Simultaneous removal of nitrogen and phosphorus from aqueous environments with recyclable La(OH)3/Fe3C ordered mesoporous carbon electrode

Abstract

Effective removal of both nitrogen and phosphorus from water is of great importance for maintaining the safety of the environment. In this work, ordered mesoporous carbon electrode materials containing La(OH)3 and Fe3C components (La#OMC-Fe3C) were prepared by combining solvent evaporation induced self-assembly and impregnation methods. The ordered pores in La#OMC-Fe3C facilitated electron transfer at the electrode-solution interface during nitrate reduction and provided voids for phosphate removal. In the electrochemical system, Fe3C in the electrode supplied electrons for nitrate reduction and gave the electrode a high degree of stability, whereas La(OH)3 selectively removed phosphate, thus avoiding byproduct precipitation from solution. The electrode material maintained efficient electrochemical nitrogen and phosphorus removal over a wide range of conditions including pH (3–11) and aqueous environments containing multiple ions (Cl−, SO42−, K+, Na+, Ca2+, Mg2+) or actual aqueous environments (seawater). After 10 cycles, the performance of La#OMC-Fe3C for nitrogen and phosphorus removal remained above 97%. This work realizes the simultaneous removal of nitrogen and phosphorus in the electrochemical system, and solves the problems of precipitation in water and non-circulation of electrodes, which can provide a new strategy for the treatment of eutrophic water in practical production.