CuFe2O4/diatomite composite activated peroxymonosulfate for degradation of acid orange 7

Magnetic composite CuFe2O4/diatomite (CFD) was prepared via citric acid assisted sol-gel method, and then characterized by SEM, XRD, FTIR and XPS for analysis on its microstructure and elemental valence. The effects of different oxidation systems, mass concentration of CFD, mass concentration of peroxymonosulfate (PMS), initial pH of solution, reaction temperature and anion type on the degradation of acid orange 7 (AO7) by CFD system were investigated, and the AO7 degradation mechanism by CFD was explored as well. Results from characterization indicated that the spherical CuFe2O4 particles were dispersed on the surface of diatomite, which reduced the agglomeration of CuFe2O4, while the valence cycles among the surface hydroxyl group, Fe3+/Fe2+ and Cu2+/Cu+ on CFD were involved in the PMS activation. Under the optimal conditions of 0.50 g/L mass concentration of CFD, initial pH of solution 6.68, mass concentration of PMS 0.30 g/L, mass concentration of AO7 50 mg/L and reaction temperature 30 ℃, the degradation rate of AO7 in 100 mL of the system reached 96.88% at 60 min. The degradation process of AO7 in CFD+PMS system was in line with the pseudo-first-order kinetic model, and the AO7 degradation rate constant was 1.98 times higher than that in pure CuFe2O4+PMS system. The CFD+PMS system, with a low activation energy (31.77 kJ/mol), could be applied in a wide pH range (5~11). The main active substances in the degradation process were singlet oxygen (1O2) and •O2–, while SO4–• and •OH were also produced. © 2023 Fine Chemicals. All rights reserved.