Removal of Bisphenol A from Water using Iron Oxide Adsorbents

Bisphenol A (BPA), an industrial chemical used mainly in the plastics manufacturing industry, may be hazardous to humans via estrogenic activity and has recently been designated as an endocrine disrupting compound (EDC). The aqueous medium is the major route of contamination of water with BPA through industrial water discharge, landfill leachate infiltration, and wastewater treatment plant effluent. A risk assessment of BPA indicates adverse health effects for environmentally relevant concentrations of BPA using different ingestion scenarios. Therefore, the removal of BPA from water is necessary to decrease the risk of human exposure to water contaminated with BPA. The removal of BPA from water was investigated using adsorption of BPA onto several iron oxide adsorbents: two magnetites (Fe3O4) and one hematite (Fe2O3). Iron oxides may serve as sustainable adsorbents due to lower cost and ease of regeneration using a blast furnace, when compared to organic adsorbents such as activated carbon. The adsorption of BPA from water onto iron oxide adsorbents was evaluated as a function of pH, ionic strength, time, adsorbent dosage, and type of adsorbent. The effect of pH on adsorption was investigated, showing that hematite H was able to remove more BPA at lower pH values. The maximum adsorption capacities on hematite at pH 2 were found to range from 253 to 302 mg/kg and from 337 to 396 mg/kg after 2 and 7 days, respectively. The effect of solution ionic strength on adsorption was investigated. There was a positive effect on adsorption due to calcium with and without bicarbonate with an increase in the adsorption with increasing ionic strength. The effect of potassium was not as strong as the effect of calcium. The results from this research show that the removal of BPA using hematite under acidic conditions has the potential to be developed into a technology for removal of BPA from water and wastewater. Statistical analysis of the data using multivariate linear regression (MLR) models determined the independent variables having the greatest effect on the adsorption and removal of BPA from water.