Bioelectrochemical hydrogen production with hydrogenophilic dechlorinating

生物传感器中生物组分的固定化方法生物传感器由两部分组成: 生物敏感元件与信号转换器。

生物传感器的选择性主要取决于敏感材料的选取,而灵敏度的高低则与转换器的类型、生物组分的固定化技术等有很大的关系。

因此固定化技术的发展就是提高传感器性能的关键因素之一。

生物传感器要呈现良好的工作性能, 其固定化技术应满足以下条件:(1) 固定化后的生物组分仍能维持良好的生物活性;(2) 生物膜与转换器须紧密接触,且能适应多种测试环境;(3) 固定化层要有良好的稳定性与耐用性;(4) 减少生物膜中生物组分的相互作用以保持其原有的高度选择性。

为了研制廉价、灵敏度高而且选择性好的生物传感器,固定化技术已成为研究者们努力探求的目标。

经过近20年的不懈探索,已建立了对各种不同生物功能材料的固定化方法。

1、1、3、1 物理吸附法此法就是通过生物分子的极性键、氢键、疏水键的作用将生物组分吸附于不溶性的惰性载体上。

文献已经报道了一些材料可用作吸附其它材料的载体,比如,石墨粉[25]、石墨-聚四氟乙烯[26]、活性碳[27]、离子交换树脂[28]等。

物理吸附法的特点就是方法简便、操作条件温与,缺点就是生物分子与载体表面的结合力弱,在表面进行任意取向的不规则分布,因此使制得的生物传感器容易发生生物分子的脱落与泄漏,从而造成传感器的灵敏度低,重现性差。

1、1、3、2 包埋法将生物组分与合成高分子经溶剂混合而使生物组分包埋于其中,制成敏感膜的方法称作包埋法。

采取的包埋方式通常包括凝胶包埋法与胶囊包埋法二种形式[29,30]。

包埋法的优点就是操作条件比较温与,膜的孔径与形状可随意控制,对生物组分活性的影响较小,缺点就是需控制很多实验因素,而且生物组分在聚合物膜内的活性会受到影响。

1、1、3、3 共价键合法将生物组分通过共价键与电极表面结合而固定的方法称作共价键合法。

该法就是利用基体表面进行活化处理,然后与生物组分偶联,从而使生物组分结合到基体表面。

Product Stewardship SummaryPotassium HydroxideSummaryPotassium hydroxide (caustic potash) serves a wide range of end use markets. The largest users of potassium hydroxide are the soap and detergent, fertilizer, and chemical industries. Minor uses include the production of molten salts, dyes, pharmaceuticals, and photographic chemicals. OxyChem markets potassium hydroxide in both liquid and dry form. The solutions are available in 45% and 50% concentration. The dry form is marketed in flake and crystal form. The chemical formula of potassium hydroxide is KOH. Potassium hydroxide is corrosive, and it must be stored and handled with this hazard in mind.1. Chemical IdentityName: Potassium hydroxideSynonyms: Caustic potashChemical Abstracts Service (CAS) number: 1310-58-3Chemical Formula: KOHMolecular Weight: 56.112. ProductionOxyChem manufactures potassium hydroxide by the electrolysis of potassium chloride brine in a membrane electrolytic cell. The co-products are chlorine gas and hydrogen gas. The reaction is:2 KCl + 2H2O → Cl2↑ + H2↑ + 2 KOHIn the membrane process, a solution of approximately 30% in strength is formed. The solution is then sent to evaporators, which concentrate it to a strength of 45% or 50% by removing the appropriate amount of water. The resulting caustic potash solution is stored in tanks prior to shipment.OxyChem has played a leading role in providing caustic potash to meet the increasing demands of industry. OxyChem plants are strategically located to conveniently and economically serve industry. Warehouse stocks of our potassium hydroxide and other products are maintained in many principal cities. Distributor stocks are also available in these and many other cities and form a network of supply for the end user’s convenience.3. UsesCaustic potash is one of the few chemicals finding almost universal application. Some of the principal products or processes in which caustic potash is used are:• A dehydrating agent for drying gases• A lubricant in the extrusion pressing of high melting alloys• A scavenger in a gasoline treating process (dual layer) for removing mercaptans• A methylating agent• An alkaline builder in detergent formulations • In refining petroleum fractions• In electrolytic stripping baths• In chemical compounding• In a molten bath for removing polyesters and polyurethanes from steel objects• In an absorption cartridge for scavenging carbon dioxide• As a chemical desiccant • As a cleaner for eliminating scale from the surface of titanium alloy intermediates• As an agent for lowering the sulfur content of coal• In alkaline batteries• In removing insulating coatings from wire • In purifying olefin feedstock containing hydrocarbons prior to polymerization• In stabilizing synthetic lubricants• In removing napthenic acids from gas oils • In fertilizers• In descaling ferrous metals• In sweetening sour petroleum fractions• In a fused alkaline salt mixture used for metal cleaning• In lye peeling4. Physical and Chemical PropertiesCorrosivityPotassium hydroxide in both liquid and dry form has a markedly corrosive action on all body tissue. Even dilute solutions may have a destructive effect on tissue after prolonged contact. Inhalation of concentrated mists can cause damage to the upper respiratory tract. Ingestion of liquid potassium hydroxide can cause severe damage to the mucous membranes or other tissues where contact is made.ReactivityPotassium hydroxide is a corrosive chemical that is normally handled in either steel, nickel, nickel alloys or certain types of plastic equipment. The most common construction materials for handling and storing potassium hydroxide solutions are black iron and mild steel. However, liquid potassium hydroxide will attack these metals at elevated temperatures. Aluminum, copper, zinc, lead, tin and their alloys (e.g., brass and bronze) are NOT suitable. Potassium hydroxide readily attacks these materials.In addition, considerable heat is generated when liquid or dry potassium hydroxide is mixed with water, which can result in boiling or splattering and may cause a violent eruption. When diluting, always add potassium hydroxide to water. Never add water to potassium hydroxide.5. Health EffectsPotassium hydroxide solutions are alkaline solutions, meaning they have high pH. The pH can be greater than 12. This property means potassium hydroxide is a severe eye, skin, and respiratory tract irritant, and it can burn any tissue with which it comes in contact.•Eye splashes are especially serious hazards. Contact with the eyes can cause severe irritation, pain, and corneal burns possibly leading to blindness.•Direct contact with the skin may cause severe burns if the material is not quickly rinsed away with large amounts of water.•Inhaling mists of potassium hydroxide may result in irritation of the nose and throat with symptoms such as burning, coughing, choking and pain. Inhaling concentrated mist mayresult in pulmonary edema and shock.•Ingesting potassium hydroxide may cause pain and burns of the esophagus andgastrointestinal tract. Ingestion can lead to corrosion of the mucous membranes of the upperpart of the digestive tract. Death may result from shock, perforation of the esophagus,aspiration from the esophagus into the trachea (asphyxia), or infection from the corrodedtissues.Potassium hydroxide is not classified as a carcinogen by the National Toxicology Program (NTP), the International Agency for Research on Cancer (IARC), or the Occupational Safety and Health Administration (OSHA).6. Environmental EffectsPotassium hydroxide is moderately toxic to aquatic organisms. It dissociates in water and can elevate the pH of systems that are not well buffered. Since it contains no degradable functional groups, it exerts no biological oxygen demand.7. ExposurePotassium hydroxide is corrosive to the skin and eyes. The most likely ways exposures could occur are: •Worker exposure – Exposure could occur in the manufacturing facility or in industrial facilities that use potassium hydroxide. When exposures occur, they are typically skin or eyeexposures. Good industrial hygiene practices and personal protective equipment minimizethe risk of exposure.•Consumer exposure – OxyChem does not sell potassium hydroxide in retail stores, although it may be an ingredient in some consumer products.•Releases – If a spill occurs, emergency personnel should wear protective equipment to minimize the risk of exposures.8. Recommended Risk Management MeasuresPotassium hydroxide is non-flammable, non-explosive, and non-toxic. It is, however, an alkaline material and poses hazards to the skin and eyes. Potassium hydroxide can react with certain materials of construction. Prior to using potassium hydroxide, carefully read and comprehend the Material Safety Data Sheet. The following are some risk management measures that are effective against these hazards: •Provide eyewash fountains and safety showers in areas where potassium hydroxide is used or handled. Any potassium hydroxide burn may be serious. Flush areas that have come incontact with potassium hydroxide with large amounts of water, and then seek medicalattention. DO NOT use any kind of neutralizing solution, particularly in the eyes, withoutdirection by a physician.•To prevent eye contact, protective eye wear (such as splash goggles, a full face shield, or safety glasses with side shields) must be worn.•Work areas where potassium hydroxide is used should be well ventilated. If exposures exceed accepted limits or if respiratory discomfort is experienced, use a NIOSH approved airpurifying respirator with high efficiency dust and mist filters•Wear chemical resistant clothing to prevent contact with the body. Suitable materials include butyl rubber, natural rubber, nitrile, PVC, and Tychem.•Wear rubber gloves to protect the hands while handling potassium hydroxide. Gloves should be long enough to come well above the wrist, and sleeves should be securely positioned overthe glove wrists.•Potassium hydroxide causes leather to disintegrate rapidly. For this reason, wear rubber boots. Wear the bottoms of trouser legs outside the boots. DO NOT tuck in.•Residues that dry on equipment can cause irritation. Keep equipment clean by promptly washing off any accumulation.•Proper labeling, handling and storage of potassium hydroxide will reduce the likelihood of accidental ingestion.•Equipment used for potassium hydroxide storage or processing should be constructed of the proper materials. For example, bulk storage containers should be constructed of mild,carbon, or stainless steel. Do not use aluminum as a material of construction. For moredetailed information regarding materials of construction, refer to the OxyChem Handbook.•The packing glands of pumps used in potassium hydroxide service should be shielded to prevent spraying in the event of a leak.• A safety shield of wrap-around polypropylene is recommended for all flanged joints. This will protect personnel against spraying in case a gasket leaks.•When making solutions, always add the potassium hydroxide slowly to the surface of the water with constant agitation. Never add the water to the potassium hydroxide. Always startwith lukewarm water (80 -100°F). Never start with hot or cold water. Dangerous boiling orsplattering can occur if potassium hydroxide is added too rapidly, allowed to concentrate inone area or added to hot or cold liquids. Care must be taken to avoid these situations.•Personnel involved with potassium hydroxide handling operations should be properly trained.For detailed recommendations regarding personnel involved in unloading potassiumhydroxide, refer to the OxyChem Handbook.9. Product Stewardship ProgramsAn OxyChem product handbook is available for potassium hydroxide. The handbook includes extensive physical property and technical data regarding the product as well as more detailed information about the manufacturing process and product uses. In addition, specific information for storing, unloading, preparing and using potassium hydroxide safely is provided, including data on materials of construction and equipment recommendations.10. Regulatory Compliance InformationThe following is a summary of regulations and guidelines that may pertain to potassium hydroxide (additional regulations and guidelines may apply):•Potassium hydroxide is designated as a hazardous substance under Section 311(b) (2) of the Clean Water Act. See 40 CFR 116.4.• A release of potassium hydroxide in an amount greater than the Reportable Quantity (RQ) is subject to reporting under Comprehensive Environmental Response, Compensation and Liability Act, Section 103. The federal RQ for potassium hydroxide is 1000 pounds. See 40 CFR 302.4.•Possible Resource Conservation and Recovery Act (hazardous waste) Codes: D002 •Potassium hydroxide has Generally Recognized as Safe (GRAS) status as a direct and indirect human food ingredient under specific Food and Drug Administration (FDA) regulations.•Potassium hydroxide, liquid, is regulated by the U.S. Department of Transportation (DOT) and is classified as a corrosive material. The DOT identification number is UN I814 (solution) and UN1813 (solid).•The American Conference of Governmental Industrial Hygienists has established a Threshold Limit Value for potassium hydroxide. The guideline is 2 mg/m3 as a ceiling limit.11. Sources for Additional InformationAmerican Conference of Governmental Industrial Hygienists (ACGIH), Documentation of the Threshold Limit Values and Biological Exposure Indices, 6th ed., 1 (1991), Potassium hydroxide and corresponding entry in “Pocket Guide” 1992.New Jersey Department of Health and Senior Services, Hazardous Substance Fact Sheet, Potassium Hydroxide, Rev. May 2001.Hazardous Substances Data Bank (HSDB), HSDB Number 1234, Last revision date: June 24, 2005. OxyChem Product Handbook web site:/OurBusinesses/Chemicals/Products/Documents/CausticPotash/kohhandb.pdf OxyChem Material Safety Data Sheet web site: /Registry of Toxic Effects of Chemical Substances (RTECS), RTECS Number TT2100000, Review Date: May 2008.12. Contact Information: For additional information, call 1-800-752-5151 or 1-972-404-3700.13. Preparation Date: 12/12/2008Revised: 02/13/2013This Product Stewardship Summary is intended to give general information about the product discussed above. It is not intended to provide an in-depth discussion of all health and safety information about the product or to replace any required regulatory communications.“Important: The information presented herein, while not guaranteed, was prepared by technical personnel and is true and accurate to the best of our knowledge. NO WARRANTY OF MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR PURPOSE, OR WARRANTY OR GUARANTY OF ANY OTHER KIND, EXPRESS OR IMPLIED, IS MADE REGARDING PERFORMANCE, SAFETY, SUITABILITY, STABILITY OR OTHERWISE. This information is not intended to be all-inclusive as to the manner and conditions of use, handling, storage, disposal and other factors that may involve other or additional legal, environmental, safety or performance considerations, and OxyChem assumes no liability whatsoever for the use of or reliance upon this information. While our technical personnel will be happy to respond to questions, safe handling and use of the product remains the responsibility of the customer. No suggestions for use are intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patents or to violate any Federal, State, local or foreign laws.”。

离子交换膜英文Ionic Exchange MembranesIonic exchange membranes are a critical component in various electrochemical and separation processes, playing a vital role in diverse applications ranging from water treatment to energy storage. These specialized membranes possess the unique ability to selectively transport specific ions while rejecting others, making them invaluable in a wide array of industries.At the core of an ionic exchange membrane lies a polymer matrix, typically composed of a network of charged functional groups. These functional groups can be either positively charged (cationic) or negatively charged (anionic), and they serve as the foundation for the membrane's ion-exchange capabilities. The charged groups within the membrane attract and bind to oppositely charged ions, effectively creating a pathway for the selective transport of these ions across the membrane.One of the primary functions of ionic exchange membranes is in the field of water treatment. In processes such as desalination, reverse osmosis, and electrodialysis, these membranes are used to removedissolved salts and other ionic contaminants from water. The charged functional groups within the membrane attract and trap the unwanted ions, allowing for the production of high-quality, purified water. This technology is particularly crucial in regions with limited access to clean water, as it enables the conversion of brackish or seawater into a potable resource.Beyond water treatment, ionic exchange membranes find extensive applications in the energy sector. In fuel cells, these membranes act as the electrolyte, facilitating the transport of protons (H+ ions) between the anode and cathode. This proton exchange allows for the efficient conversion of chemical energy into electrical energy, making fuel cells a promising alternative to traditional combustion-based power generation. Similarly, in rechargeable batteries, ionic exchange membranes play a vital role in the movement of ions during the charging and discharging cycles, contributing to the overall performance and safety of the energy storage system.The versatility of ionic exchange membranes extends to the field of electrochemical synthesis and processing. In the production of various chemicals and materials, these membranes can be used to selectively separate and purify desired products, improving the efficiency and purity of the manufacturing process. Additionally, they are employed in the production of hydrogen gas through water electrolysis, where the membrane facilitates the separation ofhydrogen and oxygen.The development of ionic exchange membranes has undergone significant advancements in recent years, driven by the increasing demand for efficient and sustainable technologies. Researchers and engineers have been exploring new materials, designs, and manufacturing techniques to enhance the performance, durability, and cost-effectiveness of these membranes.One area of active research focuses on the development of novel polymer materials with improved ion-exchange properties. By tailoring the chemical structure and composition of the polymer matrix, scientists aim to create membranes with higher ion-exchange capacity, better selectivity, and enhanced resistance to fouling and degradation. This includes the exploration of hybrid materials, such as organic-inorganic composites, which can combine the advantages of different components to achieve enhanced performance.Another key area of innovation is the optimization of membrane fabrication processes. Techniques like phase inversion, electrospinning, and 3D printing are being investigated to produce membranes with precisely controlled pore structures, thickness, and surface properties. These advancements can lead to improved mass transfer, reduced resistance to ion transport, and enhanced mechanical stability, all of which contribute to the overall efficiencyand reliability of the membrane-based systems.In addition to material and manufacturing advancements, researchers are also exploring novel applications and integration strategies for ionic exchange membranes. For instance, the use of these membranes in redox flow batteries, water electrolyzers, and bioelectrochemical systems is an active area of investigation, as they offer the potential to enhance energy storage, hydrogen production, and wastewater treatment capabilities.As the global demand for sustainable and efficient technologies continues to grow, the importance of ionic exchange membranes is expected to increase. These versatile and essential components will play a crucial role in addressing the pressing challenges faced by various industries, from water scarcity and renewable energy to environmental remediation and chemical production.Through ongoing research, innovation, and collaborative efforts, the field of ionic exchange membranes is poised to witness further advancements, leading to the development of more efficient, cost-effective, and environmentally friendly solutions that will shape the future of various industries and communities around the world.。

CHEMICAL INDUSTRY AND ENGINEERING PROGRESS 2017年第36卷第5期·1658·化 工 进展乙酸蒸汽催化重整制氢的研究进展王东旭1，肖显斌2，李文艳1（1华北电力大学能源动力与机械工程学院，北京 102206；2华北电力大学生物质发电成套设备国家工程实验室，北京 102206）摘要：通过生物油蒸汽重整制备氢气可以减少环境污染，降低对化石燃料的依赖，是一种极具潜力的制氢途径。

乙酸是生物油的主要成分之一，常作为模型化合物进行研究。

镍基催化剂是乙酸蒸汽重整过程中常用的催化剂，但容易因积炭失去活性，降低了制氢过程的经济性。

本文首先分析了影响乙酸蒸汽重整制氢过程的各种因素，阐述了在这一过程中镍基催化剂的积炭原理，讨论了优化镍基催化剂的方法，包括优化催化剂的预处理过程、添加助剂和选择合适的载体，最后对乙酸蒸汽重整制氢的热力学分析研究进展进行了总结。

未来应重点研究多种助剂复合使用时对镍基催化剂积炭与活性的影响，分析多种助剂的协同作用机理，得到一种高活性、高抗积炭能力的用于生物油蒸汽重整制氢的镍基催化剂。

关键词：生物油；乙酸；制氢；催化剂；热力学中图分类号：TK6 文献标志码：A 文章编号：1000–6613（2017）05–1658–08 DOI ：10.16085/j.issn.1000-6613.2017.05.014A review of literatures on catalytic steam reforming of acetic acid forhydrogen productionWANG Dongxu 1，XIAO Xianbin 2，LI Wenyan 1（1 School of Energy ，Power and Mechanical Engineering ，North China Electric Power University ，Beijing 102206，China ；2 National Engineering Laboratory for Biomass Power Generation Equipment ，North China Electric PowerUniversity ，Beijing 102206，China ）Abstract ：Hydrogen production via steam reforming of bio-oil ，a potential way to produce hydrogen ， can reduce environmental pollution and dependence on fossil fuels. Acetic acid is one of the main components of bio-oil and is often selected as a model compound. Nickel-based catalyst is widely used in the steam reforming of acetic acid ，but it deactivates fast due to the carbon deposition. In this paper ，the affecting factors for the steam reforming of acetic acid are analyzed. The coking mechanism of nickel-based catalyst in this process is illustrated. Optimization methods for nickel-baed catalyst are discussed ，including optimizing the pretreatment process ，adding promoters ，and choosing appropriate catalyst supports. Research progresses in the thermodynamics analyses for steaming reforming of acetic acid are summarized. Further studies should be focused on the effects of a combination of a variety of promoters on carbon deposition. Catalytic activity and the synergy mechanism should be analyzed to produce a novel nickel-based catalyst with high activity ，high resistance to caborn deposition for hydrogen production via steam reforming of bio-oil. Key words ：bio-oil ；acetic acid ；hydrogen production ；catalyst ；thermodynamics第一作者：王东旭（1994—），男，硕士研究生，从事生物质能利用技术研究。

Development of Energy ScienceNovember 2014, Volume 2, Issue 4, PP.39-46 Research Advances in Microbial Electron Transfer of Bio-electrochemical SystemYunshu Zhang, Qingliang Zhao #, Wei LiSchool of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China#Email:**************.cnAbstractBio-electrochemical system (BES) was an emerging biomass-energy recovery technology based on electricigens electron transfer (EET), which was applied to recover electric energy (e.g. microbial fuel cell, MFC) and resources (such as hydrogen and methane) and to enhance the removal of heavy metals and refractory organic pollutants (e.g. POPs). The process of electron transfer to the electrode was identified as the key process in such a BES system. In this paper, the recent research achievements about EET both at home and abroad were analyzed and summarized, and the electricigen diversity, the electron transfer pathways and study methods were systematically presented. Finally, the direction of EET research was pointed out.Keywords: Bio-electrochemical System; Microbial Fuel Cell; Electricigens; Electricigen Electron Transfer生物电化学系统中微生物电子传递的研究进展*张云澍，赵庆良，李伟哈尔滨工业大学市政环境工程学院，黑龙江哈尔滨 150090摘要：生物电化学系统（bio-electrochemical system，BES）是一种新兴的以产电微生物电子传递（EET）为基础的生物质能源回收技术，可用于电能（如微生物燃料电池）和资源回收（包括氢气和甲烷等），此外还可用于强化重金属与难降解有机污染物（如POPs）的去除，而其中产电微生物将产生的电子传递到电极是BES的重要过程。

STERIS provides a wide range of vaporized hydrogen peroxide (VHP®) bio-decontamination systems and services, utilizing Vaprox® Sterilant for broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores. Vaporized hydrogenperoxide bio-decontamination is crucial, not only for pharmaceutical and biotechnology production, but also for agricultural industries and healthcare facilities. The STERIS bio-decontamination systems use a “dry process” hydrogenperoxide vapor distribution, which eliminates the risk of condensation on surfaces.The advantages ofdecontamination with vaporized H 2O 2 include:• Easy to use• Effective against biological contaminants• Ideal for low-temperature processes• Processes can be validated • Compatible with a wide variety of materials• Environmentally friendly and safe for operators• Leaves no toxic residue, only water vapor and oxygenA trusted partnerFor several years, STERIS has used a trusted sensing technology from Vaisala. In 2018, STERIS became interested in a new solutionfrom Vaisala: the HPP270-series hydrogen peroxide vapor probe. The probes feature PEROXCAP® sensing technology. The sensors provide accurate measurements for hydrogen peroxideconcentration or ppm (parts per million) and several other parameters, most importantly: relative humidity, temperature, and a new parameter: relativesaturation — which indicates when condensation will occur.Validating bio-decontaminationIn DSVA (surface disinfection by airways) the aim is to prove that bacteria and microorganisms have been eradicated and the results must demonstrate maximumeffectiveness throughout the bio-decontaminated area. To validate a cleanroom bio-decontamination, it is essential that STERIS use a highly accurate sensor that can provide stable, repeatable data on the concentration of hydrogen peroxide vapor ppm. Vaisala’s unique technology met STERIS’s requirements for measurement reliability and repeatability. Thanks to Vaisala, STERIS has been ableSTERIS provides efficient, effective bio-decontamination with accurate vaporized H 2O 2 sensorsSTERIS is a world leader in bio-decontamination and equipmentsterilization for pharmaceutical production. The company has advanced the science of sterilization, cleaning and infection control with solutions that meet the high standards and requirements of its customers. In particular, cleanroom applications used for pharmaceuticals andbiotechnology require a high degree of environmental control. In thesehighly regulated environments, bio-decontamination is crucial and must be controlled, validated, and documented. Case Studyto prove maximum effectiveness of bio-decontamination in clean rooms.“Today, Vaisala is the best technology on the market tomeasure the concentration of H 2O 2 reliably, accurately, and repeatably over time,” says Philippe Muylaert, Room Decontamination Service Specialist with STERIS SAS. “The Vaisala model HPP272 is the most effective sensor for bio-decontamination with hydrogen peroxide. Thus, we haveconfidence in the data, and we can prove to our customers the effectiveness of bio-decontamination cycles.”Muylaert appreciates that the HPP270 probes provide H 2O 2 concentration measurement curves throughout the bio-decontamination process in addition to real-time monitoring data.In-line data throughout a process is valuable for cycle development, especially to help determine pressure binary mixture, water concentration, temperature, etc.In-line measurement of vaporized H 2O 2To remain in a gaseous state,hydrogen peroxide vapor requires controlled parameters, including temperature, relative humidity, pressure and volume. Anydeparture from ideal conditions can cause hydrogen peroxide vapor to condense, essentially returning the H 2O 2 to its natural state: liquid. For STERIS’s dry method, it is necessary to avoid condensation that can lead to equipment deterioration.In the absence of hydrogen peroxide vapor, the relativehumidity of the air is equal to the relative saturation (1). When vaporized H 2O 2 is introduced, the relative saturation is greater than the relative humidity (2).During H 2O 2 vapor bio-decontamination processes, there is always water vapor in addition to hydrogen peroxide vapor. To control condensation, you need to know both the humidity of the air caused by water vapor and by hydrogen peroxide vapor.Relative saturation, which indicates the concentration of vaporizedhydrogen peroxide and water vapor in the air, is the only value thatrepresents both vapors. Monitoring the relative saturation value during a process is therefore crucial, because it indicates saturation point of the combined vapors: water and hydrogen peroxide.Reliable measurements mean reliable processesSTERIS systems required a probe capable of providing accurate measurements for hydrogen peroxide ppm, temperature, relative humidity and relative saturation. Using the unique Vaisala PEROXCAP ® hydrogen peroxide sensor technology, the HPP272 probe can also measure two other parameters: dewpoint and vapor pressure, which can also be useful parameters in bio-decontamination. The probe guarantees reliable and precise hydrogen peroxide measurements throughout thebio-decontamination cycle, even in high humidity.The reliable and reproducible measurements of Vaisala’s vaporized hydrogen peroxide probes allow STERIS to achieve a high degree of confidence in their bio-decontamination procedures, success during annual audits, and a high level of product quality.Please contact us at/contactusScan the code formore informationRef. B212075EN-A ©Vaisala 2020This material is subject to copyright protection, with all copyrights retained by Vaisala and its individual partners. All rights reserved. Any logos and/or product names are trademarks of Vaisala or its individual partners. The reproduction, transfer, distribution or storage of information contained in this brochure in any form without the prior written consent of Vaisala is strictly prohibited. All specifications — technical included — are subject to change without notice.。

第46卷第2期 2021年4月天然气化工一C1化学与化工NATURAL GAS CHEMICAL INDUSTRYVol.46 No.2Apr. 2021•试验研究•2鄄丙基-2-庚烯醛加氢制2鄄丙基庚醇催化剂制备工艺研究王雪峰，夏伟，许红云，李扬，李文龙(西南化工研究设计院有限公司国家碳一化学工程技术研究中心工业排放气综合利用国家重点实验室，四川成都610225)摘要：为制备高性能2-丙基-2-庚烯醛(PBA)加氢制2-丙基庚醇(2-PH)催化剂，探索最优的催化剂制备方法，对催化剂制 备工艺进行了研究，考察了盐溶液浓度、沉淀剂种类、加料方式、沉淀pH、焙烧温度等制备条件对Cu-Cr催化剂性能的影响。

结果 表明，当盐溶液浓度为0.5 mol/L、沉淀剂为Na2CO3、并流方式沉淀、pH为5.5、焙烧温度为400 T时催化剂活性最高，此时PBA转 化率达100%，2-PH收率97.9%。

关键词：2-丙基-2-庚烯醛;2-丙基庚醇;加氢；Cu-Cr催化剂中图分类号：TQ426;O643.3 文献标志码：A 文章编号：1001-9219(2021 )02-44-03Study on preparation process of catalysts for hydrogenation of 2-propyl-2-heptaneal to2-propyl heptanolWANG Xue-feng, XIA Wei, XU Hong-yun, LI Yang, LI Wen-long(State Key Laboratory of Industrial Vent Gas Reuse, National Engineering Research Center for C1 Chemistry, Southwest Institute ofChemical Co., Ltd., Chengdu 610225, Sichuan, China)Abstract: In order to prepare high performance catalysts for hydrogenation of 2-propyl-2-heptaneal (PBA) to 2-propyl heptanol (2-PH) and search the optimal preparation method, the preparation conditions of the catalyst were studied. The effects of salt solution concentration, precipitant, feeding method, precipitation pH and calcination temperature on the performance of Cu-Cr catalysts were investigated. The results show that when the concentration of salt solution is 0.5 mol/L, precipitant is Na2CO3, co-precipitation, pH is 5.5 and calcination temperature is 400 the activity of the catalyst is the highest, and the PBA conversion reaches 100% and the yield of 2-PH is 97.9%.Keywords: 2-propyl-2-heptaneal; 2-propyl heptanol; hydrogenation; Cu-Cr catalyst2-丙基庚醇(2-Propyl Heptanol，2-PH)主要用于 生产高性能环保增塑剂一邻增塑剂DPHP。

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Electrochimica Acta 132(2014)15–24Contents lists available at ScienceDirectElectrochimicaActaj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e l e c t a c taElectrochemical processes in macro and microfluidic cells for the abatement of chloroacetic acid from waterO.Scialdone a ,∗,E.Corrado a ,b ,A.Galia a ,I.Sirés b ,1aDipartimento di Ingegneria Chimica,Gestionale,Informatica,Meccanica,Universitàdegli Studi di Palermo,Viale delle Scienze,90128Palermo,Italy bLaboratori d’Electroquímica dels Materials i del Medi Ambient,Departament de Química Física,Facultat de Química,Universitat de Barcelona,Martíi Franquès 1-11,08028Barcelona,Spaina r t i c l ei n f oArticle history:Received 19December 2013Received in revised form 15March 2014Accepted 17March 2014Available online 31March 2014Keywords:Boron-doped diamond anodeCombined electrochemical processes Electro-Fenton process Haloacetic acids Microreactor.a b s t r a c tThe remediation of solutions contaminated with monochloroacetic acid (CAA),which is one of the most resistant haloacetic acids (HAAs)to chemical degradation,dramatically depends on the adopted electrochemical approach:(i)CAA is only poorly oxidized either by homogeneous hydroxyl radical in electro-Fenton (EF),electrogenerated active chlorine or electro-oxidation on Pt anode;(ii)it is moder-ately abated by direct reduction on silver or compact graphite cathodes (from 30%in macro cells to 60%in the microfluidic devices);(iii)it is quantitatively removed by direct electro-oxidation on a boron-doped diamond (BDD)anode.The use of a microreactor enables operation in the absence of supporting elec-trolyte and drastically enhances the performance of the cathodic process.Simultaneously performing direct oxidation on BDD and reduction on graphite in a microfluidic cell yields the fastest CAA removal with 100%abatement at low current densities (∼5mA cm −2).©2014Elsevier Ltd.All rights reserved.1.IntroductionHaloacetic acids (HAAs)are ubiquitous,toxic and persistent contaminants introduced into the environment through water chlorination,organochlorinated pesticide degradation,herbicide utilization,atmospheric cleavage of refrigerants and even by nat-ural formation [1–3].A number of techniques has been proposed for the treatment of water containing HAAs,including biodegrada-tion [4,5],ultrasound-or microwave-assisted photolysis [6,7]and reduction and adsorption processes [8,9],most of them exhibit-ing relevant drawbacks such as poor abatements,long reaction times,high costs or production of hazardous wastes.Some elec-trochemical methods have also been proposed for the treatment of organic halocompounds [10–28].Reduction processes were used for the efficient dehalogenation of a large number of light halocom-pounds either in water [10–15,21–26]or aprotic solvents [17,20].Silver and copper have proven the most promising cathodes for such processes.Recently,it has been shown that aliphatic chlo-rides can also be treated by direct electro-oxidation [24,29–32]or electro-Fenton (EF)process [33].In addition,coupled processes∗Corresponding author.Tel.:+3909123863754;fax:+3909123860841.E-mail addresses:onofrio.scialdone@unipa.it (O.Scialdone),i.sires@ (I.Sirés).1Tel.:+34934039243;fax:+34934021231were also proposed for the treatment of 1,2-dichloroethane and 1,1,2,2-tetrachloroethane,thus yielding a higher abatement after a given charge passage and entailing a lower accumulation of by-products compared to single routes [24,33].It is worth noting that the electrochemical oxidation of both chloroethanes results in the formation of chloroacetic acids that are more resistant to degrada-tion than the parent compound [33].The electrochemical removal of HAAs by electrochemical reduc-tion at gold and copper cathodes was evaluated in detail by Korshin and Jensen [34].Copper was found to be more effective than gold,leading to almost complete dehalogenation of brominated HAAs.The reduction of chlorinated acetic acids gave rise to the formation of monochloroacetic acid (CAA),whose reduction was more dif-ficult than that of parent compounds.Recently,it has been shown that chloroacetic acids can be effectively reduced at activated silver plate or silver nanoparticles-modified cathodes [35,36]and Ag-Pd foam [37]or by sonoelectrochemical methods [38].This paper reports the treatment of CAA,one of the more resistant HAAs to chemical and electrochemical processes [8,33].It may appear as an ultimate intermediate in the degradation pathway of other halo-derivatives,but it is also a typical by-product formed during disinfection of waters by chlorination,and its control is mandatory due to its potential carcinogenic and mutagenic effects [1,39].Different electrochemical approaches,including direct cathode and anode processes,mediated oxida-tion by means of electrogenerated active chlorine,EF process and/10.1016/j.electacta.2014.03.1270013-4686/©2014Elsevier Ltd.All rights reserved.16O.Scialdone et al./Electrochimica Acta132(2014)15–24coupled systems have been investigated in order to compare the performance of each route andfinally propose the most suitable one.One of the main drawbacks that are inherent to the electro-chemical technologies operated in conventional cells arises from the need of a high conductivity in order to minimize the ohmic drop in the aqueous solution and the overall potential difference between the anode and cathode.Consequently,the addition of a certain amount of supporting electrolyte is usually a must.This is certainly an important obstacle for the widespread introduc-tion of many electrochemical technologies in the market,as in the case of water decontamination.Indeed,the addition of chemicals to polluted water streams is often a problematic issue,being con-trary to general administrative regulations because this may lead to the formation of secondary pollutants during the electrochemical degradation of initial contaminants.Furthermore,it increases the operation costs.Recently,different research groups have demon-strated the successful application of microfluidic electrochemical reactors(i.e.,cells with a distance of tens or hundreds of microme-ters between the anode and cathode)to both,the electrochemical treatment of aqueous solutions of organic pollutants[40–44]and the synthesis offine chemicals[45–48],in the absence of suppor-ting electrolytes with a small potential difference between both electrodes.Therefore,the drastic reduction of distances between electrodes leads to a major reduction of the ohmic resistance. Furthermore,higher current efficiencies were achieved in microre-actors for the electrochemical abatement of organic pollutants performed by both direct anodic oxidation and EF processes caused by an intensification of mass transport phenomena[41–44].Hence, the treatment of aqueous solutions of CAA has been carried out in macro and microfluidic devices equipped with different anode and cathode materials in order to improve the performance of the elec-trochemical processes under study in terms of CAA and chemical oxygen demand(COD)abatement.2.ExperimentalTwo macrofluidic cells,namely system I and system II,and a microfluidic cell were used to carry out galvanostatic electroly-ses by employing an Amel2053potentiostat-galvanostat and a 3300current integrator.Macro-scale electrolyses were performed in batch mode.System I was a bench,open,undivided,cylindrical glass cell of150mL capacity with a double jacket for circulation of external thermostated water to regulate the solution tempera-ture at25◦C.The anode was either a3cm2Pt sheet(SEMPSA)or a3cm2BDD thin-film electrode(Condias).The cathode was a3 cm2carbon-PTFE air-diffusion electrode(ADE)from E-TEK,which was fed with air at1.0L min−1for ensuring continuous H2O2 electrogeneration from the two-electron reduction of O2.The inter-electrode gap was about1cm.The solutions were always vigorously stirred with a magnetic bar at800rpm to enable mixing and trans-port of parative experiments were performed with 100mL of solution.For the photoelectro-Fenton(PEF)process,a Philips TL/6W/08fluorescent black light blue tube(320-400nm with␭max=360nm)was placed above the solution.System II was equipped with an undividedfilter-press reactor(ElectroCell AB)to work in aflow configuration.This reactor was composed of a BDD (Condias)or Ti/IrO2-Ta2O5(ElectroCell AB)anode and a cathode made of either compact graphite(Carbone Lorraine),Ag(Electro-Cell AB),Cu or AISI304stainless steel plate.The exposed surface area of the plates was10cm2and the interelectrode gap was4mm. Comparative experiments were performed with200or300mL of solutions,which were placed in a jacketed glass reservoir of350mL and sparged with nitrogen or compressed air.The solutions were continuously recirculated at1L min−1by a centrifugal pump.The experiments in the microreactor were performed inflow mode with a single passage of the solution through the cell,which was enabled by a syringe pump(New Era Pump Systems,Inc.)that fed the solutions at aflow rate between0.05and0.6mL min−1.The microreactor consisted in the abovementioned commercial undi-videdfilter-pressflow cell from ElectroCell AB,now equipped with one or two PTFE spacers(thickness of the spacer in the microme-ter range,i.e.,50or100␮m)placed between the electrodes,which were selected among those used in system II(see references[41,48] for a more detailed description of the micro device).Thus,BDD or Ti/IrO2-Ta2O5and compact graphite or stainless steel,were employed as anode and cathode,respectively.The spacers were cut so as to expose a working area of5cm2.For each tested operating condition,at least2samples of1mL were analyzed.The concentrations of CAA and acetic acid were evaluated by high-performance liquid chromatography(HPLC)using an HP1100 LCfitted with a Prevail Organic Acid5␮column(Grace Davison Dis-covery Sciences)at25◦C and coupled with a UV detector selected at ␭=210nm.A25mM KH2PO4aqueous solution at pH2.0(H3PO4) was eluted at1.0mL min−1as the mobile phase.The concentra-tion of accumulated H2O2was determined spectrophotometrically from the light absorption of the Ti(IV)–H2O2colored complex at ␭=409nm,by using titanium(IV)oxysulfate(TiOSO4·H2O)from Fluka.The COD was determined by using commercial Merck cell tests.The total organic carbon(TOC)abatement was evaluated by using a Shimadzu VCSN TOC analyzer.The oxychlorine ions(chlo-rate and perchlorate)were quantified by ion chromatography(IC) using a Shimadzu10Avp HPLCfitted with a Shim-Pack IC-A1S (100mm×4.6mm(i.d.))anion column at40◦C and coupled with a Shimadzu CDD10Avp conductivity detector.The mobile phase was a solution with2.4mM tris(hydroxymethyl)aminomethane and2.5mM phthalic acid at pH4.0eluted at1.0mL min−1.All the species were identified by comparison of their retention times with those of pure standards.The electrolyses were performed using bidistilled water to prepare solutions of5mM CAA(Merck),which usually contained 0.035M Na2SO4(Janssen Chimica)as supporting electrolyte for macro-scale experiments.For the study of electrochemical Fenton processes,0.25-1.0mM FeSO4(Fluka)was added as catalyst.Sulfu-ric acid(Aldrich)was used to adjust the pH of the solution when necessary.Prior to each experiment with the BDD anodes,an anodic polarization was carried out at3.0V vs.SCE for5min.In the case of silver,the surface was polished with alumina powder and then activated by means of either an oxidation–reduction cycle process, at10mV s−1in the range from-0.4to0.4V(4cycles,at298K)or amperostatic pulses in Na2SO4or pact graphite and cop-per cathodes were mechanically polished with alumina powder.The percentage of abatement(i.e.,the CAA conversion and the COD removal)was defined by Eq.(1),while the current efficiency (CE,%)for the conversion of the pollutant was defined by Eqs.(2) and(3)for macro and a microfluidic cells,respectively.X=100C0−C fC0(1) CE=100nFVC0Xapp(2) CE=100nFC0ϕV Xi app A(3)where C0and C f are the initial andfinal CAA concentrations or COD values,n is the number of required electrons for the conversion of the pollutant to carbon dioxide for oxidation processes(6)and to acetic acid for the reduction route(2),F the Faraday constant (96487C mol−1),i app the applied current density,A the exposedO.Scialdone et al./Electrochimica Acta132(2014)15–2417 Table1Abatement of CAA by various electrochemical routes.aEntry Process System(reactor)Current density(A m−2)Flow rate(mL min−1)Time(h)b Abatement(%)and(Current efficiency(%))1c EF or PEF with an ADE and electro-oxidation on Pt System I1000>5Not significant2Cathodic reduction on System II•copper4005<10(<0.5)•silver d400527(1.1)•graphite e100528(4.4)(Anode:Ti/IrO2-Ta2O5)3Electro-oxidation on BDD System II100589(42) (Cathode:stainless steel)4Electro-oxidation on BDD and cathodic reductionon graphiteSystem II100591(43)f5e Cathodic reduction on graphite System III(micro)1000.4 6.340(5.1) (Anode:Ti/IrO2-Ta2O5)800.5536(7.2)6g Electro-oxidation on BDD System III(micro)2000.38100(15) (Cathode:stainless steel)1000.5587(42)500.3875(44)7e Electro-oxidation on BDD and cathodic reductionon graphiteSystem III(micro)2000.38100(15)f1000.5595(46)f500.3886(50)fa Electrolyses of aqueous solutions of5mM CAA,using Na2SO4as supporting electrolyte for conventional reactors I and II.Unless stated otherwise,the considered volume was300mL.b Normalized time for the treatment of300mL of solutions considering a nominal geometric electrode surface of10cm2.Actually,system II has an electrode surface of10 cm2.In the case of the microreactor,the calculation is made by considering the utilization of two microreactors(each one with an electrode surface of5cm2)in parallel.c100mL of aqueous solution(pH3.0).d Preliminary activation of the silver cathode by two oxidation(10mA cm−2)and reduction(-10mA cm−2)amperostatic pulses(2min each).e At pH2.7,in the presence of0.5mM FeSO4.Nominal distance between the electrodes:100␮m.f Current efficiency conventionally calculated by considering the oxidation of CAA to CO2.g Nominal distance between the electrodes:50␮m.area,t the average residence time of the solution in the cell,V the solution volume and V the volumetricflow rate.Note that,if gas bubbles are formed at the electrodes,their presence can affect the mass transport of the organic molecules toward/from the electrode surface.Furthermore,the gas evolu-tion can result in a decrease of the effective surface area.However, according to the literature,for macro cells there exists an extended current density region(up to about100–1000A m−2)in which the convection caused by gas bubbles is not strong enough so as to modify the mass transport mechanism[57].Gas evolution can also affect dramatically theflow pattern in microreactors,although it did not seem to exert a remarkable influence on the abatement of organic pollutants for current densities up to about23mA cm−2, when the process was controlled by the mass transport of the pol-lutant toward the anode surface[41].At higher current densities, the mass transport rate of the pollutant(and,as a consequence, its abatement)was enhanced.Most of the trials reported in the present work were carried out with quite low current densities (<25mA cm−2).Nevertheless,the partial coverage of the elec-trode surface by gas bubbles cannot be discarded and hence,all the current densities are the nominal ones since they refer to the ratio between the applied current and the geometric electrode surface.3.Results and discussion3.1.Electrolyses in conventional cellsAfirst series of experiments was performed in conventional macrofluidic cells to assess the effect of the electrochemical route on the removal of CAA from contaminated,synthetic aqueous solutions.The performances of reduction processes on silver,cop-per and graphite cathodes,direct electro-oxidation on Pt and BDD,mediated oxidation by electrogenerated active chlorine,EF and PEF processes and some coupled processes were carefully investigated.3.1.1.EF and PEF processesIn EF process,oxygen is usually reduced at carbonaceous cathodes to hydrogen peroxide(Eq.(4))that,in the presence of catalytic amounts of iron(II),is converted to hydroxyl radicals(Eq.(5))that can oxidize organic pollutants in aqueous solution[49]. In undivided cells,which are preferred to avoid the high voltage penalty caused by separators,the required O2is directly fed as compressed air through an ADE or can be simply provided by the oxidation of water at the anode(Eq.(6))when graphite or carbon felt are used as cathode materials.Cathode)O2+2H++2e−→H2O2(4) Fe2++H2O2→Fe3++•OH+OH−(5) Anode)H2O→0.5O2+2H++2e−(6) Preliminary experiments were carried out by using system I as the macro cell,aiming to evaluate the production of hydrogen per-oxide in an undivided cell equipped with an ADE cathode and a Pt anode.A steady concentration of H2O2of about50mM was achieved after6h at300mA,pH3.0and25◦C with0.035M Na2SO4 as supporting electrolyte.When experiments were repeated in the presence of5mM CAA,with or without addition of0.5mM FeSO4, no significant abatements of either CAA or TOC were observed after protracted electrolyses,thus demonstrating that neither electro-oxidation on Pt nor EF process are able to degrade this resistant molecule(Table1,entry1).CAA was also resistant to PEF process performed with UVA light irradiation under the same operat-ing conditions.Quite interestingly,when the electrolyses were repeated on compact graphite cathode,the TOC still remained unchanged but a significant conversion of CAA to acetic acid was observed,presumably as a result of a reduction process(see the following section).18O.Scialdone et al./Electrochimica Acta132(2014)15–24Fig.1.Effect of pre-treatment of silver cathode on the cathode abatement of chloroacetic acid(CAA).The electrolyses of300mL of solution were carried out in system II at40mA cm−2in the same medium used for the pre-treatment stage after the addition of5mM CAA.Anode:Ti/IrO2-Ta2O5.Electrode surface:10cm2. Pre-treatment:( )Two oxidation(1mA cm−2)and reduction(-1mA cm−2)amper-ostatic pulses(2min each)in0.035M Na2SO4aqueous solution;two oxidation (10mA cm−2)and reduction(-10mA cm−2)amperostatic pulses(2min each)in:(᭹) 0.035M Na2SO4,( )0.5M Na2SO4or( )0.5M NaCl;( )four oxidation–reduction cycles in0.035M Na2SO4(scan rate of10mV s−1ranging from-0.4to0.4V).3.1.2.Electroreduction processThe galvanostatic reduction of CCA was carried out using system II on silver and copper cathodes,the more promising materials, according to literature,for the cathode reduction of chlorinated compounds and,in particular,of HAAs[34–37].Based on the above mentioned results,compact graphite was tested as well.An iridium-based electrode was used as the anode to favor the oxygen evolution reaction(Eq.(6)).The expected reduction process at the cathode was:ClCH2COOH+H++2e−→CH3COOH+Cl−(7) First experiments carried out at different current densities with mechanically polished silver gave very low CAA abatements(<7%) even after5h.Xu and co-authors have shown that the cathode abatement of HAAs on silver can be enhanced if the electrode is pretreated using an oxidation–reduction cycling method[35].Also in our case such a pretreatment enhanced the CAA abatements.As shown in Fig.1,similar trends(ending in ca.12%CAA abatement at 5h)were achieved activating the electrode in an aqueous solution of0.035M Na2SO4by both a cyclic voltammetry procedure(four oxidation–reduction cycles,scan rate of10mV s−1in the range from -0.4to0.4V vs.SCE similar to that proposed by Xu et al.[35])or by means of two oxidation and reduction amperostatic pulses(10and -10mA cm−2).A lower CAA abatement of about7%was obtained using the galvanostatic pulse pretreatment at lower current den-sity,whereas a higher degradation of about27%at5h was achieved upon increase of the supporting electrolyte concentration to0.5M (Fig.1).The use of NaCl instead of Na2SO4did not lead to any signif-icant change.In all cases,the abatement of CAA led to the formation of corresponding amounts of acetic acid.However,a rather low CAA abatement(<30%)was achieved in all experiments despite the high charge passed,therefore resulting in very low current efficiencies(< 2%).When experiments were repeated at a copper cathode,signif-icantly lower abatements were achieved(<10%after5h at20and 40mA cm−2).A quite complex picture was observed on graphite cathodes.In particular,it was observed that this material gave rise to a reduction of CAA to acetic acid while the solution TOC remained unchanged.Worth noting,the addition of small amounts of iron(II) at pH2.7allowed reaching even higher conversions of CAA to acetic acid.As shown in Fig.2,the performance of the reduction process with this cathode strongly depended on the current density and solution pH.A higher CAA abatement,always<30%,was achieved at an intermediate current density value of10mA cm−2and at a higher pH value,as shown in Fig.2A and2B,respectively.In order to understand the role of iron ions and the effect of pH,one can con-sider that p K a of CAA is2.87[50].Hence,at the employed pH values, both the dissociated and non-dissociated forms of CAA are present in solution.Chloroacetate ion(ClCH2COO−),whose concentration increases with pH,is expected to become complexed by iron(III) formed in the medium,thus appearing as a cationic species such as[Fe(OOCCH2Cl)]2+[51],which is likely to be more easily reduced than both ClCH2COO−and ClCH2COOH.When the reduction exper-iments were repeated on silver cathode,quite similar results were achieved both in the absence and presence of iron(II).Hence,the effect of iron ions is likely to be due to specific interactions with the graphite surface.As shown in Fig.2B(see image(a)as an example),at the end of the electrolyses performed with graphite at higher pH(i.e.,2.5 and2.7)some iron deposits appeared on the edge of the cathode plate,where the mixing of solution is expected to be less effec-tive.The iron precipitation is expected to take place at pH values higher than3.Hence,the phenomenon was probably caused by a local increase of pH due to the parallel hydrogen evolution reaction (Eq.(8))in the area where the mixing is less effective.As shown in Fig.2B,the utilization of pH close to2prevented the precipitation on the cathode surface but gave rise to lower abatements.In con-clusion,silver and graphite cathodes can be used to reduce CAA but, in both cases,under best adopted operating conditions rather low abatements close to30%were achieved in macro cells.H2O+e−→OH−+0.5H2(8) 3.1.3.Direct electro-oxidation processThe direct electro-oxidation of CAA was carried out on Pt and BDD,which according to literature is the most promising material for the anodic oxidation of aliphatic organochlorinated compounds [31].Stainless steel was used as an inert cathode to favor the hydro-gen evolution.The main expected redox processes are then given by Eq.(9)on the anode and Eq.(8)on the cathode.ClCH2COOH+2H2O→2CO2+Cl−+7H++6e−(9) While on Pt no CAA abatement occurred,on BDD the direct oxi-dation process allowed a very fast and complete degradation of CAA,as shown in Fig.3.The trends of both CAA and TOC abate-ments were very similar,thus showing that electro-oxidation at BDD allows the effective conversion of CAA to carbon dioxide.An increase of current density(i)from5to40mA cm−2resulted in a faster abatement of CAA(Fig.3,curves a-d)but in a progressively lower current efficiency(CE=36%and20%at20and40mA cm−2, respectively,after3h).Indeed,at higher current densities the pro-cess is likely to be under mass transport control(i.e.,transport of CAA towards the anodic surface)or under a mixed control regime and,consequently,a larger fraction of current density is used for parasitic processes such as the oxygen evolution.It has been reported in literature that chloride ions can be oxi-dized on BDD to form chlorate and perchlorate[33,52,53].As shown in Fig.4A,at40mA cm−2,the abatement of CAA led to the forma-tion of corresponding amounts of both oxychlorine ions,although they presented different profiles.In particular,the curve for chlo-rate concentration vs.time exhibited a maximum,which can be explained by the conversion of chlorides to chlorate and the subse-quent transformation of chlorate to perchlorate under the action of hydroxyl radicals formed on BDD.At the end of the electrolysis,the oxychlorine ions were mainly accumulated in the form of perchlo-rate.The concentration trends at100mA cm−2can be commented in the same manner,as depicted in Fig.4B and4C,although a faster decay of chlorate was accompanied by a quicker accumulation ofO.Scialdone et al./Electrochimica Acta132(2014)15–2419Fig.2.Effect of(A)current density and(B)pH on the abatement of CAA using compact graphite as cathode.Plot A:( )5,( )10and( )20mA cm−2,at pH2.7.Plot B:pH (a, )2.7,(b, )2.5,(c,᭹)2.0and(d, )1.8,at10mA cm−2.The electrolyses of300mL of5mM CAA in0.035M Na2SO4with0.5mM FeSO4and H2SO4(to adjust the initial pH)were performed in system II.Anode:Ti/IrO2-Ta2O5.Electrode surface:10cm2.perchlorate,as expected from the production of a higher amount ofoxidizing hydroxyl radicals.In contrast,at20mA cm−2,the chlorideions released during the CAA oxidation were mainly accumulated aschlorate,whereas only a small concentration of perchlorate couldbe detected.Thisfinding is relevant because it suggests that theaccurate selection of the operating parameters such as current den-sity may prevent the accumulation of toxic reaction by-productsupon the electrochemical decontamination process.3.1.4.Oxidation by electrogenerated active chlorineBesides the possible generation of chlorates and perchloratesexposed above,chlorides are expected to be converted intoactiveFig.3.Abatement of CAA using a BDD anode at(a, )5,(b,᭹)10,(c, )20and(d, )40mA cm−2.The electrolyses of300mL of5mM CAA were carried out in0.035M Na2SO4(curves a-d)or0.5M NaCl at40mA cm−2(curve e, )employing system II with continuous recirculation.Cathode:Stainless steel.Electrode surface:10cm2.chlorine(HClO/ClO−and Cl2)at BDD or Dimensionally-Stable Anodes(DSA),which can oxidize the organic pollutants present in the solution[54,55].The abatement of CAA by means of active chlo-rine was assessed by treating solutions of5mM CAA at40mA cm−2 in the presence of0.5M NaCl as supporting electrolyte using the following electrodes:a)Ti/IrO2-Ta2O5electrode as a DSA anode and silver cathodeb)BDD anode and stainless steel cathodeAs mentioned in section3.1.2(Fig.1),in the presence of iridium-based anode and silver cathode,very similar CAA profiles were achieved in the presence of Na2SO4or NaCl as supporting elec-trolyte,thus demonstrating that active chlorine does not contribute in a significant way to the CAA abatement under the adopted oper-ating conditions.On the other hand,the use of NaCl in the BDD/steel system resulted in a drastic decrease of the CAA abatement,as clearly revealed by comparing curves(d-e)in Fig.3.This result was probably due to the waste of a large current percentage in the oxidation of chloride to active chlorine,chlorate and perchlo-rate,which resulted in lower current efficiencies and a slower and poorer CAA abatement because:(i)the oxidation power of these chlorinated species is lower than that of•OH easily formed on BDD in Na2SO4,and(ii)the highly oxidizing•OH are wasted in side reac-tions with chlorinated species to yield chlorinated radicals with a low oxidation power,such as ClOH•−,Cl•and Cl2•−[56].3.1.5.Coupled processSome of the authors have previously shown that the adoption of coupled processes can enhance dramatically the abatement of。