Boron removal by hydrotalcite-like, carbonate-free Mg-Al-NO73-LDH and a rationale on the mechanism

Removal of boron from boric acid and tetraborate solutions by hydrotalcite (HT)-like, carbonate-free, Mg-Al-NO3-layered double hydroxide (LDH) was studied. Data from batch experiments were computed as a function of the adsorbent dose and contact time. Synthesis in CO2-free conditions provided a material with high anion exchange capacity and more than 95% adsorption could be achieved. The physical and structural properties of the material before and after boron adsorption were investigated to describe the uptake mechanism. Interpretation of the results of d-spacing, surface area and zeta potential measurements indicated an anion exchange mechanism rather than surface adsorption. Calcination at 400 degrees C did not make any significant change in the removal process. (C) 2006 Elsevier Inc. All rights reserved.