Laterite, Sandstone and Shale as Adsorbents for the Removal of Arsenic from Water

This study aims at exploring arsenite (As (III)) removal from water using naturally available rocks (laterite, sandstone and shale) in Cote d’Ivoire. The study focused on the adsorbent dose, operating pH, contact time, initial arsenite concentration, and modelisation on the removal of arsenite by performing batch adsorption experiment with well water. The optimal dosage related to an initial As (III) concentration of 5 mg/L was about 50, 75 and 145 g/L for laterite, sandstone and shale respectively. Laterite has a better adsorption capacity in comparison to sandstone and shale. On the other hand, kinetic study reveals that the equilibrium times are 5 h for laterite, 3 h for sandstone and 8 h for shale. Results showed that laterite, sandstone and shale could remove the arsenic in groundwater at initial arsenic concentrations below 5 mg/L, satisfying the World Health Organization (WHO) standard for drinking water. Moreover, kinetics study showed that the overall adsorption rate of arsenite was described by the pseudo-second-order kinetic model.