Preparation Of PDIP/WO₃/Br-g-C₃N₄/Cotton Fabric Photocatalytic Material And Its Degradation Of Organic Pollutants

Organic pollution in the ecosystem is a serious threat to human survival,especially antibiotics and dyes in water bodies.Traditional treatment technologies are not only costly but also cause secondary pollution.Therefore,efficient and sustainable semiconductor photocatalytic technology has emerged.As an emerging semiconductor photocatalytic material,perylenimide polymer（PDIP）is considered as one of the most promising organic semiconductor materials due to its excellent light absorption ability and strong chemical stability.However,PDIP has the problems of low photogenerated carrier transfer efficiency and difficulty in recycling in practical applications.In this study,three monomers,PDIP,WO₃ and Br-g-C₃N₄,were prepared to construct PDIP/WO₃/Br-g-C₃N₄（PDIP/WO₃/CN-Br）double Z-type heterojunction to improve the photocatalytic performance of the material,and finally compounded with pure cotton fabric to improve its recycling performance.The specific research works are as follows:（1）Preparation of PDIP/WO₃/CN-Br double Z-type heterojunction materials:In this thesis,PDIP/WO₃/CN-Br double-Z heterojunction materials were prepared by simply heating and stirring PDIP and loading it onto CN-Br together with WO₃.Under the strong coupling effect between PDIP,WO₃ and CN-Br,the photocatalytic oxidation ability was enhanced by accelerating the transfer of photogenerated electrons through the electron transport channel formed due to the double Z-type structure,and the effects of reaction time,reaction temperature,ion doping amount and composite ratio on the material properties were investigated.The results showed that the synthesis time of PDIP was 5 h,the synthesis temperature of WO₃ was 180℃,the doping amount of ammonium bromide was 0.12 g,and the composite ratio of PDIP/WO₃/CN-Br was 1:1:3,which were the best preparation conditions.（2）Analysis and characterization of the structure and properties of PDIP/WO₃/CN-Br composites.By analyzing the SEM and TEM test results,it was found that PDIP and WO₃monomers were uniformly grown on the surface of CN-Br material,which proved the successful composite of PDIP/WO₃/CN-Br material from microstructure;XRD and FT-IR tests showed that PDIP/WO₃/CN-Br was consistent with the crystalline shape and chemical groups of PDIP,WO₃ and CN-Br;by XPS and EDS characterization proved the presence of five elements,C,N,W,O and Br.The results of Mott-Schottky and DRS tests determined the energy band structures of PDIP,WO₃ and CN-Br materials,and inferred that PDIP/WO₃/CN-Br is a double Z-type heterojunction.and the successful composite of PDIP,WO₃ and CN-Br;the optical absorption range and photogenerated carrier transfer efficiency of PDIP/WO₃/CN-Br composites were found to be improved using DRS,PL and EIS tests.（3）The photocatalytic mechanism of PDIP/WO₃/CN-Br materials was investigated,and the effects of the initial solution pH,concentration and ion species on the photodegradation performance of PDIP/WO₃/CN-Br materials were investigated.The results showed that the best photocatalytic performance of PDIP/WO₃/CN-Br was achieved when the initial solution pH was 3.The degradation efficiency of PDIP/WO₃/CN-Br composites decreased with increasing concentration.The inorganic salt ions were found to have little effect on the degradation performance of PDIP/WO₃/CN-Br.The degradation efficiency of the composites for tetracycline（TC）and reactive dyes（RB-19）remained above 80%after the addition of inorganic ions such as Ca²⁺,Cl^-,CO₃^2-and SO₄^2-.The results of free radical trapping experiments and ESR tests showed that superoxide radicals and photogenerated cavities play a dominant role in the degradation of tetracycline,and hydroxyl radicals play an auxiliary role in the degradation.Two degradation pathways of tetracycline macromolecules were inferred using LC-MS tests.The recycling performance of the loaded cotton fabric was investigated,and the results showed that the cotton fabric still had more than 80%degradation rate after five cycles.