表面活性剂在固/液界面吸附理论的新进展

根据两阶段吸附模型~[1], 导出了两常数及一常数吸附等温线公式。不仅可以方便地应用于各种类型的表面活性剂在固/液界面上的吸附数据, 而且具有预示能力。对于显示LS型等温线的体系只需测定第一平台处和饱和的吸附量即可给出整个的吸附等温线。对于离子型表面活性剂在反电性固体上的吸附, 可自一个化合物的吸附预示出一系列同系物在同一吸附剂上的吸附等温线。     

氨基酸在固／水界面的吸附作用

本文研究了活性炭、硅胶和氧化铝自水中吸附酪氨酸和苯丙氨酸。所得的结构表明,（1）在活性炭/水界面上两种氨基酸的吸附等温线均为Langmuir型。极限吸附量nm^S、吸附常数b与介质pH值关系曲线大约在氨基酸等电点处有最大值,这可用介质pH对氨基酸溶解度的影响解释。在活性炭表面,氨基酸主要以两性离子躺方式吸附。（2）在硅胶（氧化铝）/水界面上的吸附等温线为S型,吸附量仅为在活性炭/水界面上的1‰,在硅胶表面苯丙氨酸主要以电性作用吸附;在氧化铝表面酪氨酸以两性离子与表面形成氨键吸附。     

吸附法研究固体表面的分形性质

介绍用气体和蒸气吸附等温线数据求出的单层饱和吸附量和根据等温线毛细凝结区域数据求算分形固体表面分维值的方法;提出了用固体自溶液中吸附数据计算分维值的方法。讨论了介孔吸附剂的分维和固体表面分形性质在物理化学方面的应用。     

负载铈（IV）的D412螯合树脂氟性能的研究

以D412氨基酸型螯合树脂为载体,负载Ce(IV)制得选择性吸附剂。探讨了该吸附剂对水中的F^-的静态和动态吸附性能,实验中对含氟液pH值、浓度、流量以及再生液种类和浓度对该吸附剂性能的影响进行了研究,并采用红外分析方法推测了吸附剂吸附F^-的机理。     

利用粉状聚合物吸附剂脱除盐酸溶液中氯仿的研究

为了选择合适的吸附剂来脱除盐酸溶液中的氯仿,本文测定了几种聚合物吸附剂在298.15 K温度下对水溶液和20%盐酸溶液中氯仿的吸附等温线,考察了其吸附能力,并将其吸附能力与活性炭和固体石蜡进行了比较。所研究的吸附剂包括粉末状氯化橡胶,聚丙烯,氯化聚丙烯,聚氯乙烯,活性炭和固体石蜡。结果表明,这些吸附剂的吸附行为服从Langmuir 方程,其吸附能力的次序为活性炭>聚氯乙烯>氯化橡胶>聚丙烯 >氯化聚丙烯 >固体石蜡。该次序基本上与从聚氯乙烯到固体石蜡吸附剂中氯含量逐渐降低的次序相一致。聚氯乙烯与氯化橡胶的吸附能力与活性炭相当,其饱和吸附量大约为1.4g-CHCl3/g-吸附剂。所有吸附剂对氯仿的吸附能力均随着溶液中盐酸浓度的增加而降低。结果表明,工业级的粉状聚氯乙烯或氯化橡胶可以作为一种有效的吸附剂脱除水溶液中的氯仿,且具有成本低,吸附性好和易于通过热再生循环利用的特点。     

重量法测定环戊烷在silicalite-1分子筛上的吸附特性

用智能重量分析技术 (IGA)研究了环戊烷在silicalite 1分子筛上的吸附特性。结果表明 ,随着温度的降低 ,环戊烷的吸附等温线从第一类型过渡为第四类型 ,在 2 5 4K和 2 74K温度下吸附等温线呈现滞后环 ,为第四类型 ,而吸附等温线在 30 4K、32 3K下为阶梯形 ,在 35 4K、42 3K温度下呈第一类型 ,其中 42 3K温度下的吸附等温线可准确的用Langmuir方程来描述。本文同时讨论了吸附质分子间以及吸附质和吸附剂间的相互作用、分子结构特性、分子筛对吸附质分子的空间位阻、分子筛的能量不均匀表面等对环戊烷在silicalite 1分子筛上吸附性能的影响     

重量法测定环戊烷在silicalite—l分子筛上的吸附特性

用智能重量分析技术（IGA）研究了环戊烷在silicalite-l分子筛上的吸附特性。结果表明，随着温度的降低，环戊烷的吸附等温线从第一类型过渡为第国类型，在254K和274K温度下吸附等温线呈现滞后环，为第四类型，而吸附等温线在304K、323K下为阶梯形，在354K、423K温度下呈第一类型，其中423K温度下的吸附等温线可准确的用Langmuir方程来描述。本文同时讨论了吸附质分子间以及吸附质和吸附剂间的相互作用、分子结构特性、分子筛对吸附质分子的空间位阻、分子筛的能量不均匀表面等对环戊烷在silicalite-l分子筛上吸附性能的影响。     

吸附型“人工肝”辅助材料的合成及其性能研究：Ⅰ大孔吸附树脂对？…

合成了本乙烯型大孔吸附剂测定其孔结构参数,考察吸附剂对芳香氨基酸的吸附性能,实验结果表明,ＭＡ－２型吸附剂对芳香氨基酸具有特异性吸附,而对支链氨基酸吸附为非特异性吸附,其血液相容性良好。     

吸附型“人工肝”辅助材料的合成及其性能研究Ⅰ大孔吸附树脂对芳香氨基酸的吸附性能

合成了苯乙烯型大孔吸附剂（MacroreticularAdsorbentMA）测定其孔结构参数，考察吸附剂对芳香氨基酸的吸附性能。实验结果表明，MA－2型吸附剂对芳香氨基酸具有特异性吸附，而对支链氨基酸吸附为非特异性吸附，其血液相容性良好。     

负载铈（IV）的D412螯合树脂除氟性能的研究

以D412氨基磷酸型螯合树脂为载体,负载Ce（IV）制得选择性吸附剂。探讨了该吸附剂对水中的F－的静态和动态吸附性能,实验中对含氟液pH值、浓度、流量以及再生液种类和浓度对该吸附剂吸附性能的影响进行了研究,并采用红外分析方法推测了吸附剂吸附F－的机理。     

氨基酸在固/液界面的吸附作用

本文介绍了氨基酸在固/液界面吸附等温线的特点,氨基酸液相吸附热力学和活性炭、硅胶、二氧化钛、氧化铝、蒙脱土等自水中吸附氨基酸的机制。     

Adsorption Behavior of Potassium Ion on Planting Materials

Characterization of planting materials used as adsorbent has been studied in order to compare potassium ion adsorption on two types of planting materials, which are a fired planting material （FPM） made from a mixture of 4 kinds of wastes （bottom ash, flue gas desulfurization （FGD） gypsum, paddy soil and sawdust） formed and fired at 850 ℃and the commercial planting material called ＂hydroball＂ （HDB） bought from Jatujak market, Bangkok. The physical characteristics of both types of planting materials indicate that the FPM has a larger specific surface area than the HDB. The factors affecting potassium adsorption on both the planting materials such as an equilibration time and some solid/solution ratios were investigated. The suitable equilibration time for the adsorption to reach an equilibrium on the FPM and HDB is one and two hours, respectively. The highest amounts of potassium ion adsorbed on both the planting materials were obtained when the solid/solution ratio was 1 ： 15. The adsorption behavior on both the planting materials tends to correspond with the Freundlich isotherm.     

A review on experimental studies of surfactant adsorption at the hydrophilic solid-water interface

The progresses of understanding of the surfactant adsorption at the hydrophilic solid-liquid interface from extensive experimental studies are reviewed here. In this respect the kinetic and equilibrium studies involves anionic, cationic, non-ionic and mixed surfactants at the solid surface from the solution. Kinetics and equilibrium adsorption of surfactants at the solid-liquid interface depend on the nature of surfactants and the nature of the solid surface. Studies have been reported on adsorption kinetics at the solid-liquid interface primarily on the adsorption of non-ionic surfactant on silica and limited studies on cationic surfactant on silica and anionic surfactant on cotton and cellulose. The typical isotherm of surfactants in general, can be subdivided into four regions. Four-regime isotherm was mainly observed for adsorption of ionic surfactant on oppositely charged solid surface and adsorption of non-ionic surfactant on silica surface. Region IV of the adsorption isotherm is commonly a plateau region above the CMC, it may also show a maximum above the CMC. Isotherms of four different regions are discussed in detail. Influences of different parameters such as molecular structure, temperature, salt concentration that are very important in surfactant adsorption are reviewed here. Atomic force microscopy study of different surfactants show the self-assembly and mechanism of adsorption at the solid-liquid interface. Adsorption behaviour and mechanism of different mixed surfactant systems such as anionic-cationic, anionic-non-ionic and cationic-non-ionic are reviewed. Mixture of surface-active materials can show synergistic interactions, which can be manifested as enhanced surface activity, spreading, foaming, detergency and many other phenomena.     

Fluoride adsorption enhancement of Calcined-Kaolin/Hydroxyapatite composite

The use of waste or natural resources is an interesting approach to preparing adsorbent materials. Most adsorption materials are powder-based, making them impractical for a variety of applications. In this work, the natural kaolin clay and hydroxyapatite synthesized from biogenic waste were studied as defluoridation materials. The point of zero charge (pH_PZC), the fluoride adsorption capability and the adsorption isotherm of calcined kaolin and mixed calcined kaolin/hydroxyapatite in both powdered and moulded forms were investigated. The hardness of the moulded (post-formed) samples was tested before and after in immersion in a fluoride solution. The maximum hardness was 15.8 kilo-pounds for the post-formed calcined kaolin sample. Sample hardness values slightly decreased after immersion in a fluoride solution due to the formation of micro-cracks. Most samples presented high pH_PZC values, implying that these materials are suitable for the capture of fluoride anions. The adsorption properties varied with the ratio of calcined kaolin to hydroxyapatite. These properties for post-formed samples were different from those in powdered form. Post-formed samples showed higher fluoride adsorption. The maximum fluoride adsorption capacity and efficiency of the post-formed samples (calcined kaolin) at pH 3 were 1.74 F^? mg/g and 87%, respectively. The sorption of fluoride of hydroxyapatite and mixed calcined kaolin/hydroxyapatite powders was found to have the form of the Langmuir isotherm, which indicates a monolayer adsorption on the adsorbent surface. Isotherms of calcined kaolin powder, post-formed calcined kaolin and mixed calcined kaolin/hydroxyapatite samples followed the Freundlich isotherm, which indicates multilayer adsorption on a heterogenous adsorbent surface.     

Relation between adsorption of some anionic surfactants on barite and solution/air interfaces

The adsorption behaviour of synthesized anionic surfactants with chemical structure RO–Ph–N?N–Ph–X, where R is octyl, dodecyl or cetyl and X is SO₃Na, was analysed. Analysis of the behaviour of the surfactants was made using a modified version of the Frumkin adsorption isotherm. The values of thermodynamic parameters were calculated at the solution/air interface. The relation between adsorption of the surfactants at the solution/air interface and solid/liquid interface was investigated. The surface properties of these synthetic surfactants were studied. The results show that the length of the hydrocarbon chain of these surfactants plays a major role in determining the surface and thermodynamic properties. The results also indicate that there is a good relationship between effectiveness of adsorption of the surfactant and its efficiency as a collector. Copyright © 2003 John Wiley & Sons, Ltd.     

Adsorption of an endoglucanase from the hyperthermophilic Pyrococcus furiosus on hydrophobic (polystyrene) and hydrophilic (silica) surfaces increases protein heat stability

The interaction of an endoglucanase from the hyperthermophilic microorganism Pyrococcus furiosus with two types of surfaces, that is, hydrophobic polystyrene and hydrophilic silica, was investigated, and the adsorption isotherms were determined. The adsorbed hyperthermostable enzyme did not undergo loss of biological activity. A model was proposed for the mechanism of interaction of the enzyme with the surface based on the shape of the adsorption isotherm, the morphological characteristics of the enzyme, and the thermodynamic parameters of the system. The enzyme was irreversibly immobilized at the solid/liquid interface even at high temperatures, and most interestingly, it acquired further heat stabilization upon adsorption. The denaturation temperature increased from 108 degrees C in solution to 116 degrees C upon adsorption on hydrophilic silica particles. Adsorption on the hydrophobic polystyrene surface even shifted the denaturation temperature to 135 degrees C, the most extreme experimentally determined protein denaturation temperature ever reported. Maintenance of the biological function particularly at high temperatures is important for the development of solid substrate immobilized enzymes for applications in biocatalysis and biotechnology. This also presents an additional stabilization mechanism employed by nature where the extracellular hyperthermostable enzyme remains folded and active at the extreme temperatures of its natural environment by adsorption on the surface of rocks and other materials appearing in the surroundings of the microorganism.     

Single‐Molecule Measurement of Adsorption Free Energy at the Solid–Liquid Interface

Adsorption plays a critical role in surface and interface processes. Fractional surface coverage and adsorption free energy are two essential parameters of molecular adsorption. However, although adsorption at the solid–gas interface has been well‐studied, and some adsorption models were proposed more than a century ago, challenges remain for the experimental investigation of molecular adsorption at the solid–liquid interface. Herein, we report the statistical and quantitative single‐molecule measurement of adsorption at the solid–liquid interface by using the single‐molecule break junction technique. The fractional surface coverage was extracted from the analysis of junction formation probability so that the adsorption free energy could be calculated by referring to the Langmuir isotherm. In the case of three prototypical molecules with terminal methylthio, pyridyl, and amino groups, the adsorption free energies were found to be 32.5, 33.9, and 28.3 kJ mol^?1, respectively, which are consistent with DFT calculations.     

Adsorption of benzoic acid onto high specific area activated carbon cloth

The adsorption of benzoic acid from aqueous solution onto high area carbon cloth at different pH values has been studied. Over a period of 125 min the adsorption process was found to follow a first-order kinetics and the rate constants were determined for the adsorption of benzoic acid at pH 2.0, 3.7, 5.3, 9.1, and 11.0. The extents of adsorption and the percentage coverage of carbon cloth surfaces were calculated at 125 min of adsorption. Adsorption isotherms at pH values of 2.0, 3.7, and 11.0 were derived at 25 degrees C. Isotherm data were treated according to Langmuir and Freundlich equations and the parameters of these equations were evaluated by regression analysis. The fit of experimental isotherm data to both equations was good. It was found that both the adsorption rate and the extent of adsorption at 125 min were the highest at pH 3.7 and decreased at higher or lower pH values. The types of interactions governing in the adsorption processes are discussed considering the surface charge and the dissociation of benzoic acid at different pH values.     

Interaction of supramolecular centers of silica surface with aromatic amino acids

Surface grafting of β-cyclodextrin onto aminopropylsilica has been carried out under mild conditions using 1,1'-carbonyldiimidazole as an activator. The obtained β-cyclodextrin-silica has been characterized by means of chemical and IR spectral analysis. Adsorption of para-aminobenzoic and para-aminosalicylic acids onto the surface of hydroxylated silica, aminopropylsilica, and silica with chemically attached β-cyclodextrin moieties has been studied in relation to duration of contact, equilibrium concentration, and solution pH. Chemical immobilization of β-cyclodextrin onto silica surface improves adsorption parameters for aromatic amino acids. The well-known mathematical models for the kinetic and equilibrium adsorption processes have been used, and the main adsorption parameters have been calculated. Kinetic curves of aromatic amino acids adsorption correspond to the model of pseudo-second order reaction. The major contribution to the equilibrium adsorption of para-aminobenzoic and para-aminosalicylic acids onto β-cyclodextrin-containing silica is due to the formation of surface inclusion complexes between grafted oligosaccharide molecules and aromatic amino acids.