Construction Of Fenton-like System Based On Transition Metal Phosphides And Its Study In The Removal Of PPCPs-like Pollutants

With the development of industry and the improvement of people’s demand for quality of life,pharmaceuticals and personal care products（PPCPs）are widely used in many fields such as medicine,industry,aquaculture,animal husbandry,etc.However,with the gradual increase in the use of PPCPs,a large amount of residual,expired,treated or untreated PPCPs are discharged into surface water and groundwater,causing serious environmental pollution.Therefore,there is an urgent need to develop targeted wastewater treatment technologies to remove PPCPs pollutants effectively.Fenton reaction,as a typical advanced oxidation technology,has the advantages of easy operation,high efficiency and in-situ generation of large amounts of^·OH with high oxidation potential,and has been widely studied as a promising technology for deep sewage treatment in recent years.However,the conventional Fenton reaction requires severe reaction conditions,such as p H close to 3,difficult recovery of Fe²⁺,low utilization of H₂O₂,and accompanied by the generation of large amounts of iron sludge,which limits the application of this technology in practice.In view of the above problems,the heterogeneous Fenton-like process with solid catalysts instead of Fe²⁺has received increasing attention in recent years,such as transition metal phosphides can be used as a class of highly applicable multiphase catalysts because of their low price,wide variety,environmental friendliness and controllability.In addition,phosphorus atoms have high electronegativity,which can attract electrons in metal atoms,become negatively charged centers and adjust the surface charge state of metal atoms.Therefore,both metal atoms and phosphorus atoms in transition metal phosphides may become catalytic activity centers,and their abundant active sites make transition metal phosphides a potential Fenton-like catalyst for the removal of PPCPs.Based on the above research background,this study uses transition metal phosphides as Fenton-like catalysts,takes PPCPs as the target pollutants,and systematically studies the optimization of their technical parameters,degradation efficiency of PPCPs,active species and reaction mechanism by screening transition metal phosphides and their complexes,so as to provide technical support for promoting transition metal phosphides as Fenton-like catalysts in the removal of PPCPs.The main research contents and results are as follows:（1）Molybdenum phosphide（Mo P）with dual active sites was prepared as a catalyst to study its removal efficiency and degradation mechanism of the pollutant DCF in a Fenton-like system.In this system,the degradation constant of DCF within 40 minutes was 0.13 per minute,indicating that Mo P had efficient catalytic ability.In addition,the catalyst showed good applicability and stability in the experiments,it can be applied to a wide range of p H values（4-8）,different ionic medium solutions environments and real wastewater conditions.The above efficient Fenton-like catalytic ability was attributed to the presence of metal sites Mo^δ+and electron-rich sites P^δ-,which facilitated the activation of H₂O₂ to generate hydroxyl radicals and superoxide radicals for the rapid removal of DCF.This study provides technical support for the development of novel Fenton-like catalysts and optimization of Fenton-like technology for the removal of PPCPs pollutants.（2）Based on the above study,the functional materials of Fe P and Fe single-atom graphene oxide（Fe₁-GO）with the dual action of photocatalysis-Fenton-like catalysis were further synthesized to investigate the removal efficiency and degradation mechanism of tetracycline（TC）pollutants in the visible light-Fenton-like system.Under visible light irradiation,the degradation efficiency of Fe P/Fe₁-GO-based Fenton like system for TC was 1.36 and 2.32 times higher than that of Fe P and Fe₁-GO single components,respectively.In addition,the system has excellent stability,and its efficiency in removing organic pollutants does not decrease significantly after100 cycles.The system exhibits excellent catalytic activity over a wide p H range（3-11）.The efficient photogenerated charges separation efficiency and abundant Fe single-atom active sites contribute to the good Fe³⁺/Fe²⁺cycling,which leads to the excellent activity and stability of Fe P/Fe₁-GO in the visible light Fenton-like system.Finally,the degradation pathways of TC and the toxicity of intermediates were also evaluated in this study.This work provides theoretical guidance and technical support for the efficient removal of antibiotics from aqueous environments by constructing a highly stable Fenton-like catalytic system with a synergistic strategy of dual-action function and abundant single-atom active sites.