Phosphorous removal from water by polyolefins: effect of Al2O3 addition

Abstract

Phosphorus is the main nutrient responsible for eutrophication of aquatic ecosystems, therefore it is important to develop new processes to remove phosphorus that avoid the formation of precipitates. Polyolefins with and without prior activation with aluminum oxide (Al2O3), processed as flat plates, were investigated for phosphate removal from an aqueous solution. The maximum amount of phosphorus removal was 0.042 μgP/cm2 for PE (polyethylene), 0.049 μgP/cm2 for PE-g-MA (polyethylene grafted with maleic anhydride), and 0.071 μgP/cm2 for PE-g-MAe (PE-g-MA enriched in MA). Increasing polyolefins’ polarity did not result in a significant increase in phosphate removal. Activated polyolefins with Al2O3 presented maximum amounts of phosphorus removal of 0.863 μgP/cm2 for PE, 0.948 μgP/cm2 for PE-g-MA, and 0.884 μgP/cm2 for PE-g-MAe. As expected, addition of Al2O3 considerably increased phosphate removal. In kinetic experiments carried out with polyolefins activated with Al2O3 during 3 months a very high percentage of phosphorus removal was obtained for (> 90 %) as well as a very low remaining phosphorus concentration in solution (< 10 μgP/L). As a conclusion, polyolefins activated with Al2O3 effectively removed phosphorous from aqueous solutions with low concentrations which indicate that this material might be used for in-situ remediation of eutrophic waters. The possibility to recover the material after use to recycle phosphate and the absence of precipitates’ formation are two major advantages of this process.