Heterogeneous activation of persulfate using delafossite AgFeO2/α-MnO2 for efficient degradation of tartrazine under visible light

Abstract

For the first time, delafossite AgFeO2/α-MnO2 nanocomposites were successfully synthesized and used as heterogeneous persulfate (PS) activators for degradation of water pollutants. The potential of several systems, such as AgFeO2/α-MnO2/light, AgFeO2/α-MnO2/PS/light, etc., as well as reaction conditions, stability, and radicals involved, were all assessed for degradation of tartrazine (TZ). The exceptional activity of optimal AgFeO2/α-MnO2 (AFM50) nanocomposite was attained because of improved redox cycling between Ag0/Ag+, Fe2+/Fe3+, Mn3+/Mn4+ cycles, enhanced electron transfer, reduced e−/h+ pair recombination, long electron lifetime, high charge transfer and mobility, and electron density, which facilitated efficient PS activation and subsequent generation of various reactive oxidizing species. Interestingly, AFM50 showed exceptional degradation efficiency (67.4%) under dark conditions. The AFM50/PS/Vis system also demonstrated excellent stability and activity for degrading several dyes (rhodamine B (97.8%), methyl orange (94.5%), methylene blue (100%), and congo red (97.7%)). Based on quenching experiments, active radicals (•OH, SO4•-, O2•-), and non-radical (h+, 1O2), all contributed towards efficient degradation of TZ. Following that, a reasonable PS activation mechanism was proposed. This study propounds insightful synergistic activation of PS using delafossite AgFeO2/α-MnO2 nanocomposite under visible light and dark conditions, as well as its potential application in wastewater treatment plants.