Phase equilibria in the system sucrose—glucose—fructose

The melting points of mixtures of sucrose, glucose and fructose have been determined, so as to cover the full range of concentrations in the two- and three-component systems. Three binary eutectics and one ternary eutectic were identified each with a fixed melting point, but all other concentrations showed a melting point range corresponding to liquidus—solidus characteristics.     

Electronic absorption spectra and electron transport properties of 1-benzothiopyrylium ions

The electronic absorption spectra of a series of 1-benzothiopyrylium salts have been calculated by the variable β PPP method. The agreement between calculated and experimental data is satisfactory in most cases using a general parameter set. The calculated results show that the bathochromic effect of a methoxy group is essentially due to a HOMO-HOMO interaction, and the bathochromic effect of a benzothiopyran ring in the 2-position is due to raising of a HOMO.The electron transfer properties of 1-benzothiopyrylium salts were examined by means of cyclic voltammogram and xerographic discharge techniques. It was found that the reduction wave of thioflavylium ions is reversible.     

Vapor-liquid equilibria of some pollutants in aqueous and saline solutions Part I: experimental results

Vapor-liquid equilibria were measured for dilute aqueous solutions of formic acid, acetic acid, pyridine, aniline, isobutyl alcohol, isoamyl alcohol, n-butyl acetate, dimethyl phthalate, diethyl phthalate and dioxane, respectively, at various pH, temperatures and concentrations of sodium chloride.The substances chosen are very important raw materials or intermediates in chemical industry and are widely used. Phthalates are used as plasticizers and leach, in small amounts, into water from plastics. Recently in Japan, we are recognizing phthalates as a new polluting material in sea water and river water.The vapor-liquid equilibria were severely affected by the pH of the solution, not only for the electrolytes (such as formic acid and pyridine), but also for esters. This is probably due to the effect of pH on the degree of the dissociation of electrolytes and on the hydrolysis of esters. The phase equilibria of some organic materials which are less soluble in water (such as phthalates and higher alcohols) were greatly affected by the salting-out effect of salinity.If the feed sea water to distillation plants is contaminated by volatile organic materials, some of them concentrate in the distilled water. Therefore, attention must be given to the properties of volatile, polluting materials in sea water when the product water from desalination processes is for human consumption.     

Kinetics of growth on aqueous — oil and aqueous — solid dispersed systems

Dispersed phase continuous culture systems are very complicated. Indeed, they can differ considerably in their behaviour from the usual homogeneous continuous culture systems. Experimental studies on cell adsorption—desorption rates under various conditions of surfactant concentrations and droplet coalescence and break-up is needed in order to understand fully the mechanism of substrate utilisation in these continuous systems.     

Behavior of acrylic acid–itaconic acid hydrogels in swelling,shrinking, and uptakes of some metal ions from aqueous solution

An experimental research of the absorption properties of metal ions onto synthetic hydrogel obtained by solution polymerization of acrylic acid and itaconic acid in presence of N,N′‐methylenebisacrylamide as crosslinking agent was carried out. The swelling behavior in aqueous salt solutions was studied as a function of divalent cation concentration (Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cd²⁺, Pb²⁺, Hg²⁺) in the external solution ranging from 10^?5 to 1M, at 25°C. The ability of these hydrogels to bind cations was measured at different pH values and metal ion concentrations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 530–536, 2003     

Preparation of recyclable polybutadiene rubber based on acid–base complexation

Thermoreversible polybutadiene (PB) rubber is prepared by the self‐assembly of thiol‐ene functionalized PB oligomers containing amine and carboxylic acid groups, respectively, via acid–base reaction. The as‐formed ionic hydrogen bonds between the amine and carboxylic acid groups function as the crosslinking points to construct the polymer network. By controlling the crosslinking density, a series of materials ranging from soft gel to stiff solid with different physical properties can be obtained. The thermal reversibility of the ionic hydrogen bonds is evidenced by rheometry and temperature‐dependent FTIR spectra. In contrast to conventional covalently crosslinked rubbers, the thermoreversible PB rubbers prepared exhibit the capability of thermally reshaping and recycling. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45280.     

Vapor-liquid equilibria of some pollutants in aqueous and saline solutions part II: correlation for dilute weak electrolytes in aqueous buffered solutions

A thermodynamic procedure is described for predicting vapor-liquid equilibria in buffered, dilute aqueous solutions containing one weak electrolyte: ammonia, hydrogen cyanide, formic acid, acetic acid, pyridine or aniline.The procedure requires the dissociation constant of the weak electrolyte and either the Henry's constant or a vapor-liquid equilibrium ratio (K') determined for a dilute weak electrolyte solution in a pH region where most of the electrolyte is not ionized.Predicted results agree well with experiment. The thermodynamic procedure described here is effective for estimating phase equilibria for weak electrolyte pollutants in sea water or waste water as encountered in desalting plants or pollution abatement processes. The correlation is also useful in the design of secondary refrigerant freezing processes which utilize a direct contact melting-condensing system. In this scheme the volatiles present in the feed would be stripped out of solution by the evaporating refrigerant and then reintroduced to the product water.     

Interpolymer complexes of novel linear and crosslinked acrylic acid–Schiff base copolymers

Novel linear and crosslinked copolymers of acrylic acid and Schiff base, containing the amine groups in the main chain and the carboxylic groups in the side chain, have been synthesized by the Michael addition reaction followed by radical copolymerization. The copolymers that exhibited poly(ampholyte–electrolyte) behaviour were used to prepare complexes by reaction with anionic (poly(acrylic acid), poly(styrene sodium sulfonate)), cationic (polyethyleneimine, poly(hexamethylene guanidine)) and non‐ionic (poly(N‐vinylpyrrolidone), poly(ethylene glycol), poly(vinyl alcohol)) polymers. The influence of external factors, such as solvent quality, temperature, pH and ionic strength, on phase (coil–globule) and volume (swelling–collapse) transitions has been studied. © 2003 Society of Chemical Industry     

Membrane formation with presence of Lewis acid–base complexes in polymer solution

This work investigated membrane formation using Lewis acid–base complexes in a polymer solution, which consisted of poly(ether sulfone) (PES), Lewis acid–base complexes formed by N‐methyl‐2‐pyrrolidone (NMP, Lewis base), and dicarboxylic or monocarboxylic acids from a homologous series (Lewis acids). The solutions were characterized by viscosity measurements, IR spectroscopy, cloud point determination, and light transmission experiments. The membranes were characterized by scanning electron microscopy and gas permeation tests. The results indicated that the solvent–additive interaction, which is a function of their capacity to form complexes, and the acid chain length directly affect the viscosity and miscibility region. Consequently, these parameters combined with the complex dissociation influence the precipitation velocity of the polymer solutions, which will then affect the membrane transport properties. It is also pointed out that the membranes prepared by using 25 wt % PES at the same acid/NMP molar ratios and with different acids presented permeability coefficients in agreement with the binodal shift obtained in pseudoternary phase diagrams. Furthermore, when these solutions were exposed to the environment for a long period of time, the demixing onset sequence also agreed with the miscibility region for all solutions, except for the adipic acid solution because of its extremely high viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2022–2034, 2002     

Electrochemical reactions of stage 1 sulfuric acid—Graphite intercalation compound

By means of cyclic voltammetry, a study of the redox reactions has been made on stage 1 sulfuric acid-graphite intercalation compound (H₂SO₄-GIC) prepared by anodic oxidation of graphite in sulfuric acid electrolyte. It was found that further oxidation of the stage 1 GIC gives rise to the reversible ionization reaction of carbon atoms in the graphite basal plane and also of sulfuric acid molecules produced in the interlayer spacing. This ionization reaction and the reverse deionization reaction are responsible for plateaus observed in the current vs. potential curve. These redox reactions between the stage 1 GIC and its ionized state were analyzed in situ by means of X-ray diffractometry.     

Vapor—liquid equilibria of acetonitrile-1-propanol mixtures

Experimental P-T-x data have been measured for acetonitrile-1-propanol mixtures. The Margules, UNIQUAC, UNIFAC and ASOG models and the method of Mixon et al. have been used to predict the vapor compositions from the P-T-x data. A good agreement has been found between the vapor compositions predicted by the above except in the case of UNIFAC. The parameters obtained by using the single set data treatment gave satisfactory representation of vapor liquid equilibria of acetonitrile-1-propanol mixtures.     

Synthesis and absorption spectra of some novel hetaryldisazocalix[4]arene derivatives

In this study, a convenient method for the synthesis of thirteen novel disazo dyes containing 25,26,27‐tribenzoyloxy‐28‐hydroxycalix[4]arene have been described. 5,11,17,23‐Tetra‐tert‐butyl‐25,26,27,28‐tetrahydroxycalix[4]arene, 25,26,27,28‐tetrahydroxycalix[4]arene and 25,26,27‐tribenzoyloxy‐28‐hydroxycalix[4]arene were synthesised based on previously published literature. 2‐Arylhdrazone‐3‐ketiminobutyronitriles were synthesised and reacted with hydrazine hydrate to afford the corresponding 5‐amino‐4‐arylazo‐3‐methyl‐1H‐pyrazoles. Thirteen novel hetaryldisazocalix[4]arene derivatives were achieved by diazotisation of 5‐amino‐4‐arylazo‐3‐methyl‐1H‐pyrazoles using nitrosylsulphuric acid, coupled with 25,26,27‐tribenzoyloxy‐28‐hydroxycalix[4]arene. The obtained hetaryldisazocalix[4]arene dyes were characterised based on Fourier Transform–infrared, proton nuclear magnetic resonance and mass spectroscopic techniques, as well as elemental analysis. The solvatochromic behaviour of these dyes in various solvents was examined. Acid‐base effects on the visible absorption maxima of the dyes were also reported.     

Peracetic acid‐enhanced photocatalytic and sonophotocatalytic inactivation of E. coli in aqueous suspensions

BACKGROUND: Although chlorination is an effective and widely employed method of water disinfection, it suffers serious drawbacks such as the formation of toxic chlorinated by‐products. Therefore, other disinfection technologies have been researched and developed, including advanced oxidation. RESULTS: The efficacy of heterogeneous photocatalysis and sonophotocatalysis induced by UV‐A irradiation and low frequency (24–80 kHz) ultrasound irradiation in the presence of TiO₂ as the photocatalyst and peracetic acid (PAA) as an additional disinfectant to inactivate E. coli in sterile water was evaluated. PAA‐assisted UV‐A/TiO₂ photocatalysis generally leads to nearly complete E. coli inactivation in 10–20 min of contact time with the extent of inactivation depending on the photocatalyst type and loading (in the range 100–500 mg L^?1) and PAA concentration (in the range 0.5–2 mg L^?1). The simultaneous application of ultrasound and UV‐A irradiation in the presence of TiO₂ and PAA prompted further E. coli inactivation. CONCLUSIONS: The proposed advanced disinfection technology offers complete E. coli inactivation at short treatment times and low PAA doses. Copyright © 2010 Society of Chemical Industry     

Model for phase equilibria correlation and prediction. Characteristics and application to binary liquid—vapor and binary,ternary and quaternary liquid—liquid equilibria

A new model for the excess Gibbs energy has been developed. The model has three binary parameters. The presence of the third parameter, k_ij, the power of the composition, gives to the model an extraordinary flexibility. The model has been widely tested for different types of equilibria, such as binary liquid-vapour equilibria, both isothermal and isobarid; as well as on liquid-liquid equilibria, binary, ternary and quaternary, for both correlation and prediction. Results obtained for the average errors were always lower than those obtained by the Van Laar, Wilson and UNIQUAC models, and even by a three parameter model such as NRTL.     

Synthesis and Electronic Spectra of Some Disperse Dyes Derived from N—2—Cyanoethyl—1,2,3,4—tetrahydroquinoline

Various monoazo dyes suitable for transfer printing have been prepared from N—2cyanoethyl—1, 2, 3, 4—tetrahydroquinoline and compared with the corresponding N—methyl (kairoline) derivatives. The presence of a β—cyanoethyl group brings about significant hypsochromic shifts of the first absorption band and leads to some improvement in light—fastness properties on polyester fibre.     

Phase equilibria in the two-phase system polystyrene—liquid sulphur dioxide

The concentration and molecular weight distribution (GPC) of polystyrene (PS) in the two phases of the PS-SO₂ (δ)-system were determined. Typical concentrations of PS in the upper phase were around 30%, while the lower phase contained at most 1% PS. An exception was a PS-grade with a low molecular weight (MW 3.5 · 10³), which dissolved homogeneously. The molecular weight of PS in the lower phase was substantially below an the one found in the concentrated phase. Mechanical agitation was necessary to attain an equilibrium state; during the equilibration the upper phase became more diluted. At the same time the molecular weight of the lower phase PS-fraction increased, while the MW value in the upper phase remained practically unchanged and equal to that of the virgin sample. The fractionation with regard to the molecular weight between the two phases was also reflected in the Tg-values of the fractions. The value of X(Flory-Huggins parameter) determined from vapour pressure data above the concentrated phase was 0.8–1.     

Influence of acid–base pairs on film formation and catalysis for acidic acrylic latexes

The influence of neutralizing agents was investigated using strong and weak acids with three different amines. Acidic acrylic latexes were synthesized through free radical emulsion copolymerization of butyl acrylate, methyl methacrylate and methacrylic acid or 2-sulfoethyl methacrylate. Both strong (sulfonic) and weak (carboxylic) acids were neutralized with three amines, N,N-dimethyl-methylamine, N,N-dimethyl-1-butanamine and N-methyl-morpholine. Uncrosslinked neutralized and un-neutralized latex samples were monitored for water loss (drying parameters), pH development and amine evolution during drying. Surface morphology was monitored during the later stages of film coalescence. For the weak acid, amine volatility was the controlling factor for film formation kinetics, and pH reduction. For the strong acid, volatility of the amine was not a factor. The process of deblocking was governed by the acid–base equilibrium.     

Influence of casting substrate on the acid–base interaction energies of various polyesters

The acid–base surface characteristics of four polyesters: poly( -lactic acid) (PLLA), poly( -lactic acid) (PDLLA), polyhydroxybutyrate (PHB) and copoly(hydroxy butyrate–20% hydroxyvalerate)P(HB–20% HV) have been determined from contact angle and surface tension experimental data. Smooth surfaced polyester films were prepared by solution casting against a number of substrates ranging from high surface energy (aluminium, mercury, glass and freshly-cleaved mica) to low surface energy (poly(ethyleneterephthalate)(PET), poly(tetrafluoroethylene)(PTFE) and dry nitrogen gas).

Results show that the acid–base interaction energy of the polyester surface is dependent on the casting substrate and ageing time. For a particular casting substrate, the equilibrium acid–base interaction energy between a polyester surface and an acidic liquid decreases in the order: PDLLA; PLLA; PHB; P(HB–20%HV).

The time dependence of the acid–base interaction energy is interpreted in terms of orientation of surface acidic or basic sites. Furthermore, detailed results suggest that the initial acidic or basic character of the cast polyester surface is influenced by the acid/base surface properties of the casting substrates.     

Determination of the acid–base characteristics of lignocellulosic surfaces by inverse gas chromatography

The surface acid–base characteristics of samples of cellulose, pine wood, and kenaf powder were determined by inverse gas chromatography (IGC). The test substrates were packed in a deactivated glass column and the IGC probes were injected at infinite dilution. The surface acid–base parameters were expressed in terms of the acceptor K_A and donor K_D parameters, analogous to the Gutmann acceptor and donor numbers derived from the Lewis concept of acids and bases. The K_A and K_D values were calculated from the experimental values of the enthalpy of desorption, corresponding to the specific acid–base interactions, and literature values of the acceptor and donor numbers for the acid–base probes, chloroform, carbon tetrachloride, ethyl acetate, and diethyl ether. Values of K_A and K_D suggest that the surfaces of cellulose, pine wood, and kenaf powder that have been washed by extraction with toluene/ethanol (2 : 1, v/v) are amphoteric, with a relatively greater capacity to accept electrons. The effect of the washing procedure on the dispersive component of the surface energy of the pine wood and kenaf powder was also determined. It was observed that the values for the washed substrates were relatively greater than those of the nonwashed counterparts. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1013–1020, 1997