取代基效应对三苯甲酸纤维素酯类吸附剂的吸附性能的影响

采用催化合成法制备三苯甲酸纤维素酯（CTB）、三（4-甲基苯甲酸）纤维素酯（CTMB）和三（4-氯苯甲酸）纤维素酯（CTCB），将其分别负载于Gas Chrom Q载体上，用不同类型的探针分子及气相色谱法表征其吸附性能，研究取代基团的电子效应和空间效应对其吸附性能的影响。实验结果表明：在三苯甲酸纤维素酯类吸附剂和苯衍生物吸附质的苯环上的取代基效应（电子效应和立体效应）对吸附质在吸附剂上的吸附热（-Δha）的影响显著，但两者的影响各不相同。     

胺基功能化的炭材料上二氧化碳吸附的密度泛函理论研究

本文利用色散作用校正的密度泛函理论研究了炭材料上含氮官能团对CO₂吸附的作用。通过计算比较了不同含氮官能团炭材料结构片段吸附二氧化碳后的结构参数和能量,由于较强的静电作用和形成弱氢键,含单个苯环的酰胺和吡啶类的吸附剂吸附二氧化碳的作用强于单个苯胺和吡咯类吸附剂。但当增加苯环数时,色散作用主导的吡咯型吸附剂的吸附能力显著增强。以上结果预示着酰胺和吡咯类将是大π体系中具有良好CO₂吸附性能的吸附剂。因而,色散作用在CO₂吸附过程中也占据着重要地位。计算得到的结果与我们之前的实验结果一致,并且将有利于筛选更有效的二氧化碳吸附剂。     

超高交联吸附树脂对芳香有机物的吸附机理

通过3种吸附树脂AmberliteXAD-4、AM-1和JX101对芳香化合物苯胺、苯酚和苯甲酸在不同温度下的吸附特征,利用前线轨道理论进行了合理解释。结果表明,吸附剂表面进行适当的修饰,可以改变吸附剂的LUMO或HOMO,使吸附质分子与吸附剂表面的功能基产生化学作用,从而产生额外的化学吸附量,为优化设计吸附剂提供了理论指导。     

EFFECT OF pH ON THE ADSORPTION OF p-AMINOBENZOIC ACID ON POLYSTYRENE-BASED ADSORBENTS

In the present study the adsorptive properties of p-aminobenzoic acid with hypercrosslinked and multi-functional polymeric adsorbents at different solution pHs were systematically investigated in accordance with the particular physicochemical characteristics of the aromatic amphoteric compound involving both Lewis acid and Lewis base functional groups. It was found that the equilibrium adsorption data of the three polymeric adsorbents fitted well in the Langmuir and Freundlich isotherm equations. Studies at various pH levels indicate that the capacity of the adsorbents for adsorption of the ionic forms of adsorbate is less than that for the corresponding neutral species. At pH 3.78, the adsorption capacities of the three adsorbents are the highest. Whereas the adsorption property of multi-functional polymeric adsorbent NJ-99 is the largest, which may be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of p-aminobenzoic acid. The trend of the adsorption capacities of the three adsorbents towards p-aminobenzoic acid with the solution pH is in accord with the dissociation curve of the neutral molecular p-aminobenzoic acid. The adsorption forces include π-π interaction, hydrogen-bonding interaction and electrostatic attraction or repulsion when there exist the molecular and ionic adsorbing species at different pHs in aqueous solution.     

The influence of the structure of the surface of functional organosilicas on the adsorption of cholic acid

High-dispersity silica was modified by functional groups capable of protonating or carrying a constant positive charge. IR and UV spectroscopy, temperature-programmed thermogravimetry, pH metry, and quantitative analysis of grafted compounds were used to determine the structure of the surface of functional organosilicas. The adsorption of primary bile (cholic) acid on silica adsorbents and cholestiramine was studied. The adsorption of cholic acid from solutions with pH 2–8 was substantially higher on adsorbents with positively charged surfaces. The silica adsorbents synthesized were shown to have higher cholic acid adsorption parameters compared with adsorbents used in medicine.     

胺基修饰的高度交联聚苯乙烯树脂对间苯二酚吸附行为研究

研究了AH系列胺基修饰的超高交联树脂对水溶液中间苯二酚的静态吸附行为特征,结果表明,它们对间苯二酚的吸附容量明显高于母体交联树脂NDA-100和大孔弱碱性阴离子交换树脂D301.AH系列树脂与吸附质分子之间不仅有范德华作用力,还存在着氢键等作用力.该类树脂对间苯二酚的吸附为自发的放热过程,属于以物理作用为主兼有弱化学作用的吸附过程.吸附速率符合准一级动力学方程,表观吸附速率常数随树脂胺基含量的升高而降低.     

Properties of new fibrous adsorbents with amidoxyme and hydrazidine groups

Data on sorption properties of new fibrous adsorbents with respect to heavy metals are presented. The POLYORGS 34 and POLYORGS 35 filled fibrous adsorbents and POLYORGS 33 fibrous adsorbent contain amidoxyme and hydrazidine groups. Is has been shown that these adsorbents can be used for the adsorption preconcentration of heavy, noble, and rare metals and radionuclides from aqueous salt solutions. Examples of using adsorbents under study for the dynamic preconcentration of copper from a 0.5 M NaCl solution during filtration through a series of disks, column, or adsorption cartridges are presented.     

螯合吸附分离功能纤维的研究进展

螯合纤堆是一类能与金属离子形成多配位络合物的纤堆状吸附功能材料,是近年来发展起来的一种新型离子交换纤堆,具有吸附选择性高、易洗脱、容易再生等优点。综述了近年来螯合纤堆的制备方法及种类,对其螯合机理进行了探讨,概括了该纤堆的应用范围并指出了其应用前景。     

Microcalorimetric studies of interactions between proteins and hydrophobic ligands in hydrophobic interaction chromatography: effects of ligand chain length, density and the amount of bound protein

Using isothermal titration calorimetry (ITC), this investigation directly measured the adsorption enthalpies of proteins on various hydrophobic adsorbents. Various amounts of butyl and octyl groups were attached onto CM-Sepharose to form C4 and C8, two types of hydrophobic adsorbents. The adsorption enthalpies of both trypsinogen and alpha-chymotrypsinogen A were measured at 4.0 M NaCl and pH 10.0, in which most ionic interaction was suppressed. The adsorption isotherms of both proteins on various adsorbents were also measured, thus allowing us to calculate the Gibbs free energy and entropy of adsorption. Experimental results indicated that the adsorption of both proteins on butyl-containing adsorbents was exothermic, while their adsorption on octyl ones was endothermic. In addition, binding of both proteins with the butyl ligand is basically an adsorption process, while binding with the octyl ligand is adsorption and partition processes. Moreover, on both butyl or octyl, the adsorption enthalpy became increasingly positive as the ligand density increased, while the adsorption entropy became more positive as the alkyl chain length or density of the adsorbent increased. In addition, ITC was used to measure protein-protein interaction. The adsorption enthalpy of both proteins increased as the amount of bound protein increased, and the enthalpy increase of trypsinogen appeared to be higher than that of alpha-chymotrypsinogen A. This observation implies that protein-protein repulsion was stronger among trypsinogen molecules in the experiments.     

不同基团修饰的吸附树脂对芳香两性化合物的吸附等温线研究

研究了带有不同功能基团的超高交联吸附树脂NG-10和NJ-99对水溶液中芳香两性化合物氨基苯甲酸的静态吸附性能,并与不带功能基团的吸附树脂CHA-111和XAD-4进行了比较.研究结果表明,树脂NJ-99对水溶液中氨基苯甲酸的吸附能力高于其他树脂.邻氨基苯甲酸在4种树脂上的吸附量均大于对氨基苯甲酸,主要原因是其溶解度小.吸附等温线采用经验的Freundlich方程和理论的Langmuir吸附方程来拟合,在实验所研究的浓度范围内,方程的拟合相关性均很好.     

二乙烯苯-异氰酸三烯丙基酯-丙烯腈共聚物大孔树脂对原花青素的吸附

根据原花青素含有疏水性的苯环和酚羟基的特点,设计合成了含有苯环和酰胺基的大孔二乙烯苯-异氰酸三烯丙基酯-丙烯腈(DTA)共聚物吸附树脂,DTA树脂通过疏水作用和氢键吸附原花青素.比较了DTA吸附树脂和3种商品化吸附树脂ADS-5(非极性)、ADS-8(弱极性)和ADS-17(中极性)对原花青素的吸附性能.结果表明,DTA、ADS-8、ADS-17对原花青素的吸附既包含疏水作用又有氢键参与.在合适的单体和致孔剂配比情况下合成的DTA吸附树脂对原花青素有很好的吸附性能.     

石墨烯基吸附剂的设计及其对水中抗生素的去除

抗生素的大量使用,所带来的环境污染问题受到广泛关注。吸附法因去除效率高、普遍适用性强,呈现出广阔的应用前景,开发新型吸附剂是高效能吸附处理的关键。近年来石墨烯优良的物理和化学性质以及吸附性能,使其成为重要的抗生素吸附剂。由于石墨烯自身的局限性以及对石墨烯吸附剂处理效能和稳定性的要求,基于石墨烯设计开发了多种石墨烯基吸附材料。而目前基于水体中抗生素的石墨烯基复合材料的设计、合成及其吸附作用机制缺乏相关的系统性综述。本文综述了目前水体中抗生素的危害,针对石墨烯基复合吸附材料中,广泛关注的磁性石墨烯吸附剂、聚合物/石墨烯吸附剂、三维石墨烯凝胶和石墨烯/生物炭吸附剂的设计和制备方法进行了总结和概述,并阐述了石墨烯基吸附材料对水体中抗生素的主要吸附作用机制。最后,本文对石墨烯基吸附材料去除水体中抗生素未来的发展方向进行了展望。     

氢同位素吸附容量与吸附剂比表面积的关系

采用容积法测量了77 K下氢气与氘气在不同微孔与介孔分子筛吸附剂上的吸附容量与比表面积. 结果表明, 同类吸附剂上氢同位素的吸附容量与其比表面积之间存在较好的线性关系, 这有力地证明了超临界温度下氢同位素吸附遵循单分子层吸附机理. 在相同的温度、压力和比表面积条件下, 氢同位素气体在微孔分子筛上的吸附容量比介孔分子筛上的大, 这是由于在吸附剂微孔内吸附势场叠加所致, 并通过构建的吸附势模型, 较好地解释了该实验结果.     

Clickable SBA‐15 to Screen Functional Groups for Adsorption of Antibiotics

Pharmaceutical antibiotics, as emerging contaminants, are usually composed of several functional groups that endow them with the ability to interact with adsorbents through different interactions. This makes the preparation of adsorbents tedious and time‐consuming to screen appropriate functionalized materials. Herein, we describe the synthesis of clickable SBA‐15 and demonstrate its feasibility as a screening material for the adsorption of antibiotics based on similar adsorption trends on materials with similar functional groups obtained by a click reaction and cocondensation/grafting methods.     

吸附树脂和活性炭对气体中苯的吸附研究

采用了动态吸附实验方法研究了吸附树脂NDA-201和椰壳型活性炭C1对苯蒸汽的吸附行为.对吸附平衡数据采用Dubinill-Astakov方程进行了拟合分析,并根据吸附剂孔结构特征探讨了吸附机理.实验结果表明,两种吸附剂的苯吸附等温线存在交叉现象,对高浓度苯蒸汽吸附治理可采用NDA-201树脂,低浓度则采用椰壳型活性炭C1;Dubinin-Astakov方程能用来对两种吸附剂的等温线进行拟合,表明吸附剂的微孔区域对吸附起着重要作用.微孔体积计算值的比较和特征曲线叠合的程度说明了.Polanyi吸附势理论更适合于描述椰壳型活性炭C1对苯的吸附,这可能是由于椰壳型活性炭C1的孔分布集中于微孔区,而NDA-201树脂除了微孔外还有一定量的中孔和大孔.     

树脂填充EVAL纤维吸附剂的制备及其吸附性能表征

采用具有亲水性的乙烯-乙烯醇共聚物(EVAL)作为纤维吸附剂基质材料,粉末型Lewatit阳离子交换树脂CNP80ws为功能材料,采用可控相分离方法,制备了不同表面形态结构的树脂填充EVAL吸附剂.当使用外部液体调控相分离过程时,在纤维的表面形成了粗糙的开孔结构,并且随树脂的填充量提高纤维表面的粗糙度与开孔度有所提高.研究结果表明:树脂填充EVAL纤维吸附剂具有较大的吸附容量与较高的脱附率,其吸附容量不低于53.9mg BSA/g吸附剂(树脂填充量50%).     

树脂对化工废水中有毒有机化合物的吸附作用机理与技术研究

超高交联吸附树脂对多种芳香有机化合物较高的吸附容量主要源于其密集的微孔和双峰孔分布.对大孔吸附树脂及超高交联吸附树脂采用不同极性功能基团进行化学修饰可以制得系列离子交换与吸附双重功能吸附树脂,该类树脂对亲水性有机污染物同时具有疏水、静电、络合等多重作用.丙烯酸酯类吸附树脂在吸附芳香磺酸盐时,树脂的骨架和功能基团对吸附过程都有重要的贡献.     

Cadmium ion adsorption on different carbon adsorbents from aqueous solutions. Effect of surface chemistry, pore texture, ionic strength, and dissolved natural organic matter

Adsorption of Cd(II) species at pH = 5 was studied on three carbon adsorbents: granular activated carbon, activated carbon fiber, and activated carbon cloth. As-received and oxidized adsorbents were used. Cd(II) adsorption greatly increased after oxidation due to the introduction of carboxyl groups. The use of a buffer solution to control the pH introduced some changes in the surface chemistry of carbons through the adsorption of one of the compounds used, biphthalate anions. The increase in ionic strength reduced Cd(II) uptake on both as-received and oxidized carbons due to a screening of the electrostatic attractions between the Cd(II) positive species and the negative surface charge, which in the case of as-received carbons derived from the biphthalate anions adsorbed and in the oxidized ones from the carboxyl groups. Tannic acid was used as a model compound for natural organic matter. Its adsorption was greatly reduced after oxidation, and most of the carbon adsorbents preadsorbed with tannic acid showed an increase in Cd(II) uptake. In the case of competitive adsorption between Cd(II) species and tannic acid molecules, there was a decrease in Cd(II) uptake on the as-received carbon whereas the contrary occurred with the oxidized carbons. These results illustrate the great importance of carbon surface chemistry in this competitive adsorption process. Finally, under all experimental conditions used, when the adsorption capacity of carbons was compared under the same conditions it increased in the following order: granular activated carbon < activated carbon fiber < activated carbon cloth.     

Kinetic,isothermal and thermodynamic studies on Th(IV) adsorption by different modified activated carbons

In this study, the performance of modified adsorbents obtained from activated carbon for the adsorption of thorium(IV) ions from aqueous media was investigated. The analytical and spectroscopic methods such as FT-IR, BET, SEM and UV–Vis were used to examine the properties of the modified materials. According to the analysis results, the both adsorbents had large surface areas after modification. Then, temperature, pH, mixing time and solution concentration parameters were observed to determine optimum thorium adsorption conditions on modified materials. The obtained results from the experiments were applied different three kinetic models and adsorption isotherms and thermodynamic parameters were calculated and then all of the results were interpreted. The adsorption process for both adsorption systems was observed to be compatible with the pseudo-second-order kinetic model. The adsorption equilibrium data were best described by the Langmuir model for modified adsorbent with KMnO₄ and by the Freundlich model for modified adsorbent with NaOH. Furthermore, the calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed that the both adsorption processes were endothermic and spontaneous. The data show that modified adsorbents can be used as influential and low-cost adsorbents to remove thorium ion. Modified new adsorbents were highly selective for thorium ion in competitive adsorption studies.

     

High-throughput isotherm determination and thermodynamic modeling of protein adsorption on mixed mode adsorbents

The thermodynamic modeling of protein adsorption on mixed-mode adsorbents functionalized with ligands carrying both hydrophobic and electrostatic groups was undertaken. The developed mixed mode isotherm was fitted with protein adsorption data obtained for five different proteins on four different mixed mode adsorbents by 96-well microtitre plate high throughput batch experiments on a robotic workstation. The developed mixed mode isotherm was capable of describing the adsorption isotherms of all five proteins (having widely different molecular masses and iso-electric points) on the four mixed mode adsorbents and over a wide range of salt concentrations and solution pH, and provided a unique set of physically meaningful parameters for each resin-protein-pH combination. The model could capture the typically observed minimum in mixed mode protein adsorption and predict the precise salt concentration at which this minimum occurs. The possibility of predicting the salt concentration at which minimum protein binding occurs presents new opportunities for designing better elution strategies in mixed mode protein chromatography. Salt-protein interactions were shown to have important consequences on mixed mode protein adsorption when they occur. Finally, the mixed mode isotherm also gave very good fit with literature data of BSA adsorption on a different mixed mode adsorbent not examined in this study. Hence, the mixed mode isotherm formalism presented in this study can be used with any mixed mode adsorbent having the hydrophobic and electrostatic functional groups. It also provides the basis for detailed modeling and optimization of mixed mode chromatographic separation of proteins.