SYNTHESIS AND SWELLING PROPERTIES OF NOVEL SUPERABSORBENT POLYMER

1　INTRODUCTIONSuperabsorbentpolymers (SAPs)arenewfunctionalmaterials,whichcanabsorbandretainanunusuallylargeamountofwaterandbodyfluid .Theyhaveavarietyofvaluableapplications[1,2 ] becauseoftheiruniquecharacteristics ,andtheycanbedividedintotwoclasses:non…     

CALCULATION OF THERMODYNAMIC PROPERTIES OF REAL FLUIDS AND VAPOR-LIQUID EQUILIBRIA BY USING A CANONICAL PARTITION FUNCTION (Ⅰ) THERMODYNAMIC PROPERTIES OF PURE FLUIDS

The Anderson-Prausnitz equation of state has been improved by modifying the attractive term of the generalized van der Waals canonical partition function.In this modification, the parameter characterizing the intermolecular attractive forces is considered to depend not only on temperature but also on density.By this new equation of state the calculated results for pressure and fugacity coefficient of pure gases have slightly better accuracy than those by the original Anderson-Prausnitz equation, and those for saturated vapor pressure are in good agreement with observed results.     

ETHANOL FERMENTATION OF MIXED GLUCOSE AND XYLOSE BY PICHIA STIPITIS

Pichia stipitis CBS 5773 yeast cells were used to ferment the mixed substrates consisted of glucose andxylose to produce ethanol.The effects of aeration rate,initial substrate concentration and pH on substrateutilization and ethanol yield were evaluated.During batch fermentation,the oscillation phenomena in cell growthwere observed at low aeration rate,whereas the diauxic growth at high aeration rate.The substrate utilizationratio and ethanol yield reached 95％ and 0.46g/g respectively under appropriate operation conditions.Amodified unstructural model was proposed to simulate the diauxic cell growth,substrate consumption andproduct formation.     

SYNTHESIS OF COMB-LIKE POLYMERS FROM MACRO-MONOMERS OF ETHYL ACRYLATE–METHYL ACRYLATE AND THEIR PROPERTIES

An experimental investigation of comb-like polymers (CP) was conducted in three synthesis steps by using two monomers: ethyl acrylate and methyl acrylate. The synthesis of comb-like homo and copolymers was achieved by using macroinitiators. These compounds imply the formation of hydroxyl terminates polyacrylates (HTP) by a chain transfer reaction. The HTP possessed a broad molecular weight distribution (Mw/Mn = 1.61). The CP was freed of its precursors and its molecular weight distribution was rather narrow (1.31–1.44). In addition, the length and number of the “comb” can be controlled. The products were characterized by UV-VIS, FTIR, Gel Permeation Chromatography (GPC), microRaman Spectroscopy (RS), Differential Scanning Calorimetry (DSC), and hydroxyl number titration. The results show that there are situations where it is possible to produce comb-like polymers of interest with high efficiency.     

CALCULATION OF THERMODYNAMIC PROPERTIES OF FLUID MIXTURES WITH A NEW EQUATION OF STATE †

The subject of this paper is the evaluation of the applicability of constant temperature anemometry (CTA) with a modified version of Delhaye's method to aerated stirred tanks. A calibration technique that takes into account the variation in medium temperature was developed and verified experimentally. The directional sensitivity of the conical film probe was investigated in a streamline flow field as well as in the impeller discharge stream in an stirred tank.

The reliability of the setup and the technique was verified through the comparison of the vertical and radial velocity profiles of water in a stirred tank with those obtained from the literature. The directional response of the conical probe follows the cosine law for intersection angles smaller than 45° in a streamline flow field, but the directional sensitivity in the impeller discharge stream is rather poor, owing to the rolling characteristics of flow in this region. Due to the inability to detect bubbles smaller than the sensing element of the conical probe, the CTA usually gives lower values of local gas holdup. However, this discrepancy is considered to have no influence on the velocity measurement.     

SYNTHESIS AND CHARACTERIZATION OF CADMIUM SULFIDE NANOPARTICLE–LOADED ACTIVATED CARBON AS A NOVEL ADSORBENT FOR EFFICIENT REMOVAL OF REACTIVE ORANGE 12

The objective of this study was to evaluate the adsorption potential of cadmium sulfide nanoparticle–loaded activated carbon (CdSN-AC) for removal of reactive orange 12 (RO-12) dyestuffs from aqueous solutions. The characterization of CdSN-AC was performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) techniques. The effects of experimental parameters such as initial solution pH, contact time, initial RO-12 concentration, amount of CdSN-AC, and temperature on the adsorption process were evaluated in detail. The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics model. The experimental data were analyzed by the Langmuir, Freundlich, and Tempkin isotherm models, and the monolayer adsorption capacity of CdSN-AC was found to be 150.0 mg g^?1 by using the Langmuir isotherm model. The thermodynamic parameters indicated that the adsorption of RO-12 onto CdSN-AC was feasible, spontaneous, and endothermic in nature.     

A NEW SIMULATION APPROACH TO THE ENTROPY-RELATED PROPERTIES OF FLUIDS——CHEMICAL POTENTIAL AND HELMHOLTZ FREE ENERGY OF HARD SPHERE FLUIDS

A new approach to the computation of entropy-related properties of fluids has been pre-sented.Application of the new technique to hard sphere fluids shows that it is capable of providingreliable estimates of such properties as the chemical potential and Helmholtz free energy,even athigh density where other existing methods are hardly applicable.The chemical potential of an infinitedilute component in hard sphere systems has been estimated,and compared with that calculated fromthe Carnahan-Starling equation.     

EFFECT OF MODIFICATION WITH MELAMINE–UREA–FORMALDEHYDE RESIN ON THE PROPERTIES OF EUCALYPTUS AND POPLAR

Fast-growing eucalyptus (Eucalyptus robusta Smith) and poplar (Populus tomentosa Carr.) were impregnated with melamine–urea–formaldehyde (MUF) resin by vacuum. The weight percent gain (WPG), water absorption, bulking rates, anti-swelling efficiency (ASE), and density distribution of the impregnated wood were examined. The characterization of eucalyptus and poplar was performed by Fourier transform infrared spectroscopy and scanning electron microscope. WPG of the impregnated wood increased with increasing concentrations of MUF resin, however, rate of water absorption was nearly the reverse. The impregnated eucalyptus wood showed low WPG (at most 23.03%) but achieved high ASE (52.02%) values. Although a relatively high WPG (up to 59.02%) was achieved by modified poplar, the ASE (50.21%) value was not high. This was owing to the differences in the microstructure of eucalyptus and poplar. The density of impregnated wood was remarkably increased (eucalyptus from 0.48 to 0.54?g/cm³, poplar from 0.38 to 0.49?g/cm³).     

MCSPT—A MODIFIED HARD-SPHERE THREE-PARAMETE EQUATION OF STATE FOR THERMODYNAMIC PROPERTIES OF PURE COMPOUNDS

The hard-sphere three-parameter equation of state(CSPT)proposed in the previous paper(Li et al.1991)was modified by a new temperature relation for the pseudo-critical compressibility ξ and the temperaturecorrection factor α(T_r)of the attractive parameter.Vapor pressures and Saturated liquid densities of 105 purecompounds were calculated by the modified version.Results show that correlations of saturated properties at lowreduced temperatures and thermodynamic properties in the vicinity of critical region were significantly improved.Furthermore,characteristic parameters of this modified version were generalized by acentric factor ω and criticalcompressibility Z_c to predict saturated liquid densities of 72 polar substances and the latent heat of vaporizationfor 151 substances including strongly polar compounds with satisfactory results.     

SOME EFFECTS OF FLUID PROPERTIES AND LOCATION ON MIXING INDICES FOR FLOW NEAR DROPS†

The flow field and mixing behavior surrounding a rising drop were simulated using the SOLA-VOF computer code. The effects of kinematic viscosity, interracial tension, drop density and spatial location on the mixing behavior and several mixing indices were studied as a function of time. Two mixing indices, one based upon material line extension and rate variations in material line extension and the other based upon a Lagrangian correlation coefficient and a Lagrangian time scale, were shown to be directly related to the fluid mechanics causing the mixing. Another index, the scale of segregation, was found to be inadequate in describing the mixing since its scale was too large to discern small scale mixing behavior.     

THE SYNTHESIS AND PROPERTIES OF SOME NEW CARBAMOYL( ALKYL) PHOSPHINE OXIDES∗, ∗∗

Several substituted carbamoyl( alkyl) phosphine oxides have been synthesized and characterized with regard to their spectral properties and extraction capability for trivalent actinides from nitrate media. The effects that structural variation have upon the solubility, the extraction data, and the propensity to form third phases have been determined     

SYNERGISM IN THE EXTRACTION OF ZINC(II)AND CADMIUM(II) WITH SOME LOWER FATTY ACIDS IN THE PRESENCE OF AMINES AND THEIR SEPARATIONS∗

Abstract

Synergism in the extraction of Zn(Il) and Cd(II)with chloroform solution of propionic, butyric and valeric acids in the presence of n-butylamine, dibutylamine, tributylamine, β-picoline, pyridine and quinoline is reported The effect of various parameters affecting extractions has been investigated The compositions of synergistic adduct extracted into the organic phase have been proposed on the basis of slope analysis method. In general the species have been represented as MA2.2HA.B (aliphatic amine system and MA₂.2HA.2B (heterocyclic amine system), where M = zn(Il)/CdII), HA = acid and B = amine. On the basis of extraction constant (K_ex) values the relative effectiveness of different amines as synergists has been compared. Based on the extraction data some separations of metal ions have also been reported with fairly high separation factor (β).     

CATALYTICALLY ACTIVE COMPONENTS OF Fe_2O_3-Sb_2O_4 MIXED OXIDE CATALYSTS AND THEIR ROLE IN AMMOXIDATION OF PROPYLENE

The catalytically active components of a series of Fe_2O_3-Sb_2O_4 mixed oxide catalysts with differentSb/Fe ratio,calcined at elevated temperature,as well as with or without support,have been investigated byX-ray diffraction analysis,Mossauer spectroscopy and XPS in order to elucidate their catalytic behavior inammoxidation of propylene.Correlations of acrylonitrile yield with Fe~2 and Fe~3 respectively showed that,FeSbO_4 seems to bethe basic active component of catalyst,upon which the formation of new phase containing Fe~3 is responsiblefor a good selective oxidation.