INTERACTION OF AMINO ACID WITH ION EXCHANGERESIN Ⅲ．FURTHER INVESTIGATION OF SUPEREQUIVALENT ADSORPTION MECHANISM OF AMINO ACID ON ION EXCHANGE RESIN

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RAPID DETERMINA TION OF L—GLUTAMIC ACID WITH AN ENZYME REACTOR OFL—GLUTAMIC DECARBOXYLASE IMMOBILIZED ON ION EXCHANGE RESIN

The preparation and characterization of an immobilized L-glutamic decarboxylase(GDC) were studied.This work is to develop a sensitive method for the determination of L-glutamate using a new biosensor,which consists of an enzyme column reactor of GDC immobilized on a novel ion exchange resin(carboxymethyl-copolymer of allyl dextran and N.N‘-methylene-bisacrylamide CM-CADB) and ion analyzer coupled with a CO2 electrode.The conditions for the enzyme immobilization were optimized by the parameters:buffer composition and concentration,adsorption equilibration time,amount of enzyme,temperature,ionic strength and pH.The properties of the immobilized enzyme on CM-CADB were studied by investigating the initial ate of the enzyme reaction,the effect of various parameters on the immobilized GDC activity and its stability.An immobilized GDC enzyme column reactor matched with a flow injection system-ion analyzer coupled with CO2 electrode-data collection system made up the original form of the apparatus of biosensor for determining of L-glutamate acid.The limit of detection is 1.0×10^-5M.The linearity response is in the range of 5×10^-2-5×10^-5M.The equation of linear regression of the calibration curve is y=43.3x+181.6(y is the milli-volt of electrical potential response,x is the logarithm of the concentration of the substrate of L-glutamate acid).The correlation coefficient equals 0.99.The coefficient of varioation equals 2.7%.     

ADSORPTION OF SAMARIUM（III） ON DIGLYCOLAMIDIC ACID RESIN

The sorption behavior and mechanism of a novel chelate resin, diglycolamidic acid resin (DAAR), for Sm(lll) were investigated. The optimal sorption condition of DAAR for Sm(lll) is pH=6.0 in HAc-NaAc medium. The statically saturated sorption capacity is 190mg/g resin at 298K. The Sm(lll) adsorbed on DAAR can be eluted reaching 100% by 0.5-2.0mol/L HCI used as eluant. The resin can be regenerated and reused without apparent decrease of sorption capacity. The apparent sorption rate constant is k298= 1.96×10^-5s^-1. The apparent activation energy is 26kJ/mol. The sorption behavior of DAAR for Sm(lll) obeys the Freundlich isotherm. The thermodynamic sorption parameters, enthalpy change ΔH of DAAR for Sm(lll) is 16.9Kl/mol. The molar coordination ratio of the functional group of DAAR to Sin (111) is 3. The sorption mechanism of DAAR for Sm(lll) was examined by using chemical method and IR spectrometry. The coordination bond was formed between oxygen atoms in the functional group of DAAR and Sin(Ill).     

SORPTION BEHAVIOR AND MECHANISM OF SAMARIUM（Ⅲ）ON AMINO METHYLENE PHOSPHONIC ACID RESIN

Sm(Ⅲ） was quantitatively adsorbed by amino methylene phosphonic acid resin(APAR) in the medium of pH=5.0,The statically saturated sorption capacity is 251mg/g.resin.Sm(Ⅲ） adsorbed on APAR can be reductively eluted by 2.0mol/L HCl.The sorption rate constant is k298=1.35×10^-5s^-1.The sorption behavior of APAR for Sm(Ⅲ） obeys the Freundlich isotherm.The enthalpy change ΔH° of sorption is 24.9kJ/mol.The apparent activation energy is Ea=11.7kJ/mol.The sorption mechanism shows that the nitrogen and oxygen atoms of the functional group of APAR coordinated with Sm(Ⅲ） to form coordination bond.     

LIQUID-PHASE ADSORPTION KINETICS OF ISOMALTOTRIOSE ON Ca^2＋ EXCHANGE RESIN

The adsorption of isomaltotriose from aqueous solution on Ca2+ resin was investigated.The adsorption isotherm and the rate curve were determined. The pseudo-first-order model,pseudo-second-order model and the intraparticle diffusion model were used to predict the rate constants of adsorption. The activation energy of adsorption has been also evaluated using the pseudo-second-order rate constants. The results showed that the adsorption of isomaltotriose onto Ca2+ resin is an exothermically activated process. The adsorption isotherm can be described by Langmuir equation. The pseudo-second-order model can fit well to the adsorption rate curve of isomaltotriose onto Ca2+ resin. It suggests that the adsorption of isomoltotriose onto Ca2+ resin involve chemical adsorption.     

STUDY ON THE SEPARATION OF GLUTAMIC ACID BY ION—EXCHANGE

The feasibility of recovering glutamic acid by ion exchange method with macroporous resins was investigated.Their adsorption properties in stati state and the effective factors,such as pH,concentration of eeed and the ratio of ammonium ion to glutamic acid,were systematically explored.The best condition of separating glutamic acid from mother liquid were obtained.     

RAPID DETERMINATION OF L-GLUTAMIC ACID WITH AN ENZYME REACTOR OF L-GLUTAMIC DECARBOXYLASE IMMOBILIZED ON ION EXCHANGE RESIN

1. INTRODUCTION L-Glutamate is present in many physiological fluids and pays an important role in amino acid biosynthesis and metabolism. Usually, the determination of L-Glutamate acid is based on a chromatographic technique [1], but the method is unsuitable for the rapid analysis of large numbers of samples. The applications of immobilized enzymes in analytical chemistry have been stimulated because of their well-known advantages [2~8]. The key problem of their applications is the immob…     

POTENTIOMETRIC BEHAVIOR OF CHELATING ION EXCHANGE RESIN IN WATER AND IN ETHANOL—WATER MIXTURES

The potentiometric behavior of the chelating ion exchange resin D751 containing iminodiacetic acid groups has been studied at 25℃ by batch titration with alkali and acid in water and in ethanol-water mixture solvent.The titrtion curves,the amount of chemically bound counter-ions and invasive electrolytes in the resin phase,and the solvent contents the resin have been investigated.     

THERMODYNAMICS ADSORPTION OF MANGANESE ION ON 1-（2-PYRIDYLAZO）-2-NAPHTHOL-6-SULPHONIC ACID IMPREGNATED RESIN

An ion-exchange resin of type 201×7 was impregnated with the reagent 1-（2-Pyridylazo）-2-naphthol-6-sulphonic Acid （PAN-S）. The adsorption characteristics of PAN-S resin for manganese ion were studied on the static equilibrium adsorption. Within temperature range of 288K-313K and the concentration range investigated, equilibrium data for the adsorption of manganese ions from aqueous solutions by PAN-S resin were obtained and correlated with Freundlich and Langmuir equation. The results showed that the process of the adsorption of manganese ions from aqueous solution by PAN-S was an exothermic process. Estimations of the isothermic enthalpy change of adsorption, free energy change and entropy of adsorption are reported, and the adsorption behaviors are reasonably interpreted.     

STUDY ON THE DECOLORIZATION OF D—RIBOSE ZYMOTIC FLUID BY RESIN ADSORPTION

In this paper,effects on of six type of resins the decolorization of D-ribose zymotic fluid have been studied for the first time.The results show that resin NKA-II has the best effect.the decolorization rage of D-ribose zymotic fluid is 91% at velocity of 1.0BV/hr and 25℃,the adsorption capacity can reach up to 5.7BV.The effects of adsorption conditions as well as conditions of resinregeneration on the resin decolorization capability were also studied.     

EXTRACTION OF CITRIC ACID FROM FERMENTATION BROTH USING ION—EXCHANGE METHOD

A number of ion-exchange resins were tested on their capacity to adsorb citric acid,among them resin 335,d315, Amberlite IRA-35 and IRA-68 exhibited higher adsorption capacity.We chose resin 335 and D315 to be used for extraction of citric acid from fermentation broth,followed by elution with 10% ammonia liquor,decoloration with K-15 carbon and removal of ammonia with resin 732,converting citrate of free citric acid with a concentration of 10% and an amount of readily carbonizable substance meeting the GB 8269-87 standard.     

THE SIMULATION OF CONTINUOUS COUNTER—CURRENT ION EXCHANGE PROCESS

A backflow model of PSS process describing the continuous counter-current ion exchange column is proposed in this paper.The results of simulation are in agreement with experimental data considerably.     

CONDUCTIVITY METHOD APPLIED TO THE STUDY OF INTERACTION BETWEEN ADSORBENT AND ADSORBATE I．ADSORPTION OF LOW CONCENYRATION OF FREE ACID BY REGENERABLE CHITIN

The adsorption of low concentration of free acid by regenerable chitin is followed by electric conductance determination.The effect of acid concentratioin,content of functioinal amino groups,and ionic strength on adsorption was discussed.Experimental results indicate that the active centre of regenerable chitin is the free amino groups on ist surface ,and that the rate of adsorption of free acid was found to be affected by two factors:the interaction between the adsorbent and the adsorbate in solution and that between the adsorbate molecules or ions in solution.     

STUDY ON THE PHYSICAL CHEMICAL PROPERTIES OF FFA—1 ION EXCHANGE FIBER

The physical and chemical properties of FFA-1 ion exchange fiber have been characterized with IR spectrum,thermal analysis and SEM means.The pH titration curve,swelling rate,mechanical properties,resistance drop of filter layer as well as the dynamic adsorption for SO2 was determined.These experiments provided the essential parameters for the practical application of FFA-1 material in adsorption of toxic gases.     

ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE （NDA-99） AND XAD-4 RESIN

The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent (NDA-99) modified by dimethylamine group as well as a nonionic macroporous adsorbent (XAD-4). The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism. It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix.Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin, which is in agreement with the IR spectroscopic results and the △E values of HOMO (the highest occupied molecular orbit) of adsorbent and LUMO (the lowest unoccupied molecular orbit) of adsorbate calculated from the MINDO/3 model.     

SYNTHESIS OF 2—HYDROXYETHYL ACRYLATE BY USING STRONG ACIDIC CATION ION EXCHANGE RESIN AS CATALYST

2－Hydroxyethyl acrylate is synthesized from acrylic acid and ethylene glycol under a simple and mild condition by using strong acidic cation ion exchange resin as a catalyst,which could be recycled as long as 10 times with high activation.     

STUDY ON THE ADSORPTION OF OXIDATION OF CROSSLINKED β—CYCLODEXTRIN AND ITS CXOMPOSITE ADSORBENT WITH DIALYTIC MEMBRANE

An urea adsorbent with an aldo structure was obtained by the oxidation of a crosslinked β-cyclodextrin polymer.The highest urea adsorption capacity reached 56.7mg/g in 0.05Maqueous phosphate buffer 37℃ and pH=7.4,and decrease to 4.8mg/g in in aqueous human serum albumin.The composite adsorbent was prepared by the oxidation of a crosslinked β-cyclodextrin and dialytic membrane.It was found that the composite adsorbent has a higher urea adsorption selectivity and capacity compared to that of the oxidation of a crosslinked β-cyclodextrin adsorbent when urea is in aqueous human serum albumin.     

ADSORPTION BEHAVIORS OF Pt（IV） AND Pd（II） ON POLYMERIC ESTER THIOUREA RESIN

Polymeric ester thiourea resin （PDTU-I） is a new kind of chelating resin with functional atoms S, N and O, so it is an excellent adsorbent for noble metal ions. In batch testes, the adsorption capacities of PDTU-I for Pt（IV） and Pd（II） increase with the increase of contact time, temperature and initial concentration of metal ions. The adsorption data fit Boyd＇s diffusion equation of liquid film, Langmuir adsorption isotherm and Freundlich adsorption isotherm. The maximum adsorption capacities calculated by Langmuir equation are 2.54mmol/g for Pt（IV） and 4.88mmol/g for Pd（II）. According to FTIR and XPS results, functional groups of PDTU-I coordinate with noble metal ions in the adsorption process.     

L—PROLINE—FUNCTIONALIZED POLYSTYRENE WITH 1—METHYLDECYLENE SPACER AS A CHIRAL STATIONARY PHASE FOR LIGAND—EXCHANGE CHROMATOGRAPHIC RESOLUTION OF AMINO ACID RECEMATES

The L-proline-functionalized polystyrene with 1-methyldecylene spacer was synthesized from 2% divinylbenzene-crosslinked polystyrene gel via 10-bromo-1-methyldecyl polystyrene intermediate.After complexed with copper(Ⅱ） ion,the polymer with L-proline ligand was used as the chiral stationary phase (CSP) for ligand exchange chromatography of amino acid racemates.The results showed that the CSP possessed powerful enantioselectivity and all racemates of the fifteen tried amino acids were completely separated.     

STUDY ON THE DETERMINATION OF TRACE BISMUTH（III） BY THIN-LAYER RESIN PHASE S PECTROPHOTOME TRY

In this paper, a new thin-layer ion-exchange resin phase analytical method is introduced. It is based on that, the bismuthous cation can associate with iodic anions, so as to formed an anion complex [BiI4-_] in a strong acidic environments. This anion complex can also exchanges with a weaker anions on the surface active site of anion exchange resin, so that a[R+] [Bil4-] solid phase binary associational system is produced. Owing to the solid system is a great many dispersive particulates, it can be pressed to a thin-layer by press tools of the so called “thin-layer resin phase “ or “resin phase “, and using this solid association system spectrophotometry for the determination of trace metals. So it can increase the analytical sensitivity. This association system exhibits maximum absorbance at 460nm, and obeys Beer‘s law over the concentration range 0.0lug/ml-l.20ug/ml of bismuthous(lll), h has a molar absorptivity of 7.1×l^5 [L/mol.cm]. it indicated the resin phase spectrophotometry is a sensitive analytical method for trace bismuthous. It is 18 times higher than routine aqueous spectrophotometry. The relative standard deviations is 1.82% (n=6) for the F fmeasurements of 0.Sug/ml Bi(llO. The detection limit of Bismuthous(lll) is 1.4 XlO~mol/L. The method has applied to the analysis Bi(lll) in environmental water samples.