Study On The Effect Of Self-assembled Perylene Diimide Derivative/Titanium Dioxide Composite Material On The Degradation Of Carbamazepine In Water By Activated Persulfate Under Visible Light

With the development of society,more and more pharmaceutical and personal care products(PPCPs)are being produced and used.PPCPs have the characteristics of low concentration,difficult to degrade,and complex structure in the environment,and will accumulate in the organism over time,thus posing a great threat to human health and the ecological environment.The current mainstream sewage treatment process is mostly activated sludge method,the treatment effect of PPCPs pollutants is difficult to meet the requirements,so it is necessary to develop a more effective wastewater treatment process Compared with traditional water treatment technology,persulfate advanced oxidation technology has high degradation efficiency of pollutants and is environmentally friendly,and has broad application prospects.However,the current common persulfate activation methods still have some disadvantages,such as excessive energy consumption and by-products,which restrict its further applicationIn this work,2-ethylhexyl-modified asymmetric PDI derivative——EHPDI,was designed and synthesized,and a simple bis-solvent exchange polymerization method was used to successfully prepare a one-dimensional linear self-assembled EHPDI/Ti O₂composite material.Self-assembled EHPDI/Ti O₂composites were used to activate persulfate under visible light to degrade carbamazepine(CBZ),a typical PPCPs pollutant.The degradation effects of the system on CBZ under different reaction conditions and influencing factors were studied,the reaction mechanism of this system to degrade CBZ was discussed in detail,and the degradation pathway of CBZ was studied,which provided theoretical and technical support for the exploration of new and efficient persulfate activation methods and the removal of PPCPs pollutants in water environment.The specific research content is as follows:(1)One-dimensional linear self-assembled EHPDI/Ti O₂composite materials were prepared,and they were characterized by XRD,SEM,TEM,XPS,UV-Vis DRS,BET,PL,etc.The results showed that the material was successfully compounded,besides,the EHPDI and Ti O₂were closely combined.The heterojunction was formed through the C=O···H hydrogen bond,the prepared composite materials have a wider light response range,a larger specific surface area,and better photoelectric performance.(2)The composite material EPT_0.05with EHPDI loading of 0.05%wt exhibits the best ability to activate persulfate.The optimal reaction conditions are EPT_0.05=1 g/L,PS=1m M,p H=7,and the the removal efficiency of CBZ reached 97.7%,the reaction rate was40.4 times that of persulfate alone,12.8 times that of persulfate activated by Ti O2,and 36.7times of persulfate activated by EHPDI alone.Other substrate was substituted for degradation experiments,and the degradation effect proved that the system can be used for the degradation of various pollutants.The Cl^-promotes the degradation of CBZ in this system,while HCO₃^-inhibits the degradation of CBZ.Cyclic test results show that the stability of the composite material needs to be further improved.The intermolecular C=O···H hydrogen bond is susceptible to mechanical force and will break during the degradation process,thereby reducing the performance of the material.The EHPDI obtained after washing,filtering and recrystallization can be used to re-prepared materials to restore the original material performance.(3)Free radical trapping experiments and ESR testing proved that hydroxyl radicals,sulfate radicals,superoxide radicals and holes in the reaction system all participated in the degradation of CBZ,and hydroxyl radicals played a major role,furthermore,the system was further introduced Reaction mechanism model.Furthermore,the reaction mechanism model of the system was derived.The TOC removal rate in the reaction system within 60 minutes was 75.2%,indicating that CBZ was not completely mineralized.The intermediate products in the degradation process of CBZ were analyzed by HPLC/MS,and 14 intermediate products were found and three possible CBZ degradation pathways were proposed.