| With the production and usage of industrial products,various refractory organic pollutants entered the water environment through the discharge of wastewater generated during the production process.Organic pollutants in wastewater have the negative effects on human health and aquatic environment.The development of the high-efficiency organic pollutant treatment method is the key issue of current research.In recent years,advanced oxidation processes(AOPs)based on persulfate have been widely researched,which have the advantages of easy operation,strong oxidizing ability,and low use restrictions.Persulfate can generate reactive species through thermal,ultraviolet,ultrasound,alkali,carbon material,and transition metal activation to degrade organic pollutants.Among them,carbon materials,especially for biochar,have received widespread attention due to their cheap,easily available,and environmentally friendly characteristics.The biochar obtained by calcining biomass not only contains abundant active sites such as oxygen-containing functional groups,defects,persistent free radicals,etc.,but also contains elements such as N,S,Fe,etc.,which can also effectively improve the catalytic performance of carbon materials.As a new type of carbonaceous material,carbon aerogel has attracted more attention,which has the advantages of large specific surface area,narrow pore size distribution,recyclability,low cost,and good water stability.The hierarchical pore structure and unique structural characteristics of carbon aerogel give it unique advantages in catalysis.Electrons can move quickly along its three-dimensional carbon skeleton.The layered porous structure provides high surface area and high accessibility,which is beneficial to organic pollutants degradation.The abundant cellulose contained in forestry wastes gives it the potential to be prepared into biomass carbon aerogel.Meanwhile,biomass carbon aerogel was used in the field of water treatment due to its easy availability and environmental friendliness.For example,a large amount of forestry waste,such as wood powder,was not effectively used in China.The use of forestry waste to prepare biomass carbon aerogel to treat organic wastewater not only solves the problem of forestry waste treatment,but also solves the problem of water pollution."Using waste to treat waste" is conducive to the sustainable development of the environment.In this paper,poplar powder was used as the biomass source to prepare biomass carbon aerogel and N-doped biomass carbon aerogel as heterogeneous catalysts,which have the ability for peroxymonosulfate(PMS)activation to degrade organic pollutants.The specific research contents are shown as follows:1.Carbon aerogel from forestry biomass as a persulfate activator for organic contaminants degradationIn this study,carbon aerogel(CA)was successfully prepared from forestry waste,which exhibited excellent catalytic performance in PMS activation.The morphology analysis showed that CA had the hierarchical porous skeleton with abundant active sites.Electron-rich pollutants,such as bisphenol A,rhodamine 6G,phenol,and p-chlorophenol,can be efficiently removed in CA/PMS system.The quenching experiments and electron spin resonance(ESR)proved that 1O2 was the main reactive species.Part of the production of 1O2 came from the conversion of superoxide anions(O2·-).C=O on the surface of CA was the main active site.Meanwhile,CA exhibited anti-interference to humic acid and inorganic anions,and had excellent BPA removal efficiency in tap water and lake water.Therefore,CA can serve as an efficient,green,and environmentally friendly catalyst for the remediation of organic wastewater.2.N-doped biomass carbon aerogel activated persulfate to degrade bisphenol AIn this work,we used poplar powder as biomass source to prepare N-doped carbon aerogel(NCA).NCA has the ability to activate PMS for bisphenol A degradation.When 1 mM PMS was added,0.3 g L-1 NCA can remove 97%bisphenol A(10 mg L-1)within 60 min(kobs=0.0537 min-1).The system showed good removal efficiency in a wide pH range.Combined with quenching experiment and ESR analysis,the pollutants degradation pathway was discussed in NCA/PMS system,including the radical process and the non-radical process through OH,SO4·-,O2·-and 1O2.X-ray photoelectron spectrometry(XPS)was used to further analyze the possible active sites of NCA.Meanwhile,the NCA/PMS system exhibited good renewable capability and universal applicability in contaminants removal.NCA/PMS is expected to be applied in actual wastewater treatment. |
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