Preparation of efficient and reusable lanthanum and iron co-modified soda residue for selective phosphate removal from domestic sewage
Huiteng Wang, Hui Luo, Rubin Han, Wenbo Wu, Jingxin Yang, Teng Qin, Limin Chen, Meng Liu, Bao‐Jie He, Zhao Jing
Abstract
The selection of suitable raw materials as adsorbents is a key factor in effectively removing phosphorus from water. As an industrial by-product, soda residue exhibits high porosity and surface area, which can effectively adsorb pollutants. Magnetic lanthanum-iron soda residue (La-Fe-CSR) was synthesized using the co-precipitation method, and its characterization and mechanism for removing phosphate were thoroughly investigated. La-Fe-CSR exhibited good adsorption performance under acidic conditions (3 < pH < 7). A high concentration of HCO 3 − (100 mg/L) reduced the adsorption performance of La-Fe-CSR by 8.3% ± 2.5%, whereas the presence of other coexisting ions had a smaller impact. The adsorption of phosphate by La-Fe-CSR was controlled by chemisorption and reached saturation after approximately 120 min. The phosphate adsorption by La-Fe-CSR was significantly higher than that of soda residue (43.65 ± 3.39 mg/g), reaching 74.87 ± 2.46 mg/g. Ligand exchange and inner-sphere complexation constituted the primary mechanisms through which L-Fe-CSR removed phosphate. After 5 consecutive cycles, La-Fe-CSR maintained a phosphate removal efficiency of 74.5 ± 1.6%. It demonstrated good performance in removing total phosphorus from real domestic sewage, with a removal rate of 94.9 ± 0.5%. These research findings demonstrated that La-Fe-CSR held significant promise as a highly effective phosphate adsorbent in practical applications.