Modification of natural pumice by physical and chemical treatments for removal of zinc ions from aqueous solution

To increase the adsorption capability of natural pumice from Sungai Pasak, West Sumatra, Indonesia in removal of Zn from aqueous solution, modification by physical and chemical treatments were evaluated. The treatments were heating at temperatures of 300°C, 450°C, and 600°C for physical and soaking in acid solutions (HCl, H2SO4, and HNO3) for chemical treatments. The adsorption was performed in batch system with the optimum condition (6 of pH solution, < 63 um of adsorbent diameter, 3 g/L of adsorbent dose, 5 mg/L of Zn concentration, and 15 min of contact time). The results revealed that the removal efficiency and Zn uptake increase using modified pumice from 68.83% and 1.15 mg/g to 74.46% and 1.24 mg/g. The highest removal efficiency and Zn uptake were obtained from 300°C of heating temperatures and HCl for acid solution. The application of modified adsorbent for removal of Zn from aqueous solution showed that the modification technique has the potential to increase the removal efficiency and metal uptake of the natural pumice.