明胶/PEG制备多孔块状SiO2载体及葡萄糖淀粉酶的固定

本文通过溶胶-凝胶法，以正硅酸乙酯、聚乙二醇和明胶为主要原料，制得了孔径约为20 nm的生物酶载体用多孔SiO₂块状材料，并着重研究了热处理温度对多孔SiO₂载体的结构和酶活力的影响。明胶的加入能有效地防止SiO₂表面羟基在烧结过程中的失活现象，提高了多孔材料的吸附能力。制备过程中未加入明胶样品(G0)的酶吸附量和初始酶活力回收率的最高值分别为90 mg·g^-1和11%；加入质量分数为15%明胶的样品(G15)的酶吸附量和初始酶活力回收率分别提高到115 mg·g^-1和38%以上。经过5次重复使用后，G15载酶块体所显示的酶活力还高于G0载酶块体的初始酶活力。600 ℃热处理后所制得的G15样品表现出较好的综合性能，此类多孔块体材料便于酶的回收、保存和再利用。     

锂离子电池用多孔硅/石墨/碳复合负极材料的研究

在两步高能球磨和酸蚀条件下制得了多孔硅/石墨复合材料，并对其进行碳包覆制成多孔硅/石墨/碳复合材料。通过TEM，SEM等测试手段研究了多孔硅材料的结构。作为锂离子电池负极材料，电化学测试结果表明多孔硅/石墨/碳复合材料相比纳米硅/石墨/碳复合材料有更好的循环稳定性。同时，改变复合体配比、热解碳前驱物、粘结剂种类和用量也会对材料的电化学性能产生较大的影响。其中使用质量分数为10％的LA132粘结剂的电极200次循环以后充电容量保持在649.9 mAh·g^-1，几乎没有衰减。良好的电化学性能主要归因于主活性体-多孔硅颗粒中的纳米孔隙很好地抑制了嵌锂过程中自身的体积膨胀，而且亚微米石墨颗粒和碳的复合也减轻了电极材料的体积效应并改善了其导电性。     

多孔氧化物块体材料的制备及其对重金属离子吸附研究进展

目前去除重金属离子的方法较多,其中吸附法因操作简单、经济性好而被广泛使用。多孔氧化物块体材料作为新兴的吸附材料具有比表面积高、机械强度高及可回收性好等特点,但吸附选择性差以及孔结构单一的缺陷限制了其在水体重金属处理中的应用。本文详细叙述了多孔氧化物块体材料的多种制备方法,并分别讨论了各方法的优势及其不足。介绍了近几年研究较多的多孔氧化物块体材料及其制备方法与特性。最后,对多孔氧化物块体材料对Pb、Cd及Cr等重金属离子吸附性能的影响因素及改善措施方面进行了总结分析,并指出多种材料的复合、材料表面的接枝改性及分级多孔结构的构建会增强对重金属离子的吸附性能。期望本文为多孔氧化物块体材料的制备及其在重金属离子吸附方面的应用提供参考。     

应用基于第一性原理的分子模拟方法预测小分子在多孔材料中的吸附

分子在多孔材料中的吸附在工业中有着重要的应用．计算化学的发展和应用使得对多孔材料中小分子的吸附研究进入了一个新阶段．从第一性原理出发,在MP2高精度量子化学计算基础上推导小分子与多孔材料相互作用的分子力场,运用巨正则系综的蒙特卡罗模拟,研究小分子在多孔材料的吸附和脱附过程．以具有代表性的沸石分子筛ZSM-5和储氢材料MOF-5为对象,应用上述方法分别研究氨气分子和氢气分子在两种材料中的吸附,进而讨论沸石的酸性和MOF-5的储氢性能,计算得到的结果和实验数据高度吻合．     

以Pluronics~为第二组分制备聚乳酸蜂窝状规整多孔薄膜

以聚乳酸(PLA)为成膜材料,以两亲三嵌段共聚物PEO-PPO-PEO(Pluronics)为第二组分,利用水辅助法成功地制备了聚乳酸蜂窝状多孔膜.研究了环境湿度、溶液浓度和所用PLA分子量对多孔膜结构的影响.结果表明,加入第二组分PEO-PPO-PEO能有效地促进规整蜂窝结构的形成.蛋白质吸附实验结果进一步证明了PEO-PPO-PEO组分在孔洞内壁的富集,由此构建了阻抗蛋白质吸附的图案化功能结构表面.     

以Pluronics为第二组分制备聚乳酸蜂窝状规整多孔薄膜

以聚乳酸（PLA）为成膜材料,以两亲三嵌段共聚物PEO-PPO-PEO（Pluronics）为第二组分,利用水辅助法成功地制备了聚乳酸蜂窝状多孔膜.研究了环境湿度、溶液浓度和所用PLA分子量对多孔膜结构的影响.结果表明,加入第二组分PEO-PPO-PEO能有效地促进规整蜂窝结构的形成.蛋白质吸附实验结果进一步证明了PEO-PPO-PEO组分在孔洞内壁的富集,由此构建了阻抗蛋白质吸附的图案化功能结构表面.     

CO_2吸附法表征材料孔结构的研究进展

对于多孔材料孔结构的表征,N_2吸附(77K)是最常用的方法。但随着多孔材料种类的日益丰富,CO_2吸附表征引起人们越来越广泛地关注。CO_2作为N_2吸附的有效补充,被用于各种传统和新型多孔材料的表征,特别是极微孔结构的探测。概述了CO_2吸附法表征多孔材料孔结构的现状,总结了CO_2吸附等温线的类型及测试条件,阐述了用CO_2吸附数据分析材料的比表面积、孔容和孔径分布时常见的各种问题。     

多孔材料的二氧化碳吸附与光催化转化研究进展(英文)

太阳能光催化是CO_2转化和利用的新兴技术,直接利用洁净充足的太阳能将自然界富有的"温室气体"CO_2转化成化学燃料,不仅有利于消除大气温室效应,而且能缓解能源短缺问题,因而成为人们研究的一个重要方向.但目前CO_2的吸附和转换效率还很低,这是太阳能光催化CO_2资源化的最大障碍.高性能光催化剂的设计和合成是这项技术的关键.针对CO_2光还原反应的特异性,理想的光催化材料应该具有以下功能:强的CO_2吸附能力和高的光催化活性.将光催化剂与对CO_2具有高吸附性的多孔材料结合,就可以将CO_2吸附并富集在吸附剂周围的光催化剂表面上以进行催化转化,因此基于高效多孔吸附材料构筑光催化体系成为光催化转化CO_2的重要研究方向之一.CO_2的循环利用包括吸附和转化两方面,高吸附量的多孔材料是获得CO_2高转化效率的前提.本文首先以多孔材料结构参数及性能指标为主线,对无机多孔材料、金属有机框架材料及微孔有机聚合物材料的研究进展及应用前景进行了评述.通过对多孔材料的改性和新型多孔材料的开发,CO_2的吸附能力得到一定的提升,但是仅仅依靠多孔材料的吸附分离,不能实现CO_2中的碳资源循环.在此基础上,本文重点评述了多孔光催化材料在CO_2光催化转化中的最新研究进展.采用多孔材料与光催化剂结合,可增加材料的比表面积,在界面处暴露更多的活性位点,有利于光催化CO_2转化的进行;同时,通过孔结构和基团调控,可以调控光催化剂的反应活性和产物选择性.特别是金属有机框架材料与微孔有机聚合物材料,改变构建单元的官能团和制备技术还可以实现光谱响应范围的调控,提高太阳光的利用率.大量文献对比发现,引入较高CO_2吸附效率的多孔材料构建光催化体系,CO_2光催化转化的效率及产物选择性显著提高.最后,本文对多孔材料在CO_2光催化转化领域的研究现状与亟待解决的问题进行了剖析,提出了下一步可能的研究方向:(1)提高多孔材料自身的稳定性如耐水性能与光/热稳定性;(2)发展光催化材料在多孔载体的微观组装方法,不影响CO_2吸附效率的前提下提高光催化活性;(3)深入研究多孔光催化材料内部与表面的CO_2转化机理,为进一步提高吸附与转化效率提供理论指导.     

碳纳米多孔宏观体在水体净化中的应用

碳纳米多孔宏观体是指由碳纳米材料自组装形成的宏观多孔材料。该材料保持了碳纳米材料大的比表面积及化学、热稳定性,对水体中的污染物,如油污、染料分子及重金属离子等具有良好的吸附性能。此外,该类材料具有宏观结构及稳定的机械性能,方便操作,且易实现所吸附物的回收及吸附材料的再生。因此,碳纳米多孔宏观体成为碳纳米材料研究和应用的热点。本文梳理了碳纳米多孔宏观体的制备及其在水处理中的应用,包括碳纳米多孔宏观体的制备、污染物吸附及材料再生等。首先对碳纳米多孔宏观体用于水体净化的背景进行了介绍,之后,按照组成单元不同,将碳纳米多孔宏观体按照碳纳米管多孔宏观体,石墨烯多孔宏观体,碳纳米纤维多孔宏观体及碳纳米粒子多孔宏观体进行了分类。第三部分,详细介绍了制备碳纳米多孔宏观体的三种常见方法并分别讨论了各种方法的优缺点及所制备产物的性质。第四部分,按照不同污染物种类讲述了碳纳米多孔宏观体在水体净化中的应用。最后,针对碳纳米多孔宏观体在水体吸附应用中存在的问题进行了分析及展望。     

低温相变贮能材料定形技术研究进展

低温相变贮能材料广泛应用于节能和温控领域,其合成、复配及定形技术不断发展,已成为材料研究领域的热点之一。本文综述了低温相变材料的定形方法和技术,介绍了多孔基质吸附法、聚合物基复合法、微胶囊技术以及其它定形技术的国内外研究进展,重点介绍了原位聚合、界面聚合、凝聚法3种微胶囊技术。分析了各种制备方法的优缺点,并指出了制备低...     

Specific features of adsorption of azo dyes on fly ash

A possibility to utilize fly ash (FA) formed at coal-fired power plants as a cheap adsorbent for the purification of wastewater containing azo dyes methylene blue (MB) and methyl red (MR) was considered. The effect of an FA additive on the adsorption capacity of active carbon was studied. The efficiency of FA as an adsorbent for the purification of aqueous solutions from MB and MR was shown. The adsorption is also fairly efficient when active carbon is partially replaced by FA. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 545–548, March, 2007.     

Mechanism of formation of polychlorinated dibenzo-p-dioxins produced on municipal incinerator flyash from reactions of chlorinated phenols

All incinerators burning municipal waste produce chlorinated dioxins. The mechanism by which these compounds are formed is unknown. Experiments were performed that show these compounds can be produced from known precursors by surface catalysed reactions on the flyash particulates present in the incineration process. A full range of the tetra- through octachlorinated dibenzo-p-dioxins were produced from 13C-labelled pentachlorophenol and two trichlorophenols on the surface of flyash from an Ontario municipal incinerator that had been previously freed from organic material. A simple flow-tube apparatus at 300 degrees C under a 10-ml/min nitrogen flow was used for the experiments. The use of 13C-labelled pentachlorophenol gave a direct measure of the extent of the catalytic reactivity of the flyash surface. Much lower amounts of chlorinated dioxins were produced in similar experiments with flyash from a modern Japanese incinerator whose effluents are normally extremely low in these compounds. Only small amounts of octachlorodioxin, the thermal condensation product expected, were formed using ground firebrick or an empty flow-tube for the reactive surface. These results indicate that the flyash surface has constituents and properties that promote the production of chlorinated dioxins from chlorinated phenols and support the catalyzed surface reaction mechanism previously proposed.     

Gravimetric determination of flyash content in blended cement

A simple gravimetric method is devised to determine the percent flyash in flyash blended cement. Insoluble residue of the sample was determined by the British Standard method. The flyash content was calculated by taking the insoluble residue in ordinary Portland cement and flyash to be 0.46% and 70.74%, respectively. The accuracy and precision are good and the standard deviation of the method is less than 1% for three determinations.     

Polyethyleneimine-grafted polyphosphazene microspheres for rapid and efficient capture of anionic dyes from wastewater

Developing novel adsorbent to capture organic contaminants from wastewater rapidly and efficiently is highly desirable for waste treatment and environmental restoration. Herein, we reported a new amino-rich spherical adsorbent (PZS-PEI) for highly-efficient uptake of anionic dyes from aqueous solution. The PZS-PEI adsorbent was fabricated through a two-step process including synthesis of PZS-Cl microspheres via room temperature polymerization of hexachlorocyclotriphosphazene with bis(4-hydroxyphenyl) sulfone and subsequent surface grafting reaction of PZS-Cl microspheres using branched polyethyleneimine (PEI). The microstructure of as-obtained PZS-PEI microspheres was fully characterized by scanning electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, zeta potential, and N₂ adsorption test. The adsorption performance of the PZS-PEI microspheres towards organic dyes was evaluated through carrying out a series of studies including various influence factor analysis, adsorption isotherm, kinetics, and thermodynamics. Results show that the PZS-PEI adsorbent owned good adsorption selectivity towards anionic dyes, and the maximum adsorption capacities for methyl orange (MO), acid chrome blue K, eosin-Y reached 190.29, 152.90, and 92.34 mg/g at 25 °C, respectively. In addition, the uptake behavior of organic dye by the PZS-PEI adsorbent conformed to Freundlich isotherm and pseudo-second order kinetic model, and the adsorption process followed a three-stage intraparticle diffusion mode with an endothermic and spontaneous characteristic. Electrostatic interaction and hydrogen bonding were responsible for the highly-efficient adsorption of the PZS-PEI adsorbent towards typical anionic dye MO.     

Chemical homogeneity of National Bureau of Standards coal flyash (SRM 1633a)

The chemical homogeneity of 10 mg samples of the (U. S.) National Bureau of Standards standard reference material 1633a (coal flyash) was determined for several elements by instrumental neutron activation analysis. The homogeneity was tested for the purpose of using small samples of the flyash as a multielement comparator standard. For small sample masses the flyash may be unacceptably heterogeneous for Fe, Co, Ba, and perhaps As and Sb. Homogeneity is improved by grinding the flyash. For comparison, homogeneity data for USGS GSP-1 is also presented.     

Contribution of flyash from coal-fired thermal power plants to uranium contamination of ground water

The elemental concentration of uranium in flyash and coal samples has been investigated using EDXRF and WDXRF techniques. To check the contribution of flyash to uranium contamination of ground water in the Malwa region of Punjab, the flyash and coal samples are collected from Guru Nanak Dev Thermal Power Plant (GNDTPP) in the Bathinda district of Punjab state, India. It is found that uranium concentration in the flyash is below the detection limit of the XRF set up, i.e.?~?1 ppm. It is concluded that uranium contamination in the ground water of Malwa region is not due to the Thermal Power Plant.     

Study of uranium contamination of ground water in Punjab state in India using X-ray fluorescence technique

The elemental concentration of uranium in the samples collected from the ground water and the canal water in the Bathinda district of Punjab state, India, have been investigated using X-ray fluorescence technique. The residues obtained after drying the water samples were analysed using the energy dispersive X-ray fluorescence spectrometer consisting of Mo-anode X-ray tube equipped with selective absorbers as an excitation source and an Si(Li) detector. The uranium concentration values in significant fraction of the shallow ground water samples from the hand pumps is found to be above the permissible level of 15?ppb recommended by World Health Organisation for the drinking water, and its values in the canal water samples are below 5?ppb. To investigate the flyash from the coal-fired thermal power plants as a possible source of ground water contamination, the water samples collected from the surroundings of the power plants and the flyash samples were also analyzed. The results rule out flyash as a source of uranium contamination. Agrochemical processes occurring in the calcareous soils in the region are the favoured potential source of uranium contamination of the ground water.     

吸附式空调系统的原理及添加剂强化吸附工质性能的研究

氯化锂晶体具有很高的吸水性能，在吸附式空调制冷系统中常常被用作吸附剂。本文介绍了吸附式空调制冷系统的原理，研究了吸附剂（氯化锂）、吸附质（水汽）的性质；采用高真空吸附重量法测定氯化锂的等温吸附曲线及氯化锂吸附水汽的速率，并通过添加一种既有吸附增稠作用，又能强化氯化锂吸附性能的添加剂,改善氯化锂的等温吸附特性,降低氯化锂的再生温度。采用氯化锂混合吸附剂-水的开式旋转吸附式空调系统，具有显著的节能效果和双重杀菌功能，提供人们所喜爱的舒适空调域（室内温湿度26．7℃／50%RH），同时改善室内空气品质。     

Preparation of magnetic separable CoFe2O4/PAC composite and the adsorption of bisphenol A from aqueous solution

CoFe₂O₄/PAC composite adsorbent has been prepared via an immersing-calcination process, using ethylene diamine tetraacetic acid (EDTA) and citric acid (CIT) ligands containing sol as the CoFe₂O₄ precursor. The microstructure characterization and magnetic property of as-prepared sample were performed by means of XRD and VSM measurements. The adsorption kinetics, isotherms and thermodynamic process toward Bisphenol A molecules (BPA, which is considered as one of the typical endocrine disrupting chemicals) occurred on as-prepared magnetic adsorbent which were investigated by the pseudo-second order kinetic/intraparticle models, the Langmuir/Freundlich adsorption isothermal models and basic chemical thermodynamics principles, respectively.     

Monte Carlo Simulations of Adsorbed Solutions in Heterogeneous Porous Materials

We present results of a Monte Carlo simulation study of binary mixtures of ethane and methane in silica gel. The molecular model treats the adsorbent as a matrix of silica microspheres. The adsorption isotherms, adsorption selectivities and isosteric heats of adsorption have been determined for these systems. The results are compared with predictions from the ideal adsorbed solution (IAS) theory and with experiment. The heats of adsorption are accurately described by the IAS theory. The adsorption isotherms are accurately described by the IAS theory at low bulk pressure but the IAS theory overpredicts the density at high bulk pressure. This latter effect is opposite to that observed in bulk mixtures of this type where nonidealities generally lead to a density increase on mixing. The pressure dependence of the selectivity does not exhibit a maximum at low pressure. We discuss this effect in terms of the adsorbent microstructure.