Adsorption of arsenite (As 3+) on nano-sized Fe 2O 3 waste powder from the steel industry

Abstract

An attempt has been made to utilize nanoparticles of iron oxide, obtained as waste from the Cold Rolling Mill (CRM) of an integrated steel company, to remove arsenite (As 3+) from arsenic contaminated water. The iron oxide fines from the CRM were characterized with regard to their composition, phase, morphology and magnetic properties and capacity to adsorb arsenite. The major component of the CRM fine powder is the rhombohedral phase, α-Fe 2O 3. Kinetics study revealed that adsorption of arsenic by CRM fines within the first 60 min of contact was 60–80% of the amount removed after the equilibrium was achieved in 120 min. The adsorption efficiency increases with the decrease of initial pH. The powder, with a mean particle size of ~ 90 nm, has been found to have an excellent arsenic adsorption capacity, which can be explained by the Langmuir isotherm equation. The monolayer adsorption capacity of the CRM fines has been found to be 1.94 × 10 3 μg/g. A water filter containing CRM fines appears to be a very effective low cost arsenic removal system for people of developing countries. It has been clearly demonstrated that such a system can substantially reduce other hazardous contaminants and bacteria also.