Enhanced trace phosphate removal from water by zirconium(IV) loaded fibrous adsorbent

This study was investigated for the trace phosphate removal at high feed flow rate by ligand exchange fibrous adsorbent. The zirconium(IV) loaded bifunctional fibers containing both phosphonate and sulfonate were used as a highly selective ligand exchange adsorbent for trace phosphate removal from water. The precursory fiber of the bifunctional fibers was co-grafted by polymerization of chloromethylstyrene and styrene onto polyethylene coated polypropylene fiber and then bifunctional fibers were prepared by Arbusov reaction followed by phosphorylation and sulfonation. Phosphate adsorption experimental work was carried out in column approach. Phosphate adsorption increased with decreasing the pH of feed solutions. An increase in the feeds flow rate brings a decrease in both breakthrough capacity and total adsorption. The effect of competing anions on phosphate adsorption systems was investigated. The experimental findings reveal that the phosphate adsorption was not affected in the presence of competing anions such as chloride and sulfate despite the enhancement of the breakthrough points and total adsorption. Due to high selectivity to phosphate species, low concentration level of phosphate (0.22 mg/L) was removed at high feed flow rate of 450 h⁻¹ in space velocity. The adsorbed phosphate on the Zr(IV) loaded fibrous column was quantitatively eluted with 0.1 M NaOH solution and then the column was regenerated by 0.5 M H₂SO₄ for the next adsorption operation. During many adsorption-elution-regeneration cycles, no measurable Zr(IV) was found in the column effluents. Therefore, the Zr(IV) loaded bifunctional fibrous adsorbent is to be an effective means to treat wastewater to prevent eutrophication in the receiving water bodies for long time without any deterioration.