THERMODYNAMICS OF ALKANOLAMINE + WATER SYSTEM

Design of gas treating processes requires knowledge of the vapor-liquid equilibrium behavior of the (acid gas + aqueous alkanolamine) system. The present study is focused on thermodynamics and associated nonideal behavior of binary MEA + H₂O, DEA + H₂O, and MDEA + H₂O systems, which is required to predict the vapor-liquid equilibrium of acid gases such as CO₂ and H₂S over aqueous alkanolamine solutions. Determination of binary interaction parameters and analytical prediction of infinite dilution activity coefficient, heats of solution at infinite dilution, the excess Gibbs free energy, and excess enthalpy for nonideal alkanolamine-water systems are the objectives of this study.     

MEASUREMENT AND CORRELATION OF LIQUID-LIQUID EQUILIBRIA FOR TERNARY SYSTEMS OF WATER + RUBIDIUM CHLORIDE + PROPANOL

Liquid-liquid equilibria for ternary systems of water + rubidium chloride + 1-propanol and water + rubidium chloride + 2-propanol were measured at T = 298.15, 308.15, and 318.15 K. The experimental data were correlated using Othmer-Tobias and Bancroft correlations. The salting-out effect of 1-propanol in the two-liquid region was greater than that for 2-propanol, but the effect of temperature on the equilibrium was not significant.     

PHASE EQUILIBRIA STUDIES IN THE SYSTEM CaSO_4-PbSO_4

In this paper a study of the system CaSO_4-PbSO_4 has been made using a high temperature microscope to determinethe solidus and liquidus temperature of mixtures of CaSO_4 and PbSO_4,and the phase diagram for the system constructed.Solid state reactions of mixtures of CaSO_4 and PbSO_4 at temperatures below the solidus temperature have been performedand a new compound,3CaSO_4·PbSO_4,has been found and subjected to differential thermal analysis to check for its re-versible transitions.     

DETERMINATION OF PHASE EQUILIBRIA AND CRITICAL LOCUS OF CO_2-HCFC22 SYSTEM

1 INTRODUCTIONHydrochlorofluorocarbons(HCFCs)and hydrofluorocarbons(HFCs)are alternatives tochlorofluorocarbons(CFCs),such as CFC12(freon 12),which has been widely used asan aerosol agent and working fluid of domestic1:ICthdflC(CHCIFZ,HCFC22,R22)is one of the potential alternatives.It Is also one of the po-tentlal entralner for supercrltlcal fluid CO,extraction.     

VAPOR-LIQUID AND LIQUID-LIQUID EQUILIBRIA OF THE SYSTEM OF 4-METHYL-2-PENTANOL AND WATER

IntrodUCtion 今Methyl一2一Pentanol 15 a very imPortant solvent for eoPPer,iron and eoal floating.The mutual solubility of it with water 15 exeeedingly small at ordinary Pressure.50 far in the1 iterature available we ean find only the LLE(Liquid一Liquid Eq…     

SOLUBILITY OF AMMONIA IN WATER IN MULTICOMPONENT SYSTEM UNDER HIGH PRESSURE

The solubility of NH_3 in water in multicomponent systems under high pressure is of extreme importance to the new integrated ammonia and urea process. This paper proposes a new method for calculating the vaporliquid equilibria for aqueous ammonia solutions under high pressure. Based on the experimental data of the binary system of NH_3-H_2O in the high concentration range, a model has been established for the activity coefficients of NH_3 and H_2O to describe the non-ideality of the liquid phase; and the modified SIRK equation of state for polar compounds has been used to describe the non-ideality of the vapor phase under high pressure. The reliability of this model has been examined in the light of the experimental data of the solubility of NH_3 in H_2O under high pressure in the systems of NH_3-H_2O-N_2, NH_3-H_2O-N_2-H_2-Ar-CH_4 and NH_2-H_2O-N_2-H_2, the last being from Guerreri et al. Both the accuracy of calculation and the concentration range for applicability of this model have been found to surpass those of Guerrerl's model.     

ON THE POSSIBILITY OF PREDICTING PHASE EQUILIBRIA FROM MOLECULAR STRUCTURE

The abvent of the ASOG and UNIFAC group-contribution methods for the prediction of activity coefficients approximately 15 years ago was a significant boost to the ability of chemical engineers to model chemical processes. This paper reviews the status and recent progress in the group-contribution approach to predicting liquid-phase activity coefficients.Several different types of liquid mixtures arc considered: non electrolyte mixtures with normal-boiling components; mixtures with dissolved gases; mixtures with polymers; and mixtures including strong electrolytes. It is concluded that in recent years much progress has been made in the development of group-contribution models for the prediction of activity coefficients. It is in addition shown that combining activity coefficient models with equations of state renders the group-contribution approach applicable also to the highpressure region.Due to space limitation, this review emphasizes UNIFAC and related models.     

A STUDY ON THE SCALING RATE MODEL OF CALCIUM CARBONATE IN SATURATED WATER SYSTEM

1 INTRODUCTIONCalcium carbonate scaling is quite common in chemical processes,especially in heatexchangers.Only limited work has been done in mathematical modelling describingthe calcium carbonate scaling phenomenon.Hasson’s ionic diffusion model happenedto be one being rather broadly accepted.     

CORRELATION AND PREDICTION OF VLE OF WATER + CONGENER MIXTURES FOUND IN ALCOHOLIC BEVERAGES USING AN ARTIFICIAL NEURAL NETWORK

Artificial neural networks have been used for the correlation and prediction of vapor-liquid equilibrium data of binary water mixtures found in alcoholic beverage production. The main interest of the study is the accurate modeling of the bubble pressure and concentration of congeners in the vapor phase (substances different from ethanol and water), considered to be an important enological parameter in the alcoholic industry. Nine binary water + congener mixtures were considered for analysis. Vapor-liquid equilibrium data of these systems were taken from the literature (333 data points for training and 111 data points for testing), the artificial neural network results were compared with available literature data, and the accuracy of the modeling is discussed. The study shows that the neural network model is a good alternative method for the estimation of phase equilibrium properties for this type of mixture.

Supplemental materials are available for this article. Go to the publisher's online edition of Chemical Engineering Communications to view the free supplemental file. http://www.informaworld.com/smpp/title~db=all~content=t713454788     

EXPERIMENTAL MEASUREMENT OF SUPERCRITICAL CO_2-LOW VOLATILITY LIQUID PHASE EQUILIBRIA

Extraction equilibria of three low volatility liquids (benzyl alcohol,2-phenethyl alcohol and citronellol)separately with supercritical CO_2 were determined in a semi-flow apparatus at two temperatures(308.2K and318.2K)and pressures up to 20MPa.The solubility data of CO_2 in methyl benzoate were also obtained at thetwo temperatures in two-phase region.The experimental data were correlated by means of the Peng-Robinsonequation of state with two characteristic parameters.     

OPTIMIZATION OF FLOW RATE OF MOBILE PHASE IN COUNTERCURRENT CHROMATOGRAPHY

1 INTRODUCTIONCountercurrent chromatography(CCC)[1,2] is distinguished from other chromatographicmethods by its eliminating the solid support matrix from the separation column.Themethod employs an open tubular column where the partition process takes place be-tween the flowing mobile phase and the stationary phase retained by the effect of gra     

NONUNIFORMITY OF TWO PHASE FLOW IN CAPILLARY SYSTEMS

Gas-liquid flow in simple systems consisting of capillaries is analyzed by theory of irreversible thermodynamics so as to shed light on induction of nonuniformity of multiphase flow. By the Prigogine's theorem of minimum entropy production, stability of uniform two-phase flow and possible transition to nonuniform distribution are discussed. The analysis of model systems suggests potential application of irreversible thermodynamics to research of multiphase hydrodynamics in chemical reactors.     

THE APPLICATIONS OF A GENERALIZED EQUATION OF STATE TO THE CORRELATION AND PREDICTION OF PHASE EQUILIBRIA∗

Two methods of generalizing an equation of state are demonstrated and their limitations are outlined. One method involves the correlation of the equation of state constants and the second method involves a recently proposed Generalized Corresponding States Principle based on the properties of two (nonspherical) reference fluids. The PVT properties of pure fluids are represented by a new cubic equation of slate with four parameters which are obtained from vapor pressure and saturated liquid density data. It is demonstrated how a limited amount of data on key components may be used to obtain phase equilibria in mixtures.     

SOLUBILITY AND TIE-LINE DATA FOR WATER + FORMIC ACID + METHYL ISOBUTYL KETONE TERNARY SYSTEM AT DIFFERENT TEMPERATURES

The solubility and tie-line data of the ternary system comprising water, formic acid, and methyl isobutyl ketone were experimentally determined at the temperatures 288.15, 298.15, and 308.15 K, and atmospheric pressure 101.3 kPa. The plait points were also determined using Treybal's method. The results indicate that formic acid distributes preferentially in MIBK compared to water. Experimental tie-line data were regressed with the NRTL model to obtain binary interaction parameters. It is found that the NRTL model correlates the present system satisfactorily with average root-mean-square deviation of 0.34%.     

SOLUBILITIES OF HYDROGEN CHLORIDE AND CHLOROMETHANE IN 1,2,4-TRIMETHYLBENZENE

An experimental apparatus was set up for the measurement of gas solubility in liquids.The solubilitydata of pure hydrogen chloride and chloromethane in the temperature range of 293-323 K and pressurerange of 6-130 kPa and those of the mixture at 298.15 K were obtained and correlated with modifiedHenry's equation.The activity coefficients were calculated with Margules' equation.     

MASS TRANSFER IN MEMBRANE ABSORPTIONDESORPTION OF AMMONIA FROM AMMONIA WATER

Hydrophobic membrane can provide fast mass transfer for absorption-desorption of gasesform liquid to absorbent.The removal of ammonia from ammonia water and absorption with dilutesulphuric acid was studied in a pilot plant with polypropylene hollow fiber column,The removalrate and influences of operation temperature,flow rate and concentration on mass transferperformances were discussed mathematically.Experimental results and computer calculation show thatthe ammonia removal rate is not affected by the feed concentration for a given system.Both partialand overall mass transfer coefficients vary along the axis of the fiber,and the mass transfer for themembrane process is controlled by membrane resistance.     

SOLUBILITY OF ACETAMINOPHEN AND IBUPROFEN IN BINARY AND TERNARY MIXTURES OF POLYETHYLENE GLYCOLS 200 AND 400, PROPYLENE GLYCOL,AND WATER AT 25°C

The solubilities of acetaminophen and ibuprofen in the mixtures of propylene glycol-water, polyethylene glycols 200- and 400-propylene glycol, and polyethylene glycols 200- and 400-propylene glycol-water (122 data points) at 25°C were determined and mathematically represented by the Jouyban-Acree model. The solubilities were measured using the shake flask method, and the model was used to fit the solubility data of each drug in the solvent mixtures. The density of the solute-free solvent mixtures was measured and the density of the drug-saturated solutions was predicted. The obtained overall mean relative deviations (OMRDs) for fitting the solubility data of acetaminophen and ibuprofen in binary mixtures are 1.5% and 11.7%, respectively. The OMRDs for fitting the solubilities in ternary solvent mixtures for acetaminophen and ibuprofen are 16.3% and 42.0%, respectively, and the OMRD values for predicting all solubilities of acetaminophen and ibuprofen by these trained versions of the Jouyban-Acree model were 5.7% and 20.4%, respectively. The prediction OMRD for the density of saturated solutions was 2.5%.     

LIQUID-LIQUID EQUILIBRIA FOR THE SYSTEM WATER-PHOSPHORIC ACTD-1-PENTANOL-3-PEHTAHONE AT 25°C IN THE PRESENCE OF SODIUM CHLORIDE.

A quantitative study of the effect of sodium chloride has been made on the quaternary liquid-liquid equilibria Water-Phosphoric Acid-i-Pentanol-3-Pentanone at 25°c and atmospheric pressure. Mutual solubility and tie-line data are obtained at saturation of sodium chloride in both conjugated phases. The addition of sodium chloride increases the distribution coefficient of phosphoric acid and the selectivity of extractant solvents for i-Pentanol and mixtures of 1-Pentanol and 3-Pentanone, whereas it has no significant influence when the extractant solvent is 3-Pentanone.     

HYDROGEN BONDING IN AGGREGATES OF DIALKYL-SUBSTITUTED DLPHOSPHONIC ACIDS AND MONOFUNCTIONAL ANALOGUES∗

ABSTRACT

Hydrogen bonding of dialkyl-substituted diphosphonic acids in nonpolar (toluene and CC1₄) and alcohol (1-decanol) solutions is examined. The compounds are monomeric in 1-decanol and dimeric or higher in nonpolar organic diluents. Infrared spectroscopy and molecular mechanics calculations suggest that the dimers of P,P'-di(2-ethylhexyl) methanediphosphonic acid (H₂DEH[MDP]) and its straight-chain isomer, P.P'-dioctyl methanediphosphonic acid (H₂DO[MDP]), adopt rigid highly hydrogen-bonded structures such as C or D. The homologous P.P'-di(2-ethylhexyl) ethane- and butanediphosphonic acids, H₂DEH[EDP] and H₂DEH[BuDP], respectively, adopt structures that are also intermolecularly hydrogen-bonded but more flexible. The effect on the P=0 stretching vibration of increasing 1-decanol concentration in the solvent differs for these compounds. In the case of H₂DEH[MDP]and H₂DO[MDP], the frequency remains constant until all CC1₄ has been replaced by the alcohol, then the P=0 stretching frequency shifts to a lower energy. In the case of H₂DEH[EDP] and H₂DEH[BuDP], a gradual shift to higher energy occurs as the alcohol concentration increases. The magnitude of the difference in the P=0     

MACROPROCESS OF PARTICLE FORMATION IN SUSPENSION POLYMERIZATION OF STYRENE WITH INORGANIC STABILIZER SYSTEM

The macroprocess of particle formation from suspension droplets of styrene in a pdymerizationsystem was investigated.Inorganic hydroxyapatite or its mixture with polyvinyl alcohol as thepolymerization system was used.Those items such as the effects of the Weight fraction of dispersed-phase,the amount of the inorganic stabilizer and the agitation speed on the breakup and coalescence of thetransient dispersed drops etc.Were examined.Results showd that the dynamic behavior of the transi-ent polymer droplets changed in the presence of the suspension stabilizer during the reaction.