Nontronite mineral clay NAu-2 as support for hematite applied as catalyst for heterogeneous photo-Fenton processes

Abstract

This study describes the characterization of Nontronite, a clay mineral with high content of structural iron, before and after iron incorporation and 600 °C heat treatment. The Nontronite was classified as a mesoporous material, with high absorption in the UV–Vis range and band gap energy of 1.9 eV, indicative of the presence of superficial hematite, also verified in XRD analysis. The heat treatment promoted a structure rearrangement and the conversion of other iron phases to hematite, allowing the formation of surface irregular sites on Nontronite and facilitating the access for the decomposition of H2O2 into HO[rad]. Its catalytic activity in heterogeneous photo-Fenton process was evaluated during the degradation of the antibiotic sulfathiazole (STZ) and showed high activity achieving undetectable levels of STZ after 20 min under UV-LED irradiation and solar irradiation, and showing no iron leaching under controlled pH = 3. The degradation intermediates identified indicated hydroxylation as the main degradation route.