Outstanding performance of magnetic La2O2CO3/Fe3O4 nanosheets for simultaneous removal of phosphate and arsenate from wastewater

The chemical similarities and co-occurrence of phosphate and arsenate contamination have heightened the focus on their efficient simultaneous removal. In this study, magnetically recoverable La 2 O 2 CO 3 /Fe 3 O 4 nanosheets were synthesized through the calcination of La-Fe binary metal glycolate. Based on magnetic and adsorption properties, La 2 O 2 CO 3 /Fe 3 O 4 nanosheets with a La to Fe molar ratio of 1:1 (La 2 O 2 CO 3 /Fe 3 O 4 -1) were selected for further exploration. Electron microscopy characterization revealed that the nanocomposites consist of stacked La 2 O 2 CO 3 and Fe 3 O 4 nanosheets. The La 2 O 2 CO 3 /Fe 3 O 4 -1 nanocomposites exhibited exceptional adsorption capacities of 114.6 mg P/g and 230.2 mg As/g. Additionally, the material exhibited rapid adsorption kinetics and maintained excellent adsorption performance within a pH range of 3.0 to 9.0, showing significant selectivity for phosphate and arsenate even in the presence of various coexisting ions. Adsorption-desorption cycling tests indicated good potential for recycling. When applied to the spring water of Yangzonghai Lake, the material efficiently reduced the concentrations of phosphate and arsenate from 0.725 mg P/L and 1.380 mg As/L to below 0.020 mg P/L and 0.010 mg As/L, respectively. Mechanistic studies suggest that La 2 O 2 CO 3 facilitates the removal of phosphate and arsenate primarily through electrostatic attraction and ligand exchange. These findings indicate that La 2 O 2 CO 3 /Fe 3 O 4 holds significant promise for the co-removal of phosphate and arsenate, even at low concentrations.