Removal of sulphates from acid mine drainage using desilicated fly ash slag

Abstract

The removal of sulphates from acid mine drainage (AMD) using desilicated fly ash (DFA) was investigated. The effects of DFA solid loading, residence time and removal temperature were investigated. A 2% DFA solid loading gave the highest sulphate removal of 75% at a temperature and residence time of 35ºC and 90 min respectively. The maximum adsorption capacity for DFA was found to be 147.06 mg/g DFA. The sorption mechanism followed the Langmuir isotherm and pseudo second order kinetics. The Gibbs free energy and enthalpy for the sorption was found to be 17.26 and 125.096 J/mol respectively. This research showed that DFA was an attractive alternative adsorbent for sulphates in AMD.