Metal removal from industrial waste by hydrochloric acid

Abstract

Leaching of metals from industrial solid waste in hydrochloric acid, HCl solution was studied. In this study, the significant of parameters such as HCl concentration, temperature, liquid to solid ratio and leaching time on the removal percentage of metal impurities were investigated using response surface methodology (RSM) with central composite design (CCD). The ANOVA study concluded that the quadratic model was fitted well to the 27 experimental runs based on p-value (<0.0001), R2 (0.9876) and Adj-R2 (0.9731). This study also revealed that the liquid to solid ratio was the most significant factor for the leaching of metal impurities compared to HCl concentration for this specific industrial solid waste. However, temperature and leaching time showed no significant impact on the leaching rate of metal impurities. Under suitable conditions, a high removal percentage of metal (88 %) was readily achieved at condition of 6 M HCl at 70 °C with liquid to solid ratio of 10 over a leaching period of 70 mins.