【作者】 刘莉；

【导师】 李莉莉； 庞烜；

【作者基本信息】 吉林大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 随着造纸、纺织、食品、印染和医药等工业的快速发展,有机染料的需求量不断的增加,染料废水成为水污染的主要来源之一。具有芳香环结构和异质生物质特性的有机染料有毒、易致癌,并且不可生物降解。在众多有机染料废水净化的方法中,吸附法具有易操作、效率高、成本低等优势。吸附法常采用聚合物膜材料,具有能耗低、易控制、操作简单、去除过程无污染等优点。光催化法具有氧化能力强、无二次污染等优点。二氧化钛（TiO₂）具有优异的光催化性能,无毒且成本低廉,常用于光催化处理染料废水。然而,TiO₂较大的禁带宽度（3.2 e V）限制了其在光催化领域更为广泛的应用。将吸附与光催化技术相结合可以使有机染料的移除率大大提高。通过制备TiO₂基复合材料,构建界面异质结构或提高导电性,从而加快光生载流子的迁移,也是提高光催化剂性能的常用方法。本工作选用锐钛矿相TiO₂纳米颗粒作为光催化剂的主体,分别选用导电性聚合物聚酰亚胺（PI）和非导电性聚合物聚偏二氟乙烯/碳布（PVDF/C）双层复合膜作为光催化剂载体,构建了具有两相界面异质结构和三相界面异质结构的复合光催化剂。以两种阳离子染料（亚甲基蓝（MB）、罗丹明B（RhB））以及两种阴离子染料（刚果红（CR）、甲基橙（MO））为目标污染物,研究了复合光催化剂对染料的去除性能。讨论了导电性、多级结构以及光催化剂组分对其光催化性能的影响,并对光催化机理进行了详细的研究。本工作主要包括以下两个部分:（1）将TiO₂纳米颗粒和导电性碳化钛（TiC）分散在聚酰胺酸（PAA）聚合物溶液中,通过静电纺丝和煅烧技术制备了一种导电性能优异的Z-机制复合光催化剂（PI/TiC/TiO₂）。在模拟太阳光下辐照90 min,pH=10.0时,PI/TiC/TiO₂对RhB和MB的移除率分别为98.12%和97.93%。光催化降解机理研究表明,TiC的加入赋予复合材料优异的导电性以及较强的光吸收性能。TiO₂纳米颗粒和聚合物半导体材料PI所形成的Z-机制载流子传导路径提高了光生载流子的利用率。（2）以导电碳纤维布(C_FC)为基底,通过静电纺丝技术将含TiO₂纳米颗粒和SiO₂气凝胶的PVDF复合纳米纤维膜与改性C_FC结合,制备了一种具有三相界面异质结构的复合光催化剂（P-S-T/C）。通过研究其在低氧水环境中对有机染料的光降解效率,验证了其光催化性能。结合双层结构的毛细凝聚作用,P-S-T/C对阴离子和阳离子染料都表现出了优异的移除性能。机理研究表明,分离的光生载流子在P-S-T/C三相界面处快速扩散至复合光催化剂表面。吸附在多孔SiO₂气凝胶表面丰富的氧气（O₂）分子可以作为电子（e^-）捕获剂,同时减小复合材料的功函数。自由基捕获实验表明超氧自由基（·O₂^-）在光催化降解过程中起主导作用。此外,P-S-T/C表现出优异的稳定性和可回收利用性。本工作通过设计光催化剂结构,使其吸附活性物质来实现高效性,为制备TiO₂/高分子复合光催化剂提供了理论指导。更多还原

【Abstract】 With the rapid development of papermaking,textile,food,printing and dyeing,medicine and other industries,the demand for organic dyes continues to increase,dyes wastewater has become one of the main sources of water pollution.Organic dyes with aromatic ring structure and xenobiotic properties are noxious,highly carcinogenic and non-biodegradable.Among many methods of treatment for organic dyes wastewater,adsorption method has the advantages like easy operation,high efficiency and low cost.Polymer membrane materials are commonly used for adsorption,which has the benefit of low energy consumption,easy control,simple operation and no pollution in the removal process.Photocatalysis has the advantage of strong oxidation ability and avoidance of secondary pollution.Titanium dioxide（TiO₂）has excellent photocatalytic performance,non-toxic and low cost,which is commonly used in the photocatalytic treatment of dye wastewater.However,the wide band gap of TiO₂（3.2 e V）limits its wider application in photocatalysis.The removal rates of organic dyes can be greatly improved by combining adsorption with photocatalysis.By constructing interface heterostructures or improving the conductivity of TiO₂composite materials,the migration rate of photogenerated carriers can be accelerated,thus achieving high photocatalytic performance.In this work,anatase TiO₂nanoparticles were selected as the main photocatalyst,conductive polymer polyimide（PI）and non-conductive polymer polyvinylidene fluoride/carbon cloth（PVDF/C）dual layer composite membranes were selected as photocatalyst carriers,respectively,the composite photocatalysts with the interface heterostructures consisting of two phase or three phase were constructed.The removal capacities of composite photocatalysts for organic dyes was studied using two cationic dyes（Methylene blue（MB）,Rhodamine B（RhB））and two anionic dyes（Congo red（CR）,Methyl orange（MO））as the target contaminants.The effects of conductivity,multistage structure,and composition of photocatalysts on their photocatalytic performance were discussed.And the photocatalytic mechanism was studied in detail.This work mainly included the following two parts:（1）A Z-scheme composite photocatalyst（PI/TiC/TiO₂）with excellent electrical conductivity was prepared by electrospinning and calcination technique,TiO₂nanoparticles and conductive titanium carbide（TiC）were dispersed in polyamide acid（PAA）polymer solution.At pH=10.0,the removal rates of RhB and MB by PI/TiC/TiO₂under simulated sunlight irradiation within 90 min were 98.12%and 97.93%,respectively.The photocatalytic mechanism study indicated that the addition of TiC endowed the composites excellent electrical conductivity and strong light absorption property.The Z-scheme carrier conduction formed by TiO₂nanoparticles and PI improved the utilization rate of photogenerated carriers.（2）A composite photocatalyst（P-S-T/C）with three phase interfacial heterostructure was ingeniously designed.The conductive carbon fiber cloth(C_FC)was used as the substrate.Activated poly（vinylidene fluoride）（PVDF）with titanium dioxide（TiO₂）and a silicon dioxide（SiO₂）aerogel were combined with the modified-C_FCsubstrate by electrospinning.Its photocatalytic performance was validated by photodegradation of organic dyes in a low-oxygen（O₂）water environment.On combining with the capillary condensation of a bilayer structure,P-S-T/C exhibited excellent removal capability for anionic and cationic dyes.The mechanism study indicated that the separated photogenerated carriers diffused to the composite photocatalyst surface rapidly on the three-phase interface of P-S-T/C.The abundant O₂adsorbed on the porous SiO₂aerogel surface acted as an electron（e^-）-trapping agent,which could also decrease the work function of the composite materials.Superoxide radicals（·O₂^-）played a dominant role in the reaction of photodegradation supported by a free radical-trapping experiment.Moreover,P-S-T/C showed excellent stability and recyclability.This work paved a way to design a membrane with photocatalytic performance by constructing the interface heterostructure.更多还原