Evaluation of Iron and Manganese-coated Pumice from Sungai Pasak, West Sumatera, Indonesia for the Removal of Fe (II) and Mn (II) from Aqueous Solutions

The objective of this study was to evaluate the performances of iron and manganese-coated pumice from Sungai Pasak, West Sumatera, Indonesia as the adsorbents for removal of Fe (II) and Mn (II) from aqueous solutions. The effect of soaking time for iron and manganese coating was evaluated and as comparison, the adsorption of Fe (II) and Mn (II) using uncoated pumice was conducted. The experiments were performed in batch mode at room temperature (20-25̊C), pH 7; 10 g/L of adsorbent dose; 0.30-0.50 mm of adsorbent diameters; 100 rpm of agitation speed and 90 minutes of contact time. In addition, the desorption process of Fe (II) and Mn (II) from the three kinds of adsorbent was also investigated. The results showed that the optimum soaking time for iron and manganese coating for removal of Fe (II) and Mn (II) were 100 and 48 hours, respectively. Iron-coated pumice showed to have high removal efficiencies of two ions compared to uncoated and manganese-coated pumice. More than 84% of Fe(II) and 72% of Mn(II) with initial concentration of 15 and 5 mg/L, respectively, were removed by 10 g/L iron-coated pumice, while by using uncoated and manganese-coated pumice, the removal efficiencies were less than 75% for the two ions. The desorption study noticed that up to 20% of Fe (II) and 100% of Mn (II) were recovered from the three kinds of pumice adsorbent. Overall study indicated that pumice from Sungai Pasak may be a promising adsorbent for iron and manganese removal from water and wastewater.