光催化及其协同电化学降解VOCs的研究进展

各类行业的废气排放导致环境污染问题严重。挥发性有机污染物（VOCs）作为工业废气中首要组成部分，因其成分的复杂性而难以处理，无选择性氧化的光催化高级氧化技术在VOCs降解领域引起广泛研究。为了解决光催化反应历程中存在的效率低问题，本文从VOCs的光催化工艺参数影响因素（温度、相对湿度、初始气体浓度、氧浓度和气体流速）展开描述，总结了各种工艺参数的影响机理和影响趋势。随着光化学技术和电化学技术的不断发展，将光电技术结合起来成为新的研究方向，外加偏压能够有效降低光催化反应历程中电子空穴对的复合率，本文总结了各类光电催化反应器中外加偏压对光电催化的影响机理和影响趋势。总结近五年的光/光电催化的实验研究进展，对于光/光电催化领域降解工业废气VOCs的工艺流程设计与优化具有借鉴意义。文中指出，未来进行与工业废气VOCs相契合参数范围的实验研究和简洁且高效的光/光电催化反应器研发将成为今后的发展趋势。     

LED可见光下Au/TiO2光催化氧化甲醛表观动力学

甲醛是室内空气中典型的挥发性有机化合物（VOCs）之一。等离子激元型光催化剂可吸收可见光,可在室温常压下利用太阳光驱动光催化氧化脱除室内空气中甲醛的反应,其表观反应动力学研究对设计等离子激元型光催化剂及应用于脱除VOCs等污染物具有重要意义。研究了LED可见光下等离子激元型Au/TiO₂光催化脱除气相中甲醛的表观反应动力学,考察不同波长的可见光源、光强及反应气相对湿度对表观反应动力学的影响,根据对实验数据的分析求得LED可见光催化氧化甲醛表观反应速率常数k（I,H）。结果表明,在13%相对湿度、蓝光光强为38.5 mW·cm^-2的条件下,光反应的甲醛转化率达77%,是暗反应的近5倍。在LED红、绿、蓝、白光照射下,随着光强增加,甲醛转化率快速增加后缓慢增至基本不变。相同光强（低于42 mW·cm^-2）和湿度条件下,红、绿、蓝光源的甲醛转化率相近,白光略低于其他光源。干气氛下,光反应和暗反应的甲醛转化率几乎为0。湿气氛下,光反应和暗反应均有甲醛转化率,光反应的甲醛转化率更高。不同光源条件下甲醛转化率随相对湿度变化规律相似。相对湿度为21.9%时甲醛转化率最高,而后保持不变,基本在80%左右。通过对红、绿、蓝、白光的数据拟合计算,得到表观动力学参数k（I）_H、k（H）_I、k（I,H）以及速率方程。     

光催化涂层净化室内VOCs研究进展

近年来,室内空气污染问题逐渐成为人们关注的焦点,挥发性有机物（VOCs）是造成这一问题的主要来源。光催化涂层作为一种新型VOCs净化技术,可以在太阳光下自发将VOCs降解为水和CO2,高效节能,不会产生二次污染,引起研究者的广泛关注和深入研究。结合国内外研究现状,该文系统介绍了用于室内VOCs净化的光催化涂层的制备方法以及涂层光催化性能和稳定性的影响因素,并对VOCs的光催化净化机理和影响因素进行阐述,同时对不同光催化涂层种类的研究进展及应用现状进行介绍,最后对光催化涂层进行了总结和并对其未来的发展方向进行展望。     

纳米光催化剂降解室内微量苯类挥发性有机化合物

社会的迅速发展给人类带来物质文明的同时,也使得环境污染变得日益严重,特别是在近年来由人类活动产生的气态污染物严重威胁到环境和人体健康。习近平总书记曾说过,绿水青山就是金山银山。但是,气态污染物相继排放到大气中,促使人们有必要开发出合适的技术来净化空气。苯类挥发性有机化合物(苯类VOCs)是室内空气中常见的气态污染物之一,应该经过物理吸附并转化成无危害的化合物等。光催化氧化技术(PCO)可以在光照作用下,利用光子的能量使光催化剂表面产生高活性物质来有效降解苯类VOCs,并且不会产生二次污染。目前,已有许多不同结构和物理化学性能的光催化体系被应用于降解苯类VOCs,本文首先对光催化降解苯类VOCs的基本原理、影响光催化反应的因素和提高降解效率的方法进行了系统分析,综述了各类纳米催化剂的设计理念以及其在光催化降解苯类VOCs过程中的性能,并对未来纳米催化剂的设计进行了展望。     

光催化氧化技术在室内空气污染治理中的应用研究进展

概述了室内空气污染的危害及特点,分析了光催化氧化技术净化室内空气的原理,介绍了光催化氧化技术的研究现状,分析了光催化氧化技术净化室内空气研究中存在的问题,并对其发展前景进行了展望。     

光催化氧化技术在VOCs废气治理过程中存在的难点及对策

光催化氧化技术在VOCs废气治理领域有较为广泛的应用。光催化氧化技术在VOCs废气治理过程中的效率和稳定性受污染物吸附性能、光催化氧化接触时间、湿度、催化剂活性、光子利用效率、催化剂附着稳定性等诸多因素影响。总结了光催化氧化技术在VOCs废气治理过程中存在的难点问题,并多角度探讨了解决以上问题的相关对策。     

用于VOCs降解的TiO_2光催化剂的研究进展

综述了近几年纳米二氧化钛(TiO_2)光催化材料在降解挥发性有机物(VOCs)领域的最新成果,探究了光催化降解的VOCs的反应机理、反应影响因素,总结了各种提高催化剂光催化效率的改性方法,并对其未来发展进行了展望。     

VOCs脱除技术的研究进展

文章主要叙述了吸收法、吸附法、冷凝法、催化燃烧法、生物法、光催化氧化法、等离子法等VOCs脱除技术的最新研究进展及存在的问题,综合对比各种方法的优缺点,讨论分析了VOCs的各种脱除技术的应用前景。     

气态挥发性有机化合物去除方法的研究进展

本文介绍了气态挥发性有机化合物(VOCs)的种类和危害,重点阐述了治理VOCs的各种方法,包括普通燃烧法、吸附法、生物法、光催化氧化法和膜分离技术等,以及治理方法的研究现状和展望。     

光催化氧化技术在室内环境空气净化中的应用

目前,室内环境空气中含有的挥发性有机化合物(VOCs)严重影响着人类的健康和生产力,各种处理技术的研究都围绕着解决这一难题而展开。在这些技术之中,光催化氧化法被视为当前最具潜力和希望的方法技术,已成为许多相关研究的重点方向。本文将介绍光催化氧化法的基本原理,光催化剂的基本特点及研究现状,并对影响光催化剂活性的因素,和催化氧化法在实际净化空气中VOCs的应用方面的问题进行展开讨论。     

Determination and risk assessment of by-products resulting from photocatalytic oxidation of toluene

The generation of harmful by-products during photocatalytic oxidation (PCO) of volatile organic compounds (VOCs) is a bottleneck problem for the application of PCO technology in indoor environment. Toluene is a typical VOC found in indoor air. In this work, the by-products at ppb level were studied during PCO decomposition of toluene in a plate-type reactor and identified using PTR-MS (proton transfer reaction-mass spectrometry) and GC–MS (gas chromatography–mass spectroscopy). The results indicated that benzaldehyde, methanol, acetaldehyde, acetone/propionaldehyde, formic acid/ethanol and acetic acid were the main by-products in the gas phase. By adjusting the concentration of water vapor, some compounds adsorbed on the TiO₂ surface were ascertained, which resulted in the deactivation of TiO₂. They were benzoic acid, benzene, acrylaldehyde, butyraldehyde and pentanal. Some of these by-products have not been reported in the literature. Possible photocatalytic oxidation pathways of toluene were proposed. A health-related index (HRI) was introduced to assess the risk level to human health of these ppb-level by-products. It concludes that although some undesired by-products (even carcinogenic) are generated during PCO decomposition of toluene, it seems that these by-products do not have negative effects to human health because of their low concentrations.     

Indoor air purification using heterogeneous photocatalytic oxidation. Part I: Experimental study

Heterogeneous photocatalytic oxidation (PCO) has shown to be a promising air purifying technology in outdoor conditions using TiO₂ as photocatalyst activated with UV light. Also to indoor air quality more and more attention is paid because of the very important role it plays on human health, and it can be influenced by many factors like ventilation system, building materials, furniture, cooking, and outdoor pollutants.The present work addresses the indoor air purification using photocatalytic oxidation. The photocatalytic reaction setup is introduced for the assessment of the indoor air quality. A modified TiO₂ that can be activated with visible light (VIS) is used as photocatalyst due to the shortage of UV light in indoor condition. One special wall paper is applied as the substrate for the coating of the photocatalyst in the present study.Nitric oxide (NO) is one typical indoor air pollutant, which is used as target pollutant for the photocatalytic oxidation with indoor concentration level. Influential parameters like initial NO concentration, flow rate, relative humidity of the experimental environment, irradiance, photocatalyst dosage that can affect the PCO are studied. Furthermore, the second part content of the present study is introduced at the end of this paper.     

A review of prospects and challenges of photocatalytic decomposition of volatile organic compounds (VOCs) under humid environment

Volatile organic compounds (VOCs) are harmful for humans and the surrounding ecosystem. Emissions from these pollutants have caused a significant reduction in air quality, which has an effect on people's health. Alkanes, alkenes, alcohols, aromatics, and other VOC pollutants have all been broken down by TiO₂ photocatalytic processes. Due to several operating inefficiencies and deactivation issues in humid environments, the practical application of photocatalysis has not been realized on a broader scale. The effectiveness of photo-oxidation of VOCs is impacted by a variety of environmental conditions. In the photocatalytic oxidation of the VOCs, relative humidity (RH) is critical. Therefore, it is important to review the recent findings on how humidity affects the photocatalytic breakdown of VOCs in air. To satisfy this need, this work provides a critical review of the related literature with focus on the fundamentals of photocatalysis, photocatalytic degradation of air pollutants, and the influence of humidity on the photocatalytic process degradation for selected air pollutants. It also highlights the kinetic models and typical photocatalytic reactor and supports for VOC removal.     

Investigation of inter‐relationship between tensile behavior and photocatalytic activity of an acrylic‐based composite upon UVA exposure

The aim of this work is to produce a photocatalytic pseudo‐paint for benzene removal from air and find the role of TiO₂ nanoparticles, TiO₂ pigment, and CaCO₃ extender on photocatalytic performance of this paint along with their role on stress–strain behavior after ultraviolet (UV) exposure. For this purpose, TiO₂ nanoparticles were dispersed into an indoor paint resin (i.e., copolymer acrylic–styrene). The impact of main components of the paint on photocatalytic oxidation (PCO) rate of benzene was studied. It was found that dispersion of nanoparticles had the most dramatic effect on photo activity of nanocomposite. TiO₂ pigment generally increased PCO rate and also made the paint more stable under tensile stress. CaCO₃ may increase and/or decrease PCO of benzene, whether there is pigment in the formulation or not. However, it does not generally contribute to making the formulation resistant to UV exposure. Nanoparticles bring PCO and mechanical strength into the paint, but fail to strengthen the composite against UV deterioration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44447.     

光催化与吸附联合技术的应用初探

从室内空气的分类出发,介绍了其来源、污染现状以及其对人体的危害,并在此基础上具体地介绍了目前净化室内空气的基本方法,比如吸收技术、光催化、膜分离技术、植物净化技术等。同时探讨了光催化技术和吸附技术在净化室内空气上的应用。从而提出了光催化与吸附技术在联合应用上急需解决的问题以及发展趋势。     

多物理场中热扩散效应对传热传质的影响

为了便于消除或控制室内挥发性有机化合物(VOCs),分析了VOCs在室内环境中的扩散规律。基于不可逆过程热力学原理,在考虑交叉耦合扩散效应的基础上,建立了3个物理量的梯度驱动下封闭空间内自然对流传热传质的数学模型。采用数值方法研究了室内环境中同时存在温度梯度、湿度梯度和VOCs浓度梯度时的自然对流传热传质现象,并着重考察了多物理量的梯度耦合作用下热附加扩散效应对传热传质的影响,展示了流场、温度场和浓度场等热附加扩散准则数STC的变化状况,研究结果表明,多物理场中热附加扩散效应对传热传质具有一定的影响,且具有复杂多解性。     

低浓度挥发性有机物吸附浓缩材料的研究进展

由于挥发性有机物（VOCs）会对环境造成严重的危害,因此VOCs的处理一直备受人们的关注,但发展高效的VOCs处理技术仍然存在严峻的挑战。本文针对大风量、低浓度VOCs的处理展开了综述,重点围绕吸附、催化燃烧处理展开讨论。对于大风量的低浓度VOCs,虽然浓度较低但VOCs排放量非常巨大。通过VOCs浓缩技术,提高浓度减少风量成为降低VOCs处理成本的有效途径。其中,发展高性能VOCs吸附材料是VOCs浓缩技术的关键。阐明了活性炭、分子筛等重要吸附材料的性质及其吸附VOCs的原理,并对吸附材料性质和VOCs种类对吸附效果的影响进行了探讨。展望了活性炭浓缩-催化燃烧技术和分子筛转轮浓缩-催化燃烧技术在大风量的低浓度VOCs处理中的应用前景。     

Technical Note: Performance of a Personal Electrostatic Precipitator Particle Sampler

Currently, photocatalytic oxidation (PCO) is considered to be an effective process for removing and destroying low-level pollutants, which makes it a strong candidate for indoor air quality applications. Our study evaluated the titanium dioxide (TiO 2 ) filter media in controlling bioaerosols in a laboratory test chamber. The influences of microorganism species, relative humidity, and face velocity on the germicidal effectiveness of a TiO 2 -coated filter with 365 nm 8 W and 36 W blacklight irradiation were investigated. A Collison nebulizer generated Escherichia coli ( E. coli ), Bacillus subtilis ( B. subtilis ) endospores, yeast cells of Candida famata ( C . famata ) var. flareri , and spores of Penicillium citrinum ( P. citrinum ). The PCO control effectiveness was determined as the ratio, N S / N 0 , where N S and N 0 were the culturable concentrations collected by an Andersen one-stage sampler downstream of TiO 2 -coated filters with and without blacklight irradiation, respectively. Our results demonstrated that there were no significant differences in microorganism penetrations for TiO 2 -coated filters with and without blacklight irradiation. It was recommended that TiO 2 filter media used in this study did not perform as a good germicidal capability for airborne microorganisms.