Biochar-supported MnFeO2 for heterogeneous photo-Fenton degradation of doxycycline: Collaborative promotion of electron transfer and H2O2 activation

• A biomass waste derived biochar-supported MnFeO 2 (MnFeO 2 /BC) was constructed. • Efficient degradation of DC by MnFeO 2 /BC activated H 2 O 2 under visible light . • Biochar accelerated photoinduced electron transfer of MnFeO 2 under visible light. • The synergistic effect of Mn and Fe dual active sites promoted H 2 O 2 activation. • MnFeO 2 /BC had fine anti-interference and universality for pollutants degradation. The present work has successfully constructed a novel biomass waste leaf derived biochar-supported MnFeO 2 (MnFeO 2 /BC) catalyst with dual reactive sites by one-step calcination method, and the MnFeO 2 particles were dispersed on biochar surface. The biochar promoted H 2 O 2 activation to degrade doxycycline (DC) by regulating light absorption performance and accelerating photoinduced electron transfer of MnFeO 2 under visible light. The photoinduced electrons facilitated the regeneration of Mn 2+ and Fe 2+ on the typical MnFeO 2 /BC (MnFeO 2 /BC-50) catalyst surface, which significantly improved H 2 O 2 activation for DC degradation with OH and O 2 − were major active species and subordinate species, respectively. The DC degradation pathway was proposed systematically based on the identified intermediates, and the acute toxicities for fathead minnow and daphnia magna, developmental toxicity, mutagenicity of DC as well as the stress effect of DC on mung bean germination and root development were effectively relieved after degradation. The MnFeO 2 /BC-50 existed fine anti-interference property and environmental applicability in activating H 2 O 2 to degrade pollutants. This research provides a new strategy for coupling resources utilization of biomass waste with the preparation of highly active catalysts with multifunctional water purification properties.