Adsorptive Removal of Manganese from Water Intended for Consumption by Use of Cost-effective Gisenyi Volcanic Rocks

This study determined the capacity of Gisenyi volcanic rocks (GVR) located in Rwanda (Nothern Province) to remove manganese from groundwater. Various experimental conditions such as adsorbent dosage and contact time were investigated. The dosage of GVR has shown to be a highly influencing factor in manganese removal from groundwater. The adsorption proceeded via a fast initial metal removal followed by a slow uptake during the first 6 h and equilibrium after 24 h. For the initial manganese concentration of 1.5 mg/L, the removal efficiency varied from 42.5–72.9% for 4g/l and 20g/l of VGR dosage respectively. The Freundlich and Languimur isotherm constants indicated that the adsorption of Mn 2+ on GVR is a physical process and favorable. The pseudo-first-order and pseudo-second-order kinetic models also show that the adsorption of Mn 2+ onto GVR is a physical process.