Xe-doped and F-doped amorphous SiOx double layer thin films were fabricated using a RF magnetron sputtering method, and the phase transition from semiconductor to insulator was induced by DC voltage impression. The dose of Xe atoms in the SiOx films was found to be controllable by changing the sputtering power and the distance between the target and substrate. The surfaces of the films were smooth, and the DC electric properties of the films were investigated. The SiOx double layer with a thickness of 0.82 µm in total showed 4 to 20Ω below DC 5 V, and the phase transition occurred upon applying DC 5V. The resistance of the films suddenly and dramatically increased to more than 1 MΩ. The phase change occurred when either plus or minus voltage was applied to the Xe-doped SiOx film. Such a bipolar manner indicates that the charge transfer from Xe to F atoms is not essential in the mechanism and that two-layer contexture of the SiOx films might be unnecessary. The possible mechanism and future strategies to understand the nature of this material are discussed.

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Although crystalline silicon solar cells are promising candidates for the large-scale solar cell applications, their production cost needs to be reduced to gain widespread acceptance. Recent work has focused on the production of thin silicon films, since the crystalline Si wafers account for about a half of the module cost of solar cells. Thin silicon films should be possible in principle to produce cells with high efficiency at significantly lower cost than current silicon cells, made on cast polycrystalline or monocrystalline silicon substrates. We propose a different approach of a layer transfer process, termed the epitaxial lift-off process, which leads to the production of monocrystalline silicon films.
As a case study of the epitaxial lift-off process, high quality Si / CoSi₂ / Si double heteroepitaxial structures were developed using a conventional magnetron sputtering system on a Si (100) substrate with texture patterns and via holes produced by anisotropic etching. A Si layer of a few micrometers thickness was fabricated easily using a chemical vapor deposition (CVD) process on the double heteroepitaxial structure. CoSi₂ was etched away by the hydrofluoric acid and the thin film monocrystalline Si could be easily separated from the supporting single crystal silicon substrate, which is found to be reusable.

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The authors developed several experimental technique to elucidate the main reaction path ways to deposit thin films by chemical vapor deposition (CVD). These techniques includes the analyses of step coverage profile in micron sized trenches, growth rate profiles of selective growth, growth rate profiles in tubular reactor, and the effect of residence time to the film growth rate. The step coverage profiles and growth rate profiles in selective area growth will provide information on surface reactions, while the other analyses will provide the information of gas-phase and surface kinetics. The combination of these techniques in different size dimension (multi-scale analysis) is a powerful technique to elucidate the important reaction paths in CVD. In this work, a-C:F film deposition by plasma-enhanced CVD (PECVD) and epitaxial growth of InGaAsP thin films by metal-organic vapor phase epitaxy (MOVPE) were chosen as the example for the demonstration of multi-scale analysis. The selective area MOVPE (SAMOVPE) shows non-uniformity in the epitaxial growth area, mostly due to the gas phase concentration distribution of film forming species. This micro-scale profile was mostly controlled by the ratio of diffusion coefficient and the surface reaction rate constant of film forming species, while the growth rate profile in MOVPE reactor (macro-scale) was governed by the diffusional mass transport. Thus the combination of these analysis can give the information of surface reactivity of film forming species. The residence time dependencies of PECVD growth rate and chemical species in gas phase give the information on overall reaction mechanism. The growth rate profile inside the micron size "test structure" gives the detail information of surface reaction mechanism. This is another demonstration of multi-scale analysis.

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An integrated approach to guide the synthesis of reaction systems is presented, with the objective of identifying the best design while reducing development time. The approach is applicable to a variety of reaction systems including catalytic and non-catalytic single as well as multiphase reactions, polymerizations, and reactive extraction and crystallization. The systematic methodology integrates the Experiments, Synthesis, and Modeling activities into an efficient workflow. This minimizes wasted efforts in doing random experiments and modeling, while obtaining information necessary for a validated reactor design. The synthesis component assimilates the available information and drives all other activities. Required information flows between each of the components. Each iteration of the overall loop leads to greater certainty regarding the system behavior, and hence a tighter design for the reaction system. This methodology represents a new approach to the synthesis of reaction systems, and provides an efficient workflow to progress from a process demonstrated in the laboratory to a production reactor on the ground.

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Many kinds of volatile organic compounds (VOCs) have been treated in the biofilters based on the degradation of VOCs by the biolayer on the surface of packing media. Such a bed is easily subjected to compaction or clogging due to separation of biolayer and to an increase in pressure drop of gas flow. To overcome the drawbacks, our previous study has proposed the packed column containing the immobilized activated sludge gel beads together with the hollow plastic balls to avoid the bed compaction. In the present study, the biofilter is applied to remove the binary mixture of benzene-ethylbenzene (BE) or benzene-toluene (BT) using the gel beads which have been acclimated during the earlier stage of the respective removal operations. As in the case of the binary acetaldehyde-propionaldehyde mixture in our previous work, the modified Michaelis-Menten type rate equation is determined for the biodegradation of the binary VOCs mixture by the gel beads taking account of the coexistent VOC. The gel beads are efficient for removing both binary mixtures in the biofilter. The design equations similar to those for the binary aldehydes mixture are applicable to predicting the removals of each VOC component. The predictions are successful with the degradation kinetic parameters as well as the Henry's law constants which depend on the VOC concentration and are modified by the partition coefficient of the respective VOC between gel and aqueous phases as opposed to the case of the aldehydes.

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In pharmaceutical industry, cryogenic reaction is frequently used for the organometallic reaction or stereoselective synthesis of active pharmaceutical ingredient and its intermediate. Cryogenic condition is required for above reactions because of thermal instability of organometallic compound or improvement of the selectivity. This paper focuses on continuous cryogenic organic reactions using mini size multi-stage reactors (their volume range is from 10^-6 to 10^-3m³). Mini size reactor has many advantages such as high heat exchange efficient and fast mixing etc. similarly to micro reactor. In addition, mini size reactor has an advantage of operability over micro-scale reactor. Reactions of this study are two successive cryogenic reactions, which are highly exothermic, therefore a large amount of heat removal is required. Currently, the production scale reaction is carried out by batch method, and the temperature control is performed by slow charging of reagents and slow addition of reactant, which causes the yield loss especially in the 2^nd reaction. Herein, the reactions have been demonstrated by using mini size multi-stage reactor and compared the results for the product yield, by- products and stereoselectivity of product with a production scale batch reaction. The results and issues are discussed in this study.

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In order to keep this analysis within reasonable bounds, attention is confined to homogeneous gas phase reactions in round tubes. Other reactors and conditions are considered separately. The existence of a radial variation in the mixed-mean velocity in a tubular reactor for all rates of flow is universally recognized, but its effects on the conversion are often ignored. The direct effects of the interactions between reaction and transport, including that of the heat of reaction on the heat transfer coefficient, the change in composition on the mass transfer coefficient, and the turbulent fluctuations in temperature and in concentration on the rate of reaction, have been the subject of many analyses, but have not been generalized, and go unmentioned in most textbooks on either chemical reaction engineering or transport. These several effects are examined and evaluated. It is found that although they are second-order in magnitude in some applications, they are critical in others, and should not be ignored.

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The radiative heating of small particles in a flammable atmosphere by laser light may lead to ignition and explosion. The mechanisms of ignition and detonation of quiescent methane/air mixtures caused by a radiatively heated inert particle involves a set of chemical reactions among the gas-phase species. A system of ordinary differential equations that comprises the net reaction rates of the species, which are initially present in the system, and the products of their reversible reactions is solved for the entire inflammability range of methane with air under isothermal conditions and within the temperature region of interest (800-1000 K). Two criteria tests are carried out to identify the chain initiating reaction. The first criterion tests the contribution a given reaction made to the main chain branching while the second criterion tests its contribution to the total heat release. It is found that the reaction, O₂ + CH₄→HO₂ + CH₃ satisfies the criteria at all grid points of the calculation. A simplified kinetic scheme is adopted and a system of differential equations, representing the net reaction rates of all species included in the scheme is solved. The data are used in the explosion-delay time calculations.

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In order to analyze the reaction performance and enhance the selectivity of industrial catalytic processes with fluidized-beds, the direct contact model for consecutive reaction proposed previously is extended theoretically to be applicable to parallel consecutive reactions. From mathematical derivation, it is shown that the reaction performance in a parallel consecutive reaction, such as the conversion of raw material and the yield and selectivity of intermediate product, can be obtained by use of the basic reaction model for a consecutive reaction by introducing a factor for parallel reaction and a simple relationship between reaction rate constants in the parallel consecutive reaction and those for the consecutive reaction model. By comparing with reported conversion and selectivity data in industrial processes of propylene ammoxidation, the reaction performance simulated by the proposed model was in good agreement with the data. From this investigation, it is also concluded that the synergy effect of basic parameters, such as the ratio of reaction rate constants in the consecutive reaction step, N_rr, the ratio of the mass transfer capacitance coefficient to the reaction rate constant, N_mr , and the proportion of direct contact catalyst-particles in the total catalyst-particles in the reactor, on the reaction performance is analogous to that in the consecutive reaction and essential for enhancing the reactivity and selectivity in parallel consecutive reactions.

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Hydrogen gas is manufactured by the hydrothermal reaction of calcination dolomite and aluminum in Kimoto's patent. The authors obtained an important hint from his patent and conducted the following experiment. There were prepared aluminum sample of 5g, 5g of calcium hydroxide sample,which is the main ingredients of calcination dolomite, and 10g of mixture sample of them and the experiment was conducted over three weeks in atmosphere. As a result of measuring weight at every three days interval, the weight increase was hardly observed in the alumin sample. About 0.2g of the weight increase was observed in the calcium hydroxide sample due to the molecule conversion, in which calcium hydroxide and carbon dioxide in the atmosphere reacted and calcium carbonate and water were generated. However about 1.0g of weight increase which is 5 times larger than calcium hydroxide sample was observed in the mixture sample. It was found from compound analysis by the XRD method and elemental analysis by the EDX method that 0.8g of weigh difference that was calculated by subtracting 0.2g from 1.0g was brought about by the atomic conversion and succeeding molecular conversion where about 13% of aluminum was converted to calcium and further to calcium hydroxide. And this weight difference was confirmed to depend on the average humidity in three kinds of experimental results carrying out by changing years and months. And it showed that the atomic conversion mechanism might be able to be scientifically explained by the quantized water theory advocated by Takao and others.

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Conventional catalytic processes of CH₄ conversion to produce synthesis gas require high temperature and high pressure. Nonthermal plasma is considered to be a promising technology for CH₄ conversion since it can operate in ambient conditions. In this study, a multi-stage gliding arc discharge system was employed in this study to investigate the effects of stage number, CH₄/O₂ molar ratio, total flowrate, frequency, voltage, and gap distance on CH₄ and O₂ conversion and product distribution. Air was used instead of pure O₂ in the feed gas since it can reduce investment and operating cost. The results showed that increasing stage number, voltage or gap distance enhanced both CH₄ and O₂ conversion in contrast with the effects of increasing CH₄/O₂ molar ratio, total flowrate and frequency. The optimum condition was found at a CH₄/O₂ molar ratio of 3/1, a feed flowrate of 150 cm³/min and a frequency of 300 Hz for the maximum CH₄ and O₂ conversion with high synthesis gas selectivity and very low energy consumption. The energy consumption of the gliding arc system was found to be very low about 15.3-18.5 eV/molecule of CH₄ converted as compared to 21 eV/molecule of CH₄ converted for the corona discharge system with pin and plate electrodes.

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Alkali compounds contained in wood have been said to significantly influence the wood reaction. Although many researchers reported wood and cellulose gasification with alkali catalysts, the detailed reaction mechanism of alkali metals on pyrolysis of biomass is not yet clear.
Pyrolysis of wood with/without potassium carbonate (K₂CO₃) under relatively high temperature increasing rate was carried out to elucidate the role of alkali metals on wood pyrolysis. Gaseous species produced by wood pyrolysis were measured by TCD and FID gas chromatographs. Tar was analyzed to quantify polycyclic aromatic hydrocarbons (PAHs) by GC/MS. Changes in chemical bonds in solid residue(char) were analyzed by ¹³C-NMR.
By adding alkaline salts, gaseous products increased and tar decreased. The gas products except for ethylene and light PAHs increased while heavier PAHs decreased. Without potassium carbonate, saccharide structure contained in cellulose remained in the char obtained from pyrolysis at 500°C but with potassium carbonate, the structure dramatically changed, for example C-O bond disappeared. It was suggested that not only K₂CO₃ but also K₂O produced around 300°C - 400°C by pyrolysis of K₂CO₃ caused such effects on pyrolysis. From results of various measurements, effects of alkaline on the pyrolysis process were discussed.

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In the study of mercury removal from a substitute condensate of diphenylmercury contaminated in n-heptane on 3A, 4A, 5A, NaX and NaY zeolites and activated carbon was carried out in batch and continuous operations. In a batch adsorption system, the adsorption characteristics such as pore size effect and adsorption isotherm revealed that the diphenylmercury molecules can penetrate into the supercage of the NaX and NaY zeolites but only partially of the 5A zeolite, and a bi-Langmuir model can fit well with the experimental data. The adsorption of the diphenylmercury occurs only on the external surfaces of the 3A and 4A zeolites. In the kinetic study of the adsorption at 25°C, very low diffusivity constants indicate the limitation of diphenylmercury molecule adsorption. In a continuous adsorption system, the results of diphenylmercury adsorption on NaX and NaY zeolites revealed that the adsorption mechanism is chemisorption rather than physisorption.

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A grand canonical ensemble Orientational-Bias Monte Carlo technique has been utilized to simulate adsorption isotherms of pure and mixed propane/propylene in NaY zeolite at 303 K. Propylene is adsorbed more strongly than propane, and the adsorption energy of propylene is found to be about 10-20 kJ/mol larger than that of propane mainly through the Coulomb interactions between molecules and zeolite atoms/Na ions. The adsorption isotherms of pure gases are correlated with four theoretical models: Langmuir, multi-site occupancy, two-dimensional van der Waals fluid and Ruthven+U models. The latter three models are found to fit much better than the Langmuir model. The simulation isotherms of propane/propylene mixtures, calculated at 100 kPa in total pressure, are qualitatively well predicted by the latter three models.

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The Grand Canonical Monte Carlo (GCMC) method is simulation method for solving a phenomenon from a microscopic level, and it is turning into the powerful analysis technique in the field of the adsorption engineering. It is becoming possible to interpret the adsorption characteristic in a molecule level rationally, and to predict the macroscopic characteristic such as adsorption isotherms in recent years. However, information on forcefield parameters and charges are often inadequate, even in systems where the structure is well known. From the environmental point of view, the adsorption of chlorinated hydrocarbons by the use of zeolites may have some potential utilities in ground water or soil remediation and other areas.
In this study, equilibria and isosteric heat of adsorption for the system of chlorinated hydrocarbons and high-silica zeolite were obtained with gravimetric method and chromatographic method. By comparing an experiment result with a molecular simulation result, the validity of forcefield parameters and zeolite model was examined.

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Perturbation chromatography with multicomponent gas carrier and non-equilibrium thermodynamics liner law was applied for discussion of the interference effect and the displacement effect on multicomponent gas adsorption. Moment analysis method and stop & go simulation method were utilized to obtain each mass transfer parameters of adsorbate gases. Dependency of micropore diffusion on amount adsorbate and correlation of micropore diffusion with chemical potential driving force for microporous adsorbent were discussed.

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Fixed-bed adsorption experiments of laboratory-scale were carried out to remove organic solvent vapors by Y-type zeolite adsorbent. Some of binary adsorption equilibria of azeotropic mixture-HSZ systems showed two azeotropic points. Breakthrough curve could be simulated using the Stop & Go method for these systems. Those experiment data were compared with molecular simulation by the Grand Canonical Monte Carlo (GCMC) method.

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In this study, adsorption measurement of various chlorinated hydrocarbons on Y-type zeolites were performed using the chromatographic method to examine the adsorption phenomena. Dichloromethane (DCM), chloroform (TCM), trichloroethylene (TCE), and tetrachloroethylene (PCE), were used as the chlorinated hydrocarbons, and PQ-USY, USY-6.18, Na-Y and Pentasile-2 were used as adsorbent. Each adsorption measurement was performed to get the heat of adsorption and the activation energy of micro pore diffusivity. The amount adsorbed and isosteric heats of adsorption became low, when SiO₂/Al₂O₃ ratio of zeolite became high. The isosteric heats of adsorption were roughly 1.4 to 2.0 of the heats of vaporization. The activation energies of diffusion in the micropore of zeolite were found to be almost 40% to 60% of the isosteric heats of adsorption.

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Zeta potential of ink with three different cationic surfactants: dodecyl-, tetradecyl-, and hexadecyl or cetyl-trimethylammonium bromides (i.e., DTAB, TTAB, and CTAB, respectively) was measured at two pH levels of 11 and 12. These surfactants are chemically different in the number of carbon atoms of the alkyl tail group (i.e., 12, 14, and 16 for DTAB, TTAB, and CTAB, respectively). The zeta potential of ink particles increases and fractional ink removal increases with increasing alkyl chain size and increases with surfactant concentration, plateauing at some higher concentration. The zeta potential of each surfactant at pH 12 was higher than that at pH 11, while the efficiency for ink removal of these surfactants worked particularly well at pH 12. Inducing a higher negative charge on the ink particles by increasing pH or surfactant hydrophobicity and concentration is correlated with ink removal as repulsion between ink particles and polymer surface increases and dispersion stability of detached ink particles increases, presumably due to increased surfactant adsorption on the ink particles.

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In this study, the adsorption of a cationic surfactant (CTAB) and a nonionic surfactant (Triton X-100) on precipitated silica and the adsolubilization of two organic solutes, toluene and acetophenone, were investigated in both single- and mixed-surfactant systems. In mixed-surfactant systems, the adsorption was studied at three different molar ratios, 1:1, 3:1 and 1:3, while the adsolubilization was studied in both single- and mixed-solute systems. The adsorption results showed that the addition of Triton into the mixed CTAB/Triton surfactant systems caused a reduction of CMC when compared to the pure CTAB system. The adsorbed amount of each surfactant was found to be quite close to the molar ratio of CTAB/Triton in the mixed systems. In single-solute systems, the adsolubilization of toluene appeared to be directly related to the amount of surfactant adsorbed on silica surface for both single- and mixed-surfactant systems. For acetophenone, when compared to single-surfactant systems, the adsolubilization was much higher in the mixed-surfactant systems, especially at molar ratios of 3:1 and 1:1. In mixed-solute systems, the synergistic effect was observed in the adsolubilization of acetophenone in the presence of toluene whereas the presence of acetophenone had little effect on the adsolubilization of toluene.

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The equilibrium isotherms for adsorption of phosphate on an OH-type strongly basic ion exchanger, DIAION SA10A, in both single and binary systems were studied experimentally. The results appeared technically feasible. Phosphoric acid, acetic acid, lactic acid, and pyroglutamic acid were used as adsorbates. Phosphoric acid as well as the other three organic acids has been found to contain mainly in the aqueous-phase component of the sub-critical water hydrolysis of organic wastes. Phosphoric acid is a very important basic material to many industries. However, the worldwide supply of high-grade phosphate rocks is now rapidly decreasing and would likely be depleted in the next few decades. Thus, it is very important to develop a production process of phosphates from various phosphate-utilizing industrial processes, phosphate-containing wastewaters, and from sub-critical water hydrolysis of organic wastes to become alternative sources of phosphates to prevent a global exhaustion of high-grade phosphate ores in the very near future. In all single-component systems, the adsorption isotherms showed a high amount of phosphoric acid, acetic acid, lactic acid, and pyroglutamic acid adsorption and the equilibrium isotherms were not affected by the initial concentrations of the solution. In the three binary systems considered: phosphoric-acetic, phosphoric-lactic, and phosphoric-pyroglutamic acids, it is apparent that phosphoric acid is selectively adsorbed on DIAION SA10A than lactic, acetic, and pyroglutamic acids. The ion-exchange reaction models were then proposed. By applying the mass action law to the dissociation reactions of the adsorbates in the liquid phase and ion-exchange reactions, the theoretical equations for the adsorption isotherms for the single-component systems were derived and the unknown equilibrium constants were determined.

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Styrene is used in a variety of chemical industries. Environmental and occupational exposures to styrene occur predominantly through inhalation. The major metabolite of styrene is present in two enantiomeric forms, chiral R- and S- 1-hydroxy-1-phenyl-lacetic acid (R-and S-mandelic acid, MA). Thus, the concentration of MA, particularly its enantiomers, has been used in urine tests to determine whether workers have been exposed to styrene. This study describes a method of analyzing mandelic acid using molecular imprinting techniques and HPLC detection to make the separation of the diastereoisomers of mandelic acid possible. The molecularly imprinted polymer (MIP) was prepared by non-covalent molecular imprinting using (+) MA, (-) MA or (+) phenylalanine, (-) phenylalanine as templates. Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were copolymerized in the presence of the template molecules. The bulk polymerization was carried out at 4°C under UV radiation. The resulting MIP was ground into 25~44µm particles, which were slurry packed into analytical columns. After the template molecules were removed, the MIP-packed columns were found to be effective for the chromatographic resolution of (±)-mandelic acid. This method is simpler and more convenient than gas chromatography or other methods.

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In this study, several surfactant-modified zeolite (SMZ) adsorbents were prepared from a naturally occurring zeolite, clinoptilolite, using a surface modification technique by forming a bilayer of a cationic surfactant (CTAB) and metal ligand such as palmitic acid (PA) on the zeolite surface. These SMZ adsorbents were further evaluated for their adsorption characteristics for heavy metal and organic contaminants as a function of metal ligand to surfactant loading ratio. The results showed that the adsorption of cadmium by SMZ was strongly affected by PA/CTAB loading on the SMZ. The cadmium uptake increased with increasing PA/CTAB loading ratio in the range of 1:1 to 4:1. In contrast, the adsorption of toluene slightly decreased with increasing PA/CTAB loading on the SMZ. In the mixed-solute systems where cadmium and toluene were adsorbed simultaneously, higher adsorption was observed in the case of toluene but not in cadmium adsorption. The regeneration of the SMZ was also demonstrated and the regenerated SMZ was shown to be reusable for several adsorption cycles with an acceptable loss in the adsorption capacity.

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Magnetite prepared by adding the aqueous sodium hydroxide solution to the mixture solution of Fe²⁺: Fe³⁺ = 1 : 2 was investigated on the adsorptive properties for arsenic(V) anion and cations such as cobalt(II), copper(II), cadmium(II), lead(II), nickel(II) and zinc(II) at 303K. Especially, arsenic(V) and lead(II) with high toxicity were studied in detail. Adsorption of arsenic(V) and lead(II) was dependent on equilibrium pH. The adsorption percentages of arsenic(V) and lead(II) showed the optimum values at around pH_eq 4-5 and pH_eq 5, respectively. From their chemical species existing at each pH and pH of zero point of charge on the magnetite surface, arsenic(V) and lead(II) were probably adsorbed on the surface of the magnetite by electrostatic force and ion exchange, respectively. The adsorption of arsenic(V) and lead(II) was the Langmuir type. The adsorption capacity and the adsorption equilibrium constant for arsenic(V) were 2.28 x 10^-1 mmol g^-1 and 1.21 dm³ mmol^-1, respectively and those for lead(II) were 2.13 x 10^-1 mmol g^-1 and 5.03 dm³ mmol^-1, respectively, at 303K. The adsorption of lead(II) was an endothermal reaction from the effect of the temperature on the adsorption. An aqueous sodium hydroxide solution was useful as an agent for desorption from arsenic(V)-loading magnetite.

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This study is to elucidate the feasibility of utilizing BDHDMA (Benzyldimethylhexadecylammonium)-modified Montmorillonite for the removal of 2,2-bipyridyl from aqueous solution and to find the kinetic rate of adsorption. The 2,2-bipyridyl is an aromatic amines used in the production of pigments, rubber and pesticides. The disposal of such organic component leads to substantial organic wastes. Montmorillonite is a smectite clay mineral based on alumino-silicate structure. It has been proposed as an adsorbent in water treatment application by various researchers. BDHDMA is the Quaternary Ammonium Compounds (QACs), which can alter the clay surface properties from hydrophilic to hydrophobic. BDHDMA-modified clay is, therefore, organophilic clay. It was prepared by replacing natural exchangeable inorganic cation of Montmorillonite with BDHDMA cation. The physical properties of both precursor and modified clays were compared. Adsorption experiments were carried out using a batch and fixed-bed column technique. Mixed sand-clays bed was used for the column experiments due to the fine particle size of clays. The permeability of the mixed sand-clay bed was also studied. The results showed that the permeability the mixed bed was decreased considerably in the presence of even small amount of clays. The experimental results of batch and fixed-bed column adsorption demonstrate the feasibility of utilizing BDHDMA-clay as an adsorbent for removing 2,2-bipyridyl from aqueous solution. Breakthrough volumes of the fixed-bed adsorption column tests were 921 and 498 mL at initial concentration of 2,2-bipyridyl equal to 0.88 and 1.5 mg L^-1 respectively. The carbon content of BDHDMA-clay was increased from 20.17 to 25.12 %wt after the batch adsorption because 2,2-bipyridyl intercalated into BDHDMA-clay structure. The 2,2-bipyridyl removal by BDHDMA-modified Montmorillonite is exothermic. The kinetic rate of adsorption is pseudo-second order with the rate constant (k) of 1.0029exp (-0.0003/T) g mg^-1 min^-1.

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We have investigated a method to produce carbonaceous adsorbents from moist and partially carbonized residues generated from a biomass refinery process in which biomass feedstock is converted into bio-chemicals. A series of laboratory-scale tests were conducted with some existing biomass (e.g., Japanese cedar and bamboo). The biomass feedstock was subjected to a steam-explosion treatment at 230°C to obtain saccharides and furfurals from the aqueous phase by the decomposition of the hemicelluloses fraction. The exploded solid material was further decomposed under the hydrothermal condition at 260 °C and water-soluble chemicals were separated. We used the solid residue from the series of treatments to produce chemicals, as the raw materials of the carbonaceous adsorbents. The solid residue was carbonized at 350 °C in aqueous phase with no oxidant, followed by aqueous phase oxidation of the intermediate at the same temperature under the coexistence of hydrogen peroxide. Thus-obtained carbonaceous materials were found to have mesoporous structures with 300-400 m²/g in BET surface area by nitrogen adsorption. The surface area was around one-third of typical commercial activated carbons.

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KDP crystals in a dye solution were colored by using an MSMPR crystallizer. The CSD (crystal size distribution) of KDP crystals was correlated by the size-dependent growth rate model. Two different concentrations of dye in the solution were examined for the MSMPR crystallization of KDP crystals. The coloring crystals from the concentrated dye solution formed the special shape having no (100) sector of KDP crystal. The dye distribution into the special KDP crystals from the dye solution was larger than unity. However, the coloring crystals from the dilute dye solution generated the general shape of KDP crystal. The dye distribution into the general KDP crystals was less than unity. The dye distribution as a function of crystal size was discussed.

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The measurement of supersaturation is important in the operation of crystallization processes, because it is a key factor to control crystal size distribution and shape which determine product quality. A monitoring system of the supersaturation using a quartz crystal sensor is applied to the supersaturation measurement. From the sudden drop of resonant frequency, the beginning of the formation of salt crystal on the sensor surface is determined while the sensor is directly cooled. The degree of supersatuation is computed from the temperature difference between the salt solution and the sensor at the moment. The performance of the supersaturation measurement is examined applying the sensor system to three different salt solutions. The experimental outcome, observational determination and photographic comparison indicate that the proposed measurement system is effective and useful to determine the supersaturation in the crystallization process.

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Oiling out phenomena (liquid-liquid phase separation phenomena) was often observed in crystallization of low molecular organic compounds such as pharmaceutical and/or agrochemical active ingredients. Oiling out phenomena was reported to affect crystal size, crystal habit and polymorphs of product crystals, but little operation design methods have been reported. In this study, oiling out phenomena of Mono Sodium Glutamate (MSG) was reported, and operational design for the profile of antisolvent addition was suggested in drowning out crystallization of Mono Sodium Glutamate (MSG). Three components solid-liquid equilibrium in the existence of MSG crystals (MSG- water- ethanol systems) was obtained by measuring the equilibrium solution concentration through HPLC, GC and Karl Fischer moisture meter. Over the critical zone, separated two liquid phases were observed (water rich and ethanol rich phase), and then MSG crystallized mainly from the water rich phase non-agitated supersaturated solution. To control optimum supersaturation it was suggested that operation design of antisolvent addition profile was needed, considering oiling out phenomena using the obtained phase diagram. The proposed crystallizaion operation would contribute to prevent nucleation, in order to control crystal size distribution.

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As well as the variation of particle size, the polymorphism of calcium carbonate was investigated using an anionic micelle system in a standard mixing reactor. Anionic surfactants of SDS (sodium dodecyl sulfate) and AOT (sodium bis (2-ethylhexyl) sulfosuccinate) were used to stabilize the aqueous reactant solutions for the reaction crystallization in continuous phase of cyclohexane (water in oil microemulsion system). As fractions of the surfactant and cyclohexane in the microemulsion gradually increased, the structural transformation of calcium carbonate from calcite to vaterite suddenly occurred. The polymorphic ratio of vaterite over calcite, X_v, could allow evaluating the homogeneity and completeness of micellization in each operating condition. The impact of SDS micelle on the morphological transformation was clearer than AOT. Based on the concurrent fluctuation of size and morphology in AOT reverse micelle, the phase discrepancy region of R (= [H₂O]/ [surfactant]) was also confirmed in the crystallization of calcium carbonate experimentally.

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Crystallization has been widely used for product separation and purification in the pharmaceutical, chemical and food industries. To reduce the time and cost in synthesizing crystallization processes, a number of systematic procedures have been established. However, the basis of these procedures requires the acquisition of the solid-liquid equilibrium (SLE) phase diagrams of the chemical systems under consideration, which are often not available in the literature. There is thus a great demand for determining SLE phase diagrams through experimental means. This work aims at presenting a generic scheme that can be carried out to experimentally construct the desired isobaric SLE phase diagram of a given system. Being driven by the process objectives, the scheme helps to generate phase diagrams that contain specific data useful for the development of the targeted process. To demonstrate the implementation of the generic scheme, an experimental apparatus and technique have been developed to measure the isobaric SLE phase diagrams of the ternary system phenol, bisphenol A and water at 1 atm. The technique utilized is based on the solid-disappearance method, in which a point on the saturation boundary is determined by detecting the temperature at which the last trace of solid in the sample mixture disappears. To provide auxiliary information for the phase diagram, crystals are also sampled by suction filtration and analyzed for identities. The resulting SLE phase diagram of the system is found to be in a high degree of accuracy and from which the saturation region of BPA and phenol/BPA adduct can be identified.

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Japan is poor in natural resources, so it is very beneficial if components dissolved in seawater can be used as resources. In our laboratory, the reactive crystallization process with the solution of components dissolved in seawater has been investigated by the absorption of CO₂ gas that causes the greenhouse effect. In this study, Ca ion was selected as a component of seawater so calcium carbonate particles were produced by gas-liquid reactive crystallization. A multistage column crystallizer was used, which is a column crystallizer partitioned with perforated plates. From an economical viewpoint, the multistage column crystallizer has been developed to overcome the redundancy of equipment due to the duplication of mixers and hardware in the cascade of MSMPR crystallizers. The aims of this study are to evaluate the characteristics of the multistage column crystallizer and to control the particle size of calcium carbonate. The staging effects of the multistage column crystallizer and the effects of operating parameters on the particle size and conversion of Ca ion were experimentally investigated by the three-stage column crystallizer.
The following conclusions were obtained:
1. The particle size distribution of calcium carbonate obtained in the multistage column crystallizer becomes sharp compared to that obtained in the standard column crystallizer.
2. With increasing initial concentration of calcium hydroxide, the particle size decreases and the particles are agglomerated easily.
3. When large particles are required, agglomerated particles are preferable to primary particles that are produced in the low-supersaturated liquid.

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The drying characteristics of porous materials immersed in the superheated steam fluidized bed drying (SSFBD) under reduced pressure were examined, experimentally. The B2 brick ball (Φ20 mm) and the glass beads (Φ0.12 mm) were used as the drying sample and the fluidizing particle, respectively. The effect of pressure in drying chamber on the drying characteristics for SSFBD was compared with that of hot air fluidized bed drying (HAFBD).The sample temperature in drying is almost equal to the boiling point of water even in the case of SSFBD. The sample temperature becomes lower as the pressure in drying chamber decreases since the boiling point of water decreases. The drying time becomes shorter as the pressure in drying chamber decreases. The drying characteristics of SSFBD become almost equal to those of HAFBD at the relatively low pressure (less than 20 kPa in this study), though the sample temperature in drying is higher and drying time is longer in the case of SSFBD than in the case of HAFBD at atmospheric pressure.

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Present study is focused on developing a rigorous thermodynamic model to correlate and predict the vapor-liquid equilibria of CO₂ in aqueous blends of DEA / MDEA. Modified Clegg-Pitzer equations have been used to develop the model for (CO₂ - MDEA - DEA- H₂O) system using the interaction parameters derived from the corresponding ternary systems (CO₂ - MDEA - H₂O) and (CO₂ - DEA - H₂O) without any additional parameter. Simulated annealing (SA), a non-traditional algorithm has been used in the numerical part of the model solution. Present work also reports new experimental results for CO₂ solubility in (DEA+MDEA+H₂O) blend in the temperature range 303 - 323 K, CO₂ partial pressure range 1- 100 kPa, and for relative amine compositions 1.5 mass% DEA + 28.5 mass% MDEA, 3 mass% DEA + 27 mass% MDEA, and 4.5 mass% DEA + 25.5 mass% MDEA. The model predictions have been found to be, in general, in good agreement with the literature results as well as experimental results of this work.

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In this work, the simultaneous absorption of CO₂ and H₂S into aqueous solutions of DEA is studied theoretically and experimentally. The effect of contact time, amine concentration and temperature on the rate of absorption and the selectivity were studied by absorption experiments in a wetted wall column. The diffusion-reaction processes for CO₂ and H₂S mass transfer into aqueous DEA are modeled according to Higbie's penetration theory with the assumption that all reactions are reversible. The pseudo-first-order rate constant of the reaction between CO₂ and DEA was obtained by adjusting the value of rate constant in the mathematical model and correlated. Model predicted results have been found to be in good agreement with the experimental results of rates of absorption of CO₂ and H₂S into (DEA+H₂O).

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Surfactants are widely found in many products such as detergent, cosmetics, shampoo and drugs. As environmental regulations tightened, there is increasing concern about reducing the surfactant concentration in effluent streams. Foam fractionation is the direct and continuous treatment which would allow for the reuse of both water and surfactant. In this study, two multi-stage foam fractionators with different tray spacing were set up to investigate the recovery of cetylpyridium chloride (CPC), a cationic surfactant, from aqueous solution. Effects of several important variables, including surfactant feed concentration and flow rate, air flow rate, foam height, number of trays and recycle position ratio, were systematically studied. It can be seen from the results that increasing air flow rate and surfactant concentration resulted in lowering enrichment ratio but increasingly % surfactant recovery. Effect of foam height on surfactant recovery was not as significant as it was on the enrichment ratio. With increasing feed flow rate, both enrichment ratio and surfactant recovery decreased. On a contrary, increasing number of trays was found to enhance both enrichment ratio and recovery. Lastly, changing recycle position was shown to have more impact on the column performance than changing the recycle ratio or tray spacing.

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Although there is a universal consensus on the importance of Process System Engineering, PSE technology in the real world seems to be heading for a plateau in recent years. PSE engineers have not been responding to the expectations of process industry which desires new concept and technology for the innovative process industry. This paper will discuss on a next generation of production management for the innovative process industry.

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A data-driven methodology for improving product yield by integrating principal component analysis (PCA) and liner discriminant analysis (LDA) is proposed. Referred to as Data-Driven Quality Improvement (DDQI), the proposed method can cope with qualitative as well as quantitative quality variables, determine the operating conditions that can achieve the desired product quality, optimize the operating condition under various constraints, and also evaluate the validity of the results. The relationship between product quality and operating conditions can be modeled by PCR when quality variables are quantitative. On the other hand, LDA can be used for modeling when quality variables are qualitative, e.g., good or bad. For such a qualitative quality variable, the yield, that is the percentage of good products to all products, can be specified on the basis of histograms for given categories. The histograms can be obtained from operation data, and they can be drawn against the axis defined by LDA. Once the desired yield is specified, the operating condition that can achieve the desired yield can be determined. The usefulness of the proposed method is demonstrated through a case study.

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This paper presents a framework for assessment and ranking of chemical manufacturing systems based on machine productivity indicators. The integrated approach discussed in this paper is based on Principle Component Analysis (PCA). The validity of the model is verified and validated by Numerical Taxonomy (NT) approach. Furthermore, a non-parametric correlation method, namely, Spearman correlation experiment shows high level of correlation between the findings of PCA and NT. To achieve the objectives of this study, a comprehensive study was conducted to locate all economic and technical indicators (indexes) which influence machine performance. These indicators are related to machine productivity, efficiency, effectiveness and profitability. 10 indicators were identified as major indexes impacting machinery conditions in manufacturing systems. Standard factors such as down time, time to repair, mean time between failure, operating time, value added and production value were considered as shaping factors. The industrial sectors are selected according to the format of International Standard for Industrial Classification of all economic activities (ISIC). Furthermore, Iranian industries are classified as 4-digit ISIC chemical sectors. Then, a comparative study is conducted through PCA among the 4-digit chemical sectors by considering the selected 10 indicators. PCA ranked the chemical sectors based on 10 indexes discussed in this paper. This in turn shows the weak and strong points of chemical manufacturing sector with respect to machine productivity. Furthermore, PCA identified which machine indicators have the major impacts on the performance of chemical sectors.

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Crystallization is fast becoming the separation operation of choice in the pharmaceutical and specialty chemical industries. As a result, the problem of development of crystallization-based separations is becoming more and more important. Typically, this development problem consists of several experimental, synthesis, and modeling tasks that need to be performed in an evolutionary manner by a development team of chemical scientists and process engineers. Due to the complexity and magnitude of these tasks, software tools that provide quantitative results and qualitative insights to help the development team in handling them are extremely valuable. This is especially true in view of the ever-present time pressure and resource limitations. We have developed one such software tool called SLEEK ("Solid-Liquid Equilibrium Engineering Kit"). In this paper we will provide a glimpse into SLEEK and focus on demonstrating its use in handling various process development tasks.

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In this paper, we apply the recent results that estimated an operator’s mental state to human interfaces in plant operations. We introduce a function that judges comprehensively the situation from both the state of the plant and mental state of the human operator. Such a human interface system can inform the operator of his/her mental state, give him/her alerts or timely guidance, and activate automatic sequences in place of the operator if required. An intelligent human interface will adjust its appearance and contents according to the situation. We propose a framework for an intelligent human-machine interface that provides adaptive aiding functions. We develop a simulation environment to evaluate various candidates of adaptive aiding methods. The total simulation system consists of a plant simulator, a human-computer interface model, and a human operator’s model that incorporates human mental state and attention. This human operator model can simulate the perception, cognition and execution abilities of an operator under various situations. The analysis at the level of cognition and judgment through simulation runs will help us evaluate the effects of all kinds of adaptive aiding.

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A fuel cell system needs to be designed in consideration of frequent start-up, shutdown and load change operations, since it is generally operated on demand manner. The conventional design approach such as a heat integration technique gives us the optimal structure of a heat exchanger network of a fuel cell system during the steady state operation. However, the extra units need to be added in the derived structure later for the transitional operations, when the fuel cell system is designed based on the steady state operation mode. In this research, the process synthesis method is proposed for the fuel cell systems considering start-up operation. The proposed method mainly consists of two optimization steps. In the first step, the optimal heat exchanger network and operation profiles are derived so that the fuel cell system can follow the predefined temperature profile. The transshipment model used in the conventional heat integration technique is extended to the dynamic transshipment model which can handle the heat accumulation to the devices during the transitional operation. In the second step, the operation profile is optimized as a function of time using more detailed dynamic models of the process. The proposed two-step optimization method is demonstrated through a case study. The proposed method has wide applicability to other processes where frequent start-up and shutdown are requested.

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This paper proposes a practical identification method of nonlinear plants with the Hammerstein-type model by using the relay feedback limit cycle test. Almost all industry plants are nonlinear and the controllers for the plant should be designed considering the nonlinear characteristics of the plant to achieve high control performances. But, practically, it is not an easy work to identify the nonlinear characteristics of the plant. In general, there are many types of nonlinear characteristics, and a nonlinear model of the plant has high degrees of freedom. For this problem, some nonlinear models consist of static nonlinear blocks and linear dynamic blocks are proposed. The Hammerstein model is a nonlinear plant model consists of a nonlinear block at the input and a linear dynamic block. This paper shows the identification method of the input nonlinear block characteristics. The identification test is a limit cycle test with a relay feedback configuration. By changing the output values of the relay element, the nonlinear block property can be estimated with the duty ratios and the deviation amplitudes of the plant output. This identification test is practical and the dynamic block can also be identified with the test. Furthermore, the input nonlinear characteristics can be estimated almost independently of the output and feedback nonlinear characteristics because of the small deviation of the plant condition during the relay feedback. A numerical simulation example is shown to illustrate the procedure of the proposed identification method.

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This paper first shows the timing analysis of the fieldbus control system (FCS) by considering both communication and control tasks at the same time. As a result, the fieldbus control loop time is formulated, and the condition of the loop operation is represented with the loop time in the FCS. Then a modified PID control algorithm is proposed to overcome varying communication delays. Finally, a fieldbus control loop is modeled and simulated to validate the timing analysis and the control algorithm. The simulation results show that the control algorithm works well for the common processes having a first-order model with dead time and the stability of the fieldbus control loop can be assured under the unpredictable and varying time delays caused by the fieldbus.

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In the ordinary analysis for process control, the variables to be measured and/or controlled are often specified as the quantities representative for the volume or cross-section in the equipment, although they are distributed in three-dimensional space. In case where there occur some undesirable problems in controlling the process, the governing equations used for process control or the parameters adopted in them have to be reexamined. It will be uneconomical and time consuming if such examinations are conducted experimentally. Computational fluid dynamics (CFD) has been developed so successfully that one can simulate flow phenomena with reasonable accuracy, particularly for laminar flow. In addition, many studies have been conducted to simulate turbulent flows and two-phase or multi-phase flows. The situation described above signals the coming of integration of CFD into process control. In the lecture utility of CFD simulations is discussed by showing the results obtained for the flow in a vessel with an ordinary rotating mixer or reciprocating mixer. Dynamic rotational and oscillatory three-dimensional flow in the vessel will be demonstrated with animation, which will be of great help for understanding the dynamic phenomena taking place in the mixing vessel. Perception of animated phenomena with eyes is quite different from observation of their consecutive still images. In addition, it is possible to create new or high order phenomena, which cannot be observed experimentally, with animation. Combination of CFD calculation and animation will provide a new interface between process analysis and control.

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Population balance modeling, which captures the physical phenomena of nucleation and crystal growth, was used to calculate the particle size distribution (PSD) in a set of continuous crystallizers in an ammonium sulfate plant. The FORTRAN code performing this calculation was coupled with an Excel spreadsheet for calculating material balances of the process. Despite simplifications such as assuming a homogeneous mixture in the crystallizer, the model was able to correctly predict the trend of changes in PSD due to variations in operating conditions such as the circulation flow rate around the crystallizer.

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In this work, the possibility of applying periodic operation to a membrane reactor for methane steam reforming was investigated by numerical simulations. The periodic operation considered was the modulation of reactor wall temperature, which was varied along the reactor axis and remained unchanged with respect to time. Three types of the wall temperature variation, namely sinusoidally continuous modulation, step change modulation and partial adiabatic operation, were considered and the corresponding reactor performances in terms of hydrogen production rate were compared. It was found that the hydrogen production rate could be enhanced by the proper wall temperature modulation compared to that obtained by operating the reactor at constant wall temperature under the conditions studied. The partial adiabatic operation showed the best performance among the three types of temperature modulations.

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Local fluctuations in optical transmittance and dynamic pressure signals induced by different patterns of bubble flow are examined simultaneously to extract physical information specific and common, if any, to each signal via both conventional power spectral and having recently evolved wavelet analyses. Passages of bubbles are viewed/registered at a fixed region or point in a two-dimensional (2-D) bubble column through a video camera, thin parallel laser sheet and differential pressure transducer. Apparent signal energy at each level of wavelet decomposition is utilized to determine the dominant frequency. It is found that the wavelet analysis provides more distinct values of the dominant frequencies than those evaluated from the Fourier-transform analysis in terms of power spectrum density. More importantly, the wavelet analysis is explored for further extraction of detailed information, especially time-dependent (such as shift in frequency with time) characteristics of the signals, thus providing better physical interpretation of bubbling phenomena.

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Nonlinear pattern formations have been investigated in many fields. In the field of reacting flow, the oscillatory pattern occurring in a liquid shear flow with a diffusive exothermic reaction has been reported. This oscillatory phenomenon is sensitive to change of viscosity and therefore occur easily near the wall because of the large shear stress. So, its quantitative model is needed to predict and control the oscillation in reactors with very small scale. However, the dynamic mechanism among various factors in the oscillatory pattern formations has not been fully understood. In this study, the relationship between oscillatory patterns and parameters i.e., width, viscosity, flow rate, is experimentally investigated in very narrow rectangular pipe flow and the oscillatory phenomenon is visualized using dye. As the results, it is seen that the flow pattern changes in flow direction and the occurring point of the oscillation is unstable caused by nonlinear interactions among many factors. Fractal analysis is introduced to investigate on the complexity of the nonlinear oscillatory mechanism. Fractal dimension is analyzed in both Lagrangian coordinate and Eulerian coordinate to analyze the characteristics of oscillations, especially changes of the patterns and instability of the occurring points. As the results, it is made clear that there are two types of instability, namely steady instability and unsteady instability. Moreover, fractal dimension for time series data is used to discuss on the effect of viscosity, and the oscillatory patterns changing in time and space are microscopically analyzed by using fractal dimension.

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A strategy is proposed for the synthesis of a flexible heat exchange network (HEN) that involves specified uncertainties in the source-stream temperatures and flow rates. The problem is decomposed into three main iterative steps: (1) the simultaneous HEN synthesis to attain a network configuration with a minimum total annual cost (TAC); and (2) the flexibility analysis to test the feasible operation of the network over the full range of uncertain parameters; (3) the exclusion of disqualified networks. For those networks resulting from the synthesis step that are not passing the examination of the flexibility analysis, some integer cuts are appended to forbid reconsidering the disqualified network configurations. A few iterations are required between the synthesis and the flexibility analysissteps. One numerical example is used, demonstrating the efficacy of the proposed flexible HEN synthesis method.

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