前田 光治

Plastic pollution is ubiquitous in the environment, and nanoplastics (<1 μm) are of growing concern as they pose more health risks than larger particles. However, because of a lack of appropriate model particles, studies examining the risks of polyolefin nanoplastics are very limited, despite the prevalence of these plastics in the environment. Although nanoprecipitation using organic solvents is a promising method for preparing model nanoplastic particles of polyolefins, there are currently no methods for controlling the particle size. Here, we examined how the concentration and volume of the feedstock polymer solution affect the size of polyethylene particles produced by nanoprecipitation. The mechanisms underlying the particle formation were investigated by using a simple population balance model. Increasing the concentration of the feedstock solution increased the growth rate and decreased the nucleation rate, and increasing the volume of the feedstock solution increased the growth rate, resulting in an increase in the mean particle diameter in both cases. These changes in particle diameter were linearly correlated with the suspension density of the dispersion up to a suspension density of 0.4 mg·mL-1. In addition, at these suspension densities, spherical particles were prepared without generating aggregates. Together, these results show that the diameter of polyethylene particles prepared by nanoprecipitation could be controlled according to the suspension density up to a suspension density of 0.4 mg·mL-1. This study provides a basis for the development of nanoprecipitation-based techniques for the precise, scale-independent production of model nanoplastic particles, which we hope will accelerate the risk assessment of nanoplastics.

Three different salt crystals (K2SO4, KCl, and Na2SO4·10H2O) were produced via batch cooling and continuous crystallization using a bench-scale crystallization device, in order to elucidate the mechanism of inclusion of the mother liquor as a function of crystal size. The inclusion ratio of the mother liquor was higher at small sizes and decreased with crystal growth. All results were represented by the previously proposed model of core-aggregation and shell-growth processes for the three different salt crystals. Crystals with small Vickers hardness aggregated with each other, and the inclusion ratio of the mother liquor of aggregated grown crystals was high for all three salt crystals tested herein.

Continuous crystallization via indirect cooling of potassium aluminum sulfate dodecahydrate (KAl(SO4)(2)center dot 12H(2)O) was carried out using a draft tube-type crystallizer with a circulation flow path. The crystallizer was equipped with a newly designed system to monitor the degree of supersaturation in the circulation channel. The average degree of supercooling and growth rate were measured. The crystal growth rates calculated by the population balance model and the supersaturation monitor were different but close. The average supersaturation calculated from the supercooling degree and the solubility data in the literature was 0.19 g per 100 g H2O. This system is also expected to be applied to industrial crystallization where impurities are present.

To understand the inclusion of mother liquor in crystals at different sizes, the continuous crystallization of potassium sulfate was investigated. A bench-scale crystallizer of the draft-tube type was employed for both batch cooling and continuous crystallizations. A standard solution of potassium sulfate was employed as the saturated solution at 323 K. The batch cooling crystallization was first performed at 283 K at a rate of 5 K/h, after which the continuous crystallization was performed at 283 K at two different residence times. The crystal size distribution (CSD) of potassium sulfate crystals and the inclusion ratio of mother liquor in the crystals at different sizes were measured. The average size of the crystals was approximately 400-500 mu m, and the inclusion ratio was less than 1% for all sizes; however, the small and large crystals contained a considerable amount of mother liquor, and the specific crystals that exhibited the lowest inclusion ratios were investigated. Moreover, an impurity distribution model for the suspension crystals was proposed based on coreaggregation and shell-growth processes.

A new method for determining the liquidus and solidus pressures of mixtures of C18's unsaturated fatty acids at constant temperatures was proposed, and three binary isothermal SLE data under high-pressure were systematically measured in this study. The liquidus and solidus temperatures of oleic acid, linoleic acid and alpha-linolenic acid commonly rise above their normal melting temperatures when pressure is increased. This new high-pressure experimental system can closely track pressure in real time during pressure swinging changes, making it simple to measure liquidus and solidus pressures using this dynamic measurement method due to fast responsiveness of pressure. In this study, the liquidus pressures of pure oleic acid, linoleic acid, alpha-linolenic acid and three binary mixtures consisted of oleic acid, linoleic acid alpha-linolenic acid at constant temperature were determined. The isothermal SLE were first correlated based on a simple thermodynamic model. (C) 2021 Elsevier Ltd.

We found that an AAA-type battery (min. 750 mAh) pressurized with Ar or N₂ at pressures of up to 5 MPa exhibited a significant durability enhancement even under high-current conditions.

The separation of the binary unsaturated fatty acids C18:1 + C18:2 system was examined by high-pressure crystallization at 298 K (25 °C). The binary fatty acid mixture containing 0.8 mol fraction of C18:1 was packed in the glass cell with a free piston, and then pressurized by an aqueous ethanol solution around the glass cell up to 200 MPa. The complete solid mixture was obtained after cooling at 253 K (- 20 °C) as a depressurized binary solid. The solid was divided into four parts, and the composition of C18:1 was analyzed at each part of the solid using a refractometer, which revealed there was a composition distribution throughout the solid with C18:1 crystallized one-directionally from the top to the bottom of the cell. High-pressure crystallization could be effective for the separation of binary fatty acids.

<title>Abstract</title> A nickel-metal hydride (Ni–MH) prototype battery completely immersed in an aqueous electrolyte solution of KOH under high pressure was fabricated to examine the effects of high pressure on the quality of Ni–MH batteries. The small battery cell comprised positive and negative electrode materials, as used in electric vehicles, and an Ag/AgO reference electrode. The electric capacity of the Ni–MH battery was measured at different temperatures and pressures with small currents and charge/discharge voltages of 1.6 – 1.0 V. High pressures were found to clearly and effectively enhance the electric capacity of the Ni–MH battery at larger currents. The considerable effect of high pressure on the Ni–MH battery was elucidated by the change in internal resistance during the charge/discharge cycle life experiment, indicating that the voltage of the positive electrode did not appreciably change at a high pressure compared to that of the negative electrode. Moreover, the use of large currents in rapid charge/discharge cycle tests at high pressures of up to 30 MPa resulted in charge/discharge cycles that were five times faster and a quick recovery of capacity was achieved in the 0.5 – 2.1 V range.

In this study, batch crystallization via indirect cooling and continuous crystallization via direct and indirect cooling of phosphoric acid hemihydrate (H3PO4.1/2H2O) from the mixed acid solution of phosphoric acid and acetic acid are performed. In batch crystallization, needle-shaped crystals are obtained, and the impurity concentration of acetic acid in the crystals is 4.2 wt%. Primary nucleation occurred under a high degree of supersaturation, and the metastable zone width for secondary nuclei is narrow. In contrast, in continuous crystallization via indirect cooling, scaly crystals are obtained, and the acetic acid impurity concentration therein is 2.0 wt%. Additionally, continuous crystallization via direct contact cooling is performed, the crystal shape and impurity concentration under direct cooling are similar to those under indirect cooling, suggesting the possibility to downsize the apparatus. Through utilization of the equipment and approach elaborated herein, the correlation between the operating conditions and crystal quality can be assessed.

© 2019 Elsevier Ltd To enhance the reaction rate and yield during biodiesel synthesis with Novozym 435 (an immobilized lipase), a co-solvent method was applied, after which the relationships between reaction time and reaction yield during the single-phase enzymatic transesterification of triolein and methanol in the presence of co-solvents such as tetrahydrofuran, acetone, and hexane were investigated. The addition of hexane led to inactivation of Novozym 435, whereas in the presence of acetone or tetrahydrofuran, the reaction was accelerated and the yield was higher than with a conventional solvent-free enzymatic reaction. There was a clear difference in the dispersion of Novozym 435 particles between with and without co-solvents. The co-solvents prevented particle aggregation from occurring during the reaction without co-solvent. This is the likely reason for the enhanced reaction yield in the presence of co-solvents. To better understand the difference among the co-solvents employed, we estimated phase compositions during transesterification using the LLE (liquid-liquid equilibrium)-UNIFAC (UNIversal quasichemical Functional group Activity Coefficients) model, and examined the effect of these compositions on the reaction and dispersion of the glycerin by-product phase. Using the model, we also accounted for why hexane led to inactivation by estimating the transfer free energy of methanol, glycerin, and water between the initial bulk reaction solution and the water layer on the enzyme surface.

As a method for efficiently recovering marine organisms, which is expected as a resource for next generation biofuels, crystallizing concentration which can be considered as application of melt crystallization was studied. An operation of forming an ice phase from the outer wall surface to the central portion in the crystallizer was carried out by a cooling jacket with circulating solution. As the operation conditions, the stirring rotation number, the cooling temperature, and the freezing rate were varied to clarify the influence on the concentration ratio of Chaetoceros gracilis in the solution, the dilution ratio of Chaetoceros gracilis in ice, and the solid-liquid distribution coefficient of Chaetoceros gracilis measured experimentally in this study. Furthermore, it is suggested that the solid-liquid distribution coefficients are correlated by two kinds of solid-liquid distribution coefficients models, and concentration by high-speed freezing is also efficient as a result of comparison of the two models.

© 2017 Elsevier Ltd The biodiesel fuel ethyl oleate (fatty acid ethyl ester, FAEE) was produced using Novozym®435 (immobilized lipase) by transesterification of a mixture of ethanol and triolein in a fixed-bed reactor operated in circulating batch mode. The miscibility of the mixtures during transesterification was predicted thermodynamically and the conversion ratio of triolein was studied as a function of reaction time. The yield of ethyl oleate increased when the feed molar composition of ethanol was increased. The glycerin by-product could be removed from the enzyme particles by the circulating feed mixture. The inactivation of Novozym®435 by glycerin was also examined in the circulating batch mode experiments, and an effective reaction model was proposed to describe the inactivation of Novozym®435 and ethanol effect during the transesterification reaction by using the modified Michaelis-Menten equation.

The present study evaluates the lipase (Novozym 435)-catalyzed transesterification of triolein and methanol mixtures to generate fatty acid methyl esters (FAMEs) using dimethyl ether (DME) in a batch reactor and a continuous pipe reactor. The addition of DME facilitated the preparation of homogeneous mixtures of triolein and methanol. The effect of the Novozym 435 and DME contents in the feed mixtures on the time-course of FAME production was analyzed. With increasing contents of Novozym 435 and DME in the feed mixtures, the FAME concentration increased more rapidly in the batch reactor than in the continuous reactor. The feed flow rate and DME content were varied, and the FAME concentration at the outlet of the pipe reactor was measured with variation of the residence time and DME content. Increasing the DME content in the feed mixtures and the residence time led to a more rapid increase in the FAME concentration for the batch reactor than that in the continuous pipe reactor.

To account for both the growth of solid layer and solute distribution in melt crystallization, we proposed empirical equations involving heat and mass transfer at the solid-liquid interface between the solid layer and melt. With the aim of separating saturated fatty acid as a solid phase from binary mixture of fatty acids as model biofuel, we performed melt crystallization by employing three different species of binary melts which contained triglyceride as unsaturated fatty acid, and myristic acid, palmitic acid, or stearic acid as saturated fatty acid, respectively. As a result, we confirmed the validity of the proposed equations under the varied crystallization conditions.

Solid-liquid equilibria (SLE) for the binary systems of C12-C18 saturated fatty acids or their triglycerides + hexadecane (systems of dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecarioic acid (stearic acid), 1,2,3-propanetriyl tridodecanoate (trilaurin), 1,2,3-propanetriyl tritetradecanoate (trimyristin), 1)2,3-propanetriyl trihexadecarioate (tripalmitin), or 1,2,3-propanettiyltrioctadecanoate (tristearin), + hexadecane) were measured in the hexadecane: fractions of 0 to and temperatures from (2781 to 353.2) K, using differential scanning calorimetry. These systems were selected as, model systems' for blending oily content extracted from restaurant trap grease with fossil fuel oils. The obtained liquidus curves were discussed in. terms of the effects of carbon chain length, chemical form, and variation in the liquid component. In addition) the experimental liquidus curves were compared with predictions based on ideal solution approximation and on the LLE-UNIFAC and Dortmund-UNIFAC models. The triglyceride,and hexadecane binary systems were close to the ideal solution, while the fatty acid hexadecane binary systems were not. The Dortmund-UNIFAC model successfully predicted all liquidus curves of the nonideal, fatty acid-hexadecane systems.

To study solute distribution at the solid-liquid (S-L) interface during melt crystallization, we examined the applicability of the interfacial solute distribution factor proposed based on a kinetic model involving both mass and heat balances at the interface. The factor derived from the model was compared with the experimental results obtained by employing a binary melt with the different species and concentrations of fatty acids as biodiesel related mixtures. As a result, we were able to reveal the empirical relation between the purity of the crystal and the solidification conditions of the melt. Based on the model, we also numerically calculated the transient changes in the interfacial solute distribution factor as well as the temperature of the S-L interface in the solidification process of the melt. The minimization of the factor was confirmed when the melt was supercooled at the S-L interface after starting solidification. (C) 2015 Elsevier Ltd. All rights reserved.

The present study investigates the charge-discharge processes of a Plante lead-acid battery performed under atmospheric pressure and 10 MPa. The ampere-hour efficiency of the lead electrodes was substantially increased by the secondary formation of the Plante electrode, and the ampere-hour efficiency under 10 MPa was slightly higher than that under atmospheric pressure. The active PbSO4 crystals on both electrodes were observed by SEM at different currents, and the morphology and crystal size distribution (CSD) were obtained. Active PbSO4 crystals nucleated and grew during discharging; whereas, they disappeared during charging. This is similar to the crystal behavior during continuous crystallization in a battery. Therefore, a simple population balance model was used to express the CSD of PbSO4 crystals on both electrodes. The CSD of both electrodes were similar at 10 MPa, but the CSD of the positive electrode was different from the CSD of the negative electrode. The current density on both electrodes was balanced under 10 MPa.

Anti-solvent crystallization from a ternary mixture was examined by an NpT ensemble molecular dynamics simulation. The co-solvent and anti-solvent effects were represented by the Lennard-Jones interaction energy parameter, epsilon(ij). The homogeneous binary solution of the solute and solvent was achieved at a constant temperature and pressure. Anti-solvent crystallization was introduced by changing some co-solvent molecules to anti-solvent molecules, immediately. The configuration of solute molecules was investigated by using the radial distribution function, g(r), and the local composition, X-L. The value of epsilon(ij) affected the configuration of the solute molecules significantly; the decrease in epsilon(ij) provided the localization and crystallization of the solute molecules. The composition of the anti-solvent molecules in the solution also affected the configuration of the solute molecules; the increase in the anti-solvent composition produced the crystal structure of the solute molecules more rapidly. These qualitative results corresponded well to anti-solvent crystallization. The radial distribution function represented the crystal structure for solute molecules, and the local composition of the solute was increased from the bulk composition as the effect of the anti-solvent increased. We proposed that the time variation of the local composition of the solute represents the temporal development of the crystal structure and the time to crystallization well. (c) 2015 Elsevier B.V. All rights reserved.

To make larger capacity of charge-discharge of lead-acid batteries at high pressure after the initial formation of Plante-type electrodes, we studied the effect of high pressure on prolonged life testing. Electrode life was evaluated by determining the time of detachment of active crystals (Pb, PbOx and PbSO4) or the drop in ampere-hour efficiency during the charge-discharge cycle. Prolonged life testing, active crystals (Pb, PbOx and PbSO4) on the electrodes used in charge-discharge cycles at atmospheric pressure were easily detached when the electric current was increased to 2.7 mA/cm(2), but the electrodes used at 100 MPa remained very tough until 8.0 mA/cm(2) was reached. To increase the electric capacity of electrodes (i.e. in the second formation process), long-term charge-discharge was performed at a high electric current (5.3 mA/cm(2)). Faster second formation of electrodes at this high current was impossible at a charge of 3.6 As under atmospheric pressure, but it was possible at 6 As and 100 MPa. (C) 2014 The Electrochemical Society. All rights reserved.

Lead-acid batteries were electrically charged and discharged more quickly under high pressures than under atmospheric pressure due to high-pressure crystallization induced by the former condition. High-pressure crystallization can generate extremely small crystals with large supersaturation and small mass transfer rates. Crystals of PbSO4 on the electrodes were observed by scanning electron microscopy, and the crystals became smaller when the operative pressure increased, even when faster charging was carried out. Additionally, the amount of electrical current transferred to the electrodes was larger for electrodes charged and discharged at high pressure. This high-pressure charge-discharge process is expected to improve the quality of lead-acid batteries.

The electrical charging and discharging of a battery involves the crystallization of electrolytes or metal oxides on both electrodes. Crystallization technology that can control nucleation, growth, and distribution of solute crystals might be effective for improving battery properties. We performed charge/discharge cycling of a lead acid battery under high pressure. The charging efficiency at high pressure was compared with that at atmospheric pressure. Charging efficiency at high pressure was found to be higher than that at atmospheric pressure under a high charging current. Observation of the positive electrode by scanning electron microscopy revealed that high pressure caused the crystals on the electrode to become extremely fine. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved.

Melt crystallization using an annular vessel with two circular cylinders was applied to produce high-quality vegetable oil from waste oil. The inner cylinder was cooled at a constant rate and rotated, and the outer cylinder was heated at a constant temperature. The melt was solidified on the inner cylinder surface. The binary system of triolein and palmitic acid was used as the model waste oil. We measured the distribution coefficient of triolein. Suitable operation conditions were proposed to attain a high yield and a high purity of triolein from waste oil. The distribution coefficient correlated well with the theoretical equation derived on the basis of the "local lever rule" at the interface of the crystal layer and melt [1]. (C) 2012 Elsevier B.V. All rights reserved.

The molar equivalent electrical conductivity of aqueous ethanol solutions containing ammonium chloride or ammonium nitrate was measured under high pressure, up to 400 MPa, at 298 K. The concentration range of the ammonium salts in solution was broad because their solubility is relatively high compared with that of other salts. A common result was that the molar equivalent electrical conductivity decreased as a function of solute concentration. Additionally, the molar equivalent electrical conductivity decreased considerably when the ethanol content was increased and decreased slightly as the pressure was increased. The molar equivalent electrical conductivity was treated as a function of the square root of electrolyte molality, in accordance with the Debye-Hückel- Onsager equation, but could not be represented by one function because of dependence on ethanol concentration and on pressure. Therefore, use of the electrolyte-nonrandom two-liquid (NRTL) model is proposed for extending the Debye-Hückel-Onsager equation to these two electrolyte solution systems. © 2013 American Chemical Society.

A new monitoring device for the nonisothermal crystallization of thermoplastic polymers, polyethylene, polypropylene, polystyrene, and polyamide, is developed utilizing a quartz crystal resonator, and its performance is evaluated by comparing the measurements with the results of DSC thermoanalysis and microscopic observation. The experimental results of four different polymers indicate that the variation of resonant freency of the quartz crystal resonator is a good means to monitor the crystallization process. Though the measurements of melting and crystallization are close to the DSC outcome, more deviation is observed with the new device. The change in crystalline morphology during the crystallization process is also detected from the slope changes of the frequency decrease. In comparison with the microscopic observation of polymer films, it is found that the processes of nucleation and crystal growth in nonisothermal crystallization can be explained with the variation of the resonant frequency of the quartz crystal resonator. In addition, crystallization kinetics is modeled with the Avrami equation. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 3370-3380, 2011

Transesterification in a homogeneous mixture with the volatile co-solvent dimethyl ether (DME) has been proposed as a new fatty acid methyl ester (FAME) processing technique. Ternary feed mixtures of triolein, methanol and DME form a homogeneous solution, but the product mixtures of FAME, glycerin and DME form an emulsion after transesterification. In order to obtain FAME only, the glycerin phase mush be separated out from their mixtures by a centrifuge or settler. Therefore, we investigated the de-emulsification process at different methanol compositions in the feed mixtures, either with or without DME co-solvent. The rate of de-emulsification of the product mixture increased as the methanol content in the feed mixture increased: moreover, the rate of de-emulsification with DME co-solvent was 3-5 times faster than that without DME. The rate of de-emulsification was evaluated as a function of the molar ratio of dispersed glycerin phases in the product mixture. When the molar ratio of dispersed glycerin phases increased in the product mixture, the coagulation of the dispersed glycerin phases accelerated according to the Smoluchowski model. The de-emulsification was measured by UV spectroscopy as a function of time, and the relative transmissivity measured by UV spectroscopy was fit to the simple Smoluchowski equation, and the rate of de-emulsification was considered with respect to the molar ratio of dispersed glycerin phases, as calculated from the liquid-liquid equilibrium using the universal functional activity coefficient (UNIFAC) model. (C) 2011 Elsevier B.V. All rights reserved.

Used for biofuel production, fatty acids and their corresponding triglycerols are stored in most plants. At room temperature, saturated fatty acids and their triglycerols are solid, whereas unsaturated fatty acids and their triglycerols are liquid. Solid-liquid equilibrium data were measured for various binary systems of fatty acids and their triglycerols by differential scanning calorimetry. The freezing temperatures from liquidus curves for the binary systems containing tripalmitine were higher than those for systems containing palmitic acid. At the eutectic point, the melting temperatures for binary systems containing tripalmitine or palmitic acid were similar. The liquidus curves from the Solid-liquid equilibrium data were compared with the predicted values obtained by using the LLE-LTNIFAC model, and good agreement between the experimental and calculated results was found.

海洋資源の大半は電解質であり，主としてイオンとして溶解状態にある．その70 wt％以上は塩化ナトリウムであるが，塩化ナトリウム以外にも多くの電解質資源が溶解している．ここでは，海水中の電解質の回収分別操作の開発を目指して，海水中に含まれる主な電解質に適用できる電解質溶液モデルを検討した．電解質溶液モデルは，高濃度多成分系にも適用できる電解質NRTL（Non-Random Two Liquid）モデルである．海水中に溶解している主な電解質に関する2成分系（水＋単1電解質）の溶解度データを電解質溶液モデルで整理し，塩の溶解度積パラメータを求めた．そして，いくつかの3成分系（水＋2成分電解質）の溶解度データを電解質溶液モデルで検討した．

A seeded batch cooling crystalliser in a laboratory setup was utilised to produce mono-ammonium phosphate (NH(4)H(2)PO(4)) crystals. The effects of different initial saturation, seed size and seed loading ratio on crystal size distribution were thoroughly studied to gather more insight into mono-ammonium phosphate batch crystallization, its kinetics, and for model validation purposes. The seed loading ratio shows the most significant effect on the crystal size distribution profiles followed by the supersaturation factor and seed size. The supersaturation level not only influences the growth rate but the crystal shape as well. A simultaneous method has been applied in the procedure for the estimation of crystallisation kinetics. The nucleation constant (k(b)) was found to be in the range of 1.0-6.9 x 10(8) [no/kg s (kg/kg)(b+1)] and the growth constant (k(g)) measured was in the range of 3.0-9.4 x 10(-5) [m/s (kg/kg)(g)] with the nucleation (b) and growth (g) exponents determined as 2.2 and 1.4, respectively. Wavelet orthogonal collocation method was utilised to solve the seeded batch crystalliser model and the solution was compared with the experimental data. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

NH(4)H(2)PO(4), mono-ammonium phosphate (MAP) and (NH(4))(2)HPO(4), di-ammonium phosphate (DAP) have become leading phosphate fertiliser products worldwide. Ammonium phosphates are produced by reactions of ammonia and phosphoric acid resulting in the formation of the mono-basic, di-basic, or tri-basic salts. Inefficiencies in the MAP/DAP production process are due to the lack of a fundamental understanding of the crystallisation-reaction mechanisms. A semi-batch reactive crystalliser equipped with a cooling jacket, a dual feed system and a turbine type agitator has been used in this study. Effects of N/P ratio, seed crystals, feeding system, feed flow rate, initial supersaturation, feeding time and mixing intensity to the real-time supersaturation, crystal yield, crystal shape (aspect ratio) and final crystal size distribution (CSD) were studied in order to understand the kinetics. This study aims to provide new insights into the MAP/DAP reaction-crystallisation mechanisms. (C) 2009 Elsevier B.V. All rights reserved.

The movement of particles with a size smaller than few microns is governed by random Brownian motion. This motion causes the fluid to flow around the particles. The force acting upon Brownian particles as well as their velocities are measured by using the dynamic light scattering (DLS) technique. It provides the relationship between fluid shear stress and shear rate over the Brownian particle and determines the viscosity properties of the fluid. In this study, we propose a new rheometer which is widely applicable to fluid viscosity measurements at both normal and high pressure levels for Newtonian and non-Newtonian fluids.

We demonstrate a new apparatus for optical observation under high pressure conditions with 4-way optical glasses. We use the proposed apparatus to study solubility of ammonium salts in aqueous solutions and to measure the nucleation pressure for different concentrations of salts in the solution. Despite the fact that the solubility of electrolytes usually increases as the pressure increases, it is found that the solubility of ammonium salts decreases as the pressure increases. In both cases, high pressure can be used towards a crystallization process. Finally, we observe high pressure induced nucleation of electrolytes in an aqueous solution.

To promote the biodiesel production, low-quality fats in addition to waste vegetable oils are still required. Low-quality waste vegetable oils and low-quality fats as feed mixtures contain free saturated fatty acids and/or commercial solidifiers in addition to triolein as a main component, and they are solid at room temperature. However, liquid feed is desired for biodiesel production processes. In this study, solidification properties of a system of commercial solidifier and commercial vegetable oil as low-quality fats and a binary system of palmitic acid and triolein as low-quality vegetable oils were investigated, and the melting temperature was calculated by a simple thermodynamics function of composition. The binary mixture of palmitic acid and triolein could be liquefied at above 65 degrees C regardless of the composition, and the melting temperature of the mixture could be represented by the simple thermodynamic function. On the other hand, the melting temperature of the mixture of the commercial solidifier and commercial vegetable oil increased sharply to 80 degrees C even at low solidifier concentration, and the melting temperature of waste fats could not be represented by the simple thermodynamic function.

Vapor-liquid equilibrium (VLE) of the methanol-biodiesel (BDF)/glycerin binary system and liquid-liquid equilibrium (LLE) of the water-BDF binary system and the methanol-BDF-glycerin and methanol-water-BDF ternary systems were predicted using several UNIFAC models: the latest original UNIFAC model, Kikic&apos;s model, Fornari&apos;s model, Dortmund-UNIFAC model, and LLE-UNIFAC model. The former VLE and latter LLE are used to design methanol recovery processes and separation and purification processes of crude BDF, respectively, Unfortunately, LLE data on the water-BDF binary system was not available. Instead, solubility of water in fatty acid methyl ester (one of the BDF constituents) was measured. By examining the deviation between predicted and experimental results, we determined which of the UNIFAC models was more useful for the design of those processes as follows: either the original UNIFAC model or Dortmund-UNIFAC model should be used for the methanol recovery process. The LLE-UNIFAC model and Dortmund-UNIFAC model were more useful for the recovery and water-washing processes of crude BDF and purification process of water-washed BDF, respectively. (c) 2009 Elsevier Ltd. All rights reserved.

Spray evaporation of aqueous ethanol solution with dilute potassium chloride (KCl) was examined for the generation of extremely small electrolyte crystals in dry state. Ethanol content in the aqueous solution played an important role in decreasing the solubility of KCl. Evaporation of small liquid droplets of the aqueous ethanol solution produced a small amount of KCl crystals. The concentration of ethanol in the solution was the operative variable,and the ultrasonic spray nozzle and flow rate of the solution were fixed in this study. The crystals collected were observed by SEM, and crystal size distributions were obtained for different operative conditions. The average crystal size ranged from 100 to 800 run. When the ethanol content increased in the solution, the crystal size decreased. We consider the crystal size according to the slight solubility of KCl in liquid droplets of aqueous ethanol Solution. (C) 2009 Elsevier B.V. All rights reserved.

The solubilities of electrolyte salts, such as sodium chloride (NaCl) and potassium chloride (KCl), are small in alcohol solution. As an application of such dilute solubility, nucleation phenomena were investigated by the dynamic laser scattering (DLS) method at different supersaturation degrees, prepared by different solubilities of KCl in aqueous ethanol solutions. The supersaturated solution of KCl was very stable, and therefore ultrasonic irradiation was utilized as a trigger of nucleation. The time-change of the sizes of fine KCl crystals was measured, and the nucleus size was obtained by extrapolating the size of the fine crystals to zero-time. The nucleus size of KCl was correlated by the modified Gibbs-Thomson equation as a function of supersaturation. it was found that the nucleus size tended to increase when supersaturation decreased, but three different curves for three different temperatures could be obtained. The modified Gibbs-Thomson equation represented the nucleus size at three different temperatures. The correlated "minimum supersaturation energy" parameters were converged to zero at the saturated temperature. The parameter "minimum supersaturation energy" could be interpreted as "ultrasonic effective energy" that could be defined as the received energy in the solution from ultrasonic irradiation. (c) 2008 Elsevier B.V. All rights reserved.

The solubilities and complex phase equilibria for the system of MnSO4·4H2O + MgSO4·7H2O + H2O + CH3OH were determined at the temperatures 291.2 and 301.2 K over the methanol mole fraction range of 0.00-0.12.The solubility data were used for modelling with the modified extended electrolyte non-random two-liquid equation. The salting-out effect of MgSO4and methanol on the solubilities of two manganese salts (MnSO4·H2O and MnSO4·4H2O) are represented in the several thermodynamic figures as a function of temperature. The solventing-out effect was stronger than the salting-out effect, which results in a decrease of the solubilities of manganese, salts even though the solubility of MnSO4·H2O decreased and solubility of MgSO4·4H2O increased as temperature increased. Crown Copyright © 2008.

BACKGROUND: The use of fatty acid mixtures, natural biochemical compounds, will be extended to various chemical industries for the production of a wide variety of products, and various mixtures of fatty acids are necessary for production. Separation of a binary fatty acid mixture of lauric acid and myristic acid using physical vapour deposition (PVD) on a cold quartz crystal resonator is examined. The extremely small amount of deposits can be measured with the quartz crystal resonator. The vapour phase is prepared by vaporizing a calculated composition of melt according to the vapour-liquid equilibrium (VILE). RESULTS: The composition of lauric acid in the melt and the melt temperature were utilized as operating variables in the PVD. The growth rate of deposit increases when melt temperature and the composition of lauric acid in the melt are increased. The composition of lauric acid in the deposit is significantly lower than that of the melt of 19% lauric acid, but the composition of lauric acid in the deposit is much higher than that of the melts of 50% and 75% lauric acid. CONCLUSION: The distribution coefficient of lauric acid between solid and vapour phases can be correlated as a function of the growth rate of deposit. The possibility of separation of fatty acid mixtures by PVD is suggested experimentally and theoretically. (C) 2008 Society of Chemical Industry

The complex phase equilibria for the solubilities of MnSO4 center dot H2O and MgSO4 center dot 7H(2)O in three different organic solvents (methanol, ethanol, and 2-propanol) were predicted by the ion-specific electrolyte NRTL model. The salting-out effect of Mg2+, solventing-out effects of alcohols, and their combined effects on the solubility of MnSO4 center dot H2O were represented in several thermodynamic figures as a function of temperature. We found that the solventing-out effect was stronger than the salting-out effect for the solubility of MnSO4 center dot H2O even though the solubility of MnSO4 center dot H2O decreased as temperature increased.

Superfast transesterification of triolein (a biodiesel feedstock model) was achieved in the presence of liquefied dimethyl ether using the co-solvent effect and low viscosity. Furthermore, a method for higher ester yield, in which methanol was additionally introduced into the reaction system immediately before the beginning of phase separation due to byproduct glycerin to maintain the reaction system in a homogeneous state, was proposed. This method led to superfast and high-yield transesterification with a yield exceeding 96% at 3 min.

The decomposition temperature and pressure (quadruple point) of chlorodifluoromethane (R22) gas hydrate in aqueous sodium chloride (NaCl) solution was measured at different NaCl concentrations in the Solution as a phase diagram. The operative concentration curve of NaCl was obtained as a function of temperature. The maximum decomposition temperature of R22 hydrate was about 290 K at 0.9 MPa pressure, and it decreased as the NaCl concentration increased in the solution. R22 hydrate caused supercooling, and the supercooling Occurrence temperature was much lower than the decomposition temperature. The ultrasonic charge reduced the supercooling of hydration effectively even though the ultrasonic charge did not change the decomposition temperature at all. The concentration experimental results from the several NaCl solutions having different NaCl concentrations were in good agreement with the theoretical operative concentration curve for NaCl. (C) 2008 Elsevier B.V. All rights reserved.

In biodiesel production, transesterification in a homogeneous mixture is possible if a solution of triolein and methanol could be prepared with the use of a cosolvent. The volatile solvent dimethyl ether (DME) can make the immiscible mixture of triolein and methanol miscible; moreover, it can be easily recovered due to its high volatility after reaction. Therefore, the vapor-liquid-liquid equilibrium for the triolein + fatty acid-methanol + DME system was measured by determining the liquid composition, temperature, and pressure of the system. Results showed that DME and palmitic acid effectively promoted the mutual solubilities of triolein and methanol. In addition, the UNIFAC prediction was compared with experimental data, and it was found that the UNIFAC model could represent the complicated phase equilibrium of biodiesel compounds.

Directional crystallization from a binary mixture was performed by pseudo-NpT ensemble molecular dynamics. The initial crystal phase having a face-centered-cubic (fcc) structure grew toward the whole cell according to the temperature gradient in the universal cell. The growing crystal phase was not planar even though the solute molecules grew in two-dimensional coordinates because the solvent molecules disturbed the crystallization of the solute molecules at the diffusive crystal-solution interface. This represented the essential phenomenon of solute distribution during crystallization. Consequently, the growing crystal phase still contained solvent molecules having a liquid structure. The time change of the solute composition in the early phase of crystal growth showed an increase in solute composition as the time step proceeded. The resulting solute composition in this early phase was considered at different temperature gradients in the universal cell and it increased as the temperature of the initial crystal-solution interface increased. A new distribution coefficient model was proposed as a function of the difference between the local solute composition and bulk solute composition in the solution around the crystal-solution interface. The impurity-solvent distribution coefficient could be represented by the new model for faster growth of the lower temperature&apos;s initial interface. As regards a better distribution coefficient, there was found to be a very dilute solution phase over the crystal phase. The new variable "distribution rate" instead of the ambiguous variable "growth rate" was considered as a function of temperature gradient in the universal cell. (C) 2008 American Institute of Physics.

Ice was formed on it rotating cold cylinder, and the distribution of cations (i.e., K(+), Na(+), Mg(2+) and Ca(2+)) between ice and water as a function of the operating variables of ice crystallization was discussed. Ice growth rate was controlled by the rotation speed and temperature of the cold cylinder. The shape of the ice formed on the rotating cold cylinder depended on (lie flow structure of Taylor vortices in the water solution, The effective distribution coefficients of the cations were extremely, small compared with those in the fatty acid system. The effective distribution coefficients of the cations correlated well as it function of ice growth rate. According to the correlation model, pure ice can form if the ice growth rate is lower than the critical growth rate. The critical temperatures of the four cations showed no difference front each other. and increased with the supercooling temperature.

Data on the solubility of manganese sulphate monohydrate in water, and in aqueous alcohols is essential for salting-out crystallization studies. The solubilities of the quaternary system MnSO4·H2O + MgSO4·7H2O + H2O + (CH3)2CHOH were determined in the temperature range 293.2-313.2 K over the 2-propanol mole fraction range of 0.00-0.07. The solubility data were used for modelling with the modified extended electrolyte non-random two-liquid (NRTL) equation. The present extension uses ion-specific parameters instead of the electrolyte-specific NRTL binary interaction parameters. This approach has feasibility for many electrolytes and mixed aqueous solution systems in principle. The model was found to correlate the solubility data satisfactorily. Crown Copyright © 2007.

A fatty acid mixture of lauric acid and myristic acid was deposited on a cold quartz crystal sensor from the binary vapor phase of the mixture by physical, vapor deposition (PVD). The cold quartz crystal sensor could detect a small amount of deposit in real time, and provided the growth rate of the thin solid deposit by the PVD. The composition of lauric acid in vapor phase was fixed at a mole fraction of about 0.5 by controlling the composition of lauric acid in melt phase computed from the vapor-liquid equilibrium (VLE). The growth rate of solid phase in the PVD increased with the elevation of the melt temperature, because the vapor pressure of the melt raised by the temperature elevation was the driving force of the PVD. The composition of lauric acid in the solid phase was considerably lower than that in the vapor, and it was increased as the growth rate in the solid phase rose. The distribution coefficient of lauric acid between solid and vapor phases was much less than that between solid and melt phases. We compared the separation capacity in melt crystallization with that in the PVD using the effective distribution coefficient, and found that the PVD had higher separation capacity. (c) 2006 Elsevier B.V. All rights reserved.