Degradation Of Typical PPCPs In Water By Visinle-light Photocatalysts Based On Metallic Sulfide

Pharmaceuticals and personal care products（PPCPs）,as emerging organic pollutants,have attracted great attention due to its widespread use worldwide and its potential risks to the aquatic environment and human health,which has become a major challenge in the field of wastewater treatment.High-efficiency photocatalytic technology with semiconductors as the core enjoys great application prospects in processing PPCPs.In the past decade of development and research on photocatalysts,a large number of photocatalytic materials with excellent performance have come into being,but there is still no new-generation applicable material to replace TiO₂.For its primary reason,the photocatalytic materials with much attention in recent years generally have unrealistic shortcomings such as complicated preparation processes,fragile and undurable property,unstable chemical properties,expensive or rare metals,difficulty in recycle and reuse.In view of the above limiting factors,this study developed two defect-type sulfide-based nano-photocatalysts-P-doped Mo S₂ and Fe-Zn S with sulfur vacancies（S_V）through reasonable design of the process flow.The two micro-catalysis mechanisms are investigated and analyzed.A new type of ZFS@TiO₂/NF（ZFS@TiO₂/NF）macro-photocatalytic system was developed by combining micro-catalysts with macro-loading materials.A complete set of macro-photocatalytic degradation mechanisms was analyzed and summarized.Five typical PPCPs,estrone（E1）,diclofenac（DCF）,cyclophosphamide（CF）,triclosan（TCS）and sulfamethoxazole（SMX）were selected as the target substances to investigate and analyze the degradation kinetics,degradation pathways and intermediate product toxicity of the five PPCPs in ZFS@TiO₂/NF.First,P was successfully doped into the Mo S₂ molecular structure by O-assisted doping（POMS）,and inert base surface of Mo S₂ was activated,thereby activating the potential photocatalytic performance of Mo S₂,so that SMX can be completely degraded within 20 min.The density functional theory（DFT）calculations show that P doping can improve the band structure and light absorption range of Mo S₂ by inducing charge diffusion and hybridization on the base surface.At the same time,studies on the structure and molecular properties of POMS show that activation of Mo S₂inert base surface is due to the transformation of Mo S₂ molecules from crystalline phase to amorphous phase during P substitution.H₂O₂ etching method was used to construct S_V of different concentrations in the ZFS nanostructure（S_V-ZFS）,thereby improving the photocatalytic performance of ZFS.The optimal S_V state in ZFS was summarized through experiment and calculation analysis.The results show that the activity of S_V strongly depends on its concentration in the ZFS crystal,and vacancy concentration is not a control parameter of activity,but a defect form caused by vacancy concentration.The main defect type changed from the isolated a state defect to the cluster state—e state（S_V concentration reached 18.75%）.DFT calculations and quantitative structure-activity relationships reveal two different mechanisms for defect activation of crystals:a state mainly activates the crystal activity by reducing the average valence charge of Zn²⁺,while in the e state,since the band edge of the acceptor defect state approaches the VBM,the Fermi energy level drops sharply,and it is necessary to adjust the ZFS structural performance by changing the energy band position.The optimal and stable S_V density for ZFS activation is obtained from the above conclusions.Accordingly,a ZFS@TiO₂/NF composite macrophotocatalyst with high-efficiency photocatalytic activity and easy recovery was developed through reasonable design,and the catalytic principle of the system was tested and analyzed.From the perspective of charge transfer,it provides a reference regarding how to determine the correct combination of microscopic medium and macroscopic carrier and then design an effective catalyst.ZFS@TiO₂/NF photocatalytic degradation of PPCPs showed high efficiency of charge collection and transfer,and could be completely degraded SMX in80 min.Compared with traditional powders or nanoparticles,this macroscopic material also demonstrates good recovery stability.Meanwhile,the material can be directly recovered from the water environment without complicated recovery processing,and can be directly taken out of the water with tweezers,which solves a key problem in the practical application of particulate catalysts.Finally,the paper summarized and analyzed the degradation kinetics,degradation pathways of five typical PPCPs treated by ZFS@TiO₂/NF under two backgrounds（deionized water and actual Songhua River water samples（SHR））.The degradation kinetic k_obs of the five PPCPs in the ZFS@TiO₂/NF treatment process ranged between3.77×10^-2-4.87×10^-2 mol^-1;The p H change in the reaction solution will also exert different effects on the degradation of the five PPCPs.SHR surface water background of three different dates has different degradation effects on the five PPCPs treated by ZFS@TiO₂/NF.In addition,different ions had significantly different effects on the degradation efficiency of PPCPs.For example,SO₄^2-and HSO₄^2-will promote the photocatalytic degradation rate of PPCPs.It suggests that the degradation of PPCPs by ZFS@TiO₂/NF does not depend on a single ROS,but different water environment will produce different effects on the degradation of PPCPs.The degradation pathways of five PPCPs in the ZFS@TiO₂/NF process were preliminarily determined,and the cytotoxicity and estrogen（ER）-binding activity of the intermediate products were analyzed.Only two hydroxylated products were detected in E1;A variety of hydroxylated,dechlorinated hydroxylated,cyclized and decarboxylated products were detected in DCF;Four hydroxylated and dechlorinated products were detected in CF;A variety of dechlorinated-hydrogenated products were detected in TCS;A variety of S-N bond,S-C bond rupture and deaminated products were detected in SMX.After photocatalytic degradation at different times,the cytotoxicity and ER-binding activity of the five PPCPs showed different degrees of degradation or small range of increase.In addition,the cytotoxicity and ER receptor activity of five PPCPs decreased to different degrees after photocatalytic degradation at different times.The results indicate that ZFS@TiO₂/NF can effectively degrade typical PPCPs in water in a short time,and can significantly improve the environmental risk of some PPCPs.In this study,three kinds of highly efficient sulfide-based photocatalysts were developed,and the action mechanism of photocatalytic degradation of PPCPs in water was elucidated from the micro molecular level and macro structural system,respectively.The mechanism and environmental risk of the end products of the five typical PPCPs treated by macro photocatalysts with promising applications were explore.This study provides the research foundation and reference value for the application and development of photocatalytic technology.