Resin-Based Photocatalytic Self-Fenton Degradation Of Organic Pollutants In Water

The emission of organic pollutants during industrial production poses a serious threat to the ecological environment.Among many technologies,advanced oxidation process has attracted the attention of researchers all over the world due to its characteristics of high efficiency and simplicity,friendly environment,mild conditions,simple operation and no secondary pollution.Homogeneous Fenton is considered to be one of the most cost-effective advanced oxidation technologies.However,it is difficult to be widely used in environmental purification due to its narrow pH application range（pH≤3）,low utilization rate of hydrogen peroxide（H₂O₂）and transportation and storage risks.Based on the above background,this paper takes the combination of photocatalysis and Fenton technology as the core,through the construction of resin photocatalysis homogeneous self-Fenton system and heterogeneous iron resin photocatalysis self-Fenton system to solve the drawbacks of Fenton technology in the degradation of difficult organic pollutants,and expounds the mechanism and mechanism of the system in the rapid degradation process of pollutants in detail.The main research contents and conclusions are as follows:（1）A kind of in situ photocatalysis self-Fenton system based on non-metallic resorcin formaldehyde（RF）resin semiconductor photocatalyst with no additional oxidant as the core was successfully constructed for efficient and stable degradation of organic pollutants in mineralized wastewater.The system showed excellent visible light catalytic degradation of mineralization for many typical organic pollutants（phenols,antibiotics,endocrine disruptors and dyes,etc.）.Taking bisphenol A（BPA）as an example,its degradation rate is 11 times and14.6 times that of P-g-C₃N₄,Cd S/r GO photo-self-Fenton system,and the mineralization rate of the same degradation rate is 4.5 times that of homogeneous Fenton system.At the same time,the system shows excellent stability in the 100 h liquid reaction system.Its excellent catalytic degradation performance of mineralization is mainly due to the following two factors:First,the rapid reduction of iron ion in RF conduction band electron pair（93.4%）can greatly improve the utilization rate of H₂O₂（82.1%）,which is 106.6 times that of homogeneous Fenton.High concentration of hydroxyl radical（·OH）can effectively improve the degradation rate of organic pollutants.Hydroxylation and polymerization of·OH and BPA produced a large number of macromolecular intermediates,resulting in weak ring opening and low mineralization rate（9.5%）;However,in the synergistic degradation path of·OH and hole（h⁺）,the macromolecular intermediates can be directly ring-opened by the strong oxidizing h⁺to degrade into small carboxylic acids,thus greatly improving the mineralization efficiency of the system（67%）.In brief,the above study found that the construction of an external H₂O₂independent,separation-free,low-cost,strong mineralization capacity resin photocatalytic in situ self-Fenton catalytic mineralization system provides a new idea to solve the key scientific problem in homogeneous Fenton method.（2）The homogeneous Fenton reaction is limited by the application range of pH value brought by the added iron source and the risk of high concentration of H₂O₂ transportation and storage,which seriously hindering the scientific progress of the reaction to the practical application.In this paper,we have successfully constructed a heterogeneous photocatalytic self-Fenton system of iron-doped resorcinol formaldehyde（FRF）resin,which can be used in situ to generate and efficiently degrade and mineralize many antibiotics（macrolides,sulfonamides,tetracycline,quinolones）by H₂O₂ without additional reagents at natural pH.The degradation rate constant of oxytetracycline（OTC）was 32.4 times that of RF photocatalysis.The high degradation performance comes from the following two aspects:Fe anchored on RF promotes the rapid transfer of photogenerated electrons,accelerates the fast cycling of iron,and improves the migration and separation efficiency of photogenerated carriers.Secondly,heterogeneous Fenton reaction realizes efficient utilization of in-situ H₂O₂ and generates abundant·OH.Finally,the mechanism of action and the mineralization pathway of OTC were systematically studied,which underwent demethylation,hydroxylation and ring-opening processes,and finally completely mineralized into CO₂ and H₂O.This work provides a new sustainable approach for the extensive construction of heterogeneous photocatalytic self-Fenton systems.In summary,taking Fenton system as the center,this paper constructs photocatalytic homogeneous self-Fenton system and heterogeneous photocatalytic self-Fenton system respectively.By systematically studying the generation of active species and their degraded intermediates and degradation paths in the collaborative degradation reaction process,it reveals the degradation mechanism of organic pollutants in the photocatalytic self-Fenton.At the same time,a continuous photocatalytic self-Fenton reaction system has been established,and organic matter degradation in the actual wastewater system has been studied,which provides a scientific and technical basis for the application of the new method in water treatment.