate from synthetic nitrate solution. In the present study Mg-Al-Cl hydrotalcite was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To know the practical applicability, a detailed removal study of nitrate ion was carried out. The removal of nitrate was 87.6% under neutral condition, using 0.3 g of adsorbent in 100 mL of nitrate solution having initial concentration of 10 mg/L Adsorption kinetic study revealed that the adsorption process followed first-order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R-2 (correlation coefficient)> 0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm. The percentage removal was found to decrease gradually with increase in pH and the optimum pH was found to be 6. The process was rapid and equilibrium was established within first 40 min. (C) 2009 Elsevier B.V. All rights reserved.