Showing papers in "Journal of Chemical Engineering of Japan in 2001"
TL;DR: In this paper, the supercritical methanol method without using any catalyst is evaluated in the reaction of free fatty acids to methyl esters for biodiesel fuel production in the conventional commercial process.
Abstract: Commercially available crude oils and fats contain on average 0.5-3% free fatty acids. These free fatty acids are known to react with the alkaline catalyst and form saponified products during transesterification reactions for biodiesel fuel production in the conventional commercial process. Purification of the products therefore becomes necessary after the reaction. In addition, it causes a longer production process and increases the production costs. For this aspect, supercritical methanol method without using any catalyst is evaluated in this work for reaction of free fatty acids. As a result, complete conversion is achieved for saturated fatty acids to methyl esters at temperatures above 400°C, whereas for unsaturated fatty acids, lower temperature of 350°C is appropriate, and higher temperature resulted in a degradation of the products. Consequently, a conversion of free fatty acids to methyl esters is highest, over 95%, when treated at 350°C. Fortunately, this temperature treatment is also most appropriate for transesterification of triglycerides. Thus, the overall conversion process of rapeseed oil to methyl esters is concluded to be adequate at 350°C. This finding supports the superiority of supercritical methanol method on biodiesel fuel production, compared with the conventional method, in which the production process becomes much simpler and increases the total yield due to the methyl esters produced from free fatty acids.
183 citations
TL;DR: In this paper, three types of silica-zirconia membranes were prepared by the solgel method to test their stability and H2 separation performance in hydrothermal conditions.
Abstract: Three types of silica-zirconia membranes of different zirconia content were prepared by the sol-gel method to test their stability and H2 separation performance in hydrothermal conditions. Some silica-zirconia membranes were prepared by “steam-firing” in which firing was carried out in steamed air in order to increase the hydrothermal stability, and then tested in hydrothermal conditions. The activation energy of H2 and He permeation increased with increasing zirconia content, suggesting that the networks of silica-zirconia matrix were densified with increasing zirconia content. In the hydrothermal conditions, the activation energy of H2 and He permeation also increased, indicating clearly that silica-zirconia membranes were also densified by water vapor at high temperature. The pores for N2, Co2 and CH4 permeation decreased with the increasing zirconia content and vanished in the hydrothermal conditions, leaving some pinholes. Some silica-zirconia membranes were prepared by firing in steamed air in order to increase the hydrothermal stability. This method appeared to be effective to increase hydrothermal stability of the silica-zirconia membrane.
156 citations
TL;DR: Results indicate the FMLs could target the glioma cells in vitro and in vivo, and are efficiently applicable to the hyperthermia of tumor.
Abstract: Magnetoliposomes (MLs) were conjugated with an antibody fragment to give specificity to a tumor. The antibody fragment was cross-linked to N-(6-maleimidocaproyloxy)-dipalmitoyl phosphatidylethanolamine (EMC-DPPE) in liposomal membrane. The immobilization of the antibody fragment was optimal when the content of EMC-DPPE was 10-wt% and the reaction time for immobilization was 18 h. The Fab' fragment-conjugating MLs (FMLs) were 2.4 times higher molar immobilization density compared with the method using the whole antibody. The targetability of the FMLs to the glioma cells, U251-SP, was then investigated. The amount of FMLs uptake reached 85 pg/cell in an in vitro experiment using plastic dishes. In an in vivo experiment using glioma-harboring mice, 260 μg of the FMLs per 1 g of tumor tissue accumulated (tumor sizes was 0.1 cm3), which corresponded to approximately 60% of the total injection. This value was 7 times higher than that of the MLs. After injection of the FMLs, mice were exposed to intracellular hyperthermia using the alternating magnetic field irradiation. The temperature of tumor tissue increased to 43°C and the growth of the tumor was found to be arrested over 2 weeks. These results indicate the FMLs could target the glioma cells in vitro and in vivo, and are efficiently applicable to the hyperthermia of tumor.
105 citations
TL;DR: In this article, the effects of surfactants, the properties of continuous oil phases and the flow velocity of the dispersed water phase through the channels on the MC emulsification were studied.
Abstract: Microchannel (MC) emulsification is a novel technique for preparing monodispersed emulsions. This study investigates the preparation of monodispersed water-in-oil (W/O) emulsions by means of a hydrophobic MC. The effects of surfactants, the properties of continuous oil phases and the flow velocity of the dispersed water phase through the channels on the MC emulsification were studied. The surfactants should be dissolved in the continuous oil phase to create water droplets from the MC without continuous outflow. There was an optimal HLB of surfactant for the monodispersity and stability of the prepared emulsions. Hexaglycerin pentaoleate (PO-500; HLB, 4.9) was found to be suitable for preparing the stable water-in-ethyl oleate emulsion and water-in-tetradecane emulsion. The average diameters and the coefficients of variation of the prepared emulsions were 27.4 μm and 20.6% for the water-in-ethyl oleate emulsion, and 19.1 μm and 4.2% for the water-in-tetradecane emulsion. Hexaglycerin condensed ricinoleic acid ester (HGCR) was suitable for preparing stable water-in-triolein emulsions. The average diameter and coefficient of variation of the emulsion were 39.8 μm and 6.5%. The effects of the viscosity and the hydrophobicity of the continuous oil phase were investigated. Monodispersed emulsions were prepared in the hydrophobic oil phases because hydrophobic oil phases prevent wetting of the MC plate with the water phase. The droplet diameter increased with an increase in viscosity of the continuous oil phase. When the high-viscosity continuous oil phase was used, droplet diameter increased with an increase in the flow velocity of the dispersed water phase through the channel.
74 citations
TL;DR: A novel recovery system for gold (Au), which is one of the precious metals contained in electronic scrap, utilizing tannin gel particles, was reported, finding the adsorption capacity of gold to be extremely high, 8000 mg-Au/g-dry gel.
Abstract: Condensed tannins are ubiquitous plant polyphenols and have many potential applications. A novel tannin gel adsorbent was synthesized from natural condensed tannin and its adsorption mechanisms and properties for lead (Pb) removal from aqueous solutions were investigated. It was found that lead could be removed through three adsorption mechanisms, i.e., ion exchange, hydrolytic adsorption and surface precipitation. When the initial concentration of lead was varied from 20 mg/l to 80 mg/l, ion exchange took place preferentially in the low pH range of 3.0 to 6.0, and the stoichiometric equation could be described as 2RH + Pb2+ = R2Pb + 2H+. On the other hand, when pH > 6.0, surface precipitation and hydrolytic adsorption took the predominant parts in the adsorption. The adsorption was notably affected by pH of solutions. The adsorption isotherm corresponding to the ion exchange predominating stage was correlated well to Langmuir Equation and the maximum removal capacity in the stage was 0.15-0.19 mmol Pb/g dry tannin gel adsorbent (30-40 mg Pb/g dry adsorbent). This study has the potential to develop an effective natural adsorbent for removal and recovery of heavy metals.
66 citations
TL;DR: It is concluded that the power consumption in shaking bioreactors is much more evenly distributed than in stirred tank fermentors, which creates much lower levels of hydromechanical stress to microorganisms and dispersed phases.
Abstract: Among others, the maximum power consumption in a fermentation broth is one of the most decisive engineering parameters to characterize culture conditions and to scale-up bioprocesses, especially with filamentous microorganisms. Based on the fact that maximum drop diameter in coalescence inhibited two-phase dispersing processes is solely dependent on maximum power consumption, no matter which dispersing machine is used, drop sizes were measured in shaking bioreactors and the ratios between maximum and specific power consumption were calculated. In agreement with two different simplifying theoretical considerations relatively small ratios are obtained. It is concluded that the power consumption in shaking bioreactors is much more evenly distributed than in stirred tank fermentors. As the specific power consumptions in both types of bioreactors are of the same order of magnitude, shaking bioreactors create much lower levels of hydromechanical stress to microorganisms and dispersed phases.
58 citations
TL;DR: In this paper, pyroaurite-like compounds with a series of crystal quality were synthesized in a strong alkali solution with pH above 13 and the characterization of the synthesized compounds was carried out in terms of the crystal quality, specific surface area and intercalated anions of the compounds.
Abstract: Pyroaurite-like compounds with a series of crystal quality were synthesized in a strong alkali solution with pH above 13. The characterization of the synthesized compounds was carried out in terms of the crystal quality, specific surface area and intercalated anions of the compounds. The crystal quality of the compounds decreased with increase in the aging time. The lower crystal quality compound showed larger dissolution than the higher crystal quality one in a solution depending on buffering capacity of the solution. Removal of phosphate using the dissolution followed by coagulation and/or precipitation process of the compounds was demonstrated. Phosphate removal property of the compounds was examined as a function of the crystal quality of the compounds, buffering capacity of the solution and competitive anion in the solution. The phosphate removal was increased depending on decrease of the crystal quality of the compound and increase of the buffering capacity of the solution. The significance of crystal quality of the compounds on the phosphate removal was elucidated.
55 citations
TL;DR: Acinetobacter genospecies Tol 5 showed a sufficiently high ability in toluene elimination within 24 h after starting the operation without preliminary operation for immobilization, suggesting that this strain was effective to shorten the adaptation period, which had been considerably long on the TBAB inoculated with the original activated sludge.
Abstract: Toluene-degrading bacteria were isolated from the trickle bed air biofilter (TBAB), which had eliminated toluene efficiently for three months. Among the isolates, Acinetobacter genospecies Tol 5 demonstrated the highest efficiency in toluene removal. A. genospecies Tol 5 tended to adhere to hydrophobic materials showing water-repellent. When the bacterium was grown on toluene in the presence of polyurethane foam, almost all the cells adhered to the polymer support until the amount of 0.12 kg-cell/kg-polyurethane. Analyses of cell surface hydrophobicity by the microbial-adhesion-to-hydrocarbons test and contact angle measurements revealed that A. genospecies Tol 5 has a noteworthily hydrophobic cell surface compared with Escherichia coli. A TBAB inoculated with A. genospecies Tol 5 showed a sufficiently high ability in toluene elimination within 24 h after starting the operation without preliminary operation for immobilization, suggesting that this strain was effective to shorten the adaptation period, which had been considerably long on the TBAB inoculated with the original activated sludge.
54 citations
TL;DR: In this paper, a waste recycling technique using sub-and supercritical water was developed for obtaining useful materials from marine wastes, which could be useful in establishing a material recycling system across various industries and production processes with the goal to curtail waste emissions into the environment.
Abstract: A waste recycling technique using sub- and supercritical water was developed for obtaining useful materials from marine wastes. As a preliminary work, the effect of reaction parameters was investigated using various types of reactors and samples. In order to obtain amino acids effectively, two main reactions (i.e. hydrolysis of proteins to amino acids and decomposition of amino acids) should be considered. The highest amount of amino acids was obtained at 523 K in reaction time of 60 min. The reaction temperature of 523 K was in agreement with the temperature indicating the maximum ion product of water at saturated vapor pressure. At 573 K, the amount of amino acids produced was low since amino acid decomposition rate was higher compared to production of amino acids from protein hydrolysis. Proper control of reaction parameters is necessary in order to obtain high yield of amino acids efficiently. The technique could be useful in establishing a material recycling system across various industries and production processes, with the goal to curtail waste emissions into the environment.
51 citations
TL;DR: In this paper, the performance of several commonly used impellers (i.e., Lightnin A315 and A310, 45° pitched blade turbine, concave blade turbine and Rushton turbine with holes) were examined systematically under the same fluid and tank conditions.
Abstract: Measurement of mass transfer rate was carried out in an agitated vessel with gas sparging. The performance of mass transfer of several commonly used impellers (i.e. Lightnin A315 and A310, 45° pitched blade turbine, concave blade turbine, Rushton turbine, and Rushton turbine with holes) were examined systematically under the same fluid and tank conditions. A dynamic gassing-out method was used to measure the mass transfer rate of oxygen from gas to the de-ionised water. The variation of the dissolved oxygen concentration of the water was measured by a polarographic dissolved oxygen probe (ORION PCM800). The present data shows reasonable agreement with that in previous publications such as those of Linek et al. (1987), Hickman (1988), Warmoeskerken and Smith (1989), Martin et al. (1994), and Chen and Chen (1999). All the data collected here shows that van’t Riet’s (1979) expression, i.e.: kLa = α(P/V)0.4Us0.5 represents reasonably, well (to within ± 30%) the correlation of kLa with specific power P/V and superficial gas velocity Us. However, the present data seem to indicate that the radial flow impellers provide slightly higher (17%) mass transfer rate than the axial flow impellers.
48 citations
TL;DR: In this paper, the experimental results on physical methods for supercooling relaxation of erythritol as a phase change material were presented, and it was shown that the effect of ultrasonic irradiation is dependent on ultrasonic power and on the melt's temperature at which irradiation was initiated, and that the relaxation effect was improved with a small amount of crystals seeded at about its melting temperature.
Abstract: The present paper shows experimental results on physical methods for supercooling relaxation of erythritol as a phase change material. Solidification behavior of erythritol melt was observed under the experimental conditions using the following 3 energy loadings: 1) ultrasonic irradiation, 2) stirring with seeding, and 3) agitation by bubbling. The obtained results have shown that supercooling relaxation of erythritol during its solidification is possible using any of the 3 cases for choosing energy loading, and that ultrasonic irradiation is most effective among the 3 cases. The effectiveness of ultrasonic irradiation was found to be dependent on ultrasonic power and on the melt's temperature at which irradiation was initiated. In the case of stirring, the relaxation effect was improved with a small amount of crystals seeded at about its melting temperature. Effective relaxation was also obtained by agitating erythritol melt by bubbling of N2 gas at room temperature compared with pre-heated gas.
TL;DR: In this paper, the authors compared the applicability and potential of Modified UNIFAC (Dortmund) for the synthesis, design and optimization of thermal separation processes and other applications of industrial interest.
Abstract: Thermal separation processes are of great importance, because they usually cause the greatest part of costs (investment, operating) of a chemical process. For the synthesis, design and optimization of separation processes, in particular, a reliable knowledge of the real phase equilibrium behavior is necessary. If no experimental data are available, group contributions methods can be used to predict the required phase equilibria and excess properties. In recent years, Modified UNIFAC (Dortmund) has become very popular because of its reliable results obtained for different thermodynamic properties such as vapor-liquid equilibria (VLE), solid-liquid equilibria (SLE), azeotropic data, activity coefficients at infinite dilution (γ∞) and excess enthalpies (hE) in a wide temperature range. This paper gives an idea about the large range of applicability and the potential of Modified UNIFAC (Dortmund) for the synthesis, design and optimization of thermal separation processes and other applications of industrial interest. Furthermore, the results of an extensive model comparison for azeotropic data and excess enthalpies are presented.
TL;DR: In this article, a spray-drying method was used to generate spherical submicron silica particles, which could be used as alternative calibration aerosol for substituting DOP (dioctylphthalate) particles.
Abstract: This paper describes the investigation of the generation of spherical silica particles, which could potentially be used as alternative calibration aerosol for substituting DOP (dioctylphthalate) particles. Silica particles were generated by a spray drying method using a nanometer-sized colloidal silica suspension as the starting material. The generated silica particles have a spherical morphology, are nearly monodispersed and their size can be controlled at submicron order. The smoothness of the particle surface is greatly affected by the size of the colloidal silica particles used. Silica aerosol particles were also generated by the spray pyrolysis of an aqueous solution of tetraethylorthosilicate (TEOS), in order to compare their properties with those of silica particles obtained by spray drying method. The electrical mobility equivalent diameter of silica particles generated by spray drying method is in good agreement with the diameter determined by SEM observation. The light scattering characteristics of the silica aerosol particles were also measured using a laser particle counter and compared with a polystyrene latex (PSL) aerosol. By increasing the drying temperature of the silica sol droplets to 1200°C, the change of scattered light intensity with particle diameter shows a tendency similar to that of spherical PSL particles. Consequently, the spherical submicron silica particles generated by the present spray drying method appear to be applicable to the test of air filters.
TL;DR: In this paper, the effect of alumina particles on the enhancement of sonolysis was examined and the acceleration of decomposition rate was observed and the rate was proportional to the surface area increased by the introduction of the particles.
Abstract: Sonolysis is one of the techniques to destroy various organic contaminants in dilute aqueous solutions. The purpose of this study was to examine the effect of alumina particles on the enhancement of sonolysis. Chlorobenzene was chosen as the model organic compound and batch experiments were carried out with 20 kHz ultrasound source. The results showed the acceleration of the decomposition rate was observed and the rate was proportional to the surface area increased by the introduction of the particles. The possible mechanisms for the enhancement were discussed including the increase in the cavitation bubbles which were produced by sonication and the decomposition took place in.
TL;DR: In this article, the flow pattern and the concentration field in dense solid-liquid suspension in an industrial vessel were determined using an Eulerian approach. But the results of the analysis were limited.
Abstract: Eulerian approach is developed in order to determine the flow pattern and the concentration field in dense solid-liquid suspension in an industrial vessel. These numerical simulations are a very practical aid to understand and design the solid-liquid processes. The knowledge of solid distribution is useful for numerous processes, including crystallization, where vessel performance is closely linked to the solid phase distribution. The calculations are performed using the FLUENT commercial package. The crystallizer studied is used for alumina production. The predicted solid distributions in this crystallizer are compared with experimental solid distribution for several rotational speeds and mean concentrations. The agreement is remarkable. The behaviour of this dense solid-liquid system is studied.
TL;DR: In this article, a model for simulation of multi-phase flow field was developed based on the commercial CFD program of CFX4.2, where the volume fraction distribution of different sizes of particle was studied by the simulation results.
Abstract: Particle concentration distribution in seven phases in stirred tank is simulated on the basis of information in three dimensional flow field, as obtained by numerical solution of the flow equations (CFD), using the well known k-e model. A model for simulation of multi-phase flow field was developed based on the commercial CFD program of CFX4.2. The volume fraction distribution of different sizes of particle was studied by the simulation results. Local particle size distributions in suspension are studied as a function of agitation intensity and distance from the bottom of the tank by the use of CFD. For this purpose a multiple phase approach was used. There, the different particle size classes are taken as separate computational phases. Six classes of particle sizes were used in the simulation. The continuous phase was water. The six solid phases were composed of particle sizes of 50, 100, 300, 500, 700 and 900 μm. The particle density was 2600 kg/m 3 , different stirrer speeds were used with multiple phase flow. Further, expressions were developed and added in the program which enable the local particle size distributions to be calculated. Computed suspension densities were verified with existing experimental data in the literature.
TL;DR: In this article, the structure of isolated mixing regions was observed in a stirred vessel with the aid of flow-visualization technique, where two toroidal regions were clearly formed respectively above and below the turbine impeller in the range less than Re = 100.
Abstract: The structure of isolated mixing regions was observed in a stirred vessel with the aid of flow-visualization technique. Two toroidal regions were clearly formed respectively above and below the turbine impeller in the range less than Re = 100. Under the condition of this experiment, these regions remained visible for a couple of hours. Under the nearly same rotational condition, a set of three stable filaments surrounding the torus was found in the case of the six-bladed turbine, while a set of four filaments was found in the case of the four-bladed turbine. The velocity fluctuation of flow caused by the rotating turbine blades can be regarded as periodical perturbations for the secondary circulating flow. Hence it can be considered that these structures depend on periodical perturbations caused by the rotating turbine blades. In order to observe the inside structure of ring-doughnut-shaped core regions, the unsteady rotation procedure was applied. Another set of filaments was observed inside the core. It has been found that the isolated mixing regions have complex multi-structures consisting of various KAM tori.
TL;DR: In this article, the effects of gas and liquid velocities and solid circulation rate on the local gas holdup, solid axial distribution, phase space portrait, and Kolmogorov entropy of pressure fluctuations, as well as on the flow behavior of gas-liqid-solid mixture in the riser are determined.
Abstract: Characteristics of gas-liquid-solid flow behavior in a riser are investigated in a three-phase circulating fluidized bed (0.102 m I.D.×3.5 m in height). Local gas holdup, solid holdup distribution, and pressure fluctuations in the riser have been measured and utilized to describe the gas-liquid-solid flow behavior more conveniently. The resultant pressure fluctuations have been analyzed by adopting the chaos method: The time series of pressure fluctuations have been interpreted by means of phase space portraits and Kolmogorov entropy. The effects of gas and liquid velocities and solid circulation rate on the local gas holdup, solid axial distribution, phase space portrait, and Kolmogorov entropy of pressure fluctuations, as well as on the flow behavior of gas-liqid-solid mixture in the riser are determined. It is found that pressure fluctuations can be a quantitative tool to characterize the flow behavior and flow regime transition of multiphases in the riser. The relations between the pressure fluctuations and the distribution of phase holdup and flow regime in the riser are also discussed.
TL;DR: In this article, a novel ultra high velocity jet device was used to form fine drops of an organic phase in a continuous aqueous stream and the results were verified using a high-speed photographic technique.
Abstract: A novel ultra high velocity jet device was used to form fine drops of an organic phase in a continuous aqueous stream. Experiments were carried out for different operating conditions including number of passes through the orifice and pressure drops across it. Computational fluid dynamics (CFD) was used to map the transient continuous phase jet velocity and the associated energy dissipation rate. The results were verified using a high-speed photographic technique. The CFD predictions of the maximum energy dissipation rate at the jet orifice was combined with a population balance equation to predict the evolution of drop size distributions as a function of the number of passes through the orifice (residence time) and the operating pressure. The results compared well with the experimental data giving confidence in the theoretical predictions.
TL;DR: In this article, a simplified spray drying granulation model of a hollow granule from dispersed-system slurries was proposed, and the granulation mechanism was analyzed to replace with the solid-liquid separation by filtration.
Abstract: A simplified spray drying granulation model of a hollow granule from dispersed-system slurries was proposed in this work. The granulation mechanism was analyzed to replace with the solid-liquid separation by filtration. The factors that affect the diameter and the strength of the granule were investigated from the simulation based on the model.
TL;DR: In this article, the performance of cross-flow microfiltration in a plate and frame module with Nylon 66 membrane was investigated using a model suspension containing baker's yeast, and it was found that ultrasonically induced cavitation is effective for loosening and detaching the cake deposited on the surface of the membrane.
Abstract: In the present research, microfiltration performance was remarkably improved by ultrasonic irradiation. It has been found that ultrasonically induced cavitation is effective for loosening and detaching the cake deposited on the surface of the membrane. Cross-flow microfiltration in a plate and frame module with Nylon 66 membrane was investigated using a model suspension containing baker's yeast. The factors affecting the steady-state permeate fluxes, i.e. the ultrasonic power, the transmembrane pressure, the feed velocity and the feed concentration, have been studied.The experimental results obviously showed that the suitable application of ultrasonic wave could enhance the flux up to 3 times that without ultrasonic wave. An optimum operating transmembrane pressure and the optimum ultrasonic intensity were found. In addition, the ultrasonic effect was more pronounced at a lower feed velocity and a lower feed concentration. It was confirmed that an increase of the steady-state flux was caused by a major reduction of the cake resistance.
TL;DR: In this article, a new type of photocatalytic reaction system, in which filtration and a photocatalysis reaction occur simultaneously, is reported, and the concentration of trichloroethylene (TCE) in a permeate stream decreased by approximately 5 ppm while TCE permeating porous TiO2 membranes under conditions of blacklight irradiation.
Abstract: A new type of photocatalytic reaction system, in which filtration and a photocatalytic reaction occur simultaneously, is reported The concentration of trichloroethylene (TCE) in permeate stream decreased by approximately 5 ppm while TCE permeating porous TiO2 membranes under conditions of blacklight irradiation In addition, membrane fouling by polyethyleneimine, which caused a decrease in permeate flux, was also found to be reduced by photocatalytic reaction
TL;DR: In this paper, a unified empirical correlation is proposed, for the estimation of minimum impeller speed for solid suspension in both two-phase and three-phase systems in terms of fundamental, operational and geometrical variables.
Abstract: Experiments were performed in mechanically agitated contactors with 6 (flat) blade turbine impellers, to study the effect of various operating parameters on minimum/critical speed required for complete suspension in two-phase (liquid-solid) as well as three-phase (liquid-solid-gas) systems Based on 1212 experimental measurements, a unified empirical correlation is proposed, for the estimation of minimum impeller speed for solid suspension in both two-phase and three-phase systems in terms of fundamental, operational and geometrical variables
TL;DR: In this paper, flash pyrolysis of plastics was investigated to obtain basic data for the first reactor of the process, which contained 5 mm-diameter nonporous α-alumina balls as a thermal medium.
Abstract: This study is a starting point for the creation of a new plastic recycling process. The process consists of two successive pyrolyzing reactors, for which a spouted bed type seems to be most appropriate for the time being. In the first reactor, plastic chips are fed and instantaneously pyrolyzed into lower hydrocarbons (gas or vapor). In the second reactor, the hydrocarbons are further pyrolyzed into hydrogen and carbon. Hydrogen is a useful and clean fuel (no carbon dioxide evolution) and a chemical raw material. Carbon can be utilized as carbon black, activated carbon, and so forth. In this study, flash pyrolysis of plastics was investigated to obtain basic data for the first reactor of the process. Six types of plastics, low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), poly(vinyl chloride) (PVC), and poly(ethylene terephthalate) (PET), were flash-pyrolyzed by putting them into a pre-heated batch reactor (873 K, 5 × 10-5 m3), which was made from stainless steel and contained 5 mm-diameter non-porous α-alumina balls as a thermal medium. The products (gas, condensate and solid residue) were collected and analyzed. In most cases, solid residue (in the reactor) yield was less than 3%. Gas yield was 1 to 30%. Condensate yield was 10 to 90%. These results show that in the first reactor of the proposed process most of the fed plastics can be pyrolyzed into gas and vapor, which will move to the second reactor as a fluid.
TL;DR: In this article, Diethylenetriamine (DETA) and hexamethylene-1,6-diisocyanate (HMDI) were used as a trifunctional hydrophilic monomer and a bifunctionality hydrophobic monomer, respectively, so that a polymer with cross-linked structure was formed.
Abstract: The kinetics of membrane formation of polyurea microcapsule by interfacial polycondensation was studied both experimentally and theoretically. Diethylenetriamine (DETA) and hexamethylene-1,6-diisocyanate (HMDI) were used as a trifunctional hydrophilic monomer and a bifunctional hydrophobic monomer, respectively, so that a polymer with cross-linked structure was formed. The oil in water (O/W) emulsion was first prepared using water, cyclohexane containing HMDI, and surfactant Tween 85. The emulsion solution was then mixed with DETA aqueous solution to start the interfacial polycondensation. A mathematical model in which DETA transferred to the polymer surface in the water phase, diffused through the polymer membrane, and reacted with HMDI at an interface of the polymer and the oil phase was proposed. The size distribution of microcapsule and diffusion of DETA of both unprotonated and protonated forms were incorporated, and the relation between pH and the concentration of DETA was derived from ionic equilibrium. The calculated results explained well the time variation of the conversion of DETA at a different initial number of moles of DETA and different initial mole ratio of HMDI to DETA. The time variation of the thickness of the polymer membrane was also simulated.
TL;DR: In this paper, a self-heating microreactor was used for hydrogenation of benzene as a model reaction, and relevant kinetic data were obtained by using an anodic bonding technique so as to be gas-tight.
Abstract: Microchannels were fabricated on both sides of a (100) silicon wafer (10 mm × 40 mm) by wet chemical etching after pattern transfer using a negative photoresist. The walls of the reactor channel (upper width = 400 μm, lower width = 280 μm, depth = 100 μm, and length = 78 mm) were coated by sputtering with a Pt layer for use as a catalyst. A heating element was installed in the channel on the opposite surface of the reactor channel, and a thermocouple was installed in a channel adjacent to the reactor. The reactor channel, as well as the reverse-side heating channel, was sealed with a glass plate by an anodic bonding technique so as to be gas-tight. The self-heating microreactor was then used for hydrogenation of benzene as a model reaction, and relevant kinetic data were obtained.
TL;DR: In this article, the chemical characteristics of methanol soluble lignin separated from Eucalyptus globulus by steam explosion were clarified by measurement of number-averaged molecular weight, weight-averaging molecular weight and phenolic hydroxyl group.
Abstract: The chemical characteristics of methanol soluble lignin separated from Eucalyptus globulus by steam explosion were clarified by measurement of number-averaged molecular weight, weight-averaged molecular weight, and phenolic hydroxyl group. It was found that the methanol soluble lignin separated from the exploded wood at a steam pressure of 3.5 MPa and a steaming time of 5 min was the most adequate raw material for the synthesis of epoxidized lignin, i.e. lignin epoxy resin. The thermosetting behavior of epoxidized lignin was almost the same as that of commercial bisphenol A resin. According to E-Screen assay, the methanol soluble lignin, a raw material of epoxidized lignin, did not show estrogenic activity. Since the methanol soluble lignin was easily degraded by the lignin-degrading enzymes, the epoxidized lignin seems to be a biodegradable resin in waste treatment after its use.
TL;DR: In this article, the dominant dynamics of the open-loop can be expressed by a second order transfer function, with which the number of unstable poles varies from zero to two depending on operating conditions.
Abstract: Temperature control of a gas-phase polyolefin reactor is prone to be unstable when operating conditions and/or catalyst are changed. Using a simple first principles model, it is shown that the dominant dynamics of the open-loop can be expressed by a second order transfer function, with which the number of unstable poles varies from zero to two depending on operating conditions. The frequency domain analysis shows that these changes in the process dynamics primarily affect the process phase and cause the closed-loop instability. Thus, PID temperature controller is retuned so as to increase phase margin. A practical retuning method of a PID temperature controller, which can be performed at the onset of closed-loop instability, is developed and its effectiveness is demonstrated through simulations.
TL;DR: In this article, a batch experimental work on the fluidization hydrodynamic and entrainment phenomena of cohesive starch powders was studied, which showed that fluidization can be realized as vibration break particleparticle bond in the bed.
Abstract: Batch experimental work on the fluidization hydrodynamic and entrainment phenomena of cohesive starch powders was studied. Results show that fluidization can be realized as vibration break particleparticle bond in the bed. The higher Umf values compared to predictions indicate the formation of agglomerates in the bed. This has increased the residence time of fines to reduce material loss by entrainment. It was found that using starch powders as feed materials, entrainment was only in the range of 0.5-1.7% of the total fines (should be entrained) in the bed. As has also been found by other workers, the entrainment rate constants of group C decrease as particle size decreases. By adapting the criterion proposed by Rietema (1984) as well as Ma and Kato (1998), it was found in this case that the critical cohesion number, Ncoh* is 19.
TL;DR: Results indicate that the diffusive permeability of the cellulosic membrane grafted with molecularly imprinted copolymer discriminates between the template and its analogue.
Abstract: Graft copolymerization of ethyleneglycol dimethacrylate and merthacrylic acid onto cellulosic membrane was performed in the presence and absence of theophylline as the template for imprinting the copolymer molecularly. The effect of the presence of the template on the diffusive permeability of the grafted membrane was estimated by batch-wise dialysis of creatinine. The permeability of the theophylline-imprinted membrane was increased by the presence of theophylline, but was virtually unaffected by caffeine, which is an analogue of theophylline. The permeability of the non-imprinted grafted membrane decreased in the presence of theophylline or caffeine without discrimination. These results indicate that the diffusive permeability of the cellulosic membrane grafted with molecularly imprinted copolymer discriminates between the template and its analogue.