Removal of phosphate from wastewater by Fe-C micro-electrolysis: application of a novel integrated Fe/C aggregate

To overcome the drawbacks of typical Fe-C micro-electrolysis in wastewater treatment, we developed a new electrolysis material, integrated Fe/C aggregate (FCA) made from Fe0 and carbon powder, and used it for phosphate removal from wastewater. Results show that the free iron ions could quickly react with PO43- and form an iron phosphate precipitate in phosphate-containing wastewater. The release rate of iron ions was extremely rapid in the first 10 h, indicating that Fe-C microscopic galvanic cells formed on the aggregate surface. Acid conditions are beneficial for accelerating the Fe-C micro-electrolysis reaction and enhancing the iron ion release capacity and phosphate removal capacity. In batch experiments, the maximum phosphate removal capacity of FCA was found to be 10.84 mg P/g. The phosphate removal behaviour of FCA can be well described by the Langmuir isotherm model and the pseudo-second-order kinetic model. SEM and XPS investigations also revealed that phosphates were absorbed by ferrous or ferric hydroxide and generated Fe-P precipitate, which adhered to the surface of FCA throughout the phosphate removal process. Because of its low cost and outstanding performance, the FCA aggregate has a high potential for P removal in wastewater treatment.