The removal of zinc (Zn2+) from synthetic wastewater was investigated by adsorption method using three types of ashes resulted from burning industrial wastes, i.e. rice husk ash (RHA), palm oil fuel ash (PFA) and coal fly ash (CFA). In this research, sol-gel method was used in the preparation of RHA/PFA/CFA sorbent. Batch studies were performed to evaluate the effect of various experimental parameters, i.e. amount of sorbent, contact time, shaking rate, and pH. The optimum conditions for Zn2+ removal were obtained at sorbent amount of 1 g, contact time of 1 h, shaking rate of 100 rpm, and pH 8. From surface analysis of selected RHA/PFA/CFA sorbents, it was found that the surface of the sorbent after treated with Zn2+ had more compact structures covered by lumps of smaller particles with tetrahedron and/or octahedron-like structures. In addition, lower specific surface area was obtained for RHA/PFA/CFA sorbent after treated with Zn2+. This study showed that RHA, PFA and CFA could be combined and used as an effective sorbent for the removal of Zn2+ from synthetic wastewater and this has never been reported in the literature.
Zinc (Zn2+), Rice husk ash (RHA), Palm oil fuel ash (PFA), Coal fly ash (CFA) Adsorption, Sol-gel