Removal of Trace Elements from Aqueous System: Comparison of Two Fly Ash Materials

Abstract

A comparative study was initiated to assess the feasibility of using fly ash FA for the removal of selected trace elements from wastewater and industrial effluents. The specific objectives of this study were to (i) determine the feasibility of using FA to remove Zn, Cu, Cd, Cr, Pb, and Mn from aqueous medium by using mixed trace element solution and (ii) to identify the optimum conditions for the maximum removal of Zn, Cu, Cd, Cr, Pb, and Mn by FA from mixed trace element solution. Two FA materials with contrasting characteristics from a coal-fired power plant in Port Wentworth PWW-FA, and McIntosh McInt-FA in Savannah, GA were used in this study. Results of this study indicated that both FA materials were very efficient (∼100%) in removing most of the elements studied when 5 mg L−1 mixed trace element solution was equilibrated with 200 g L−1 FA material for 8 hours. However, when the concentrations of mixed elements were increased up to 25 mg L−1, PWW-FA was very efficient in removing about 100% of Cr, and Pb and about 45% of Cu at 8 h contact time from aqueous medium. Similar increasing trend was observed only for Pb with 60% removal but not for Cr and Cu with adsorbent McInt-FA. Results also indicated that FA material with greater carbon content depicted greater removal of trace elements from aqueous solution containing mixture of trace elements. This study suggests that FA could be successfully used as an adsorbent to remove wide variety of trace elements, which are commonly found in contaminated aquatic habitats.