Preparation Of Biomass-based Carbon Catalysts And Their Performance For Degradation Of Pollutants

Human industrial production and daily life are increasingly disturbing the natural environment.Hard-to-degrade organic pollutants such as antibiotics,dyes,and pesticides are discharged into water bodies,posing a serious threat to the environment and human health.Advanced oxidation technologies（AOPs）enable the degradation of hard-to-degrade organic pollutants into small molecules with low or no toxicity by generating highly oxidizing active species.Biomass carbon-based catalysts are widely used in advanced oxidation technologies due to their excellent physicochemical properties.To improve the catalytic performance of carbon-based materials,they can be modified by heteroatom doping of nonmetals and the loading of transition metals.Therefore,in this study,metal-loaded catalytic materials were realized by in situ mineralization of hydroxy iron oxide on polydopamine-modified carbon substrates,and a co-carbonization reaction of chitosan and sodium lignosulfonate was attempted to achieve nitrogen and sulfur co-doping of carbon materials,and finally,the performance and catalytic mechanism of the above catalysts for degradation of organic pollutants using advanced oxidation were investigated.In this study,the composite photocatalytic materials were prepared by high-temperature carbonization,polydopamine coating,and in situ growth of-Fe OOH by hydrothermal mineralization using cellulose-based fabrics as substrates.The structures of the catalytic materials were systematically characterized by SEM,TEM,XRD,FT-IR,XPS,and other testing techniques.The prepared catalytic materials were subsequently used for the study of photo-Fenton catalyzed degradation of organic dyes.The key factors affecting the catalytic reaction（hydrogen peroxide concentration,catalyst content,p H）were systematically investigated,and the degradation of methylene blue could reach 91.5%under the optimal conditions of 5 m M H₂O₂,0.3 g/Lβ-Fe OOH/PDA/CCF,p H=3.The generalization of the catalyst for the degradation of organic dyes and the cyclic stability performance was also investigated.The reactive oxygen species during the reaction were explored by control experiments,radical quenching experiments,and EPR tests.Based on this,the possible degradation pathways and degradation mechanisms were speculated.Based on the molecular weights of the eight degradation products detected by LC-MS,two possible degradation pathways of TC were postulated.AOPs based on peroxynitrite（PS）are of great interest because of their high oxidative properties and wide applicable p H range.Therefore,hybrid aerogel carbon materials synthesized from chitosan（CS）and sodium lignosulfonate（LS）,followed by carbonization reactions were prepared as nitrogen-sulfur co-doped carbons（NSCs）.NSC-2-800,prepared by CS:LS=1:2 at 800 ^oC,achieved 86.57%removal of 20 mg/L tetracycline（TC）by activation of PS within 120 min,with a degradation rate(0.0293 min^-1)32 times higher than that of the undoped sulfur carbon material(0.0009 min^-1),and was suitable for a wide p H range（p H 3-9）.In addition,the degradation efficiency of the catalysts in the natural water environment was investigated,and the common anions had little effect on the degradation of the NSC-2-800/PS system,and the degradation activity of TC in tap water reached 76.09%.The reactive oxygen species during the reaction were explored by controlled experiments and free radical quenching experiments,and the results showed that·O₂^-has an important role in the degradation of TC.