Polyvinyl alcohol-stabilized granular iron(III)-copper(II) binary oxide: An efficient adsorbent for phosphate removal from water

Abstract

Though powdered iron(III)-copper(II) binary oxide offers a good capacity for phosphate adsorption, it is unsuitable for direct use in fixed-bed systems, due to pore clogging and high pressure drop. To solve this problem, a novel granular iron(III)-copper(II) binary oxide sorbent (GFC) was successfully prepared using extrusion granulation method. The as-prepared GFC is cylindrical, with a diameter of ca. 2.0 mm and a length of 2.0–3.0 mm. Its adsorption for phosphate increased with temperature, decreased with an increase in pH value, but not significantly influenced by co-existing SO 42– , HCO 3– , and SiO 32– , indicating its high selectivity for phosphate. Its maximal phosphorus (P) adsorption capacity is 20.2 mg/g at pH 5.5 ± 0.1, superior to most of the granular sorbents reported in literature. For column tests, about 1,780 bed volumes of simulated phosphate-containing wastewater were treated before the phosphorus (P) concentration in the effluent reached the limit of 50 µg/L recommended by the United States Environmental Protection Agency (USEPA). Therefore, GFC has a high potential for use in wastewater treatment to remove phosphate.