Showing papers in "Journal of Chemical Engineering of Japan in 1990"

Determination of new ASOG parameters.

Abstract: To extend the applicable systems and improve the accuracy of ASOG (Analytical Solution of Groups), which is a predictive method for activity coefficients, the group interaction parameters have been newly determined and some of those reported are revised. The group interaction parameters are increased to 341 group pairs consisting of 43 groups against the previous 31 groups and 138 group pairs. Twelve groups are newly added: pyridine, furfural, ACRY, Cl (C=C), DMSO, NMP, C≡C, SH, DMF, ethanediol, DEG, and sulfolane. The parameters for the previous 31 groups are revised for 10 of those groups: C=C, ArOH, GOH, O, CHO, CON, CN, ArNH2, Cl, and ArCl. The parameters are then extended by providing missing values for others among the 31 previous groups. The temperature range of experimental data used for parameter determination is 293 K to 423 K.

Removal of coexisting Pb2+, Cu2+ and Cd2+ ions from water by addition of hydroxyapatite powder.

Abstract: Removal of single, binary and ternary divalent heavy metal ions, i.e., Pb2+, Cu2+ and Cd2+, respectively, from their chloride or nitrate aqueous solutions was studied by the addition of hydroxyapatite in an agitated tank adsorber.The isotherms for each single component were of the rectangular type, i.e., the amounts removed from aqueous phase were constant irrespective of the concentration of solutions. For binary and ternary systems, equilibrium relations were expressed in terms of selectivity coefficient.Concentration decay curves were prepared from experimental data for comparison with theoretical calculations.Regarding mass transfer, it was found that Pb2+ was collected on the apatite structure very fast, while the two other ions showed some resistances other than film diffusion resistance.Furthermore, the apatite structure was studied by X-ray difractometry.

Extraction equilibria of organic acids with tri-n-octylphosphineoxide

Abstract: The extraction equilibrium of organic acids (acetic, glycolic, propionic, lactic, pyruvic, butyric, succinic, fumaric, maleic, malic, itaconic, tartaric, citric and isocitric) with tri-n-octylphosphine oxide (TOPO) was measured. The solvation numbers of the acids were the same as the numbers of the carboxyl groups on each acid molecule. The extraction equilibrium constant was controlled by the hydrophobicity of the acid when hexane was used as a diluent.

Hydrolysis of Methyl Acetate in Distillation Column Packed with Reactive Packing of Ion Exchange Resin

Abstract: Ion exchange resin tablets (7 mm diameter × 7 mm length) were molded from ion exchange resin beads and polyethylene powder in a furnace. 700 ml of the tablets was packed in a Pyrex glass tube of 36 mm diameter as a reaction zone and an Oldershaw column of 30 plates and 32 mm in diameter was employed as the recovery zone of the column. A mixture of methyl acetate and methanol (75:25 by weight) was fed to the bottom of the reaction zone at a rate of 89 g/h and water was fed to the top of the column at a rate of 89 g/h. When all the condensed top vapor was recycled at a rate of 254 g/h, the concentration of methyl acetate in the resulting reaction mixture discharged from the bottom was practically negligible.The reactive distillation column can be incorporated into the process of hydrolysis of methyl acetate for recovery of acetic acid and methyl alcohol. The advantages of the new process are the elimination of two columns in the conventional process and reduction of the heat requirement of the total process. The decrease in heat requirement is estimated to be about 50% that of the conventional process.

Occurrence and Structure of Taylor–Goertler Vortices Induced in Two-Dimensional Wavy Channels for Steady Flow

Abstract: The occurrence and structure of longitudinal vortices are examined by a flow visualization technique for various sinusoidal wavy channels Longitudinal vortices are confirmed to appear in a channel with a narrow spacing in the range of geometrical parameters considered here The geometrical conditions for the onset of such vortices are shown by a diagram The longitudinal vortex is a kind of Taylor–Goertler vortex observed in a curved rectangular-section channel However, the wavy channel is different from the curved rectangular-section channel in the processes of vortex development and destruction It is found that an unstable mode, in which the vortices formed at the upper and lower walls of the channel have some interaction, leads to vortex destruction and significantly promotes the transition to turbulence

Separation of Organic Acid/Water Mixtures by Thin Porous Silica Membrane

Abstract: A method is proposed to prepare thin porous silica membrane which can be considered relatively stable against acids. The separation performance of this membrane for some organic acids (acetic acid, propionic acid, acrylic acid)/water mixtures has been studied experimentally by the pervaporation method and quite large fluxes of water and high separation factors have been achieved

Bubble Formation at a Single Orifice in Highly Viscous Liquids

Abstract: Bubble formation at an orifice submerged in highly viscous liquid was studied. The volume and shape of the bubble formed at an orifice and the pressure fluctuation in the gas chamber were measured experimentally. A revised nonspherical bubble formation model is proposed to describe the bubble formation mechanism and to estimate the bubble volume and shape and the pressure change in the gas chamber. The bubble volume, bubble shape and gas chamber pressure calculated by the present model agreed relatively well with the values obtained experimentally in a wide range of viscosity: μ = 0.001 to 1.1 Pas.

Gas Holdup and Gas Entrainment Rate in Downflow Bubble Column with Gas Entrainment by a Liquid Jet Operating at High Liquid Throughput

Abstract: Flow behavior of downflow bubble columns with gas entrainment by a liquid jet operating at high throughputs was investigated in an air–water system. With increasing liquid throughput above the churn-turbulent flow regime, stable downward bubbling flow without bubble coalescence was again obtained. Gas holdup and gas entrainment rate under bubbling downflow conditions were measured and their dependencies on operational conditions were clarified empirically. Experimental equations were proposed to estimate gas holdup and gas entrainment rate. Performance of gas supply was evaluated in terms of energy efficiency and compared with that of other gas-liquid aerators. The evaluation showed that the gas-entraining capacity of this apparatus is sufficient and that its energy efficiency for gas supply is high.

Catalytic Behavior and Phase Composition Change of Iron Catalyst in Hydrogenation of Carbon Dioxide

Abstract: Hydrogenation of CO2 was conducted on iron catalyst under various reaction conditions to explore the catalytic behavior and the change of bulk phase composition It was found by the use of Mossbauer spectroscopy that the metallic iron phase was transformed to a mixture of magnetite and carbides progressively during the course of reaction The formation of Fe3O4 phase became more favorable under conditions which led to a high H2O partial pressure on the catalyst bed On the other hand, the carburization of iron catalyst was enhanced at higher temperature, with χ-Fe5C2 phase being predominant over θ-Fe3C phase Due to the fact that H2O produced in the Fischer–Tropsch reaction also contributes to the equilibrium of the reverse water–gas shift reaction, the common product H2O of these two steps plays a major role in suppression of overall CO2 conversion level

Effective Charge Density and Pore Structure of Charged Ultrafiltration Membranes

Abstract: In the transport equation of charged ulfrafiltralion and reverse osmosis membranes which we proposed previously, the effective charge density and the membrane structure, that is, membrane thickness, tortuosity and the water content, are important transport parameters.In this study, these two parameters as determined from ultrafiltration experiments by using the previously proposed transport equation were compared with those obtained from other experiments. The effective charge density was determined from measurement of the membrane potential. It was strongly affected by the feed concentration and agreed well with that obtained from the filtration experiments. Moreover, the membrane structural parameter determined from filtration experiments was compared with that obtained from diffusion experiments. The two values showed good agreement.The measurement of membrane potential and the diffusion experiments were found to be useful for predicting the transport parameters of charged ultrafiltration membranes.

Solvent regeneration of spent activated carbon in wastewater treatment.

Abstract: Ethanol regeneration was applied to spent activated carbon which had adsorbed an organic compound in aqueous solutions, including an industrial wastewater. High regeneration efficiency was achieved except for aromatic compounds substituted by electron-donating groups. In the case where ethanol regeneration was not effective, efficient regeneration was possible using an electron-donating solvent such as N,N-dimethylformamide.From the viewpoint of practical use, the solvent regeneration of carbon which had adsorbed phenol was studied using fixed-bed runs. It was found that ethanol and toluene showed high regeneration efficiency. The column desorption of phenol was simulated and gave good agreement with observed results. The regeneration efficiency of ethanol and toluene fell to 80% after five regeneration cycles. The influence of phenol concentration in solvent on the regeneration efficiency was experimentally determined, and the results suggested that the amount of solvent can be minimized by using countercurrent multistage operation.

A novel membrane extractor using hollow fibers for separation and enrichment of metal.

Abstract: A novel membrane extractor using hollow fiber module was developed, and extraction and stripping of copper and/or zinc with 2-ethyihexyl phosphonic acid mono-2-ethylhexyl ester were carried out simultaneously. Separation and enrichment of zinc from aqueous solution containing copper and zinc were also carried out in the membrane extractor. The results were simulated by a diffusion model with interfacial reaction.

Extraction of Amino Acids by Reversed Micelles

Abstract: The aim of this paper is to present the extraction behavior of amino acids using reversed micelles with AOT ®

Predicting bed voidage in solid-liquid fluidization.

Abstract: Previously published solid-liquid fluidization data and new experimental data were correlated to develop an explicit expression for bed voidage, e, in solid–liquid systems. Based on the observed deviation between the voidage predicted by the Richardson–Zaki18) equation (eRZ) and the actual voidage, this new correlation assumes the forme = ePK + (1 – ePK)eRZA exp(B(1 – eRZ)where A = 2.2n + 8dP/D and B = 2.1n. ePK is the “packed” bed or the static bed voidage (i.e., e when the superficial liquid veIocity, UL, is zero), n is the Richardson–Zaki18) exponent, and dP/D is the particle diameter-to-column diameter ratio. A total of 811 data points were correlated with Reynolds numbers based on terminal velocity, Ret, ranging from 0.7 to 3200. The correlation satisfactorily predicts voidage with a standard deviation of less than 5%.

Sorption and Separation of Metals from Aqueous Solution by a Macromolecular Resin Containing Tri-n-Octylamine

Abstract: Experiments were conducted on the equilibrium distribution of divalent zinc between hydrochloric acid medium and macromolecular resin containing tri-n-octylamine (TOA) as an active component. The sorption of zinc on the impregnated sorbent can be expressed by the following stoichiometric relation:ZnCl2(aq.) + 2R3NHCl(s.) ↔ (R3NH)2ZnCl4(s.)where the equilibrium constant was found to be 3.59 × 105 kg-sorbent·dm3/mol2.Furthermore the separation of zinc and copper in aqueous solution by use of the sorbent was examined in a batch operation with hydrochloric acid concentrations over 5M. It was found that the sorbent gives high selective separation of zinc to copper, and they can be separated satisfactorily from a 1.0 mol/dm3 hydrochloric acid solution. The applicability of the TOA-impregnated sorbent to column operation is also reported.

A New Correlation Method for the Effect of Vibration on Forced-Convection Heat Transfer

Abstract: The forced convection heat transfer from a vibrating sphere, a cylinder and a square-section tube to water was experimentally investigated. The obtained heat transfer data with the vibration effect is well correlated in terms of the energy dissipation calculated from the fluid drag acting on the vibrating bodies. Through the use of the energy dissipation, the heat transfer from vibrating bodies to a fluid flow can be discussed analogously with the mass transfer.

Phase Equilibrium Study of the Separation of Ethanol–Water Solution with Supercritical CO2

Abstract: To provide a better theoretical basis for obtaining higher concentration of ethanol from a fermentation broth using near- or super-critical CO2 extraction, the vapor–liquid equilibria for the quaternary system of CO2, ethanol, water and an entratner were measured at 35.0°C and 10 MPa for various entrainer concentrations. Experiments were carried out for four entrainers: glycerol, ethylene glycol, 1,3-propanediol and propylene glycol. The experimental results demonstrated that the upper limit of ethanol composition for the CO2–ethanol–water ternary system could be raised by the addition of the above entrainers other than propylene glycol. It was also found that this effect of the entrainer could be estimated qualitatively from its solubility parameter value. The group parameter values of the GC-EOS by Jorgensen were redetermined using binary vapor–liquid equilibrium (VLE) data in order to improve the accuracy of prediction of the VLE of the CO2–ethanol–water and the CO2–ethanol–water-entrainer mixtures.

Jet Mixing of Liquids with a Rotating Nozzle around the Axis of a Cylindrical Vessel

Abstract: Mixing time in a jet mixing vessel with a rotating nozzle around the vessel axis was measured. The observed ratio of mixing time to mean residence time, tM/tR, was well correlated with the dimensionless angular velocity Ω* defined as the ratio of nozzle rotating velocity to jet velocity, where the profile of tM/tR was almost symmetrical with respect to Ω* value depending on nozzle angle. The minimum dimensionless mixing time (tM/tR)min was about 0.2 regardless of the jet nozzle angle for both the nozzle-rotating and the vessel-rotating systems.Baffle plates in the jet mixing vessel had a negative effect on the mixing time.Using the dimensionless variables derived here, it is expected that the mixing time for both the jet mixing vessel and the non-baffled agitated vessel can be correlated with the same equation.

Protein extraction by reversed micelles using dioleyl phosphoric acid

Abstract: In this study, we synthesized a series of dialkyl phosphoric acid surfactants. The extraction behavior of some proteins from an aqueous phase into their reversed micelles was also investigated in comparison with that with the conventional surfactant, AOT

Flow analogy of pseudoplastic liquid in geometrically similar stirred vessels based on numerical analysis

Abstract: Three-dimensional numerical analysis of flow behaviour such as velocity components, shear rate and apparent viscosity of a highly viscous pseudoplastic Ellis liquid in stirred vessels was performed. The vessels used were geometrically similar, non-baffled ones of 0.2 to 0.8 m vessel diameter each with a 6-blade turbine, a paddle and an anchor-type stirring impeller.The analogy of flow fields in model and large-scale stirred vessels was investigated by applying the concept of representative shear rate to estimate the apparent viscosity of a power-law fluid proposed by Metzner et al. and Nagata. It was found that the normalized flow profiles of a pseudoplastic liquid in the scaled-up vessels were nearly consistent with those in the model vessel within the impeller blade region, while it was quantitatively shown that the deviation between the two profiles in the outer region of the impeller expands with increasing vessel diameter.

Gas entrainment rate and flow pattern in a plunging liquid jet aeration system using inclined nozzles

Abstract: For an inclined plunging jet aeration system using liquids of low viscosity, the effects of operating conditions on the gas entrainment rate Qg when nozzles having various values of length-to-diameter ratio Ln/Dn were employed were evaluated experimentally. The changes in Qg were related to those in the jet shape before plunging and the liquid velocity distribution at the point where the gas sheath breaks up. An empirical equation was presented to predict the penetration depth Z of bubbles entrained by the diffusing jet. Bubble entrainment behavior was further examined in terms of the liquid velocity distribution in the submerged two-phase region and the size of entrained bubbles.

Swelling and Shrinking Processes of Sodium Polyacrylate-Type Super-Absorbent Gel in Electrolyte Solutions

Abstract: Some effects of electrolytes on the swelling and shrinking processes of sodium polyacrylate-type super-absorbent gel were examined systematically, using several kinds of uni-univalent and di-univalent electrolyte solutions. A gel of this type goes through a maximum degree of swelling and then shrinks in electrolyte solutions. The reason was found to be that the sodium ions dissociated from the functional groups in the gel, −COONa, are exchanged easily with the other cations in the solution. The swelling and shrinking mechanism can be reasonably explained in terms of the electric force acting on the charged network of the gel

Effect of Operating Parameters on Thermochemical Liquefaction of Sewage Sludge

Abstract: To determine the optimum combination of operating parameters for direct thermochemical liquefaction of sewage sludge, dewatered materials (raw mixed sludges) were treated over a temperature range of 150–300°C, a holding time of 0–180 min and a catalyst (sodium carbonate) loading of 0–5 wt% using a batch reactor. By variance analysis, the lower limit of reaction temperature for the production of heavy oils was found to be 250°C. At that temperature, however, organic concentrations in the aqueous phase were still high. From the viewpoint of oil production and wastewater treatment, the optimum combination of operating parameters was a reaction temperature of 275–300°C, a holding time of 60 min and operation without catalyst.

Recovery and purification of boron from coal fly ash.

Abstract: A process has been developed to recover boron from coal fly ash in which boron exists at low concentration in a mixture of high concentration of less desirable species. Of the boron contained in the ash, 72% can be leached with dilute sulfuric acid when the pH of the final pregnant liquor is kept at 7.0, the other undesirable transition metals being left in the residue. The boron is then concentrated using chelating resin with a functional group of glucamic type. Eighty-seven percent of the boron is recovered and is then concentrated to 3.6 g/dm3 with a purity of 98.9 percent. This liquor is further treated to remove impurities by a solvent extraction technique, employing 2-ethyl-1,3-hexanediol as an extractant, and a purified liquor for borax production is obtained.

Ideal flow models for palladium membrane reactors.

Abstract: The effects of flow patterns on the dehydrogenation performance of palladium membrane reactors in which a sweep gas is used to remove the permeated hydrogen were examined. By combining two idealized flow patterns, plug and perfect mixing flows, to the reaction and separation streams, five flow models—cocurrent, countercurrent, plug-mixing, mixing-plug, and mixing-mixing models—were analyzed and compared.It was evident that the countercurrent model leads to the highest degree of conversion and the shortest reactor length requirement while the performance of the mixing-mixing model is the lowest, except when the flow rate of sweep gas chosen is comparatively small. The order of performance among the other three models was dependent on the variables used in calculations.

Simulation of bifunctional palladium membrane reactor.

Abstract: A bifunctional membrane reactor using palladium was proposed by taking advantage of its catalytic and hydrogen-permeable functions and then by coupling dehydrogenation and oxidation Isothermal and adiabatic reactor models were developed and simulatedUnder an isothermal condition, the dehydrogenation taking place in a catalyst packed bed was enhanced owing to continuous removal of the hydrogen produced in the course of reaction through the membrane The amount of hydrogen removable was remarkably increased by the subsequent oxidation of hydrogen on the palladium surface of the permation side In addition to such effects, it was shown by the adiabatic model that transfer of heat by oxidation to the dehydrogenation side across the membrane can lead to further enhancement of dehydrogenation

Extraction and Separation of Rare-Earth Elements by Tri-n-Octylmethylammonium Nitrate

Abstract: The extraction of rare-earth nitrates was studied, using tri-n-octylmethylammonium nitrate in xylene as an extractant and ammonium nitrate as a salting-out agent. The capability of this extractant decreases continuously with atomic number apart from a slight increase from Gd to Tb. An extraction scheme occurring for all elements is presented. In this it is assumed that extraction occurs via reaction with monomer, R, of the extractant and the successive stage-wise formation of two extracts, Ln(NO3)3·5R and (Ln(NO3)3)2·5R. The fraction of 1:5 complex is very close to 1 at low loadings, whilst for all elements the fraction of 2:5 complex increases with increased loading. The formation of 1:5 complex is most favored with La and less favored with elements of higher atomic number. The inherent limitation of this extraction system for separation into individual elements is also discussed.