Removal of arsenic from groundwater in Tanzania using locally available magnesite

Abstract

Arsenic removal study was carried at laboratory level through batch experiment to investigate efficient of raw magnesite from Tanzania on arsenic removal. Parameters such as initial concentration, dosage, contact time and pH were investigated. Adsorption efficient was high about 98% when high dose magnesite was used. Optimization of magnesite through calcination at 500°C increases surface area for about 4 times of the raw magnesite and adsorption was increased to 99% at 20 minutes contact time at higher doses. The kinetic adsorption fitted the pseudo second order on raw and calcined magnesite with R2 0.99 and 1 respectively. Adsorption isotherm fitted strongly with Freundlich isotherm with R2 0.98, n of 1.8. Application of calcined magnesite on real water from Masinki stream, Tanzania shows arsenic reduction from 117 µg/L AsV and 5.32 µg/L AsIII to below 0.1 µg/L. The high dose of 10 g magnesite removes arsenic up to 10 mg/L in a short time of 10 min.