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.     

ADSORPTION OF 2,4-DICHLOROPHENOL IN AQUEOUS SOLUTION ONTO ADSORPTION RESIN MODIFIED BY N-ACETYLANILINE

A hypercrosslinked adsorption resin （ZH-05） modified by N-acetylaniline in the post crosslinking process was prepared. The adsorption properties of ZH-05 toward 2,4-dichlorophenol in comparison with granular activated carbon （GAC） and Amberlite XAD-4 were observed. The present study mainly focuses on the static equilibrium adsorption behaviors, desorption profiles and the proof of chemisorption. The results show that the Langmuir equation can give a perfect fitting to experimental data, and high temperature was favorable for adsorption of 2,4-dichlorophenol on ZH-05. A related equation was used to correlate the amount of chemisorption and the suppositionai chemisorption equilibrium concentration of adsorbate in aqueous solution. The adsorption capacities from different ranges of temperature and the static desorption experiment both reveal the same conclusion, i.e., the adsorption of 2,4-dichlorophenol from water on ZH-05 is a coexistent process of physical adsorption and chemical transition as on GAC.     

VISCOSITY BEHAVIOR OF LACQUER POLYSACCHARIDE IN AQUEOUS SOLUTION

The dependence of measured viscosity on NaCl concentration (0.1 to 3.0M), pH (range of 2—13) and cadoxen composition w_(cad) (from 2% to 100%) for the lacquer polysaccharide in NaCl/cadoxen/H_2O mixture containing HCl or without were obtained. All the viscosity exponents γin the Mark-Houwink equations under three different solvent condition arc close to 0.5. The w_(cad) dependence of reduced viscosity ηsp/c confirms the single strand chain of the polysaccharide. As the γvalues close to 0.5 and values of unperturbed dimension _θ/M and [η] much smaller than those for usual linear polymers, these facts suggest that the polysaccharide chains in the aqueous solutions should be dense random coil owing to the highly branched structure.     

PHOTOREDUCTION OF ALKYL VIOLOGENS AND POLYVlOLOGENS IN 2-PROPANOL AQUEOUS SOLUTION

In order to study the effect ofalkyl chain length and the polymer effect on the photoreduction behavior of some viologens, a series of alkyl viologen, polyviologen and bisviologen compounds have been synthesized. In the presence of excess 2-propanol, the initial photoreduction of alkyl viologens and polyviologens follow the peudo--seeond--order reaction, the calculated rate constants are related to the alkyl chain length: In addition, the intramoleeular association of radical cations of polyviologens has been found even in dilute solution. However the extent of association is varied with the aikyl chain length. The observed polymer effect of polyviologens in the photoreduetion is significant which can be explained in terms of the nature of second order reaction.     

LIGHT SCATTERING OF POLYSACCHARIDE FROM LACQUER IN AQUEOUS SOLUTION

The polysaccharide having weight-average molecular weight M_w=1. 09×10~5, isolated from the sap of lac trees (Vietnam), was separated into 12 fractions by aqueous-phase preparative gel permeation chromatography. The molecular weights and molecular weight distributions of the fractions were measured in aqueous 0.08M KCl/0.01 M NaAc and 0.4M KCl/0.05M NaAc at pH =7. 6 by light scattering, viscometry and gel permeation chromatography. The Mark-Houwink equation in aqueous 0.08M KCl/0.01M NaAc at 30℃was found to be [η]= 2.28×10~(-2) M_w~(0.52) (cm~3/g), which indicated the polysaccharide chain in the aqueous solution to be a spherical random coil.     

STUDY ON THE ADSORPTION OF PHENOL BY CHITOSAN FROM AQUEOUS SOLUTION

The effects of pH, initial concentration and temperature on the adsorption of phenol by chitosan were investigated in this paper. The isothermal data was applied to Langmuir linear and the Freundlich linear isotherm equation, and the thermodynamic parameters （AH, AG, AS） were calculated according to the values of binding Langmuir constant, KL. Results indicated that the adsorption between chitosan and phenol was significantly physical in nature, the negative ΔH constant at lower temperature confirmed that more phenol was adsorbed by chitosan at lower temperature. The kinetics of the sorption process of phenol on chitosan was investigated using the pseudo-first order and pseudo-second order kinetics, and results showed that the second order equation model provided the best correlation with the experimental results.     

THE STATE OF CHROMIUM (Ⅲ) ION IN AQUEOUS SOLUTION

So far few systematic studies on the hydrolytic polymerization of Cr(Ⅲ) were reported because of inertness of the ion and complication of the process. We studied it in equilibrium by pH method systematically in a wide concentration range (0.0002—0.32 M). The results show that, in the low concentration range, the composition of the polynuclear hydrolysis products may be represented as [Cr_3(OH)_4] (OH)_n (n=1,2,3); in the medium range, the composition of products as Cr[Cr(OH)_2]_n~((3+n))~+ (n=1,2,3); in the high range, the composition of products as Cr[Gr(OH)]_n~((3+2n))~+ (n=1, 2), and in the intermediate range between medium and high range where the hydrolysis system is in a transition state, the composition of products as [Cr_3(OH)_3]~(6+) and [Cr_3(OH)_4]~(5+). The values of hydrolysis constants of the identical species measured in different Cr concentration ranges and calculated by different methods were found in good agreement with each other. A predominance-arca diagram was made by using the hy     

GRAFTING OF ETHYLENE GLYCOL DIMETHACRYLATE ONTO SILK IN AQUEOUS ALCOHOLIC SOLUTION

The grafting of ethylene glycol dimethacrylate (EGDMA) onto silk in aqueous alcohol systems using potassiumpersulfate (KPS) in the presence of air was investigated. Effects of grafting conditions, such as concentrations of monomer,initiator and formic acid, temperature and time, on the graft yield were determined. The optimum graft conditions were foundto be: T = 80℃, t = 30 min, [KPS] = 1.85% [on the weight ofmonomer (owm)]; [formic acid] = 0.2% (V/V); [EGDMA] =80% [on the weight of fiber (owf)]. The activation energy of grafting at 50-80℃ was found to be 71.31 kJ/mol for EGDMA.Grafting equations were also evaluated. The graft yield value can be regulated by the concentration of monomer. The graftcopolymerization of EGDMA onto silk is effective in improving the crease-proofing of silk fabrics.     

A SNIFTIRS STUDY OF THE BENZOQUINONE-BENZOHYDROQUINONE REDOX SYSTEM IN AQUEOUS SOLUTION

The in-situ FTIR spectroscopic results show that a hemi-ketal in-termediate may be produced in the electroreduction of benzoquinone or electro-oxidation of benzohydroquinone,which provides a valuable insight into the me-chanism of the redox process.     

SYNTHESIS AND FLUORESCENCE STUDY OF SELF-AGGREGATION PROCESS IN AQUEOUS SOLUTION OF HYDROPHOBILIZED POLYSACCHARIDE

1.INTRODUCTIONMolecularself-assemblyorself-aggregationisthespontaneousassociationofmoleculesunderequilibriumconditionsintostable,structurallywell-definedaggregationsjoinedbynoncovalentbonds.Theself-aggregationofmoleculesleadstosupramolecularsystemsandisresponsiblefortheirfunctions.Recently,self-assemblyoraggregationofpolymeramphiphilesisofgrowinginterestwithrespecttobiologicalimportanceandpharmaceuticalorbiotechnologicalapplication.Solutionpropertiesofvariousblockcopolymerorself-aggregate…     

EXTRACTION AND PRECONCENTRATION OF SCANDIUM FROM AQUEOUS SOLUTION BY ELECTROSTATIC PSEUDO LIQUID MEMBRANE

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EFFECT OF RADIATION ON HIGH-CHARGE-DENSITY POLYDIALLY-DIMETHYL AMMONIUM CHLORIDE IN DILUTE AQUEOUS SOLUTION

The effect of radiation on high-charge-density cationic polymer, polydiallyl-dimethyl ammonium chloride (poly-DADMAC), in dilute aqueous solution was investigated. The irradiated samples were characterized in terms of reducedviscosity and electric conductivity. The crosslinking reaction of polyDADMAC chains occurs preferentially in the irradiatedsamples at a concentration of polyDADMAC higher than 1.3 g/100 mL that was induced indirectly by the OH radicals, oneof the radiolysis products of water. In more dilute samples (less than 0.8 g/100 mL) the chain scission of macro radicalsappears to be the main reaction. N_2O atmosphere enhances the crosslinking due to the extra OH radicals produced byreaction between N_2O and e_(aq), another radiolysis products of water. Methanol and some mineral salts such as KCl, KBr inhibit the crosslinking to a certain extent. The mechanism of sensitization and inhibition is discussed in detail.     

THERMODYNAMIC STUDY OF ADSORPTION OF PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTION BY A WATER-COMPATIBLE HYPERCROSSLINKED POLYMERIC ADSORBENT

Equilibrium data for the adsorption of phenolic compounds, i.e., phenol, p-cresol, p-chlorophenol and p-nitrophenol from aqueous solutions by a water-compatible hypercrosslinked polymeric adsorbent (NJ-8) within temperature range of 283-323 K were obtained and correlated with a Freundlich-type of isotherm equation, so that equilibrium constants KF and n were obtained. The capacities of equilibrium adsorption for all the four phenolic compounds on the NJ-8 from aqueous solutions are around 2 times as high as those of Amberlite XAD-4, which may be attributed to the unusual micropore structure and the partial polarity on the network. The values of the enthalpy (always negative) are indicative of an exothermic process, which manifests the adsorption of all the four phenolic compounds on the two polymeric adsorbents to be a process of physical adsorption. The negative values of free energy change show that the solute is more concentrated on the adsorbent than in the bulk solution. The absolute free energy values of adsorption for NJ-8 are always higher than those for Amberlite XAD-4, which indicates that phenolic compounds are preferentially adsorbed on NJ-8. The negative values of the adsorption entropy are consistent with the restricted mobilities of adsorbed molecules of phenolic compounds as compared with the molecules in solution. The adsorption entropy values of phenolic compounds for NJ-8 are lower than those for Amberlite XAD-4, which means the micropores of NJ-8 require more orderly arranged adsorbate.     

SYNTHESIS AND FLUORESCENCE STUDY OF SELF—AGGREGATION PROCESS IN AQUEOUS SOLUTION OF HYDROPHOBILIZED POLYSACCHARIDE

Cholesterol modified dextran(CHD) having self-aggrgation or self-assembly property was synthesized from cholesterol and 1,6-hexyldiisocyanate.The degree of substitution of cholesteryl moiety in dextran main line is 3-5 cholesterols the 100 glucose units.We have prepared water solution of CHD using probe type sonifier and N-Phenyl-a-naphthylamine(PNA) as a fluorescent probe to study CHD self-aggregate process.For each solution of two samples,we found that the maximum emission of PNA in CHD concentration.This change corresponds to the formation of micelle-like clusters self-aggregated by the cholesterol moiety once the CHD concentration.This change corresponds to the formation of micelle-like clusters self-aggregated by the cholesterol moiety once the CHD concentration exceeds 0.01mg/ml.     

EMPLOYMENT OF SPIN TRAPPING TECHNIQUE TO THE STUDY OF PHOTOCATALYTIC DEHYDROGENATION MECHANISM OF ALCOHOL IN AQUEOUS SOLUTION

Spin trapping technique was employed to study the mechanism of photocatalyticdehydrogenation of alcohol during in situ irradiation of Rh_2O_3/CdS powder which is sus-pended in aqueous aicohol solution.Evidence for production of ·OH radical is presentedand the rate of·OH radical formation corresponds to the rate of H_2 evolution.On the ba-sis of the above results,it is suggested that water cleavage is an intermediate step in this reac-tion.     

COORDINATION COPOLYMERIZATION OF STYRENE WITH MALEIC ANHYDRIDE BY RARE-EARTH COORDINATION CATALYSTS

The study on coordination copolymerization of styrene (S) with maleic anhydride (MA) by rare-earth coordination catalysts, NdL_3-Al(i-Bu)_3, has been successfully carried out for the first time. Some features, kinetic behavior, and mechanism of the SMA copolymerization by Nd(naph)_3-Al(i-Bu)_3 system are described and discussed. The copolymex of styrenemaleic anhydride prepared by the NdL_3-Al(i-Bu)_3 systems in benzene at 50℃ is an alternating-rich white powder having high number-average molecular weight of 6—8.5×10~5. The overall activation energy for the polymerization was found to be 10.5KJ/mol. The polymerization was not suppressed by addition of hydroquinone. The catalytic activity of various ligands in NdL_3 for the copolymerization decreases in the following order: Nd (naph)_3>Nd-(P_(507))_3～NdCl_3-6H_2O>Nd(P_(204))_3>Nd(acac)_3. 3H_2O. The experimental results are explained based on a mechanism to be the coordination-type copolymerization in terms of the participation of a monomer-monomer c     

SELECTIVE HYDROGEN SULFIDE ABSORPTION IN HINDERED AMINE AQUEOUS SOLUTION

The behavior of N-tertiary butyl diethylene glycolamine(TBGA)aqueous solution(2.67mol/1)for the process of selective HS removal from natural gas was compared with that of N-methyl diethanolamine(MDEA)aqueous solution(3.0 mol/1).The results indicated that the TBGAprocess had considerable advantages in selectivity,acid gas loading and clean-up level.But the applica-tions of TBGA have been kept within limits on account of the high cost.     

STEREOSPECIFIC POLYMERIZATION OF ACETYLENE BY RARE-EARTH COORDINATION CATALYSTS

This paper is the first study on the stereospecific polymcrization of acetylene by coordination catalysts based on rare-earth compounds. High cis (80-100%) polyacetylene films with silvery metallic appearance were obtained at 30℃ or 0℃ in the presence of rare-earth catalysts composed of two or three components: naphthenates or 2-ethyl hexyl phosphonates of all fifteen rare-earth elements, trialkyl aluminum and/or a third component. The resultant polyacetylene has been characterized using techniques of infrared spectrophotometry, differential scanning calorimetry, electron spin resonance, X-ray diffraction, scanning electron micrography and electrical resistivity measurements.     

MONTE CARLO SIMULATION ON AQUEOUS SOLUTION OF BIOLOGICAL MOLECULES——ALANINE SOLUTION

The Monte Carlo simulation is performed for a cluster consisting of a neutral alanine molecule surrounded by 56 water molecules. The average water-water and alanine-water interaction energies are found. The space surrounding the alanine molecule is divided into three regions, where the central atoms are C' atom for the earboxyl group region, N atom for the amino group region and C~β atom for the methyl group region. The water-water and water-alanine interaction energies as functions of the distance between the oxygen atom in a water molecule and the central atom in each region are calculated. In each region the orientational correlation function for the dipole moments of water molecules, the radial distribution function for the oxygen and hydrogen atoms of water molecules are evaluated. In addition, the numbers of water molecules in the first solvation shells of each region and of entire alanine molecule are also counted.     

INTERACTION OF POLY(SODIUM SULFODECYL METHACRYLATE)WITH CETYLTRIMETHYL AMMONIUM BROMIDE IN AQUEOUS SOLUTION

The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, resultingin the appearance of two maxima of the solution viscosity at the molar ratio (CTAB/-SO_3~-) of≈ 0.68 and≈1.30,respectively. The first one is related closely to the aggregation of polymer chains via CTAB molecules and the second oneshould be ascribed to the formation of the mixed micelles comprising surfactant and the polymer's hydrophobic chains. Theeffect of NaCl on the viscosity, the transmittance of the aqueous solution and the solubility of oil-soluble dye (dimethyl yellow) in the mixed system were also investigated.