Co-Ni LDHs/PES Hybrid Membrane Synergizes With PMS to Effectively Degrade Orange Ⅱ

Abstract

The Co-Ni layered double hydroxides (Co-Ni LDHs) were prepared using co-precipitation method and Co-Ni LDHs hybrid polyethersulfone membranes (Co-Ni LDHs/PES) were prepared by phase inversion method, respectively. The products were characterized by FT-IR, XRD, SEM, TEM, EDX, TGA and tensile strength test. Results showed that the Co-Ni LDHs/PES membranes as prepared had excellent mechanical properties. The decrease of membrane contact angle and the increase of membrane water flux indicated that the hydrophilicity of Co-Ni LDHs/PES membrane can be improved. The hybrid membranes showed a good catalytic performance. As the loading of LDHs was 5mg·L-1, the dosage of PMS and AO7 was 1mmol·L-1 and 0.05mmol·L-1, respectively, the degradation rate of AO7 can reach 96.58% within 20 minutes. The ion leaching of Co-Ni LDHs/PES was much less than that of Co-Ni LDHs, so, the dosage of the Co-Ni LDHs was much less than of Co-Ni LDHs. After repeated used for four times, Co-Ni LDHs/PES still has good catalytic performance. The effects of Co-Ni LDHs dosage, PMS dosage, initial pH, Cl- and HA on the degradation of AO7 were investigated. The catalytic degradation mechanism of Co-Ni LDHs/PES was studied by free radical quenching experiments and XPS analysis. The main active species in the catalytic oxidation system are SO4-, OH, 1O2 and O2- among which 1O2 and O2- were the main active species.