Influence of irradiation sources on the efficiency of copper-modified magnetite for photo-Fenton degradation of sulfathiazole

Abstract

A comparison of the catalytic activity of the copper-modified magnetite was carried out under different conditions (dark and irradiated) and irradiation systems (460 nm Vis-LED, 370 nm UV-LED and Solar) in the degradation of the antibiotic sulfathiazole (STZ). The catalyst copper-modified magnetite presented a mesoporous structure, with a high absorption range (200–800 nm), band gap of 1.80 eV characteristic of iron and copper oxides, negative surface charge (− 24.6 mV) at neutral pH and high stability in solution (absence of iron and copper leaching). The results showed that the degradation kinetics of STZ increased in the following order in relation to irradiation: dark < Vis-LED < UV-LED < Solar), promoting complete degradation after 15 min, indicating that under solar and UV irradiation the catalytic activity is improved, due to an increase in the speed of the Fe–Cu redox reactions from a quick transfer of electrons that occur on the surface of the catalyst, further facilitating the formation of HO· radicals. The results have further demonstrated that the copper-modified magnetite can promote heterogeneous Fenton processes under LED or solar irradiation and be applied to effective degradation of micropollutants in wastewaters and have proven the versatility and high catalytic activity.