| Oil exploitation and utilization will inevitably lead to soil pollution,and photocatalytic technology is favored in its remediation technology.Semiconductor photocatalyst can use light energy to mineralize organic pollutants into non-toxic and harmless small molecular compounds,which has broad application prospects in the field of environmental remediation.As a stable non-metallic semiconductor polymer,graphite phase carbon nitride is a hot research topic in the field of photocatalysis.However,it has some disadvantages,such as low utilization of visible light,easy recombination of photogenerated carriers,small specific surface area and easy reunion in the reaction system,which restrict its promotion and application in the field of photocatalysis to a certain extent.In this paper,aiming at the defects of carbon nitride itself,the structure optimization and performance upgrading of carbon nitride are carried out by different means without destroying the basic structure of semiconductor materials.It mainly includes:?1?A novel composite photocatalyst,biochar-supported potassium/phosphorus doped graphite carbon nitride,was prepared by high temperature calcination and impregnation.Its crystal structure,chemical structure,surface morphology and optical properties were characterized by various means.The results show that element doping can effectively improve the band structure of carbon nitride,and the loading of biochar can avoid the agglomeration of carbon nitride in the reaction system.?2?Taking the oil-contaminated soil of Karamay in Xinjiang as a sample,the total petroleum hydrocarbon concentration was 28.21 g·kg-1,and the pollution degree was serious.Using the preparation of catalyst for petroleum contaminated soil degradation,by ultraviolet spectrometry and gas chromatography-mass spectrometry technology for its determination,the results proved that the preparation of catalyst for the degradation of oil pollution of soil has obvious effect.Because of the complex composition of petroleum hydrocarbons,naphthalene,a representative polycyclic aromatic hydrocarbon in petroleum hydrocarbons,was selected as the standard sample to further study the activity and stability of the catalyst.?3?The photocatalytic degradation of naphthalene by biochar-loaded potassium-doped graphite phase-carbon nitride composite photocatalyst was studied by single factor screening experiment and orthogonal experiment.The best result of single factor screening was:illumination time 180 min,initial concentration of the compound was 20 mg·L-1,the dosage of the catalyst was50 mg,the catalyst loading ratio was 1:0.8,and the degradation rate was82.19%.In the orthogonal test,the influence of various factors on the naphthalene was as follows:illumination time>initial concentration>different loading ratio>catalyst dosage.The intermediate products of photocatalytic degradation of naphthalene,mainly naphthol,naphthoquinone,aldehyde and carboxylic acid,were determined by gas chromatography-mass spectrometry.Based on this,the possible mechanism pathways were proposed,which provided a theoretical basis for the development of potential graphite phase carbonitride-based photocatalysts.?4?The photocatalytic degradation of naphthalene by biochar-loaded phosphorus-doped graphite phase-carbon nitride composite photocatalyst was studied by single factor screening experiment and orthogonal experiment.The best result of single factor screening was:illumination time 180 min,initial concentration of the compound was 20 mg·L-1,the dosage of the catalyst was50 mg,the catalyst loading ratio was 1:1,and the degradation rate was76.41%.In the orthogonal test,the influence of various factors on the naphthalene was as follows:illumination time>different loading ratio>catalyst dosage>initial concentration.The effects of two different composite photocatalysts on the photocatalytic activity of naphthalene were further compared,which provided a variety of possibilities for the selection of photocatalysts in the field of pollution remediation.?5?Naphthalene was degraded by microwave-induced and catalytic oxidation synergism.The effects of microwave-induced degradation of naphthalene by pure microwave induction,microwave-induced biochar,carbon nitride,potassium-doped carbon nitride and potassium-doped graphite carbon nitride loaded on biochar were investigated.The results were 4.32%,28.48%,58.69%,72.54%and 93.76%,respectively.Among them,the compound catalyst has the best effect on naphthalene degradation,because microwave radiation can make the surface of biochar form high temperature arc,carbon nitride is stimulated to form explosive micro-domain,and then react with air and water in the reaction system to produce hydroxyl radicals,and attack naphthalene to make it degrade. |
PDF Full Text Request