Mineralogical characterization and sorption properties of goethite rich iron ore from daitari, Orissa, India

The present study was an attempt to find alternative uses of goethite rich iron ore, usually not used as raw material for iron extraction, as an adsorbent for removal of anionic contaminants from water. Mineralogical characterization by optical microscope, XRD revealed the presence of substantial amount goethite in the iron ore which was also supported from the TG-DTA and FT-IR results. On heating in air, the goethite content was completely converted to hematite at 400°C. The sorption behaviour of the untreated (GRI-0) and heat treated iron ore were studied using aqueous phosphate solution as the adsorbate with respect to effect of pH, initial phosphate concentration, amount of adsorbent, interfering anions and heat treatment. Phosphate uptake was seen to increase with increasing temperature of heat treatment, attains a maximum value at 300°C and thereafter decreased on further increase of temperature. The experimental equilibrium adsorption data were fitted well to Langmuir isotherm model. The complete desorption of adsorbed phosphate at pH ≥ 12.0 indicated the adsorption of phosphate was reversible and may be reused further. The results obtained could be useful for considering GRI-0 as adsorbent for removal of phosphate ions from contaminated water bodies.