The utilization of hydroxylsodalite synthesized from coal fly ash for zinc removal in acid mine drainage

Abstract

One of the alternative solution to reduce ash waste in landfills is by utilizing coal fly ash for the removal of metal ion in wastewater, especially acid mine drainage (AMD). In this study, zeolite was synthesized from coal fly ash using a two-step method, hydrothermal and fusion method. The coal fly ash and the zeolite product were characterized physically and were used for the removal of Zn2+ in AMD. The adsorption experiment was carried out using batch method in synthetic AMD solution to study the influential parameters such as adsorbent dosage, contact time, adsorbent isotherms and kinetics. The zeolite synthesized in this study resulting hydroxylsodalite zeolite type, which increases the surface area. It was revealed from the adsorption experiment that the removal efficiency of Zn2+ was 93.47% under the conditions of pH ± 3, initial concentration Zn2+ 100 ppm, optimum contact time 120 minutes, and adsorbent dose 6 g/L. Furthermore, the Langmuir isotherm model and the kinetics model of pseudo-second-order fitted the adsorption data better, with the maximum sorption capacity of 27.32 mg/g. The result of this study indicate hydroxylsodalite synthesized from coal fly ash has great potential as an economical and sustainable material for the removal of metal ion Zn2+ in wastewater.