HYDROGEN BONDING IN POLYMERIC ADSORBENTS BASED ADSORPTION AND SEPARATION

I INTRODUCTION.Ftinctional polymer materials for adsorption and separation are widely used in indtistry,agriculture, hi-tech, national defense and scientific research. Functions of these polymermaterials are displayed through interactions between the materials and small molecules or ions,which include ion bonding, covalent bonding, coordinate bonding and van der Waals forces.FunCtional polymers based on the above interactions are ion exchange resins, polymer supportedreagentS, chelating …     

ADSORPTION OF CAFFEINE BY HYDROGEN DONATING ADSORBENTS BASED ON HYDROGEN BONDING

The adsorption isotherms of caffeine from aqueous solution onto three hydrogen donating adsorbents-hydroxypolystyrene,polystryene-azo-pyrogallol,and D72 resin-were measured.The adsorption enthalpies calculated from the isotherms according to the Clausisu-Clapeyron equation were -24-36kJ/mol,-32-37kJ/mol,and -19-24kJ/mol respectively.These values implied that the adsorption processes were based on hydrogen bonding.Furthermore.the mechanism of the adsorption of caffeine onto D72 resin was studied by IR spectra and the small molecular model experiments,and the results showed that the adsorption of caffeine onto hydrogen donating adsorbents was based on hydrogen bonding.     

ADSORPTION OF CAFFEINE BY HYDROGEN DONATING ADSORBENTS BASED ON HYDROGEN BONDING

1. INTRODUCTIONHydrogen bonding is a useful mechanism for adsorptive separation. The low enemy of thisbond ensures reversibility, while the directionality and the short range of this bond conferselectivity. The adsorption of hydrogen donating solutes onto an adsorbent capable of acceptinghydrogenedmberlite XAD-7, an adsorbent consisted of polycarboxylic ester--based onhydrogen bonding has been examined in detail 11-41. However, the adsorption of hydrogenaccepting solutes onto polymeric a…     

ADSORPTION OF DINITROPHENOLS ONTO POLYMERIC ADSORBENTS AND ITS MECHANISM

The adsorption of 2,4-dinitrophenol and 2,6-dinitrophenol on non-polar and polar adsorbents was studied.The results showed that the equilibrium adsorption did not comply with the Langmuir equation and was not mono-layer adsorption .It is of interest to notice that the effect of pH on the adsorption of 2,4-or 2,6-dinitrophenol onto ADS-7 and ADS-21 was very small,The result is explained by hydrogen bonding interaction between 2,4-or 2,6-dinitrophenol and the adsorbent ADS-21.The large adsorption capacity of dinitrophenol onto ADS-21,which was about 500mg/g at an equilibrium concentration of 400mg/L,and the small dinitrophenol leakage in the effluent from ADS-21 column presented a good prospect for treatment of wastewater containing dinitrophenol with adsorbent ADS-21.     

ADSORPTION OF DINITROPHENOLS ONTO POLYMERIC ADSORBENTS AND ITS MECHANISM

1 INTRODUCTIONPhenol and many substitUted phenols, such as nitrophenols, chlorophenols and aminophenolset al, are the common organic pollutantS existing in wane water of many chemical plants.Treatment of the wastewater containing phenols is an important project for environmentprotection and has been studied by various methods, such as dialysis ['l, microbial degradation ['1,oxidation l'l, extracting with solvents I4] and adsorption with polymeric adsorbents IS]. Theadsorption method is v…     

ADSORPTION OF PHENYLACETIC ACID ON MACROPOROUS POLYMERIC ADSORBENTS

Several macroporous polymeric adsorbents(NDA-999,XAD-8,X-5 and XAD-2)were emplyed in the study to adsorb phenylacetic acid from aqueous solution.Effect of salt and ambient temperature on adsorption was studied using NDA-999 adsorbent and the adsorption process conforms to Freundlich′s model reasonably.Adsorption dynamics were conducted in batch experiments in order to make clear the mechanism of adsorption process.It is proved that the squared driving force mass transfer model can be adopted to elucidate the process.The treatment process of industrial wastewater containing high strength of phenylacetic acid was proposed for cleaner production of phenylacetic acid.     

水介质中氢键吸附与疏水吸附协同作用的研究

研究了丙烯酸型树脂(D152)在水、乙醇和正己烷中对苯胺、N-甲基苯胺和N,N-二甲基苯胺的吸附行为.在水中D152树脂对3种吸附质的吸附亲合性随N上甲基数的增加而增大,说明疏水作用是主要的吸附机理,但其吸附焓己超出范德华力的范围而在氢键的键能范围内,故氢键吸附也同时在起作用.在正己烷中,D152树脂对3种吸附质的吸附亲合性随N上甲基数的增加而减小,与水中呈相反的趋势,说明氢键作用是主要的吸附机理.在乙醇中,D152树脂对3种吸附质均无吸附,因为疏水作用和氢键作用均受到的乙醇抑制.在水中,吸附质与树脂间的氢键作用同样受到水的抑制,但氢键吸附却依然存在,说明水介质中氢键吸附和疏水吸附可能存在一种协同作用.在热力学上对水介质中氢键吸附和疏水吸附的协同作用给于合理的解释.     

ADSORPTION OF PHENYLACETIC ACID ON MACROPOROUS POLYMERIC ADSORBENTS

1. INTRODUCTION Phenylacetic acid is a common intermediate of pesticide, flavor and medicine. It is generally produced by hydrolysis of benzyl cyanide, but it will destroy the environment and human health seriously due to the toxicity of the raw material…     

ADSORPTION OF 4-METHYLANILINE IN AQUEOUS SOLUTION BY BENZOYL-CONTAINING POLYMERIC ADSORBENTS

New polymeric adsorbents (ZH-02, ZH-03) containing benzoyl group for adsorbing and removing 4-methylaniline from its aqueous solutions were prepared. Studies on the isotherms and the comparison of desorption conditions evidenced through the adsorption of 4-methylaniline in water onto ZH-02 and ZH-03, namely that there are chemisorption‘s transitions at a proper higher temperature. Mini-colunm adsorption studies of 4-methylaniline on XAD-4, ZH-02 and ZH-03 at 288 K show that the breakthrough capacities are 2.39, 2.99 and 3.19 mmol/g and the total capacities are 3.45, 3.92 and 4.35 mmol/g, respectively.     

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.     

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.     

季铵基吸附树脂的合成及其在甜菊式甙提取分离中的应用

研究了由工业二乙烯苯聚合得到的大孔树脂进行氯甲基化的可行性，考察了聚合物孔结构催化剂用量、反应温度和时间等因素对氯甲基化反应的影响，由氯甲基化树脂制备了强极性季铵基吸附剂。并研究了合成的季铵基吸附剂对甜叶菊提取物中甜菊甙及色素的吸附－脱附性能，发现该吸咐剂对甜菊甙与色素的吸附－脱附性能完全不同，因而可用该吸附剂制备高品质的甜菊式。     

几种树脂对西红花糖苷的吸附性能的研究

本文系统研究了硅胶和几种国产吸附树脂对西红花提取物溶液的吸附与洗脱性能，包括树脂的筛选，洗脱剂的选择，并研究了pH，温度和西红花提取物的浓度对西红花提取在SZ－1吸附树脂上的吸附影响，结果表明，SZ－1吸附树脂对西红花提取物的吸附能力较强，洗脱能力为最好，其吸附性能和洗脱性能均优于常用色谱固定相硅胶，SZ－1吸附树脂的静态吸附容量为1．04g/g，动态吸附容量为0．5－0．6g/g，洗脱率可达98％以上，且吸附速度快，易于洗脱和再生。     

SYNERGISTIC INTERACTIONS ON PHENOL ADSORPTION FROM AQUEOUS SOLUTIONS BY POLYMERIC ADSORBENTS

In this paper, the adsorption behaviors of phenol on polymeric adsorbents (Amberlite XAD4, NDA101, and D301)were investigated in batch system at 293, 303, and 313K, respectively. As the results shown, the adsorption isotherms of phenol on all adsorbents can be well fitted by Langmuir and Freundlich equations, which indicate a favorable and exothermic process. The adsorption capacity on a newly developed aminated adsorbent, NDA101, on which adsorption could be achieved by both hydrogen bonding interaction and π-π interaction, are higher than that on a weak base adsorbent, D301, on which adsorption could be achieved by hydrogen bonding interaction only, and on a nonpolar adsorbent, XAD4, on which adsorption could be achieved by π-π interaction only. The results of this paper indicate that the synergistic effect of some weak interactions, which occur simultaneously would contribute more to the adsorption than that occur individually.     

SINGLE AND BINARY ADSORPTION PERFORMANCE OF SALICYLIC ACID AND 5-SULFOSALICYLIC ACID ONTO HYPERCROSSLINKED POLYMERIC ADSORBENTS

Single and binary adsorption behaviors of salicylic acid and 5-sulfosalicylic acid onto hypercrosslinked polymeric adsorbents, i.e. NDA-101 and NDA-99 were investigated. The Freundlich model can successfully describe all the adsorption isotherms tested, which indicates a favorable and exothermic adsorption process. The adsorption of salicylic acid relies on π-π interaction, while the electrostatic interaction further influences the adsorption of 5-sulfosalicylic acid onto NDA-99. The adsorptive capacity of salicylic acid on NDA-99 decreases but increases on NDA-101 with 5-sulfosalicylic acid as the background component in a binary solute system. The amount of 5-sulfosalicylic acid adsorbed was decreased with the increase in initial concentration of salicylic acid on both adsorbents. The competition for the adsorption sites is considered to be predominant in the solid-to-liquid interaction process. The adsorption selectivity of salicylic acid onto NDA-101 is higher than onto NDA-99 by more than an order of magnitude. Thus, combination technique involving NDA-101 followed by NDA-99 can be effectively applied to separate and recover salicylic acid and 5-sulfosalicylic acid from wastewater.     

苯酚和苯胺在超高交联吸附树脂上的共吸附行为

研究了水溶液中苯酚和苯胺在超高交联吸附树脂NDA103、NDA101、NDA100上的竞争吸附和协同吸附行为.实验结果表明,单组分苯酚或苯胺水溶液和双组分共存水溶液中吸附质分子在超高交联吸附树脂上的吸附等温线均符合Langmuir模型.当双组分摩尔比为1∶1时,在较低平衡浓度范围内苯酚和苯胺在树脂上呈现竞争吸附行为,其主导机制是两种吸附质分子对树脂内外表面上π-π作用吸附位点的直接竞争;而在较高平衡浓度范围内呈现协同吸附行为,其主导机制是两种吸附质分子之间的氢键作用.吸附温度由293K升至313K时,苯酚和苯胺在NDA103上的协同吸附作用加强,而在NDA101和NDA100上的协同吸附作用变化不明显.     

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.     

壳聚糖衍生物吸附剂在蛋白质分离纯化中的应用

综述了近年来甲壳素及壳聚糖衍生物吸附剂、色谱填料、分离膜及医用免疫吸附剂在蛋白质分离纯化中的应用．引用文献65篇．     

高度交联聚苯乙烯吸附剂的结构与吸附性能研究

在通过Ｆｒｉｅｄｅｌ—Ｃｒａｆｔｓ后交联反应制备高度交联聚苯乙烯吸附剂的过程中，向反应体系中加入非极性芳香化合物甲苯，当加入少量甲苯时，吸附剂的比表面积、孔容等变小，但其吸附能力却明显提高；当加入甲苯超过某一量时，其吸附能力又随加入甲苯的量的增加而降低，这说明孔结构和骨架结构共同影响着高度交联聚苯乙烯吸附剂的吸附性能．     

HYDROGEN BONDING AND PHOTOTAUTOMERISM OF 3-METHYLLUMICHROME

The spectral changes of 3-methyllumichrome in 1,2-dichloroethane upon addition of hex-afluoroisopropanol, trifluoroacetic acid and acetic acid as hydrogen donor agents, have been defined. In the presence of 0.8 M hexafluoroisopropanol, the absorption and fluorescence emission spectra of 3-methyllumichrome in 1,2-dichloroethane acquire features nearly identical to those observed in aqueous solution. Therefore, hexafluoroisopropanol can be considered as a model compound for studies on hydrogen bonding of alloxazine derivatives in nonpolar media. The observed spectral changes upon addition of trifluoroacetic acid are caused mainly by protonation. The presence of hydrogen bonded and protonated forms of 3-methyllumichrome has been checked by means of excitation spectra. The addition of acetic acid causes minor hydrogen bonding effects but gives rise to the phototautomery with an efficiency of one order of magnitude higher in 1,2-dichloroethane than previously observed in methanol or dioxane. The isoalloxazinic emission band appears at about 495 nm and shifts bathochromically to 540 nm upon increasing acetic acid concentration, probably due to the opening of the primary cyclic structure between 3-methyllumichrome and acetic acid. The fluorescence emission spectra can be resolved using lognormal approximation into three bands, one ascribed to the alloxazinic form (maximum at about 440 nm) and the others to isoalloxazinic species (maxima at about 495 and 540 nm). The excitation spectra confirm the presence of two excited alloxazinic forms, one solvated by 1,2-dichloroethane with emission at 435 nm and T ˜1 ns, and the second bonded with acetic acid, bathochromically shifted with T ˜5 ns and able to phototautomerize. The sum of excitation spectra of both forms in suitable proportion reconstructs the absorption spectra of 3-methyllumichrome in 1,2-dichloroethane and acetic acid.