Formation of a ring-like deposit of solute during the evaporation of a binary liquid sessile droplet on a substrate was studied both experimentally and numerically. The effects of the droplet spread radius and substrate surface temperature on ring-like deposit of solute were investigated. The ring width increased with a decrease in the spread radius and the substrate temperature. The evaporation rate distributions on the droplet surface were numerically obtained to predict the shape of the thin film of solute after the evaporation using a theoretical model for solute transfer in a sessile droplet. When the substrate temperature was low, the increase in the evaporation rate near the contact line was inhibited. As a result, the velocity in the droplet toward the contact line, which caused the solute transfer, was small and then the ring width increases.

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By assuming that a reaction is mainly a single-radical chain termination, the mechanism, for solid-phase radical graft polymerization of acrylic acid (AA) onto polypropylene (PP), was analyzed based on our previous experimental data. The Monte Carlo simulation technique was employed to investigate the kinetics of radical graft polymerization on the solid phase to determine the kinetic rate constants of all elementary reactions. The simulated total amount of radicals, which only increases quickly at the start of the reaction, indicates that the stationary state assumption for the studied system is correct. The simulated graft yields at various initiator and monomer concentrations are shown to be quite in a good agreement with the experimental data. Furthermore, the simulated graft polymerization rate is compared with a theoretical kinetics model, which shows that the simulated results coincide with theoretical ones. All the studies in this paper prove that the Monte Carlo simulation technique is an effective method for investigating the grafting reaction of free radical polymerization on the solid phase and is a good way to get those unknown parameters in a theoretical kinetic model.

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A sonochemical luminescent (SCL) method is proposed which permits to measure the reactivity of substrates with active oxygen species. The method involves quenching of luminol’s sonochemical luminescence by addition of a substrate and kinetically analyzing the quenching behavior. Use of the method gave findings of the reactivity of halid ions, vinyl monomers, phenols and other organic compounds. The findings showed that iodide ion was more reactive than bromide and chloride ions, and that the monomers were more reactive than the corresponding polymers. Further substrates, substituted for electron donating groups, were found to increase their reactivity, which was significant for multi-substituted phenols. The method was applicable to most of the substrates experimented.

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The adsorption kinetics of residual phospholipids from hydrated and alkali-refined soy oil with regenerated clay was studied by measuring the concentration change of phospholipids in the oils before and after adsorption with time. Experimental results indicated that the adsorption efficiency and regeneration efficiency of the regenerated clay was 69.3% and 91.3%, respectively. The adsorption rate was found to increase upon increasing the ratio of clay/oil, agitation speed or temperature. It was also found to increase by decreasing the particle diameter of the clay. The effects of the particle diameter of the clay and the ratio of clay/oil were significant while those of agitation speed and temperature were not. The empirical rate expression for the adsorption of phospholipids has been determined as

ln(C/C₀) = –338.708exp(–4018/RT)d^–0.953r^0.564s^0.231t^0.1

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In this work we have investigated the thermal decomposition of N₂O in order to establish an industrial process for N₂O abatement in an adipic acid production plant. N₂O from an adipic acid plant was decomposed in a plug-flow reactor under atmospheric pressure at temperatures of less than 1500 K. Our experimental results concerning N₂O conversion and NO yields accorded with the results of simulations using kinetic parameters from the literature. Furthermore, we simulated the conversion of N₂O and NO yield by hypothesizing that the reaction was carried out in an adiabatic reactor incorporating a completely uniform mixing system. The results of the simulation indicate that N₂O at concentrations between 30 and 50 vol% is spontaneously decomposed into N₂, O₂ and NO at a reaction temperature between 1273 and 1473 K by using its own heat of reaction. The simulation used in this study can be applied to the design and optimization of a thermal decomposition process for N₂O.

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Lithium silicate has been studied mainly as a CO₂ absorbent at high temperatures of around 773 K. It has recently been observed that lithium silicate also absorbs atmospheric CO₂ at room temperature. In this study, lithium silicate absorbent was packed in an absorption column and the effectiveness of this column was confirmed. Based on this result, the effectiveness of lithium silicate in absorbing atmospheric CO₂ at room temperature was evaluated. It was found that humidity promoted absorption. This mechanism was examined and ascribed to the relationship between the water content in lithium silicate and CO₂ absorption. In addition, the effectiveness of lithium silicate absorbent was compared with that of a commercially available absorbent (soda lime) under conditions of controlled humidity, and the superiority of lithium silicate was confirmed.

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The growth phenomena of adhered fine crystals on the surface of growing L-alanine crystals were investigated under homogeneous magnetic fields of 5 T and 0 T.
Surface topography of grown crystals was observed using a differential interference microscope and an atomic force microscopy (AFM) system. We found that the direction of the adhered fine crystals could be controlled by the magnetic field. Crystal growth steps generated from the adhered crystals on a seed crystal under 5 T and 0 T were markedly different. The growth steps under the magnetic field were smooth in the [–2 1 0], [2 –1 0] directions and rough in the [0 0 1], [0 0 –1] directions. On the other hand, the growth steps under 0 T were rough and randomly spread over the surface of the seed crystal.

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A thermosensitive microgel adsorbent, which adsorbs and desorbs a specific heavy metal ion by the temperature swing, was developed. The microgels was prepared by the emulsion polymerization using anionic polymerizable surfactant. N-Isopropylacrylamide (NIPA) and N-(4-vinyl)benzyl ethylenediamine were used as the primary monomer and the chelating monomer, respectively. In the preparation, the molecular imprinting technique using Cu(II) ions as a target heavy metal ion was adopted. The thermosensitive microgel adsorbents were dispersed stably even if the temperature of the suspension exceeded the transition temperature of poly(NIPA), and Cu(II) ions were adsorbed quickly in response to the temperature change.

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Composite particles composed of poly(styrene-co-n-butyl acrylate) and magnetite powder treated with the various coupling agents were prepared by using suspension polymerization. The effect of the surface treatment by coupling agents on the structure of composite particles was mainly investigated by observing the dispersion state of magnetite powder in composite particles and triboelectric charge property. The treatment by the coupling agents with an unsaturated carbon bond and hydrophobic group of a long carbon chain resulted in a better inclusion of magnetic powder into composite particles. The coupling agent species greatly affected the triboelectric charge property of composite particles.
It was found that a specific coupling agent with a high polarity acted as the charge controlling agent for the toner application. The effect of the surface treatment on the particle size distribution was also discussed.

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Monodispersed nanosize titania partciels with a coefficient of variation of 20% (the geometric standard deviation of 1.2) or less were prepared by the hydrolysis and condensation of tetraethylorthotitanate (TEOT) in the presence of hydroxypropylcellulose (HPC). The effects of the TEOT, water, and HPC concentrations on the mean particle size and the coefficient of variation were examined. In the case where the initial TEOT concentration was low and the initial water and HPC concentrations were high, particles of small size were obtained. The particles with low coefficient of variation were obtained at low initial water concentrations, high initial TEOT concentrations and high HPC concentrations. The condition for TEOT of 0.025 mol/dm³, H₂O of 2.0 mol/dm³, and HPC of 2.5 g/cm³ in a batchwise experiment gave particles with a mean size of 38 nm and a coefficient of variation of 19% (a geometric standard deviation of 1.20). The monodispersed nanosize fine particles were continuously synthesized using a slug flow tubular reactor. The particles obtained by a continuous experiment were almost the same as those in the batchwise experiment.

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A hydro-cyclone was applied to the separation of gypsum, a byproduct of the wet limestone gypsum flue gas desulfurization (FGD) process, that uses limestone as the raw material. Using a high slurry concentration, similar to that used in an actual plant, the effect of the inlet shape and ceiling clearance of the hydro-cyclone was examined, and a model for predicting the efficiency of separation is proposed.
The results indicate that the 50% cut size decreases when the inlet width ratio is decreased. Over the entire range of inlet width ratio, the limestone content of the blow-down flow decreased by approximately half, compared with that of the feed, and it was confirmed the purity of the gypsum could be improved by decreasing the limestone content.
When the ceiling clearance of the hydro-cyclone was changed, an optimum ceiling clearance for obtaining a minimal cut size was found.
A model for predicting the slurry concentration that is proportional to the solid throughput of a hydro-cyclone and the improvement in gypsum purity in an actual plant is proposed. The results of this calculation model agreed well with experiment data.

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Expert systems can play a very important role in manufacturing processes by locating problems as soon as they arise. The most important ingredient in any expert system is knowledge. The current knowledge acquisition method is slow and tedious and there exist substantial difficulties in acquiring the knowledge for complex processes. An approach is proposed that makes use of the machine learning technique, C4.5, to generate a decision tree. The decision tree is translated into rules that are implemented into the expert system shell, G2. The rules are tested using a sensitivity analysis of the system. The approach works well, but depends on both the quality and quantity of available training data.

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This paper addresses the implementation of a dual mode nonlinear model predictive control strategy integrating a nonlinear model predictive control (NMPC) with a local linear control method to control the product concentration in a continuous stirred tank reactor (CSTR), where a single exothermic reaction is carried out. For safe reactor operation, a reactor temperature path constraint is also considered in the NMPC formulation. Two well-developed linear controllers: state feedback linearizing control (SFC) and proportional-integral-derivative control (PID) technique are studied within the dual mode control framework. An Extended Kalman Filter (EKF) is incorporated into the dual mode NMPC to on-line estimate the unmeasured concentration of substances in the CSTR as well as uncertain key model parameters using an available temperature measurement. It has been found via simulation studies that the proposed dual mode NMPC, using either SFC or PID controller, connected with the EKF provides satisfactory control performance for set point tracking problem. The robustness of the controller in the presence of parametric uncertainties is also enhanced by the inclusion of the EKF. Moreover, the on-line computational time required by the dual mode NMPC is substantially decreased compared to that of an original NMPC.

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In this paper, we propose an algorithm based on basic simulated annealing (SA) to optimize unsteady chemical systems. By parametrizing the control inputs, the system described by a set of differential-algebraic equations is first transferred into a nonlinear programming (NLP) problem. By using a linear function, we furthermore convert discretized control inputs and time grids into the control profile with a variable time length to improve numerical quality. Thus, the discretized control inputs and the corresponding execution time lengths will be considered as a set of decision variables. Then, these decision variables are globally determined by our algorithm with the help of a special integrator to optimize the performance index. In order to exhibit the facility of the proposed algorithm, several typical examples are provided.

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Simulations of the natural gas steam reforming process were carried out to investigate the effect of the steam/carbon (S/C) ratio at the steam reformer and the O₂/CO ratio at the CO preferential oxidation removal reactor on the thermal efficiency of a natural gas fuel processor in a residential Polymer Electrolyte Fuel Cell (PEFC) system. The thermal efficiency shows a maximum at a certain S/C ratio. The S/C ratio giving the maximum efficiency decreases as the O₂/CO ratio decreases. The effect of the methanation of CO, a side reaction of CO preferential oxidation, on the thermal efficiency was also investigated. Moreover, the CO methanation removal process was compared with the CO oxidation removal process in the PEFC system.

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The feasibility of improving the biodegradability of refractory pollutants in sub- and supercritical water was investigated. Poly vinyl alcohol (PVA) was chosen as a test material to represent high-molecular-weight refractory pollutants. At a temperature of 350°C, BOD increased from 100 mg/L to 3,350 mg/L within 17.4 min, while TOC reduction did not exceed 18%. BOD improvement was calculated based on the change of molecular weight distribution to the range lower than 380 and the decrease of UV absorbance to the range lower than 2.0 × 10⁴ μV in the same molecular weight range. The structural conversion from PVA to biodegradable substances was mainly obtained from hydrolysis and thermal decomposition under sub- and supercritical water conditions. The suitable values of biodegradability (BOD/TOC) for conventional biological treatment methods, 0.78 and 0.79, were obtained in 17.4 min at 350°C and in 7.4 min at 400°C, respectively. The production of biodegradable substances from refractory pollutants by sub- and supercritical water reactions was the most important factor on the viewpoint of the pretreatment of refractory pollutants.

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The negative ion species generated by DC corona discharge of ultra pure air under atmospheric pressure were observed using quadrupole mass spectrometry (QMS), and the concentrations of O^–, O₂^–, O₃^–, NO^–, and NO₂^– were measured. The behavior of the atomic oxygen radical anion (O^–) was examined intensively. The possibility of selective generation of O^– with ozone (O₃) suppression was examined under the conditions of a low O₂ concentration, water addition, and NO addition. It was confirmed that a low O₂ concentration is advantageous and that water addition is disadvantageous for the selective O^– generation with O₃ suppression. An adequate concentration of NO can control O₃ generation effectively without any O^– decrease.

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