Effect mechanism of oxygen content and Fe(Ⅲ)on biochar degradation on P-nitrophenol
Biochar has wide application potential in pollutant control due to its rich specific surface area and unique physicochemical properties,but the mechanism of its degradation process affected by environmental factors is unclear.In this paper,pine biochar(BC500)was prepared from pine wood chips,and the effects of oxygen and Fe(Ⅲ)ions on BC500's degradation of toxic organic pesticides and nitrophenol(PNP)were discussed.The results showed that under acidic aerobic conditions,the degradation of PNP by BC500 was 1.35 times that of anaerobic conditions,which indicated that in addition to its own direct degradation,biochar could also indirectly degrade PNP through oxygen-mediated formation of reactive oxygen radicals.In addition,characterization by XPS,AAS and FTIR showed that under aerobic conditions,Fe(Ⅲ)ions at different concentrations(2.8-280 mg·L-1)inhibited the degradation of PNP by BC500.This is due to the strong oxidation capacity of Fe(Ⅲ)ions at low ambient pH,and the electrons transferred to oxygen by competing BC500 cause the superoxide anion(·O2-)production pathway to be shielded.The addition of Fe(Ⅲ)under oxygen-free conditions promoted PNP degradation,from 0.68 mg·g-1 BC to 1.79 mg·g-1 BC,because Fe(Ⅲ)could enhance the adsorption of PNP by BC500 and further promote its direct degradation.The results showed that when BC500 was applied to acidic iron-containing wastewater,the anaerobic environment was more conducive to the degradation of PNP,while Fe(Ⅲ)inhibited the degradation of PNP in the aerobic environment.This study provides a theoretical basis for the application of biochar to the treatment of organic pollutants in acidic iron-containing wastewater environment.
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