Adsorptive removal of arsenic from groundwater using chemically treated iron ore slime incorporated mixed matrix hollow fiber membrane

Abstract

Iron ore slime was chemically treated and impregnated in polysulfone hollow fibers for treatment of arsenic contaminated water. Improvement of arsenic removal capacity of the treated slime was observed due to deposition of metallic hydroxide/oxyhydroxide on its surface. Successful incorporation of iron ore slime within the membrane matrix was confirmed by X-ray diffractograms. Scanning electron micrographs confirmed the blockage of pores within polysulfone membranes by the additive, resulting in decrease of porosity, permeability and molecular weight cut off. However, improved hydrophilicity, higher surface roughness and arsenic uptake capacity of prepared membranes were observed. Mechanism of arsenic removal by the mixed matrix membrane was governed by electrostatic attraction mediated adsorption. Membrane with the highest additive percentage (10 wt%) produced arsenic free water for 14 h for real life feed solution at 11.5 L/m² h, when operated in dynamic mode. Exhausted membrane was regenerated for three cycles using synthetic solution. Breakthrough time for arsenic removal was reduced from 28 h to 22 h and 14 h after second and third cycle, respectively. Maximum interference effect on removal process is shown by dissolved sulfate ions. The membrane was also able to remove microorganisms and iron simultaneously from real life feed solution below their WHO approved permissible level.