Potential of high quality limestone as adsorbent for iron and manganese removal in groundwater

Abstract

Adsorption using low cost of media plays more attention to this current research. Previous literature found that high quality of limestone was effective in removing heavy metals in water and wastewater. In this study, the potential use of limestone media was investigated. Groundwater sample and limestone properties were characterized to determine the physical and chemical composition. The batch experiments were conducted to determine the effect of varied dosage and contact time. Analysis on isotherm and kinetic was carried out in this study. Batch study results showed that the maximum removal of both Fe and Mn was greater than 95 and 80% respectively which occurs at optimum dosage of 40g. Moreover, the optimum contact time of Fe and Mn was 90 and 120 minutes, respectively. At the optimum contact time, 96.8% of Fe and 87.4 % of Mn was removed using limestone adsorbent media. In isotherm study, the result revealed that Langmuir isotherm fitted the experimental data better than Freundlich isotherm for both Fe and Mn adsorption. In Langmuir isotherm, the maximum adsorption capacity for both Fe and Mn were 0.018mg/g and 0.011mg/g. Based on kinetic study, the removal of Fe and Mn followed the pseudo-second order kinetic model which R2 (>0.99) greater than in pseudo-first order. This indicates that the chemisorption is the mechanism of adsorption, which contributed to the Fe and Mn removal from the groundwater sample. Thus, from these results, limestone could be used as an alternative for the removal of Fe and Mn from groundwater.