THE EFFECT OF IONIC STRENGTH ON THE UPTAKE OF TAURINE ON A STRONG-BASIC ANION EXCHANGE RESIN

1. INTRODUCTION Taurine (NH2CH2CH2SO3H) is one of the most important amino acids in the human body, and plays an important role in a variety of physiological functions, pharmacological actions and pathological conditions, such as in controlling epilepsy, hypertension and arrhythmia. It is also often used to recover osmotic pressure and promote cerebrum growth [1,2]. As one of amino acids, taurine had the amphoteric characteristic which can be utilized in the ion-exchange technique to e…     

牛磺酸和甘氨酸在D290树脂上的离子交换平衡

研究了牛磺酸与甘氨酸在阴离子树脂D290上的离子交换平衡.采用静态法分别进行牛磺酸/氢氧根/D290树脂和甘氨酸/氢氧根/D290树脂体系的离子交换平衡实验并测定等温线;在不同的离子强度下进行了牛磺酸/甘氨酸/氢氧根/D290阴离子交换树脂体系的离子交换平衡实验,测定牛磺酸和甘氨酸在碱性条件下的竞争交换平衡等温线.实验结果表明,牛磺酸在D290阴离子交换树脂上的交换量大于甘氨酸的交换量,阴离子交换树脂对牛磺酸和甘氨酸的选择性系数分别为STau-,OH-=2.55,SGly-,OH-=1.65.在牛磺酸/甘氨酸/氢氧根/D290树脂体系中,D290树脂对牛磺酸/甘氨酸/氢氧根3种离子的选择性从高到底顺序是:牛磺酸＞甘氨酸＞氢氧根.树脂对牛磺酸的选择性要大于对甘氨酸的选择性.随着溶液中离子强度的增大,树脂对牛磺酸与甘氨酸之间的选择性下降.     

低浓度下离子交换树脂吸附氨基酸的机理

详细地研究了在低浓度下, 酸(碱)式或盐式强酸性阳离子和强碱性阴离子交换树脂吸附氨基酸的机理·结果表明, 氨基酸通过离子交换、离子转移和物理吸附等三种机理被离子交换树脂吸附。     

批量离子交换层析和凝胶过滤层析在类人胶原蛋白I纯化中的应用

研究了利用批量离子交换层析与凝胶过滤层析相结合的方法纯化类人胶原蛋白I的最佳条件。分别考察了不同离子交换树脂、缓冲溶液pH、离子强度、进料蛋白浓度对批量离子交换的影响,以及不同凝胶过滤介质对凝胶过滤层析的影响。结果表明,采用阴离子交换树脂DEAE52吸附杂蛋白,缓冲液pH为7.0,NaCl浓度为0.2mol/L,进料蛋白浓度为40mg/mL,并采用凝胶过滤介质SephadexG-100进一步纯化后,类人胶原蛋白I的纯度可达到98.2%,总纯化倍数为3.1,总回收率为80.6%。SDS-PAGE分子量分析和N末端氨基酸序列分析均表明纯化后的类人胶原蛋白I与基因设计一致。     

Characterization of ion exchange stationary phases via pH transition profiles

New non-destructive method for characterization of ion exchange chromatographic columns based on transient pH formed by a step change in ionic strength of buffer solutions was examined. The method was used to distinguish between cation and anion or weak and strong ion exchange chromatographic supports and to determine the capacity of the chromatographic resins. The general scheme to distinguish between most commonly used types of ion exchange chromatographic columns was proposed. The duration of pH transient was shown to be linearly proportional to the total ionic capacity and was used to estimate protein dynamic binding capacity of the resin. The effects of pH, concentration and temperature on transient pH duration were examined.     

D301大孔树脂吸附钒(V)的性能研究

研究了D301大孔树脂对钒的吸附性能.结果表明,pH值对D301树脂吸附钒的影响很大,与钒在溶液中的赋存状态有关,且在pH=2时吸附效果最好:测得吸附热力学参数分别为:△H=8.97kJ/mol,△G_(313)=-5.69kJ/mol,△G_(303)=-5.2kJ/mol,△G_(293)=-4.9kJ/mol,△S=46.84J/mol·K.等温吸附服从Freundlich经验式;考察了溶液浓度、搅拌速率对交换过程的影响,并对实验数据运用相关理论模型进行拟合,结果显示钒(V)在D301树脂上吸附交换过程控制步骤为颗粒扩散控制,反应级数n为0.2391.     

谷氨酸脱羧酶在新型羧甲基化交联烯丙基葡聚糖凝胶树脂上的固定化

本文首次用合成的羧甲基化的以N，N’-甲叉双丙烯酰胺交联的烯丙基葡聚糖（简称CM—CADB）凝胶生化树脂为新型载体，研究了谷氨酸脱羧酸在CM—CADB树脂上的固定化与环境的依赖关系。确定了酶固定化最佳条件：缓冲体系为pH4．4，0．10mol／L磷酸氢二钠-0．05mol／L柠檬酸，载体为交联度35％，交换容量3．0meq／g的CM－CADB凝胶树脂，吸附平衡时间4h以上，酶用量为30．0mg／gdryresin，固定化环境温度控制在40℃。从理论上分析了上述结果。     

FACTORS AFFECT THE RELEASE OF PSEUDOEPHDRINE HYDROCHLORIDE FROM THE UNCOATED CATION EXCHANGE RESIN—BASED DRUG DELIVERY SYSTEM IN VITRO

In this paper,it was investigated that the effect of parameters such as the ionic strength,pH.counter-ion type of release medium,particle size.and cross linkage of cation exchange resin on the release of model drug pseudoephedrine hydrochloride(PE) from uncoated drug-resin complex.The drug-resin complex was pepared by the reaction of PE with strongly acidic cation exchange resin(001×4,001×7,001×14） .The result showed that the loading of PE increased with the increase of temperatures.The release of PE from drug-resin complex at 37℃ was monitored in vitro.From the experiments,it was found that the release rate of PE depends on the pH.comosition of the releasing media,increased at lower pH media or with increase of ionic strength of media.Moreover,the release rate of PE was inversely proportional to the cross-linkage and particle size of the cation exchange resin.     

pH和盐对树脂吸附芳香酸的影响研究

通过三甲胺修饰超高交联聚苯乙烯树脂NJ-00制备了一种新型树脂(NJ-03),树脂性质表征说明,通过改性季胺基被成功引入,树脂骨架上增加了一定数量的碱性基团。研究了pH、盐浓度对芳香酸类化合物在NJ-03树脂上吸附的影响,并与商品大孔强碱阴离子交换树脂D-201以及大孔弱碱阴离子交换树脂D-301进行对比,探讨了pH和盐浓度影响吸附的机理。     

聚乙烯醇硫酸钾水凝胶电机械化学行为研究

通过将交联聚乙烯醇硫酸酯化的方法制备了一种新型电刺激响应性聚乙烯醇硫酸钾(PVSK)智能水凝胶,并探讨了溶液离子强度和pH对PVSK水凝胶的溶胀吸水率、机械性能以及电机械化学行为的影响.结果表明,制备的PVSK水凝胶的平衡溶胀比随NaCl溶液离子强度的增大而减小,在pH2.39～10.83范围内基本不受溶液pH的影响;经不同离子强度和pH的NaCl溶液充分溶胀的PVSK水凝胶具有良好的机械性能,在非接触的直流电场作用下,该水凝胶向电场负极弯曲,凝胶的弯曲速度和弯曲偏转量随外加电场强度的增加而增大,随NaCl溶液离子强度的增大出现临界最大值,但不随溶液pH(2.08～10.53)的改变而改变;在循环电场作用下,PVSK水凝胶的电机械化学行为具有良好的可逆性.     

Effect of ionic strength and type of ions on the structure of water swollen polyelectrolyte multilayers

This study addresses the effect of ionic strength and type of ions on the structure and water content of polyelectrolyte multilayers. Polyelectrolyte multilayers of poly(sodium-4-styrene sulfonate) (PSS) and poly(diallyl dimethyl ammonium chloride) (PDADMAC) prepared at different NaF, NaCl and NaBr concentrations have been investigated by neutron reflectometry against vacuum, H(2)O and D(2)O. Both thickness and water content of the multilayers increase with increasing ionic strength and increasing ion size. Two types of water were identified, "void water" which fills the voids of the multilayers and does not contribute to swelling but to a change in scattering length density and "swelling water" which directly contributes to swelling of the multilayers. The amount of void water decreases with increasing salt concentration and anion radius while the amount of swelling water increases with salt concentration and anion radius. This is interpreted as a denser structure in the dry state and larger ability to swell in water (sponge) for multilayers prepared from high ionic strengths and/or salt solution of large anions. No exchange of hydration water or replacement of H by D was detected even after eight hours incubation time in water of opposing isotopic composition.     

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.     

A new sorbent for europium nitrate extraction: phosphonic acid grafted on polystyrene resin

A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid–solid extraction of europium(III). The results indicated that phosphonic resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH value of 6.5. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and ionic strength were investigated. The maximum uptake capacity of Eu(III) ions was 122.6 mg/g grafted resin at ambient temperature, at an initial pH value of 6.50. The overall adsorption process was best described by pseudo first-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, Eu(III) could be eluted by using 1.0 mol/L H₂SO₄ solution and the grafted resin could be regenerated and reused.     

DETERMINATION OF ION EXCHANGE EQUILIBRIUM CONSTANTS FOR THE WEAK ACID CATION AND THE WEAK BASE ANION EXCHANGE RESINS

The general procedure based on the potentiometric titration has developed.According to the procedure,the rational equilibrium constants of the ion exchange reactions RH/Na,RH/Ca,RH/Sr,RH/Ba for the weak acid cation exchange resin D725 and ROH/Cl for the weak base anion exchange resin D705 have been determined.     

Phenol removal from aqueous solution by adsorption and ion exchange mechanisms onto polymeric resins

The removal of phenol from aqueous solution was evaluated by using a nonfunctionalized hyper-cross-linked polymer Macronet MN200 and two ion exchange resins, Dowex XZ (strong anion exchange resin) and AuRIX 100 (weak anion exchange). Equilibrium experimental data were fitted to the Langmuir and Freundlich isotherms at different pHs. The Langmuir model describes successfully the phenol removal onto the three resins. The extent of the phenol adsorption was affected by the pH of the solution; thus, the nonfunctionalized resin reported the maximum loading adsorption under acidic conditions, where the molecular phenol form predominates. In contrast both ion exchange resins reported the maximum removal under alkaline conditions where the phenolate may be removed by a combined effect of both adsorption and ion exchange mechanisms. A theoretical model proposed in the literature was used to fit the experimental data and a double contribution was observed from the parameters obtained by the model. Kinetic experiments under different initial phenol concentrations and under the best pH conditions observed in the equilibrium experiments were performed. Two different models were used to define the controlling mechanism of the overall adsorption process: the homogeneous particle diffusion model and the shell progressive model fit the kinetic experimental data and determined the resin phase mechanism as the rate-limiting diffusion for the phenol removal. Resins charged after the kinetic experiments were further eluted by different methods. Desorption of nonfunctionalized resin was achieved by using the solution (50% v/v) of methanol/water with a recovery close to 90%. In the case of the ion exchange resins the desorption process was performed at different pHs and considering the effect of the competitive ion Cl⁻. The desorption processes were controlled by the ion exchange mechanism for Dowex XZ and AuRIX 100 resins; thus, no significant effect for the addition of Cl⁻ under acidic conditions was observed, while under alkaline conditions the total recovery increased, specially for Dowex XZ resin.     

D072型树脂脱除过氧化氢中金属阳离子的工艺研究

实验考察D072型阳离子交换树脂在交换柱中脱除过氧化氢中微量金属阳离子的动态行为．通过改变料液流速、高径比、料液中交换离子浓度及料液组成等参数，绘制不同条件下的透过曲线，以此考察D072型树脂对过氧化氢中金属阳离子的动态交换性能，从而确定适宜的工艺条件，为工业化生产提供科学依据．     

氨基葡聚糖对水溶液中铜离子的吸附与脱附

自虾、蟹壳等水产加工废料中提取的甲壳质,经脱乙酰基反应,可得氨基葡聚糖,单体结构可表示为左图。该碱性多糖无毒,不溶于水及碱性溶液,在pH～4.5的稀酸中会溶涨,酸性更强时可溶解并成盐。若要求该聚合物以稳定的固态存在于水中,介质的酸性只允许在很小的范围内变化。聚糖中的氨基与过渡金属离子有良好的螯合作用,可作为固体吸附剂吸附水中微量的有害重金属离子。据文献报导,这类吸附大多呈Langmuir型,但Pb(Ⅱ)与Cr(Ⅲ)是例外,它们的吸附等温线表现出单层吸附饱和后,又呈现多层吸附的特征。扫描电镜的照片表明聚糖吸附Pb(Ⅱ)、Cr(Ⅲ)后,表面有瘤状小结节生成。溶液pH升高有利于重     

叔胺弱碱树脂的强度研究

研究了影响苯乙烯系叔胺弱碱性阴离子交换树脂性能的诸因素．提出了经二甲胺胺化 后所形成的胺基桥是影响树脂强度的主要原因的观点．用磷酸一渗磨圆球率方法对树脂进行强 度检验,使强度数据更为可靠．     

新型树脂基水合锰氧化物对水体中磺胺嘧啶的降解去除

以大孔强碱阴离子交换树脂D201为载体, 采用离子交换和氧化还原方法制备了一种新型树脂基水合锰氧化物材料HMO-201. 考察了不同pH、 离子强度和溶解性有机质(DOM)含量条件下, 该材料对水体中磺胺嘧啶(SD)的去除能力. HPLC-MS分析表明, SD的高效去除是通过HMO-201的降解而非吸附方式实现的. 实验结果表明, pH为1.0时HMO-201在120 min内对0.01 mmol/L SD的去除效率为99.9%, 反应符合表观一级动力学模型; 体系的离子强度和DOM含量变化对SD的去除效率均无显著影响. 模拟环境离子强度和DOM浓度, 连续10批次实验中SD废水的去除效率在240 min内均大于99%; HMO-201的柱动态降解装置连续处理SD溶液2000床体积, 依然未检出SD. 表明HMO-201材料具有较稳定的重复利用性, 对环境中普遍存在的磺胺类抗生素药物具有着高效的降解去除效果, 具有广泛的应用前景.     

布洛芬在阴离子交换树脂上的负载及其缓释

将布洛芬通过静电和疏水作用的共同作用负载于聚苯乙烯型大孔弱碱性阴离子交换树脂D301R和D301T上,最佳负载条件为:布洛芬悬浮于5~10%的乙醇水溶液中,加入树脂后在60℃下搅拌12h,负载量可达到0.49g/g树脂。研究了负载的布洛芬在模拟胃肠道的条件下(pH2下2h、pH 7.4下4h和pH 6.7下18h)的释放动力学,在前12h的释放接近于线性释放,释放率为58~60%。后12h的释放量较小,释放率为13~17%。如果每12h服药1次,第2次服药后的24h的累加释放率接近于线性释放。与聚苯乙烯骨架的大孔弱碱性阴离子交换树脂相比,聚甲基丙烯酸酯骨架的弱碱性阴离子交换树脂(甲基丙烯酸正丁酯/甲基丙烯酸N,N-二甲胺基乙酯/双甲基丙烯酸乙二醇酯共聚物)负载的布洛芬在相同释放条件下突释明显,表明布洛芬与苯乙烯型弱碱性阴离子交换树脂之间的π-π作用在布洛芬的缓释中起关键的作用。