Enhanced Degradation of 1-Hydroxy-1,1-Diphosphonoethane in Three-Dimensional Electro-Fenton Process Through Selection of Ag Nanostructure in Layered Double Hydroxides-Ag @Fe3O4 Particles

The increasing of 1-hydroxy-1,1-diphosphonoethane (HEDP) in aquatic environments poses potential harm to the environment. Herein, the materials that silver nanoparticles/nanowires (Ag NPs/Ag NWs) and Fe3O4-decorated CoAl-layered double hydroxides (LDHs-Ag NPs@Fe3O4 and LDHs-Ag NWs@Fe3O4) were synthesized and applied to the degradation of HEDP in three-dimensional electro-Fenton system. Addition of Ag-doped LDHs@Fe3O4 particles greatly increased the HEDP removal rate compared with the addition of LDHs@Fe3O4 particles. The HEDP degradation rates using LDHs-Ag NPs@Fe3O4 and LDHs-Ag NWs@Fe3O4 particles were 73.34% and 79.64%. Furthermore, based on the characterization of synthesized particles, generation of free radical and H2O2, a possible mechanism of improved oxidation performance by the LDHs-Ag NWs@Fe3O4 particles was elucidated. The LDHs-Ag NWs@Fe3O4 particles possessed excellent stability and reusability, as evidenced by the stable degradation activity of 70.53% for HEDP degradation after four successive runs.