表面改性活性炭对CO_2的吸附性能

研究了用 H2 O2 ,HNO3加醋酸铜溶液进行表面改性后的活性炭对 CO2 的吸附性能 ,分析了改性前后活性炭的表面化学性质 ,测定了 2 73K下的吸附等温线 ,用 D- A方程对吸附等温线进行了很好的拟合 ,探讨了表面改性对活性炭表面化学性质的影响及其表面化学性质与吸附性能之间的关系。     

活性炭表面化学改性技术的研究进展与展望

活性炭表面官能团和杂原子的数量与种类是影响活性炭吸附性能的重要因素。国内外研究表明,通过对活性炭进行表面改性可以显著改善活性炭对特定物质的吸附性能。文章简要介绍了活性炭的物理和化学性质,并从活性炭材料的表面化学性质方面论述了近年来国内外在活性炭材料改性方面的研究进展,最后提出了活性炭表面改性技术的发展方向和趋势。     

活性炭表面化学改性及提高工业级乙二醇紫外透光率

采用活性炭为吸附剂液相吸附可去除工业级乙二醇产品中的微量杂质以提高其紫外透光率。研究了不同改性活性炭的表面化学性质对吸附乙二醇杂质效果的影响,采用静态吸附实验评价改性活性炭吸附性能,并确定最佳的吸附工艺条件。研究表明,经硝酸氧化后,氮气保护高温改性的活性炭吸附效果最佳;在45℃、乙二醇与活性炭质量比为150:1的条件下,经该活性炭处理1h后的乙二醇在220nm、275nm和350nm处的紫外透光率分别为67.7%、96.2%和98.1%,基本达到了聚酯级指标。     

活性炭对水中有机物去除的研究进展

目前我国大部分城市水源受到不同程度污染,在常规处理工艺不能有效工作的情况下,活性炭可作为饮用水处理深度处理、预处理的有效手段。通过对活性炭的基本特性、活性炭的吸附机理、活性炭去除水中有机物的影响因素以及活性炭表面化学性质改性方法进行综述,总结归纳出可联合不同的改性方法对活性炭表面进行改性,以达到更好的改性效果,从而提高活性炭对饮用水中有毒有害有机物的去除率。     

表面化学改性吸附用活性炭的研究进展

活性炭表面官能团和杂原子的种类与数量多少决定了活性炭的表面化学性质，而化学性质决定了活性炭的化学吸附特性。通过进行表面氧化、还原以及负载增加或者消除某些基团和活性中心，可以大大改善活性炭对特定吸附质的吸附能力。文章简要介绍了活性炭表面存在的官能团、杂原子和化合物，并对近年来国内外在吸附用活性炭表面化学改性方面的进展进行评述。     

玉米秸秆活性炭制备与NaOH改性对甲醛吸附的影响

以玉米秸秆为原料,在不同热解条件下制备活性炭,再运用BET模型和Boehm滴定法测定活性炭孔隙结构和表面性质,并选取性能较优的活性炭进行NaOH改性,研究其改性前后对甲醛的吸、脱附性能和表面结构与表面化学性质变化。结果表明:在最优热解参数60 min、650℃制备的玉米活性炭经NaOH改性后可使其对甲醛饱和吸附时间延长62%,饱和吸附量提高133.33%,比表面积增加3.02%,微孔容积增大0.6%,脱附峰面积和峰高明显增大,且其表面碱、酸性官能团含量分别提高了11.85%、5.51%,说明NaOH改性能提高活性炭的表面碱、酸性官能团含量,增大活性炭比表面积与孔径,从而提高其对甲醛等极性物质的吸附能力。     

HNO3改性活性炭对Cr(Ⅵ)的吸附性能及机理

活性炭的吸附性能与其表面化学密切相关,本研究为讨论活性炭表面氧化改性对其Cr(Ⅵ)吸附特性的影响,分析了Cr(Ⅵ)吸附过程与活性炭表面化学性质的关系,阐释吸附机理。结果表明,与未改性活性炭相比,硝酸氧化改性后活性炭对溶液中Cr(Ⅵ)的吸附性能提高,且改性后活性炭的比表面积和孔容积降低,表面的羧基、内酯基和酚羟基等酸性含氧官能团的数量增多。改性活性炭对Cr(Ⅵ)的吸附过程可用Langmuir、Freundlich、D-R和Temkin4种吸附模型模拟,吸附动力学数据与拟二级动力学模型吻合。采用X射线光电子能谱(XPS)表征了改性前后活性炭的表面化学性质。Cr(Ⅵ)在活性炭上的吸附机理主要为静电吸引、还原和配位络合等,与Cr(Ⅵ)发生络合作用的是活性炭表面含氧官能团。     

活性炭改性方法及其在水处理中的应用

从表面物理结构特性改性、表面化学性质的改性和电化学性质的改性三个方面综述了活性炭的改性方法;对改性活性炭在水处理中的应用做了深沉思考;分析了各种改性方法的优缺点,并展望了活性炭的改性和应用的发展方向.指出活性炭改性在水处理中的方向应根据污水水质和原活性炭的性质确定,今后的发展方向和研究重点是活性炭电化学改性、将各种改性方法结合起来对活性炭进行协同改性、活性炭负载纳米TiO2的光催化降解以及活性炭的生物吸附.     

盐酸改性椰壳活性炭的制备及表征

本文以椰壳活性炭为原料,制备了盐酸改性活性炭,考察了不同条件制备的改性活性炭对吸附苯酚性能的影响,并采用SEM和IR对改性前后椰壳活性炭形貌及表面官能团进行了表征。研究结果表明:当改性剂盐酸浓度为4mol/L时,改性椰壳活性炭对苯酚的吸附率可达93.82%,其比表面积为1117.035906m~2.g,较改性前显著增大;改性后的椰壳活性炭表面粗糙,具有发达的孔隙结构,增加了表面官能团的数量,提高了活性炭的吸附苯酚的性能。     

活性炭表面改性及其对Cr(Ⅵ)吸附性能的研究

分别用HNO3、H2SO4以及HNO3加乙酸铜溶液对活性炭进行了表面改性处理，测定了它们的表面化学性能，研究了改性活性炭对Cr(VI)吸附性能的影响。实验结果表明：通过上述改性，活性炭表面官能团数量发生了显著改变，特别是羧基增加较多；通过改性后的活性炭对Cr(Ⅵ)吸附性能有所提高。     

Estimation of adsorption energies using the physical characteristics of activated carbons and the molecular properties of volatile organic compounds

Adsorption of volatile organic compounds (VOCs) by granular activated carbons (GACs) is a highly exothermic process and leads to temperature rises, which may reduce the separation efficiency. This study points out the significant characteristics of VOCs and GACs on adsorption energies. Adsorption energies were measured for a wide variety of VOCs, representative of different chemical groups, using 8 different commercial GACs with different porous structures. Afterwards a statistical analysis was applied to the experimental database thus obtained, which enabled one to pinpoint the most significant variables, linked to either VOC molecular properties or the intrinsic characteristics of GACs. Two statistical models have been tested: multi linear regression (MLR) and neuronal networks, and their efficiencies were compared in terms of prediction skill. The best results have been obtained from the MLR approach, which discriminated five different properties of the system. These variables were the polarisability, the heat of vaporization, the ionization potential and the surface tension for adsorbates and the mean micropore radius for GACs. The MLR model enabled one to compute integral adsorption enthalpies with a precision of around 10% and to draw conclusions on the dominant adsorption mechanisms.     

Estimation of adsorption energies using physical characteristics of activated carbons and VOCs’ molecular properties

Adsorption of volatile organic compounds (VOCs) by granular activated carbons (GACs) is a highly exothermic process and leads to temperature rises, which can be hazardous for high pollutant contents. This study points out the significant characteristics of VOCs and GACs on adsorption energies. For that purpose, adsorption energies were measured for a wide variety of VOCs, representative of different chemical groups, using eight different commercial GACs with different porous structures. Afterwards a statistical analysis was applied to the experimental database thus obtained, which enabled to enlighten the most significant variables, linked to either VOCs’ molecular properties or intrinsic characteristics of GACs. Two statistical models have been tested: multi-linear regression (MLR) and neuron networks (NN), and their efficiencies were compared in terms of prediction skill. The best results have been obtained from the MLR approach, which discriminated five different properties of the system. These explicative variables were the polarizability, the heat of vaporization, the ionization potential and the surface tension for adsorbates and the average micropore radius for GACs. The MLR model enabled to compute integral adsorption enthalpies with a precision around 10%. Thanks to the properties discriminated, we came to some conclusions on the dominant mechanisms of adsorption.     

Nutshells as granular activated carbons: physical,chemical and adsorptive properties

Nutshells from seven different sources (pistachio, hazelnut, almond, black walnut, English walnut, macadamia nut, pecan) were converted to granular activated carbons (GACs) by carbon dioxide activation. A portion of the GACs were oxidized with compressed air and the physical (yield, surface area, attrition), chemical (pH, surface charge) and adsorptive (organics uptake, metal ion uptake) properties of both oxidized and non‐oxidized carbons were determined. Differences in uptake of organics, especially of polar compounds, were found between GACs made from almond shells, the group consisting of black walnut shells, English walnut shells and pecan shells, and macadamia nutshells. Oxidation had its greatest effects on pH, surface charge and uptake of metal ions. The changes due to oxidation were found to be independent of carbon source material. GACs with specific properties can be produced with judicious selection of carbon precursor and oxidative treatment. © 2001 Society of Chemical Industry     

Morphology and thermo-mechanical properties of new hybrid coatings based on polyester/melamine resin and pyrogenic silica

Polyester/melamine (PM)-based formulations used in coil-coating applications were modified with pyrogenic silicas of different types. The influence of the chemical modification of the silica surface on various properties was investigated. The viscosity of filled PM formulations was measured. Transmission electron microscopy and dynamic mechanical measurements were used to characterize nanocomposite films. Roughness and gloss measurements were done on nanocomposite coatings. The results show that the viscosity and morphology observed are directly linked to the balance and nature of the interactions developed between the silica surface and the organic medium. Both hydrophilic and hydrophobic silica lead to too high viscosity of the filled formulation, to different silica dispersion and, as a consequence, to low gloss coatings. However with an adequate organo-modification of the silica, formulations compatible with the process and having a high gloss can be obtained. Additionally, the surface modification of silica has no obvious influence on the dynamic mechanical properties.     

Application of silica-based pigments in water-borne acrylic paints and in solvent-borne acrylic paints

The amorphic silica, Syloid 244 was modified using N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. Pigments based on the silica carrier were obtained by coupling the organic dye, C.I. Reactive Blue 19 to the modified surface of the silica. The adsorption process was conducted in an aqueous suspension of the silica, supplemented with the dye. An extent of modification was evaluated using infrared spectroscopy and nuclear magnetic resonance spectroscopy. Structural and microscopic properties of the product were examined as were the zeta potential and the particle size distribution. The specific surface area was estimated using a BET approach. The efficiency of the adsorption process and the effects of the amount of dye and type of dye, on the final product, were determined. Moreover, the stability of the chemical bonds that were formed between the dye and the carrier was examined in elution tests. The pigments obtained were tested in water soluble binders and in organic solvent-solubilised acrylic paints.     

KOH预处理除尘灰制备颗粒活性炭的实验研究

用除尘灰分离炭粉为原料，采用KOH预处理，水蒸汽活化的方法制备颗粒活性炭。实验证明，KOH预处理制备的活性炭有较高的比表面积，并且KOH预处理对活性炭的微晶结构和表面形貌产生影响。当KOH含量为10％时，所制备的活性炭比表面积和收率较高，灰分较低。同时本文对KOH影响机理进行了探讨，在炭化阶段KOH有利于促进生成难石墨化的炭素前驱体；在活化阶段，KOH对碳的气化有催化作用。     

Tailoring activated carbons for enhanced removal of natural organic matter from natural waters

Several pathways have been employed to systematically modify two granular activated carbons (GACs), F400 (coal-based) and Macro (wood-based), for examining adsorption of dissolved natural organic matter (DOM) from natural waters. A total of 24 activated carbons with different physical and chemical characteristics was produced. The impact of carbon treatment on the DOM adsorption was examined by conducting isotherm experiments at a neutral pH using the modified carbons and a DOM isolated from the influent to Myrtle Beach drinking water treatment plant in South Carolina (USA). Adsorption of the DOM by two activated carbon fibers, with relatively uniform pore size distributions, showed that only pores with widths larger than 1 nm were accessible to the DOM macromolecules. Increases in the carbon supermicropore and mesopore volume (i.e., >1 nm) increased the DOM uptake, if the surface chemistry was favorable. The isotherms normalized on a surface area basis showed the significance of carbon surface chemistry on the DOM uptake. At neutral pH, adsorption of negatively charged DOM molecules was favored by basic and positively charged surfaces, while the DOM uptake was minimized when the surface had acidic characteristics. High temperature ammonia treatment of oxidized carbons considerably enhanced the DOM uptake, mainly due to the increase in accessible surface area and surface basicity. Iron-impregnated carbons indicated an enhanced affinity of iron-laden carbon surface toward the DOM species, if the surface was not negatively charged.     

四氧化三铁磁性超细粉的表面改性

在制备了Fe3O4磁性超细粉后，根据应用的需要对其表面进行处理以改变其物理化学性质。本实验从众多改性剂中进行了筛选，选出钛酸酯偶联剂作为Fe3O4的最优改性剂，通过分析改性影响因素，采用正交实验寻求其最优的改性工艺条件。     

改性石英砂强化火电厂中水回用微污染物处理效果研究

通过对石英砂滤料的改性研究改变原滤料表面物理化学性质,提高滤料吸附能力和截污能力,强化对中水中有机物的去除效率。分别试验了对石英砂进行铝盐和铁盐方法的改性,过对比了静态吸附试验和动态过滤试验改性石英砂和未改性石英砂对微污染水中有机物和浊度的去除效果。结果表明,改性砂对COD和浊度的吸附效果较之未改性前均有明显提高,COD去除率由5%提高到20%～30%,浊度的去除率由37%提高到55%～65%,动态试验与静态试验结果一致,去除率也均有提高;不同金属氧化物的改性砂性能不同。     

景观用水处理及中水再生回用示范工程

采用适合其分散处置特点的流化床和臭氧气浮装置对高档社区的景观水以及建筑中水进行再生处理。首先针对流化床工艺,用Fe3O4作为回流絮凝助凝剂,以增强悬浮层的稳定形成。其次,增设微孔曝气系统。一方面对流化床回流的Fe3O4进行水力再生;另一方面提高水中的溶解氧,降低臭味,提高系统的好氧微生物处理能力。最后,改变工艺流程,使景观水进水杂排水池,通过流化床处理。运行结果表明,出水水质完全符合GB/T18920-2002和GB/T18921-2002中的娱乐性景观环境用水、道路清扫、城市绿化和车辆冲洗的用水水质标准。