摘要
化学品的大量使用导致越来越多难降解的有机污染物进入环境水体中,对人类健康造成了极大威胁。基于过硫酸盐(PS)的高级氧化技术(AOPs),其活化后产生丰富的活性氧物种,具有高氧化电位、长半衰期和宽p H适用范围等特点,被广泛应用于废水处理中,但PS缓慢的活化过程和低降解率限制了它的发展。钼(Mo)基材料具有稳定的物化性质,良好的导电性,灵活的变价能力。这使得Mo基材料不仅可以直接实现PS的活化,还可以作为助催化剂与其他过渡金属协同作用,以活性组分和还原组分的角色参与污染物降解。同时,Mo基化合物因其优异的光吸收特性,在光照条件下可有效产生光生电子,进而显著促进PS的活化过程。本文从自由基途径和非自由基途径出发,阐述了PS的活化机制;详细介绍了几种Mo基化合物的存在形式,如MoO_(2),MoO_(3),MoS_(2),MoSe_(2),MoC,Mo_(2)C和MoP等,深入探讨了它们的结构特点以及相应的物理化学性质,归类列举了Mo基化合物在活化PS降解废水中的应用。最后,提出了目前Mo基催化剂仍然存在的问题,并对未来可能的研究方向进行讨论。
With the development of industrialization,a large number of chemicals are used in daily activities,resulting in more and more refractory organic pollutants in environmental waters,such as pesticides widely used in agriculture,pharmaceuticals employed in the medical industry,dyes and preservatives used in everyday life,even daily necessities such as skin care products and cosmetics.These organic pollutants can enter the environmental water body through various ways and accumulate residues in it and finally enter the human body through direct ingestion,bioaccumulation,and other ways,which pose a great threat to human health.Advanced oxidation technologies(AOPs)are a typical and effective water treatment method.Most AOPs are based on peroxide compounds that can be activated,such as hydrogen peroxide(H_(2)O_(2)),peroxymonosulfate(PMS),peroxydisulfate(PDS),and peracetic acid(PAA)for Fenton/Fenton-like reactions.Advanced oxidation technology using persulfate(PS)as an oxidant(including PMS and PDS)can produce a series of reactive oxygen species(ROS)such as sulfate radical(SO_(4)^(·-)),hydroxyl radical(·OH),superoxide radical(O_(2)^(·-)),and singlet oxygen(^(1)O_(2))after activation.Compared with H_(2)O_(2),PS has a higher oxidation potential,a longer half-life,and a wider pH range,which makes PS-based wastewater purification widely concerned.However,the slow activation process and low degradation rate of PS limit its development.As the largest country in molybdenum resources,China has an abundant reserve.The d-orbital electron configuration of molybdenum is flexible,which gives Mo a variety of valence states.Molybdenum-based oxides,molybdenum-based chalcogenides,molybdenum-based carbides,and other molybdenum-based compounds have stable physicochemical properties,good electrical conductivity,flexible valence ability,and excellent photoelectron-hole generation ability via light response.These make them considered good PS activators,and can also be used as cocatalysts in composite catalysts to provide electrons for the reduction of other transition metals,and also have significant advantages in the field of light-assisted activation of PS.In this paper,the mechanism of radical production by PMS,PDS,and H_(2)O_(2) was analyzed from the structural perspective and compared with the difficulty of their activation to wastewater degradation by structural symmetry.The PS degradation mechanism involved multiple steps,including O-O bond cleavage(activation),free radical generation,and degradation of target pollutants,among which PS activation and free radical generation were the key steps.Focusing on the free radical pathway and non-free radical pathway,the possible PS activation pathways in the degradation process of pollutants were described,and the fundamental differences between the formation modes and degradation mechanisms of both of the above were analyzed by combining valence bond theory and crystal field theory.The paper recommended the existence forms of several molybdenum-based compounds,such as MoO_(2),MoO_(3),MoS_(2)(one trigonal-MoS,two hexadonal-MoS,three rhombohedral-MoS_(2)),MoSe_(2),MoC,and Mo_(2)C,were discussed in detail,and their structural characteristics and corresponding physicochemical properties were discussed in depth.These Mo-based materials have shown significant advantages in many fields,such as transition metal activation and photoactivation.Mo-based materials could not only quickly break the persulfate O-O bond to form SO_(2)^(-)and·OH through the oxidation process,but also reduce the oxidized Mo(VI)and produce ^(1)O_(2)to achieve efficient degradation of organic pollutants.At the same time,Mo-based materials could also act as cocatalysts to synergize with other transition metals and participate in pollutant degradation as active and reducing components.Mo-based compounds could also play an important role in the generation of photogenerated electrons under light to assist in the activation of PS.Finally,some problems in the field of molybdenum-based catalysts were pointed out.For example,Mo-based catalysts have shown poor cycling stability in some studies,which was speculated to mean that part of the active sites were occupied by reaction intermediates,resulting in a decrease in the activation ability of PMS.Most of the Mo-based catalysts reported so far remain in the laboratory stage,and their performance in complex actual water bodies was often not ideal,which was far from the purpose of practical application.How to realize the practical application of Mo-based catalysts and then realize the industrial application should be studied.
作者
杨一统
陈巧运
李孟佳
宋利
裴克梅
李雷
Yang Yitong;Chen Qiaoyun;Li Mengjia;Song Li;Pei Kemei;Li Lei(School of Chemistry and Chemical Enginering,Zhejiang Sei-Tech University,Hangzhou 310018,China;College of Biological,Chemical Sciences and Engineering,Jiaxing University,Jiaxing 314001,China)
出处
《稀有金属》
北大核心
2025年第9期1454-1465,共12页
Chinese Journal of Rare Metals
基金
国家自然科学基金青年基金项目(22278175,22108094)
浙江省自然科学基金重点项目(LZ24B060001)资助。
