Showing papers in "Journal of Chemical Engineering of Japan in 1995"
TL;DR: In this article, structural parameters and electrical properties of nanofiltration membranes (Desal-5, NF-40, NTR7450 and G-20) were determined with permeation experiments of aqueous solutions of neutral solutes (alcohols and saccharides having different molecular weights) and sodium chloride.
Abstract: Structural parameters and electrical properties of nanofiltration membranes (Desal-5, NF-40, NTR7450 and G-20) were determined with permeation experiments of aqueous solutions of neutral solutes (alcohols and saccharides having different molecular weights) and sodium chloride. The pore radii of these nanofiltration membranes were estimated to range from 0.4 to 0.8 nm based on the steric-hindrance pore model. Neither the constant surface charge density nor the constant surface electrical potential were suitable for interpreting NaCl concentration dependency of reflection coefficients. The fixed charge density of these membranes was evaluated on the basis of the Teorell-Meyer-Sievers model; a simple empirical equation was proposed to represent the dependency of the fixed charge density on NaCl concentration.
195 citations
TL;DR: The growth inhibitory effect of 26 ceramic powder slurries on bacteria was evaluated by measurement of the conductance change of the growth medium caused by bacterial metabolism (conductance method).
Abstract: The growth inhibitory effect of 26 ceramic powder slurries on bacteria was evaluated by measurement of the conductance change of the growth medium caused by bacterial metabolism (conductance method). Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis were used as test bacteria. It was found that the growth of the test bacteria was inhibited by 10 ceramic powders. Magnesium oxide (MgO) and calcium oxide (CaO) powder slurries had a growth inhibitory effect on all test bacteria. In the cases of MgO, and CaO powder slurries, there was no difference in sensitivities among the test bacteria. These powder slurries exhibited bactericidal action on the test bacteria. On the other hand, the zinc oxide (ZnO) powder slurry inhibited the growth of Gram-positive bacteria stronger than Gram-negative bacteria. The effect was bacteriostatic action. The conductance method could provide quantitative and simple evaluation of the growth inhibitory effect of ceramic powder slurries on bacteria, and was more applicable than the conventional methods, such as the halo test.
187 citations
TL;DR: In this article, a new model that considers both the electrostatic and steric-hindrance effects based on the space charge model and the steric hindrance pore model has been proposed to evaluate the transport phenomena of an organic electrolyte across a nanofiltration membrane.
Abstract: A new model that considers both the electrostatic and steric-hindrance effects based on the space-charge model and the steric-hindrance pore model has been proposed to evaluate the transport phenomena of an organic electrolyte across a nanofiltration membrane. The dependence of the membrane parameters, reflection coefficient and solute permeability on the electrostatic and steric-hindrance effects has been analyzed in the system of an organic electrolyte and a negatively charged nanofiltration membrane. This model has been verified in the system of a tracer organic electrolyte (sodium benzenesulfonate), a supporting salt (sodium chloride) and commercial nanofiltration membranes (Desal-5, NF-40, NTR7450 and G-20); the theoretical values of the membrane reflection coefficients agreed very well with the experimental results of them.
69 citations
TL;DR: In this article, the effects of magnesium oxide (MgO), calcium oxide (CaO), and zinc oxide (ZnO) powder slurries on spores of Bacillus subtilis were examined.
Abstract: The effects of magnesium oxide (MgO), calcium oxide (CaO), and zinc oxide (ZnO) powder slurries on spores of Bacillus subtilis were examined. The CaO and MgO powder slurries were able to kill the spores of B. subtilis in physiological saline. The efficacy of the CaO powder slurry was much higher than that of the MgO powder slurry. It was considered that the efficacy of the CaO powder slurry against the spores depended on effects of Ca2+ and some factors due to contact between spores and the CaO powders. When the spores and nutrients such as growth medium existed together, it was observed that the MgO, CaO and ZnO powder slurries exhibited antibacterial activity against spores of B. subtilis. There was no difference in sensitivity to the ceramic powder slurry between the vegetative cells and the spores of B. subtilis. Further, the supernatant of the ceramic powder slurries promoted the germination of the spores. Therefore, it was suggested that the ceramic powder slurries weakened a high dormancy of spores, and acted on the germinated spores.
62 citations
54 citations
TL;DR: E. coli irradiated by FIR became more sensitive to RFP and CP, which suggests that FIR irradiation damages RNA polymerase and ribosome in E. coli.
Abstract: Injury in Escherichia coli irradiated by far-infrared radiation (FIR) was examined. We used penicillin G (PCG), chloramphenicol (CP), rifampicin (RFP) and nalidixic acid (NA) as selective reagents, and tried to evaluate the injury in bacteria irradiated by FIR on the basis of the changes in the sensitivity to selective reagents. The validity of this method was examined using UV pasteurization. E. coli irradiated by UV became more sensitive to CP and NA, which indicated that UV irradiation damaged nueleic acid in E. coli. This result agrees with those demonstrated by many researchers and suggests this method is applicable to useful evaluation of the damaged part in bacteria induced by stresses. E. coli irradiated by FIR became more sensitive to RFP and CP, which suggests that FIR irradiation damages RNA polymerase and ribosome in E. coli. Though similar changes in the sensitivity were obtained in the case of thermal conductive heating, the pasteurization effect of FIR irradiation was much greater than that of conductive heating.
50 citations
TL;DR: In this paper, an experimental apparatus equipped with three density meters was developed for measuring vapor-liquid-liquid phase separation properties at high pressures, and the phase compositions of carbon dioxide + ethanol mixture and their densities at high pressure were measured at 308.15 K with the apparatus.
Abstract: An experimental apparatus equipped with three density meters was newly developed for measuring vapor-liquid-liquid phase separation properties at high pressures. Coexisting phase composition and saturated density of each phase can be measured by means of the present apparatus with a maximum temperature of 400 K and pressure of 20 MPa. The phase compositions of carbon dioxide + ethanol mixture and their densities at high pressures were measured at 308.15 K with the apparatus. The sensitivity and absolute reliability of the equilibrium compositions appear to be 0.0001 and 0.001 mole fractions, respectively. The accuracy of saturated densities is 0.1 kg/m3. The equilibrium compositions obtained in the present study were correlated with the pseudocubic equation of state previously proposed by the authors and the Soave-Redlich-Kwong equation of state. Saturated densities obtained in the present study were further evaluated by the equations of state with the interaction parameters determined from vapor-liquid equilibrium data.
50 citations
TL;DR: In this paper, a generalized approach to the saturation carrying capacity of gas, Gs*, in high-velocity fluidized beds was presented, which is defined as the solid circulation rate at which a maximum achievable or saturation solids concentration at the dense region of the CFB starts to be reached.
Abstract: This paper presents a generalized approach to the saturation carrying capacity of gas, Gs*, in high-velocity fluidized beds. Starting from discussion of the variation of solid holdup in the dense region of circulating fluidized beds (CFBs) with the solid circulation rate, we defined the saturation carrying capacity of gas, Gs*, as the solid circulation rate at which a maximum achievable or saturation solids concentration at the dense region of the CFB starts to be reached. It has been experimentally demonstrated that above Gs*, solid concentrations in the dense region are really independent of changes in the solid circulation rate, the riser diameter, solids feeding system and the solids inventory, and a characteristic S-shaped axial solid holdup distribution would be observed. Based on this physical phenomenon, the saturation carrying capacity of gas was determined as functions of gas velocity and gas-solid properties, and a generalized correlation was therefore proposed on the basis of collected literature data. Finally, a flow diagram in which the flow conditions for occurring of S-shaped and exponential profiles of solids holdup was presented.
50 citations
TL;DR: In this article, the authors measured the lateral and axial mixing of dispersed particles in a circulating fluidized bed by using the phosphor tracer technique and the measured residence time distribution was satisfactorily described by a proposed two dimensional plug flow dispersion flow.
Abstract: The lateral and axial mixing of dispersed particles in a circulating fluidized bed were measured by using the phosphor tracer technique. The measured residence time distribution was satisfactorily described by a proposed two dimensional plug flow dispersion flow. Compared with that in the cocurrent downflow circulating fluidized bed (CDCFB), the dispersion Peclet numbers for lateral and axial mixing of dispersed particles is about the same value with that in CDCFB (downer). Correlations of the Peclet numbers under the operating conditions are presented.
49 citations
TL;DR: In this paper, the selective separation of amino acids, glutamic acid, methionine and lysine from their solution mixture was examined by electrodialysis with ion-exchange membranes, under conditions of pH 1 to 12 and current densities of 0 to 15 A/m2.
Abstract: The selective separation of amino acids, glutamic acid, methionine and lysine, from their solution mixture was examined by electrodialysis with ion-exchange membranes, SELEMION-CMV and SELEMION-AMV, under conditions of pH 1 to 12 and current densities of 0 to 15 A/m2. The amino acids were almost completely separated from each other under the conditions studied: Only glutamic acid is transported across the anion-exchange membrane; only lysine across the cation-exchange membrane; and methionine is not transported at all. Their fluxes across the membranes have maxima in the neutral pH range, increasing almost linearly with current density. A model for explanation of the experimental results has been proposed considering solution equilibrium, ion-exchange equilibrium and diffusion in the membranes. Successful simulation has confirmed the amino acid transport mechanism which was proposed in the model. The diffusivities of ionic species, model parameters, have been determined. Moreover the role of each ionic species in carrying current and the effect of water splitting are also discussed.
43 citations
TL;DR: In this paper, the effects of alginate composition, viscosity, concentration, temperature and pH on the diffusivity and mechanical properties of Ca-alginate gel beads were investigated.
Abstract: Dependencies of effective diffusivity of glucose in Ca-alginate gel beads and mechanical compression strength of the gel on alginate composition, viscosity, concentration, temperature and pH of the alginate solution were systematically investigated. Diffusional and mechanical properties of Ca-alginate gel beads depended on alginate composition and the gelling conditions. The results were discussed in relation to get structure and conformation of alginate molecule. Differences in reported diffusivities of glucose could be explained by the differences in alginate composition and the gelling conditions such as alginate concentration, temperature and pH. Furthermore, selection guidelines for preparation of Ca-alginate gel having low diffusional obstruction and large compression strength were presented.
TL;DR: In this article, the authors measured the transport velocity of a coarse particle in a multi-solid fluidized bed (MSFB) consisting of particles different in size and density using an acoustic technique.
Abstract: The transport velocity of a coarse particle in a Multi-Solid Fluidized Bed (MSFB) consisting of particles different in size and density was measured using an acoustic technique. Effects of the solid circulating rate of fine particles on the diameter of coarse particles were studied. The equation for calculating the transport velocity was established considering the collision characteristics between the fine and coarse particles. The transport velocity of coarse particles obtained by solving the related equation demonstrated a good agreement with those obtained from the experimental data. The calculated results for air-fine 50 mm and 100 mm particles coincided with the experimental results within 20% and 34% errors, respectively. Experimental results obtained in a lab-scale MSFB with a diameter of 0.05 m showed that the transport velocity of coarse particles decreased with increasing the solid circulation rate.
TL;DR: In this article, a prediction method is proposed for the design principle of honeycomb adsorbers by taking into account the optimal rotation speed and the regeneration air velocity obtained from the graphical solution using a humidity chart.
Abstract: Adsorption/desorption behavior and simultaneous heat and mass transfer in a honeycomb adsorber were investigated using a humidity chart. It was found that the dehumidifying performance is sometimes decreased remarkably owing to the mass/heat balance limitation when the feed humidity is high or regeneration temperature is low.A prediction method is proposed for the design principle of honeycomb adsorbers by taking into account the optimal rotation speed and the regeneration air velocity obtained from the graphical solution using a humidity chart. The method is simple to use, without complicated computation and it is useful to avoid the serious influence of by the mass/heat balance limitation. At a process air velocity of 1 m/s, by considering the relation between the optimal rotation speed and the moderate regeneration air velocity obtained using a graphical method, the product air humidity decreases to a value near to the thermodynamic limit.
TL;DR: In this paper, the dynamics of adsorption of benzene dissolved in supercritical carbon dioxide on activated carbon were studied by analysis of breakthrough curves in the nonlinear region of the adaption isotherm.
Abstract: The dynamics of adsorption of benzene dissolved in supercritical carbon dioxide on activated carbon were studied by analysis of breakthrough curves in the nonlinear region of the adsorption isotherm. The column was long enough to ensure constant pattern conditions, and the shapes of the experimental breakthrough curves were used for identification of the controlling mass transfer processes. The effects of intraparticle diffusion and external mass transfer were investigated by numerical solution of the corresponding differential equations. Surface diffusion was found to be the main transport mechanism inside the adsorbent particles. No considerable variation of the effective surface diffusivity was observed in the range of experimental conditions, and the measured values are in the order 10–10 m2/s.
TL;DR: In this article, a fly ash of low calcium content (1.67 wt% CaO) was ground and treated with slaked lime (Ca(OH)2) to produce an improved sorbent for high-temperature dry sorbent injection.
Abstract: A fly ash of low calcium content (1.67 wt% CaO) was ground (to particle sizes ofunder 5 μm) and treated with slaked lime (Ca(OH)2) to produce an improved sorbent for high-temperature dry sorbent injection. Four samples were treated at 350 K for 8 hours with different Ca(OH)2 concentrations (6.6–28.6 wt%). The specific pore surface area and pore volume were extensively characterized before and after treatment. Sulfation tests were performed by exposing the treated samples to a 0.31 vol% SO2 containing atmosphere at 1123 K in a thermo-gravimetric analyzer (TGA). The TGA experimental conditions were carefully controlled to closely simulate those encountered in an atmospheric fluidized bed combustor (AFBC).The treated fly ash sorbents showed higher SO2 sorptivity compared to untreated sorbents. The sorption capacity was found to increase as the Ca(OH)2 concentration increased in the range of interest. Up to 92% CaO conversion could be achieved when the 28.6% Ca(OH)2 fly ash sorbent was sulfated for 1 hour. Treatment of fly ash with Ca(OH)2 enhanced the specific surface area (by about 5 to 8 times), which was principally responsible for the high SO2 capture.
TL;DR: In this article, the size of bubbles generated from a perforated plate in a non-Newtonian liquid was investigated and the bubble size distribution may follow a logarithmic normal probability distribution despite the plate geometry and physical properties of the liquids.
Abstract: Bubble columns are frequently used in the chemical industry as absorbers, fermenters and reactors. Recently bubble columns have been used as bio-reactors for non-Newtonian liquids. Thus, experiments were performed to investigate the size of bubbles generated from a perforated plate in a non-Newtonian liquid. The bubble size distribution may follow a logarithmic normal probability distribution despite the plate geometry and physical properties of the liquids. The characteristic correlation for the size of bubbles generated from the perforated plates in non-Newtonian liquids was derived.
TL;DR: In this paper, a Shirasu Porous Glass (SPG) membrane emulsifier (POEM® from Reika Kogyo Co. Ltd) was used for the preparation of uniform oil microdroplets in water.
Abstract: Monodispersed porous polystyrene beads crosslinked with divinylbenzene were prepared by in situ polymerization. For this objective, the preparation of uniform oil microdroplets in water was successfully achieved by using a Shirasu Porous Glass (SPG) membrane emulsifier (POEM® from Reika Kogyo Co. Ltd.). Separation abilities for a gel permeation chromatograph (GPC) column were discussed with polymer microbeads obtained by changing key experimental factors such as the pore sizes of the SPG membrane and diluents. Consequently, it was evident from gel permeation chromatography that the porous beads prepared by SPG emulsification can be used for the effective separation of a molecular weight range of 102 to 106.
TL;DR: In this article, the formation of silver halide ultrafine particles in a reverse micellar system was studied and the effects of the concentrations of reactants and water content of the reverse mousellar solution on the size of formed particles were investigated.
Abstract: The mechanism of formation of silver halide ultrafine particles in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane reverse micellar systems has been studied. The particle formation process was followed by a change in the UV-visible absorption spectra. The effects of the concentrations of reactants and water content of reverse micellar solution on the size of formed particles were investigated. The size of AgCl particles decreased with increasing water content or reactant concentration, whereas the size of AgBr and AgI particles increased. A possible interpretation is the dissolution of AgCl, which is caused by some impurities in the AOT. Particle coagulation processes of AgBr and AgI particles are found to be dominated by the concentration of micellar droplets containing two or more particles.
TL;DR: In this article, the NVT and μVT ensemble MC techniques have been used for simulations of adsorptions in a slitpore from a binary mixture of benzene diluted in supercritical CO2 The LJ potential function is used for representing intermolecular interactions between CO2, benzene and surface carbon.
Abstract: The NVT and μVT ensemble MC techniques have been used for simulations of adsorptions in a slitpore from a binary mixture of benzene diluted in supercritical CO2 The LJ potential function is used for representing intermolecular interactions between CO2, benzene and surface carbon A typical curve for adsorption of benzene shows a maximum at a pressure below the critical pressure of CO2 and then decreases with increasing pressure The magnitude of maximum adsorption increases with increasing interaction energy between benzene and surface carbon It has been shown that this adsorption behavior is attributable mainly to enhanced solubility in the supercritical CO2 and partly to the competitive adsorption of CO2 The adsorption of carbon dioxide increases linearly with pressure and the slit pore becomes full of CO2 molecules under supercritical fluid conditions The local density profile of benzene in a pore is scarcely affected by CO2; however, the profile of CO2 is strongly affected by benzene molecules when they occupy the first monolayer near the wall
TL;DR: In this paper, a modified relay feedback procedure is proposed which gives control parameters for a PI controller without the second tuning procedure, such as Ziegler-Nichols tuning, for set-point tracking and regulatory control of a binary distillation column.
Abstract: For improvement of control performance and easier tuning, a modified relay feedback procedure is proposed which gives control parameters for a PI controller without the second tuning procedure, such as Ziegler-Nichols tuning. The performance of the proposed method and the original relay feedback method are compared in the set-point tracking and regulatory control of a binary distillation column
TL;DR: In this article, a diffused line source emission model is adopted and a light path length distribution is used for computing the light absorption rate in a photoreactor with multiple lamps.
Abstract: A radiation model has been developed to estimate light energy absorbed in a photoreactor with multiple lamps In this study a diffused line source emission model is adopted and a light path length distribution is used for computing the light absorption rate The results of computation were confirmed to be adequate by chemical actinometric experimentsThe optimum lamp location in a photoreactor with n lamps in symmetry is determined to attain the maximum average light intensity As a rule of thumb, the optimum ratio of the distance between the lamp center and the reactor center to the reactor radius is 1/3 for n = 2, 2/5 for n = 3, and 1/2 for n = 4
TL;DR: In this article, it was shown that the addition of volatile solvents resulted in the formation of divinylbenzene homopolymeric microcapsules with highly porous membranes by in situ polymerization accompanied by a solvent evaporation process.
Abstract: Divinylbenzene homopolyineric microcapsules with porous membranes, where pores act as channels for extraction, were prepared using various solvents in the dispersed phase such as toluene, benzene, 4-methyl-2-pentanone and Exxsol D-80. Experimental evidence suggested that addition of volatile solvents resulted in the formation of divinylbenzene homopolymeric microcapsules with highly porous membranes by in situ polymerization accompanied by a solvent evaporation process. Solvent type was found to be a significant factor to change the surface morphology of the microcapsules. A membrane structure with macropores could be prepared by using volatile solvents. However, for a system of microcapsules with non-volatile solvents or without any solvent, only mesopores were formed in the microcapsule membrane. Using microcapsules with macroporous membranes, hydrochloric acid can be sufficiently extracted from aqueous solution. This infers that macropores formed by solvent evaporation function as efficient channels for extraction. The influence of preparation conditions such as solvent type and monomer concentration on extraction properties was also discussed.
TL;DR: In this article, the effects of alcohols, column dimensions, gas velocity, physical properties of liquids, and gel particles on the gas holdup eG and the volumetric liquid-phase mass transfer coefficient kLa in a gel-particle-suspended bubble column under liquid-solid batch operation were studied experimentally.
Abstract: The effects of alcohols, column dimensions, gas velocity, physical properties of liquids, and gel particles on the gas holdup eG and the volumetric liquid-phase mass transfer coefficient kLa in a gel-particle-suspended bubble column under liquid-solid batch operation were studied experimentally. It was shown that addition of alcohols to water generally increases eG. However, kLa values in aqueous solutions of alcohols became larger or smaller than those in water, according to the kind and concentration of the alcohol added to water. It was also shown that the presence of suspended gel-particles in the bubble column reduces values of eG and kLa. Based on these observations, empirical equations for eG in the transition regime in an ethanol solution, for eG in the heterogeneous flow regime applicable to various alcohol solutions and for kLa in both flow regimes were proposed.
TL;DR: In this article, a vacuum regeneration method for an absorbent with low CO2loading was experimentally investigated, where a solution of potassium or sodium carbonate and bicarbonate mixture was used as a model solution of CO2loaded absorbent; a carbonate solution containing diethanolamine (DEA) was also examined.
Abstract: For the purpose of developing a CO2 separation process for flue gas of low CO2 partial pressure, a vacuum regeneration method for an absorbent with low CO2-loading was experimentally investigated. Since additional energy is consumed for water vaporization accompanied by CO2 desorption in the regeneration step, reducing the generation of water vapor becomes important for energy saving. A solution of potassium or sodium carbonate and bicarbonate mixture was used as a model solution of CO2-loaded absorbent; a carbonate solution containing diethanolamine (DEA) was also examined. Rates of CO2 desorption and water vaporization were obtained under the operating conditions of various pressures and temperatures. The rate ratio of water vaporization to CO2 desorption became minimum at a pressure equal to the vapor pressure of water. The rate of CO2 desorption at this pressure increased with temperature until 343 K and the increase was minimal beyond this temperature. The desorption rate was enhanced by the addition of DEA to the carbonate solution, and the rate reached a maximum at a high DEA concentration.
TL;DR: A continuous-flow fluidized-bed bioreactor system containing porous carrier particles was operated for simultaneous removal of carbonaceous and nitrogenous substances from wastewaster and a set of simple reaction kinetics interpreted the experimental results well.
Abstract: A continuous-flow fluidized-bed bioreactor system containing porous carrier particles was operated for simultaneous removal of carbonaceous and nitrogenous substances from wastewaster. The bioreactor system consisted of two aerobic reactors in series with recycle-flow. Organic oxidation, ammonification of urea and nitrification took place in both reactors, while denitrification concurrent with those reactions occurred in the reactor where the artificial sewage and recycled fluid were fed. In the steady state, measurement of microbial activities in the reactors confirmed the presence of the respective bacteria participating in the above reactions. These multiple reactions proceeded simultaneously in the bioreactor system were analyzed by a set of simple reaction kinetics, which interpreted the experimental results well.
TL;DR: In this paper, the extraction of molybdenum and vanadium from weak acidic sulfate and chloride media by bis(2-ethylhexyl)monothiophosphoric acid (D2EHTPA) and bis( 2-ethyl hexyl)phosphoric acyclic acid(D2EHPA) was investigated.
Abstract: The extraction of molybdenum and vanadium from weak-acidic sulfate and chloride media by bis(2-ethylhexyl)monothiophosphoric acid (D2EHTPA) and bis(2-ethylhexyl)phosphoric acid (D2EHPA) was investigated. The cationic species of the metals, such as MoO22+, were extracted by both extractants. In the case of vanadium, the supplied VO3– was reduced to VO2+ by contact with the organic phase containing D2EHTPA, and this extractant was partially oxidized to disulfide. While molybdenum was found to be more extractable than vanadium by both extractants, the separation factor of the metals by using D2EHTPA was greater than in the case using D2EHPA, especially when VO3– was used as feed. The oxidized D2EHTPA containing disulfide enhanced the extractability of molybdenum and vanadium. However, the separation factor of the metals decreased with the formation of disulfide. It is important to reduce V(V) to VO2+ prior to extraction in order to minimize the oxidation of D2EHTPA for separation and repeated use of the extractant.
TL;DR: In this paper, the authors quantify the relation of the number of daughter drops to the physical properties of the mother drop, its size, and the intensity of turbulence, during a single breakup of a mother drop having a high viscosity.
Abstract: We have attempted to quantify the relation of the number of daughter drops to the physical properties of the mother drop, its size, and the intensity of turbulence, during a single breakup of a mother drop having a high viscosity