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高三现代科技前沿探索英语阅读理解20题1<背景文章>Artificial intelligence (AI) is rapidly transforming the field of healthcare. In recent years, AI has made significant progress in various aspects of medical care, bringing new opportunities and challenges.One of the major applications of AI in healthcare is in disease diagnosis. AI-powered systems can analyze large amounts of medical data, such as medical images and patient records, to detect diseases at an early stage. For example, deep learning algorithms can accurately identify tumors in medical images, helping doctors make more accurate diagnoses.Another area where AI is making a big impact is in drug discovery. By analyzing vast amounts of biological data, AI can help researchers identify potential drug targets and design new drugs more efficiently. This can significantly shorten the time and cost of drug development.AI also has the potential to improve patient care by providing personalized treatment plans. Based on a patient's genetic information, medical history, and other factors, AI can recommend the most appropriate treatment options.However, the application of AI in healthcare also faces some challenges. One of the main concerns is data privacy and security. Medicaldata is highly sensitive, and ensuring its protection is crucial. Another challenge is the lack of transparency in AI algorithms. Doctors and patients need to understand how AI makes decisions in order to trust its recommendations.In conclusion, while AI holds great promise for improving healthcare, it also poses significant challenges that need to be addressed.1. What is one of the major applications of AI in healthcare?A. Disease prevention.B. Disease diagnosis.C. Health maintenance.D. Medical education.答案：B。
新概念第四册课文翻译及学习笔记：Lesson39【课文】First listen and then answer the following question.听录音，然后回答以下问题。
What does the 'uniquely rational way' for us to communicate with other intelligent beings in space depend on?We must conclude from the work of those who have studied the origin of life, that given a planet only approximately like our own, life is almost certain to start. Of all the planets in our solar system, we ware now pretty certain the Earth is the only one on which life can survive. Mars is too dry and poor in oxygen, Venus far too hot, and so is Mercury, and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres. But other suns, start as the astronomers call them, are bound to have planets like our own, and as is the number of stars in the universe is so vast, this possibility becomes virtual certainty. There are one hundred thousand million starts in our own Milky Way alone, and then there are three thousand million other Milky Ways, or galaxies, in the universe. So the number of the stars that we know exist is now estimated at about 300 million million million.Although perhaps only 1 per cent of the life that has started somewhere will develop into highly complex and intelligent patterns, so vast is the number of planets, that intelligent life is bound to be a natural part of the universe.If then we are so certain that other intelligent life exists in the universe, why have we had no visitors from outer space yet? First of all, they may have come to this planet of ours thousands or millions of years ago, and found our then prevailing primitive state completely uninteresting to their own advanced knowledge. Professor Ronald Bracewell, a leading American radio astronomer, argued in Nature that such a superior civilization, on a visit to our own solar system, may have left an automatic messenger behind to await the possible awakening of an advanced civilization. Such a messenger, receiving our radio and television signals, might well re-transmit them back to its home-planet, although what impression any other civilization would thus get from us is best left unsaid.But here we come up against the most difficult of all obstacles to contact with people on other planets -- the astronomical distances which separate us. As a reasonable guess, they might, on an average, be 100 light years away. (A light year is the distance which light travels at 186,000 miles per second in one year, namely 6 millionmillion miles.) Radio waves also travel at the speed of light, and assuming such an automatic messenger picked up our first broadcastsof the 1920's, the message to its home planet is barely halfway there. Similarly, our own present primitive chemical rockets, though good enough to orbit men, have no chance of transporting us to the nearest other star, four light years away, let alone distances of tens or hundreds of light years.Fortunately, there is a 'uniquely rational way' for us to communicate with other intelligent beings, as Walter Sullivan has put it in his excellent book, We Are not Alone. This depends on the precise radio frequency of the 21-cm wavelength, or 1420 megacycles per second. It is the natural frequency of emission of the hydrogen atoms in space and was discovered by us in 1951; it must be known to any kind of radio astronomer in the universe.Once the existence of this wave-length had been discovered, itwas not long before its use as the uniquely recognizable broadcasting frequency for interstellar communication was suggested. Without something of this kind, searching for intelligences on other planets would be like trying to meet a friend in London without a pre-arranged rendezvous and absurdly wandering the streets in the hope of a chance encounter.ANTHONY MICHAELIS Are There Strangers in Space? from The Weekend Telegraph【New words and expressions 生词和短语】Mercury n. 水星hydrogen n. 氢气prevailing adj. 普遍的radio astronomer 射电天方学家uniquely adv. 地rational adj. 合理的radio frequency 无线电频率cm n. 厘米megacycle n. 兆周emission n. 散发intersteller adj.星际的rendezvous n. 约会地点【课文注释】1.that given a planet only approximately like our own, life is almost certain to start 这是一个宾语从句，作动词conclude的宾语，其中given a planet...our own,过去分词短语作条件状语，given与if的意思相近，这个过去分词短语可译成“如果一个行星与我们所在的行星大致相同的话”。
2024年高考英语气候变化的全球影响与应对单选题30题1.Climate change leads to a rise in sea levels and more frequent extreme weather events, which have a huge impact on the environment. The underlined word “impact” can be replaced by_____.A.influenceB.importanceC.affectionD.consequence答案：A。
“impact”意为“影响”，“influence”也有“影响”之意；“importance”是“重要性”；“affection”是“喜爱”；“consequence”是“结果”。
所以选A。
2.The increase in greenhouse gases is one of the main causes of climate change. Which of the following is not a greenhouse gas?A.carbon dioxideB.oxygenC.methaneD.nitrous oxide答案：B。
“carbon dioxide”（ 二氧化碳）、“methane”（ 甲烷）、“nitrous oxide” 一氧化二氮）都是温室气体，“oxygen” 氧气）不是温室气体。
3.Climate change has caused many species to face extinction. The word “extinction” means_____.A.disappearanceB.reductionC.changeD.protection答案：A。
“extinction”意为“灭绝”，“disappearance”是“消失”；“reduction”是“减少”；“change”是“改变”；“protection”是“保护”。
探究光合作用产生氧气的实验氧气收集方法As we experiment on the production of oxygen during photosynthesis, a crucial aspect to consider is the method of collecting the oxygen gas. One common method that can be used is the downward displacement of water method. This method involves collecting the oxygen gas in an inverted container filled with water.As the oxygen is produced, it displaces the water inside the container, allowing for the collection of the gas.在进行光合作用产生氧气的实验时，收集氧气的方法是一个至关重要的方面。
一个常用的方法是使用向下排水法。
这种方法涉及将氧气集中在一个倒置的装满水的容器内。
当氧气产生时，它会排走容器内的水，从而可以收集氧气。
Another method that can be used for the collection of oxygen gas during photosynthesis experiments is the use of a gas syringe. A gas syringe is a device that can be attached to the reaction vessel where oxygen is being produced. As the oxygen gas is generated, it can be collected directly into the gas syringe, allowing for accurate measurement and observation of the gas produced.在进行光合作用实验时，可以使用的另一种收集氧气的方法是使用气体注射器。
七年级地球构造组成单选题50题1. Scientists believe that the ______ is the thinnest layer of the Earth, which is like the "skin" of our planet. It is where most earthquakes occur.A. mantleB. outer coreC. crustD. inner core答案：C。
解析：地壳是地球最外面的一层，它很薄，就像地球的“皮肤”，并且大多数地震都发生在地壳，所以C正确。
地幔是位于地壳和地核之间的一层，A选项不符合题意。
外核和内核是地核的组成部分，B和D选项也不符合描述。
2. The layer of the Earth that is mainly made up of hot, semi - liquid rock is the ______.A. crustB. mantleC. outer coreD. inner core答案：B。
解析：地幔主要由炎热的半液态岩石组成。
地壳是固态的岩石层，A选项错误。
外核是液态的铁镍层，C选项不符合题意。
内核是固态的铁镍核心，D选项也不正确。
3. Which part of the Earth is thought to be composed of solid iron and nickel?A. MantleB. Outer coreC. CrustD. Inner core答案：D。
解析：内核被认为是由固态的铁和镍组成的。
地幔主要由半液态岩石组成，A选项错误。
外核是液态的铁镍层，B选项错误。
地壳主要由岩石组成，C选项错误。
4. The ______ is the hottest part of the Earth.A. crustB. mantleC. outer coreD. inner core答案：D。
变压器油中气体含量标准The gas content in transformer oil is an important parameter that needs to be monitored and controlled inorder to ensure the proper functioning of the transformer. The presence of gases in transformer oil can indicate various issues, such as degradation of insulation materials, overheating, or the presence of faults or contaminants. Therefore, there are certain standards and requirements set for the gas content in transformer oil. In this essay, wewill discuss these standards and requirements from multiple perspectives.Firstly, it is important to understand the different types of gases that can be present in transformer oil. The most common gases found in transformer oil include oxygen (O2), nitrogen (N2), hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and ethylene (C2H4). Each of these gases can indicate different issues or conditions within the transformer. For instance, the presence of oxygen can suggest that the transformer isexposed to air, which can lead to oxidation and degradation of the insulation materials. On the other hand, the presence of hydrogen can indicate the presence of partial discharges or overheating.Now, let's discuss the standards and requirements for gas content in transformer oil. The International Electrotechnical Commission (IEC) has set certain limitsfor the gas content in transformer oil. According to the IEC 60599 standard, the total gas content in transformeroil should not exceed 10% by volume. This means that the sum of all the individual gases should not exceed 10% of the total volume of the oil. Additionally, the IEC 60599 standard also specifies limits for specific gases. For example, the maximum limit for oxygen is 2000 ppm (parts per million), while the maximum limit for hydrogen is 500 ppm.Furthermore, it is important to regularly monitor the gas content in transformer oil to ensure that it remains within the specified limits. This can be done through various methods, such as gas chromatography or dissolvedgas analysis (DGA). DGA is a widely used technique that involves extracting a sample of transformer oil and analyzing it for the presence and concentration ofdifferent gases. By regularly monitoring the gas content, any abnormal conditions or faults within the transformer can be detected at an early stage, allowing for timely maintenance or repairs.In addition to the IEC standards, different countries or regions may have their own specific requirements for gas content in transformer oil. For example, in the United States, the American National Standards Institute (ANSI) has set standards for the gas content in transformer oil. These standards, known as the ANSI/IEEE C57.104 andC57.104a, provide guidelines for the interpretation of DGA results and specify limits for various gases. It is important for transformer manufacturers and operators to be aware of these specific requirements in order to ensure compliance.Moreover, it is worth mentioning that the gas content in transformer oil can vary depending on the type anddesign of the transformer, as well as its operating conditions. For instance, transformers with higher voltage ratings or those subjected to heavy loads may experience higher gas content due to increased stress on theinsulation materials. Therefore, it is necessary to consider these factors when determining the acceptable gas content in transformer oil.In conclusion, the gas content in transformer oil is an important parameter that needs to be monitored and controlled. The presence of gases can indicate various issues or conditions within the transformer, and there are certain standards and requirements set for the gas content. The IEC standards, as well as country-specific standards such as ANSI/IEEE, provide guidelines and limits for the gas content in transformer oil. Regular monitoring of the gas content is essential to detect any abnormalities or faults at an early stage. By adhering to these standards and requirements, transformer manufacturers and operators can ensure the proper functioning and longevity of transformers.。
3d打印粉末的含氧量指标English Answer：Oxygen Content in 3D Printing Powders.Oxygen content is a critical parameter for 3D printing powders. It can affect the powder's flowability, printability, and mechanical properties of the printed parts. The optimal oxygen content for a given powder depends on the type of powder, the printing process, and the desired properties of the printed parts.Measuring Oxygen Content.The oxygen content of 3D printing powders can be measured using a variety of techniques, including:Thermogravimetric analysis (TGA): TGA measures the weight loss of a sample as it is heated. The weight loss can be used to calculate the oxygen content of the sample.Gas chromatography-mass spectrometry (GC-MS): GC-MS separates and identifies the different gases in a sample. The amount of oxygen in the sample can be determined by measuring the peak area of the oxygen peak in the GC-MS chromatogram.Elemental analysis: Elemental analysis measures the elemental composition of a sample. The oxygen content of the sample can be determined by measuring the amount of oxygen atoms in the sample.Factors Affecting Oxygen Content.The oxygen content of 3D printing powders can be affected by a variety of factors, including:Powder composition: The composition of the powder can affect its oxygen content. For example, powders that contain metal oxides will have a higher oxygen content than powders that contain pure metals.Manufacturing process: The manufacturing process can also affect the oxygen content of the powder. For example, powders that are produced using a high-temperature process will have a lower oxygen content than powders that are produced using a low-temperature process.Storage conditions: The storage conditions can also affect the oxygen content of the powder. For example, powders that are stored in a humid environment will have a higher oxygen content than powders that are stored in a dry environment.Effects of Oxygen Content.The oxygen content of 3D printing powders can have a significant impact on the powder's flowability, printability, and mechanical properties of the printed parts.Flowability: Oxygen can affect the flowability of powders. Powders with a high oxygen content tend to be less flowable than powders with a low oxygen content. This isbecause the oxygen can form hydrogen bonds with the powder particles, which can make them stick together.Printability: Oxygen can also affect the printability of powders. Powders with a high oxygen content tend to be more difficult to print than powders with a low oxygen content. This is because the oxygen can react with the printing materials, which can cause defects in the printed parts.Mechanical properties: Oxygen can also affect the mechanical properties of printed parts. Parts made from powders with a high oxygen content tend to be weaker and less durable than parts made from powders with a low oxygen content. This is because the oxygen can weaken the bonds between the powder particles.Conclusion.Oxygen content is a critical parameter for 3D printing powders. It can affect the powder's flowability, printability, and mechanical properties of the printedparts. The optimal oxygen content for a given powder depends on the type of powder, the printing process, andthe desired properties of the printed parts.Chinese Answer：3D打印粉末含氧量。
DOI: 10.1016/S1872-5813(21)60177-9铌元素改性V 2O 5-WO 3/TiO 2催化剂降低脱硝过程 SO 2 的氧化率王 博1，边 瑶1，封 硕1，王少奇1，沈伯雄1,2,*（1. 河北工业大学 能源与环境工程学院, 天津市清洁能源利用与污染物控制重点实验室, 天津 300401；2. 河北工业大学 化工学院, 天津 300401）摘 要：本文采用浸渍法制备了Nb 改性的V 2O 5-WO 3/TiO 2催化剂，研究了脱硝反应中Nb 负载量对催化剂SO 2氧化活性的影响。
结果表明，在350 °C 下，Nb 2O 5负载量为2%的Nb 2O 5-V 2O 5-WO 3/TiO 2催化剂上的SO 2氧化率最低（0.6%），而同时NO x 的转化率仍能达到95%。
采用TGA 、氮吸附、XRD 、H 2-TPR 、CO 2-TPD 、XPS 和in- situ DRIFTS 等对催化剂进行了表征分析，结果显示，Nb 改性后V 2O 5-WO 3/TiO 2催化剂的晶体结构没有发生明显改变，但是其比表面积小幅度下降，有助于减少对SO 2的吸附；同时，改性后催化剂表面的吸附氧含量下降，氧化还原性能也稍微减弱，这有利于降低其对SO 2的氧化活性。
in-situ DRIFTS 结果表明，Nb 改性后的Nb-V 2O 5-WO 3/TiO 2催化剂反应过程中表面中间产物VOSO 4的含量明显下降，从而减少了SO 3的生成量。
关键词：SO 2氧化；Nb 改性；V 2O 5-WO 3/TiO 2催化剂；NH 3-SCR 脱硝中图分类号： X51;TQ42 文献标识码： AModification of the V 2O 5-WO 3/TiO 2 catalyst with Nb to reduce its activityfor SO 2 oxidation during the selective catalytic reduction of NO xWANG Bo 1，BIAN Yao 1，FENG Shuo 1，WANG Shao-qi 1，SHEN Bo-xiong1,2,*（1. College of Energy and Environmental Engineering , Hebei University of Technology , Key Laboratory of Clean EnergyUtilization and Pollutant Control in Tianjin , Tianjin 300401, China ；2. College of chemical engineering , Hebei University of Technology , Tianjin 300401, China ）Abstract: A series of Nb-modified V 2O 5-WO 3/TiO 2 catalysts were prepared by the impregnation method and the effect of Nb loading on their SO 2 oxidation activity during the selective catalytic reduction of NO x was investigated.The results indicate that the Nb 2O 5-V 2O 5-WO 3/TiO 2 catalyst with a Nb 2O 5 loading of 2% exhibits the lowest SO 2conversion of 0.6% for oxidation at 350 °C, whereas the conversion of NO x is still above 95%. The catalysts were characterized by TGA, BET, XRD, H 2-TPR, CO 2-TPD, XPS and in-situ DRIFTS. The results illustrate that the influence of Nb modification on the crystal structure of V 2O 5-WO 3/TiO 2 catalyst is rather insignificant; however, the surface area of the Nb 2O 5-V 2O 5-WO 3/TiO 2 catalyst decreases slightly after the modification with Nb, conducing to a decrease of SO 2 adsorption on the catalyst. Meanwhile, the content of oxygen adsorbed on the catalyst surface decreases considerably upon the Nb modification, suggesting a weakened redox performance, which is beneficial to reducing the oxidation of SO 2. The in-situ DRIFTS results illustrate that the content of the intermediate VOSO 4product on the catalyst surface decreases over the Nb-modified Nb 2O 5-V 2O 5-WO 3/TiO 2 catalyst, leading to a decrease of SO 3 production.Key words: SO 2 oxidation ；Nb modification ；V 2O 5-WO 3/TiO 2；removal of NO x by NH 3-SCR烟气中的SO 3主要来源于SO 2与氧气在高温下的直接氧化以及SCR 脱硝催化剂的催化氧化[1]。
主题：2023新高考全国二卷英语阅读理解c篇一、文章导读2023年的新高考全国二卷英语科目中，阅读理解部分是考生们必须要面对的内容之一。
其中c篇作为阅读材料的一部分，往往涉及到一定的难度和深度。
本文将对2023年新高考全国二卷英语阅读理解c篇进行全面的分析和解读，帮助考生更好地应对考试。
二、文章内容1. 阅读材料内容介绍c篇作为2023年新高考全国二卷英语阅读理解的一部分，其内容可能涉及到社会热点、科技进展、文化交流等多个方面。
考生在阅读理解c 篇时需要对材料内容进行全面、准确的理解，并能够准确把握文章的主旨和细节。
2. 阅读技巧和方法在阅读c篇时，考生需要具备一定的阅读技巧和方法。
考生应该注重对文章整体结构和段落结构的把握，从而更好地理解文章的脉络和逻辑。
考生需要注重词汇的理解和语法的分析，以便更准确地理解句子和段落的含义。
考生还需要注重文章中可能涉及到的隐含信息和修辞手法，从而更深入地理解文章的内涵和意图。
3. 复习备考建议针对2023年新高考全国二卷英语阅读理解c篇，考生需要合理安排自己的复习备考时间。
建议考生在复习备考过程中，多进行真题练习和模拟考试，从而更好地适应考试的时间和压力。
考生还可以通过阅读相关文章和资料，提升自己的阅读理解能力和水平。
4. 解题技巧指导在解答阅读理解c篇的题目时，考生需要注重题目类型和解题技巧。
不同类型的题目需要采取不同的解题方法，例如细节题、主旨题、态度题等。
考生需要根据题目要求，合理选择解题方法，从而更准确地完成题目要求。
5. 注意事项和答题建议在答题过程中，考生需要注意时间分配和答题顺序的安排。
建议考生先从易到难、从简单到复杂的顺序进行答题，避免因为一道难题耽误了其他题目的答题时间。
考生还需要注意答题的规范和清晰度，确保自己的答案能够清晰地表达自己的观点和理解。
三、结语2023年新高考全国二卷英语阅读理解c篇作为考生必须要面对的内容之一，对于考生的英语水平和能力有一定的要求。
•Coal, petroleum and natural gas now yield their bond energies to man.煤，石油和天然气现在为人类提供各种各样的结合能。
•Salts may also be found by the replacement of hydrogen from an acid with a metal.盐也能通过用金属置换酸中的氢而获得。
•An acid was once defined as a substance that would form hydrogen ions(H+) in water solution and a base as one that would form hydroxide ions(OH-) in the same.人们曾把酸定义为在水溶液中能产生氢离子的物质，而碱则是在同样溶液中会产生氢氧根离子的物质。
•These books are packed in tens. 这些书每十本装一包。
•These products are counted by hundreds. 这些产品是成百成百计数的。
•They went out by twos and threes. 他们三三两两地出去了。
•They consulted tens of magazines. 他们查阅了几十本杂志。
•Automation helps to increase productivity hundreds of times over. 自动化使生产率提高了几百倍。
•More weight must be placed on the past history of patients. 必须更加重视患者的病史。
•The continuous process can be conducted at any prevailing pressure without release to atmospheric pressure.连续过程能在任何常用的压力下进行，而不必暴露在大气中。
高一生物学英语阅读理解30题1<背景文章>Cells are the basic units of life. Every living organism is made up of one or more cells. The cell has many different structures that perform specific functions.The cell membrane is a thin, flexible layer that surrounds the cell. It controls what enters and leaves the cell. The cytoplasm is the gel-like substance inside the cell. It contains many different organelles.One of the most important organelles is the nucleus. The nucleus contains the cell's genetic material, DNA. The DNA contains the instructions for making proteins. Proteins are essential for life. They perform many different functions in the cell, such as catalyzing chemical reactions and providing structural support.Another important organelle is the mitochondria. The mitochondria are the powerhouses of the cell. They produce energy in the form of ATP. ATP is used by the cell to perform all of its activities.Cells also contain other organelles such as the endoplasmic reticulum, Golgi apparatus, and lysosomes. Each of these organelles has a specific function.In summary, cells are complex structures that perform many differentfunctions. They are the building blocks of life.1. The cell membrane controls what ________ the cell.A. enters and leavesB. stays insideC. is made ofD. surrounds答案：A。
气体透过率、透过量以及透过系数应用指南摘要: 本文详细介绍了三项透气性参数（气体透过率、透过量以及透过系数）的定义、应用范围以及相互之间的差异和换算关系，同时对于目前国际、国内标准中定义不清晰的情况给予说明。
关键词：透气性，透过率，透过量，透过系数目前，国内、国际标准在一些透气性参数的定义上存在细微差异，致使参数概念及应用较为混乱。
这不但会影响数据传递，同时还能引起对材料评价的失误。
本文着重分析透气性参数气体透过率、气体透过量以及气体透过系数的定义，对它们之间的关系进行介绍，并指出实际应用中应当注意的问题。
1.透气性参数的标准定义由于在等压法中存在载气（氮气）的逆向渗透，使得它与传统压差法存在着本质上的不同，是两类不同的测试方法。
测试方法的差异会对其应用范围以及参数定义带来影响（例如等压法基本上只用于进行氧气检测，而压差法对于测试气体几乎没有限制），因此这里按照测试方法的种类分别对透气性参数的定义进行介绍。
1.1 压差法1.1.1 ASTM D1434-82ASTM D1434-82中，用于描述材料透气性能的参数有以下三个：1. Gas Transmission Rate (GTR): The quantity of a given gas passing through a unit of the parallel surfaces of a plastic film in unit time under the conditions of test. The SI unit of GTR is 1 mol / (m2·s).译文：气体透过率（GTR）：在试验环境下，在单位时间内、单位面积上透过塑料薄膜两平行平面的特定气体总量。
GTR的SI单位为mol / (m2·s)。
2. Permeance (P): The ratio of the gas transmission rate to the difference in partial pressure of the gas on the two sides of the film. The SI unit of permeance is 1 mol / (m2·s·Pa).译文：（气体）透过量（P）：气体透过率与薄膜两侧的测试气体分压差的比值。
Effect of graphene oxide on the behavior of poly(amide-6-b-ethylene oxide)/graphene oxide mixed-matrix membranes in the permeation processDan Zhao,1,2Jizhong Ren,1Yongtao Qiu,1,2Hui Li,1Kaisheng Hua,1Xinxue Li,1Maicun Deng11National Laboratory for Clean Energy,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,457Zhongshan Road,Dalian116023,China2University of Chinese Academy of Sciences,Beijing100049,ChinaCorrespondence to:J.Ren(E-mail:renjizhong@)ABSTRACT:Polyether-block-amide(Pebax)/graphene oxide(GO)mixed-matrix membranes(MMMs)were prepared with a solution casting method,and their gas-separation performance and mechanical properties were pared with the pristine Pebax membrane,the crystallinity of the Pebax/GO MMMs showed a little increase.The incorporation of GO induced an increase in the elastic modulus,whereas the strain at break and tensile strength decreased.The apparent activation energies(E p)of CO2,N2,H2,and CH4permeation through the Pebax/GO MMMs increased because of the greater difficulty of polymer chain rotation.The E p value of CO2changed from16.5kJ/mol of the pristine Pebax to23.7kJ/mol of the Pebax/GO MMMs with3.85vol%GO.Because of the impermeable nature of GO,the gas permeabilities of the Pebax/GO MMMs decreased remarkably with increasing GO content,in par-ticular for the larger gases.The CO2permeability of the Pebax/GO MMMs with3.85vol%GO decreased by about70%of that of the pristine Pebax membrane.Rather than the Maxwell model,the permeation properties of the Pebax/GO MMMs could be described successfully with the Lape model,which considered the influence of the geometrical shape and arrangement pattern of GO on the gas transport.V C2015Wiley Periodicals,Inc.J.Appl.Polym.Sci.2015,132,42624.KEYWORDS:gas transport;graphene oxide;mixed matrix membranes;pebaxReceived17March2015;accepted15June2015DOI:10.1002/app.42624INTRODUCTIONMembrane-based processes have been used in various applica-tions,such as chemical processing,energy production,and envi-ronmental protection.Membranes can be prepared with many methods.The most applied technique for the preparation of homogeneous membranes is solution casting.1For asymmetric membranes,it includes the dip-coating2and phase-inversion techniques.3,4For different applications,some modifications of the membrane are usually needed;these include blending,cross-linking,and grafting.Among these,mixed-matrix membranes (MMMs),a blend of organic polymers and inorganic fillers, have drawn considerable attention because they can combine the advantages of polymers and inorganic materials,5and they have been widely researched for the separation of O2/N2,6CO2/ CH4,1and so forth.To improve the membrane performance,some fillers,such as zeolites,carbon molecular sieves,metal organic frameworks, and carbon nanotubes,have been used to prepare MMMs.7–10 In addition to these permeable fillers,impermeable fillers,such as SiO2,TiO2,and C60,have also been investigated.11–13In recent years,nanocomposites and MMMs based on flake fillers such as graphene have attracted more pared with traditional molecular-sieving materials,flake fillers usually have a high aspect ratio(A f),which is favorable for the preparation of thin MMMs.Graphene is a two-dimensional carbon monolayer composed of sp2-hybridized carbons,and graphitic materials of all other dimensionalities can be built with graphene,such as fullerene (zero dimensional),carbon nanotubes(one dimensional),and graphite(three dimensional).14Graphene has very strong mechanical properties15and is impermeable to all gases.16 Nanocomposites containing graphene have been used in a vari-ety of applications,such as those in electricity,17,18mechanics,19 separation,17,20and catalysts.21It has been pointed out that the mechanical enhancement of nanocomposites can be achieved when graphene is dispersed homogeneously in the polymer matrix and the interfacial interactions between the fillers and the polymer matrix is strong.19However,because of theV C2015Wiley Periodicals,Inc.intrinsic van der Waal forces,graphene tends to agglomerate; this can usually weaken the reinforcement of the nanocompo-sites.The functionalization of graphene,such as oxidation,can effectively reduce its agglomeration in the polymer matrix.Gra-phene oxide(GO)can be synthesized from graphite by Hummer method.18,21GO is heavily oxygenated,and its oxygen-containing functional groups include hydroxyls,epox-ides,diols,ketones,and carboxyls;these can make GO strongly hydrophilic and give it a good dispersion in water.22In addi-tion,the functional groups are also beneficial for the improve-ment of the interfacial interaction between the fillers and the polymer matrix.23Some studies have shown a reinforcement effect of graphene.19,24,25Liang et al.19achieved a76%increase in the tensile strength and a62%improvement in Young’s mod-ulus for poly(vinyl alcohol)/GO MMMs with0.7wt%GO. Steurer et al.25found that the Young’s modulus of polyamide6/ thermally reduced graphite oxides nanocomposites increased by 32%,whereas the strain at break decreased by94%with5wt% thermally reduced graphite oxide.The permeation properties are very important for MMMs and can be affected by the physical and chemical properties of the fillers.For graphene,because of its impermeability to all gases and its high surface area,its incorporation into polymers creates a large barrier effect for gas diffusion.17,26,27Kim et al.17modi-fied polyurethane with thermally reduced graphite oxide via melting compounding and solvent blending and found that the N2permeability decreased by about50and80%,respectively,at 1.6vol%thermally reduced graphite oxide;this indicated that solvent blending was more effective.Kim and Macosko27 observed a47%decrease in the H2permeability when6.1vol% graphite was added to poly(ethylene-2,6-naphthalate). Polyether-block-amide(Pebax)is a commercial thermoplastic elastomer,and it is known for its prior penetration of CO2over other light gases,such as H2,N2,and CH4.The general chemi-cal structure of Pebax is shown in Figure1,where PA is the polyamide block[e.g.,as nylon6(polyamide6)and nylon12 (polyamide12)]and PE is the polyether block[e.g.,poly(tetra-methylene oxide)and poly(ethylene oxide)].28The gas-permeation properties of Pebax have been studied,28,29and some modifications aimed at improving its permeabilities and selectivities,have also been made.30–33The modifiers are mainly organic materials,such as poly(ethylene glycol)(PEG)and pol-y(dimethyl siloxane)(PDMS).Car et al.31,32modified Pebax with PEG and found that the CO2permeability and permeation flux of the Pebax/PEG membrane(50wt%PEG)increased by two to three times compared to those of pristine Pebax.Reijer-kerk et al.30prepared Pebax/PDMS–PEG blend membranes and found that the CO2permeability increased by five times at a50 wt%PDMS–PEG loading.Recently,the modification of Pebax with inorganic materials has attracted some attention,but the research on this area is still limited,and more investigations are needed.As mentioned previously,different kinds of fillers,including permeable/impermeable fillers and organic/inorganic fillers, have been used for preparing MMMs.So,it is necessary to describe and explain the influence of different fillers on the MMMs permeation properties;these can guide and optimize the separation performance of the MMMs.In this study,GO was incorporated into the Pebax matrix to prepare the Pebax/GO MMMs with a solution casting method. The Pebax/GO MMMs were characterized by X-ray diffraction (XRD),Fourier transform infrared(FTIR)spectroscopy,scan-ning electron microscopy,and stress–strain tests.Moreover,the influence of the GO content on the gas-permeation performance of the Pebax/GO MMMs was investigated.We determined the transport properties of the Pebax/GO MMMs by considering the geometrical shape and arrangement pattern of GO. THEORYThe widely accepted theory for gas transport in dense mem-branes is that it is done through a solution–diffusion mecha-nism.34Some theoretical models have been developed to predict the gas permeabilities of MMMs.The steady-state permeabilities of MMMs can generally be estimated by the Maxwell model,35 shown in eq.(1),which is suitable for the prediction of MMMs filled with molecular sieves and other polymers,in particular for those filled with low contents of spherical fillers:P MMMsP05P f12P022/ðP02P fÞP f12P01/ðP02P fÞ(1)P MMMs5222/(2)P MMMsP05112/12/(3) where P0is the permeability of the pristine polymer membrane (Barrer),P MMMs is the permeability of the MMMs(Barrer),P f is the permeability of the fillers(Barrer),and/is the volume fraction of the fillers.P MMMs/P0is called the normalized perme-ability.When the fillers,such as C60,SiO2,are impermeable (i.e.,P f50),the Maxwell model can be rewritten as eq.(2).If the fillers are highly permeable,P f51can be assumed,and the result is shown in eq.(3).For fillers with special geometries that are significantly different from a spherical one,the gas permeabilities may deviate from the predication of eq.(1).For MMMs composed of imperme-able flakes,the impermeable flakes have a much larger effect on the gas permeabilities when they are parallel to the membrane surface.When/of the flakes is small(/<<1)and A f/>1, P MMMs/P0can be described by the Lape model36shown in eq.(4):P MMMsP051114A f2/212/21(4) where A f is used to characterize the geometrical shape of the fil-ler and is defined as the flake length(d)divided by the thick-ness(h).This model assumes that the flakes are placed in a regular array,as shown schematically in Figure2. Figure1.Schematic diagram of Pebax.The models mentioned previously do not consider the struc-tural changes of the membrane induced by the fillers;the inter-actions among the polymers,fillers,and penetrates;and the nature of penetrates,such as the gas molecular sizes.According to eqs.(2–4),the gas selectivities of the MMMs are not affected by the fillers and are the same as those of the pristine polymer membranes.EXPERIMENTALMaterialsPebax MH1657[Pebax1657,consisting of60wt%poly(ethyl-ene oxide)and40wt%polyamide6,density51.14g/cm3]was purchased from Arkema,Inc.GO(diameter51–5l m, thickness50.8–1.2nm)was purchased from Nanjing XFNANO Material Tech Co.,Ltd.A mixture of ethanol and water(70/30 wt%)was used as a solvent for Pebax.Ethanol(analytical grade)was provided by Sinopharm Chemical Reagent Co.,Ltd. Pure CO2,CH4,H2,and N2were supplied by Dalian Gases Co. All of the materials were used as received.Membrane PreparationThe membranes were prepared with a solution casting method. Pebax(1.8g)was added to the ethanol/water mixture(40mL) to prepare the Pebax solution at about808C under reflux and with vigorous stirring for4h.GO was dispersed in deionized water and then ultrasonicated for6–18h to form a suspension of GO,and the GO/H2O concentration was1–3.6mg/mL.The mass ratios of GO to Pebax(Y)were0:100–8:100,and the compositions of the Pebax/GO MMMs are denoted as P100G0–P100G8,accordingly.After the Pebax solution was cooled to ambient temperature,the Pebax solution and GO aqueous dis-persion were mixed and stirred slowly for at least5h at ambi-ent temperature.Then,the mixed solution was cast into a Teflon ring mold,and the solvent was evaporated at about 408C.After the membranes were formed,they were dried in a vacuum oven at508C for at least3days to remove the residual solvent,and then,the dried membranes were held in a vacuum oven at ambient temperature.The membranes thicknesses were 65–85l m.Here,the density of GO was assumed to be2.28g/ cm3,17so/of GO could be calculated with eq.(5):/5m GO=q fm GO=q f1m Pebax=q05Y=2:28Y=2:2811=1:14(5)where m GO and m Pebax are the masses of GO and Pebax,respec-tively,and q f and q0are the densities of GO and Pebax, respectively.Membrane CharacterizationThe crystalline properties of the Pebax/GO MMMs were meas-ured with a wide-angle X-ray diffractometer(X’Pert Pro-1)with Cu K a radiation(k51.5406A˚).The morphologies of the Pebax/GO MMMs were observed with a field emission scanning electron microscope(Quanta 200FEG).The samples were fractured in liquid nitrogen and then coated with gold by a sputtering method.FTIR spectra of GO and Pebax/GO MMMs were obtained in attenuated total refection mode with an Equinox55FTIR spectrometer.Stress–Strain TestsStress–strain measurements were conducted via a Reger univer-sal material testing system at room temperature.Specimens with a gauge length of20mm and a width of5mm were used, and the thickness of the specimens was determined with a thickness tester.The test speed was10mm/min.The results are the average values of several measurements.Gas-Permeation MeasurementsThe gas-permeation properties of the Pebax/GO MMMs were determined with a constant-volume/variable-pressure technique. The permeate side of the membrane was evacuated before each test.The permeation properties of the pure N2,CH4,H2,and CO2were studied.The gas permeabilities and diffusion coeffi-cients could be calculated with eqs.(6)and(7):P5176273:15TVAlD pdpdt(6)D5l26h(7) where P is the gas permeability[Barrer;1Barrer510210 cm3(STP)cm(cm2ÁsÁcmHg)21],V is the downstream volume (cm3),A is the area of the membrane(cm2),T is the operating temperature(K),D p is the transmembrane pressure difference (cmHg),l is the membrane thickness(cm),dp/dt is the rate of pressure increase measured by a pressure sensor in the down-stream chamber(cmHg/s),D is diffusion coefficient(cm2/s), and h is the diffusion time lag(s).The relative standard devia-tion of gas permeabilities were calculated by the following equa-tion,and the relative standard deviation of the gas permeabilities was within10%:D Pj P j5j D V jV1j D A jA1j D T jT1j D l jl1j DðD pÞjD p1j Dðdp=dtÞjdp=dt(8) The ideal selectivity(a)of one penetrant(subscript A)over another(subscript B)is given by eq.(9):a A=B5P AP B(9) where P A and P B are the permeability of penetrant A and pene-trant B,respectively.RESULTS AND DISCUSSIONPhysical Properties of the Pebax/GO MMMsXRD was used to determine the crystalline properties of the Pebax/GO MMMs,and the results are shown in Figure3.The Figure2.Schematic diagram of the Lape model.pristine Pebax membrane (P100G0)was a semicrystalline poly-mer with diffraction peaks at 14,17,and 248of 2h ,and the peak at 2h 5248resulted from the crystalline region of the PA segment by hydrogen bonding.37All of the Pebax/GO MMMs showed similar XRD patterns;this proved that GO did not destroy the semicrystalline structure of Pebax.It has been reported that the characteristic peak of GO was at a 2h of 118.19,21However,this was not observed in the Pebax/GO MMMs,which were similar to the poly(vinyl alcohol)/GO MMMs observed by Liang et al .19and Xu et al .24Exfoliated GO,in the monolayer form,showed no intensity characteristic peaks.38So,the results proved that GO was well exfoliated and uniformly dispersed in the polymer matrix.19,24The intensity of the diffraction peak at 2h 5248of the Pebax/GO MMMs was higher than that of the pristine Pebax membrane;this indicated that GO acted as a nucleating agent and induced the increase of crystallinity just like in multiwalled carbon nanotubes.39The FTIR spectra of GO,P100G0,and P100G8were detected and are shown in Figure 4.For GO,the characteristic peaks around 3265,1730,1556,and 1342cm 21were the stretching vibrations of O A H,C @O,and C @C and the bending vibrations of C A OH,respectively;40,41this suggested that there were atleast some hydroxyl and carboxyl groups in GO.The peak at 1111cm 21represented the stretching vibrations of C A O.42The stretching vibrations at 2872cm 21suggested the presence of ali-phatic C A H groups,which was consistent with a nonaromatic carbon structure in GO.41,42For the pristine Pebax,the peaks at 3296and 1097cm 21repre-sented the stretching vibrations of N A H and C A O,respec-tively.37The peak at 1740cm 21was assigned to the free C @O,and the peak at 1641cm 21indicated the presence of hydrogen-bonded C @O in H A N A C @O.37,43The characteristic peaks of GO were not shown clearly in the spectrum of P100G8,which might have been because they were so weak that they were overlapped by those strong peaks of Pebax.On the other hand,because some of the Pebax matrix was present on the surface of GO,the spectrum of GO might not have been detected,and only that of Pebax was shown.The morphologies of the Pebax/GO MMMs are shown in Figure pared with that of P100G3[Figure 5(b)],the surface of P100G0[Figure 5(a)]was much smoother.As shown in Figure 5(b,d),GO was in the form of flakes,and it seemed that GO was well dispersed in the Pebax matrix.This was consistent with the XRD analysis.This suggested that the agglomeration of GO was inhibited with the aids of functionalizationandFigure 3.XRD patterns of Pebax/GOMMMs.Figure 4.FTIR spectra of GO,P100G0MMM,and P100G8MMM.Figure 5.(a,b)Surface scanning electron microscopy images,(c,d)cross-sectional scanning electron microscopy images,and (e,f)digital pictures of Pebax/GO MMMs:(a)P100G0,(b)P100G3,(c)P100G0,(d)P100G3,(e)P100G3,and (f)P100G8.[Color figure can be viewed in the online issue,which is available at .]ultrasonic treatment.The color of the Pebax/GO MMMs with less GO was golden,such as that of P100G3shown in Figure 5(e).With increasing GO,the Pebax/GO MMMs became darker in color;for example,P100G8,shown in Figure 5(f),was dark brown.Mechanical Properties of the Pebax/GO MMMsThe mechanical properties of the Pebax/GO MMMs were eval-uated by stress–stain tests,which are shown in Figure 6.As shown in Figure 6(a),with increasing GO content,the stain at break decreased,whereas the elasticity modulus increased.For the Pebax/GO MMMs with 3.85vol %GO (P100G8),the strain at break decreased by 98%,and the elasticity modulus increased by 56%.This suggested that the Pebax/GO MMMs were more brittle and rigid than the pristine Pebax membrane.44Because the elasticity modulus was used to characterize the resistance to elastic deformation,the higher elasticity modulus of the Pebax/GO MMMs indicated that the incorporation of GO was benefi-cial for the improvement of the antideformation capacity of the Pebax/GO MMMs.The tensile strength decreased by 34%at a 3.85vol %GO loading [Figure 6(b)];this suggested that the incorporation of GO inhibited the molecular rearrangement and orientation during deformation 45and that the interaction between GO and Pebax was not strong enough to enhance the tensile strength.19Gas-Permeation Properties of the Pebax/GO MMMsFigure 7shows the influence of the pressure on the gas perme-abilities of the P100G4MMMs.It was clear that the relationship between the gas permeability and pressure could be expressed with the following linear equation:46P 5P D p 5011n D p ðÞ(10)where P D p 50is the gas permeability when D p is 0(i.e.,infinite dilution permeability)and n is an adjustable constant that char-acterizes the effect of pressure on gas permeability.Just as that shown in Figure 7,the CO 2permeability increased with pressure,so the n value was positive for CO 2;this was induced by plasticization.For H 2,CH 4,and N 2,the permeabil-ities were influenced little by the pressure,and the n values were a little negative because of the hydrostatic compression effect.47The n values of the Pebax/GO MMMs for CO 2,N 2,H 2,and CH 4are listed in Table pared with the pristine Pebax membrane,the n values for CO 2became larger,and the abso-lute values of n for H 2,CH 4,and N 2became smaller with increasing GO content.This suggested that the plasticization of CO 2increased,whereas the hydrostatic compressive effect of H 2,CH 4,and N 2decreased.In fact,the increased crystallinity and more rigid nature of the Pebax/GO MMMs contributed to the changes in the n values.The increased crystallinity and the more rigid nature of the MMMs made the fractional free vol-ume decrease and resulted in a smaller hydrostatic compressive effect and subsequently made the absolute values of n for H 2,CH 4,and N 2become smaller.For CO 2,n was determined by the plasticization and hydrostatic pressure;a lower hydrostatic compressive effect made the increase of CO 2with pressure more ly,the plasticization effect became more obvious.The influence of the temperature on the gas permeability is shown in Figure 8.The gas permeabilities increased with tem-perature.For CO 2,its solubility in the rubbery polymer decreased with increasing temperature;however,for H 2and N 2,the solubility increased with increasing temperature.48There-fore,in particular for CO 2,the diffusivity made agreatFigure 6.Influence of the GO content on the mechanical properties of the Pebax/GOMMMs.Figure 7.Influence of the pressure on the permeabilities of ()CO 2,( )H 2,(~)CH 4,and (!)N 2for P100G2MMM at 358C.contribution to the increase in the gas permeability with tem-perature.There was a linear relationship between the logarithm of the gas permeability and the reciprocal of the temperature;this could be expressed by the Arrhenius equation:P 5P o exp2E pRT (11)where P 0is the pre-exponential factor,E p is the apparent activa-tion energy for permeation (kJ/mol),R is the gas constant (8.314J ÁK 21Ámol 21),and T is the absolute temperature (K).Table II lists the E p values of the Pebax/GO MMMs for CO 2,N 2,H 2,and CH 4.The E p of CO 2was the smallest;this was con-tributed by its interaction with the poly(ethylene oxide)segment and its high condensability,which was characterized by the crit-ical temperature (the critical temperatures of CO 2,N 2,H 2,and CH 4were 304.2,126.2,33.2,and 190.6K,respectively).Com-pared with that of the pristine Pebax membrane,the E p values of the Pebax/GO MMMs for CO 2,N 2,H 2,and CH 4increased with the addition of GO.This might have been because the polymer chains were more difficult to rotate when GO was incorporated,and this resulted in a higher activation energy for diffusion.37Figure 9shows the influence of the GO content on the perme-abilities of CO 2,H 2,CH 4,and N 2.With increasing GO content,the permeabilities of CO 2,H 2,CH 4,and N 2all gradually decreased.For the Pebax/GO MMMs with 3.85vol %GO (P100G8),the permeabilities of CH 4,CO 2,and N 2decreased by74,70,and 69%,respectively,compared to that of the pristine Pebax membrane.So,the selectivities of CO 2/N 2and CO 2/CH 4did not change much (shown in Figure 10);this was consistent with the model prediction from eq.(4).The structural changes in the membranes,such as the chain flexibility,had a minor effect on H 2compared to their effects other gases because of hydrogen’s small size,31as shown later in Table IV,so the H 2permeability only decreased by about 59%at 3.85vol %GO loading.As a result,the CO 2/H 2selectivity decreased by 27%,and the H 2/CH 4selectivity increased by 56%.The remarkable decrease in the gas permeabilities for the Pebax/GO MMMs illustrated that GO inhibited gas diffusion and formed a diffu-sion barrier in the polymer matrix.17First,the addition of impermeable GO decreased the available diffusion area because of the replacement of permeable Pebax by impermeable GO.36Second,the diffusion tortuosity became greater,and the gas dif-fusion channel was restricted after GO was incorporated.37The diffusivities of larger gases decreased to a greater extent than those of smaller gases,13and this also illustrated the changes in the gas selectivities,shown in Figure 10.Meanwhile,the increase in the crystallinity caused by the incorporation of GO,shown in Figure 3,also contributed to the decrease in the gas permeabil-ities.The h of CH 4for the Pebax/GO MMMs are shown in Fig-ure 11;they clearly explain the gas-diffusion properties of the Pebax/GO MMMs with different GO contents.As shown in Fig-ure 11,with increasing GO content,h /l 2l was the membrane thickness for CH 4increased.According to eq.(7),the gas diffu-sivity is inversely proportional to h /l 2,so the CH 4diffusivity decreased with increasing GO content.At present,the represen-tative gas membrane materials mainly include PDMS,cellulose acetate,polyimide,and so on,and their permeation properties are listed in Table III for a comparison with the Pebax/GO MMMs.The Pebax/GO MMMs had high CO 2/N 2and CO 2/H 2selectivities.Table I.n Values of the Pebax/GO MMMs for CO 2,N 2,H 2,and CH 4at 358CP100G0(0vol %GO)P100G2(0.99vol %GO)P100G4(1.96vol %GO)P100G6(2.91vol %GO)P100G8(3.85vol %GO)CO 20.160.160.170.180.18N 220.1520.1720.1120.09320.12H 220.05220.02920.03520.02520.027CH 420.05820.03520.04720.02220.037The relative standard deviation of n was within10%.Figure 8.Influence of the temperature on the permeabilities of ()CO 2,( )H 2,(~)CH 4,and (!)N 2for P100G2MMM at 0.7MPa.Table II.E p Values of the Pebax/GO MMMs for CO 2,N 2,H 2,and CH 4at 0.7MPaP100G0P100G2P100G4P100G5P100G8CO 216.516.019.822.723.7N 235.634.542.143.344.8H 230.830.435.536.336.7CH 434.133.240.342.343.0The relative standard deviation of E p was within 5%.Prediction of the Gas-Permeation Properties for the Pebax/GO MMMsFigure 12shows the experimental and model predicted normal-ized permeabilities for the Pebax/GO MMMs.GO was imperme-able to all gases,so the permeation properties of the Pebax/GO MMMs could be described with eq.(2)or (4).For the Maxwell model described in eq.(2),the predicted normalized permeabil-ities almost did not change with increasing GO content from 0to 4vol %,and there was a big deviation between the experimen-tal and predicted values.That is to say,the Maxwell model could not predict the transport properties of CO 2,N 2,H 2,and CH 4for the Pebax/GO MMMs.Unlike in the Maxwell model,the geo-metrical shape of the fillers was considered in the Lape model with the A f parameter.The experimental values of CO 2,N 2,H 2,and CH 4were well fitted with the Lape model;this suggested that the geometrical shape of the filler played an important role in the transport process of the gases.For the Pebax/GO MMMs,the values of P MMMs /P 0for different gases and /of GO could be calculated,so the A f values of CO 2,N 2,H 2,and CH 4could be regressed with Origin software according to the Lape model.Thevalues of A f are shown in Table IV,and small deviations for CO 2,N 2,H 2,and CH 4was observed.Theoretically,A f should have been a constant value for the Pebax/GO MMMs;this was not rel-evant to penetrates.However,on the basis of the assumption of a parallel regular array of the fillers,the Lape model does not con-sider the size distribution and random orientation of fillers,the physical properties of the penetrates (e.g.,molecular size),and the interaction among polymers,fillers,and penetrates;these might have caused some deviation of the A f values for CO 2,N 2,H 2,and CH 4.As shown in Table IV,A f increased with increasing gas critical volume.Thus,the impermeable GO had a larger inhi-bition on the transport of larger gases.An average A f of 86for CO 2,N 2,H 2,and CH 4was calculated by the regression of the normalized permeabilities of different gases with the Lape model.It seemed that the transport properties of the Pebax/GO MMMs could be described successfully by this model.Obviously,the A f value from the Lape model (86)was much lower than its theoret-ical value.The ultrasound destruction,layer misalignment,stack-ing of the flakes,and random orientation of the flakes might have led to a lower effective A f .17,50To observe the influence of the geometrical shape of the fillers on the permeation properties of different MMMs,the CO 2nor-malized permeabilities of the Pebax membranes with different fillers,such as SAPO-34,51amino-modified multiwalled carbon nanotubes (MWNTs-NH 2),52and GO,are shown in Figure 13.MWNTs-NH 2was highly permeable to gases;thus,P f 51could be assumed,and the permeation properties of the Pebax/MWNTs-NH 2MMMs could be described with eq.(3).As shown in Figures 12(a)and 13(a1),the experimental P MMMs /P 0values were a little higher than those predicted with eq.(3).The difference might have been due to the voids between the tangled MWNTs-NH 2s.52For SAPO-34,its CO 2permeability was assumed to be 600Barrer,53and the permeation properties of the Pebax/SAPO-34MMMs could be described with eq.(1).As shown in Figure 13(b,b1),the experimental P MMMs /P 0values were lower than the predicted values at low SAPO-34contents,and they were higher than the predicted values whentheFigure 9.Influence of the GO content on the permeabilities of ()CO 2,( )H 2,(~)CH 4,and (!)N 2for Pebax/GO MMMs at 358C and 0.7MPa.Figure 10.Influence of the GO content on the selectivities of ()CO 2/N 2,( )CO 2/CH 4,(!)H 2/CH 4,and (~)CO 2/H 2for the Pebax/GO MMMs at 358C and 0.7MPa.Figure 11.Gas-permeation curves of the Pebax/GO MMMs for CH 4at 358C and 0.7MPa:p down was the pressure of downstream chamber,t was the permeation time.。
专利名称：A PROCESS OF REDUCING THE OXYGEN CONTENT IN GAS MIXTURES发明人：FRANZEN, Bengt Gustaf申请号：EP82902097.0申请日：19820628公开号：EP0082864A1公开日：19830706专利内容由知识产权出版社提供摘要： A method of reducing the oxygen content in gas mixtures at 0.0 to 1.5% by volume, wherein the gas is contacted with a solution containing anthrahydroquinone derivatives capable of being oxidized with molecular oxygen with a hydrogen peroxide formation. The oxygen supply is adjusted such that the amount of oxygen supplied, with a quantitative formation of hydrogen peroxide, stoichiometrically corresponds to a value not exceeding 90%, preferably 50%, of the quantity supplied derivatives of anthrahydroquinone. The hydrogen peroxide content to the contact surfaces between the solution and gas must not exceed 100 millimoles per liter at a simultaneous oxygen pressure of gas not exceeding 100 mbar. The gas mixture with low oxygen content obtained by this method can be used as protective or inert gas in the processes of the chemical industry which are used flammable gases.申请人：EKA AB地址：Fack S-445 01 Surte 1 SE国籍：SE代理机构：Wiklund, Ingrid Helena, et al更多信息请下载全文后查看。
