Adsorption of copper, nickel and chromium ions using silica aerogel synthesized by ambient-pressure drying and modified with EDTA

Abstract

Adsorption of heavy metal ions was studied widely since it is one of the promising methods for treating wastewater. Silica aerogel was selected as an adsorbent in this study because it was easy to modify surface. Although most of aerogels were synthesized by supercritical drying, the silica aerogel in this work was dried at atmospheric pressure which safer. It was modified further with APTES (Aminopropyltriethoxysilane) and EDTA (Ethylenediaminetetraacetic acid) to increase adsorption capacity. The modified silica aerogels were used to adsorb copper, nickel and chromium ions from aqueous solution. It was found that efficiency of heavy metal removal in case of EDTA modified silica aerogel was better than those of APTES modified silica aerogel and unmodified adsorbent. The adsorption data agreed well with Langmuir isotherm model than Freundlich isotherm model. The maximum adsorption capacities of copper, nickel and chromium on EDTA modified silica aerogel were found to be 94.34, 84.75 and 169.49 mg/g, respectively.