Ultrasonic effects on electrolysis of methyl viologen (MV²⁺) in surfactant and polymer solutions were investigated using an ultrasonic vibrating electrode (USVE). Addition of an anionic polymer or surfactants decreased the efficiency of the electrolysis of MV²⁺ due to a complex formation between MV²⁺ and the additives and, at a certain [additive]/[MV²⁺] ratio, the complex was adsorbed on the electrode. CV measurements using the USVE showed that ultrasonic irradiation increased the efficiency of the electrolysis greatly but was not able to avoid the adsorption of the complex on the electrode. Optical reflection measurements around the USVE indicated that the ultrasonic irradiation caused little change in the concentration of free MV²⁺ around the electrode. The results showed that the ultrasonic irradiation increased the efficiency of the electrolysis by promotion of mass transport around the electrode, while it was doubted that the irradiation increased the efficiency through decomposition of the complexes.

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In this study, a theoretical model for prediction of bubbling regimes in bubble formation from a single submerged orifice has been developed. The model takes into account both chamber pressure fluctuations, and bubble–bubble and bubble–wall interactions on bubbling regimes. In order to investigate the bubbling regimes experimentally, high-speed photographic, and bubble frequency measurements were used. The bubbling regimes included single bubbling, pairing and multiple bubbling. Predictions of the bubbling regimes using the model were in excellent agreement with the experimental results.

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We explored the mutual incorporation tendency of branched chain amino acids (L-leucine, L-isoleucine, L-valine) and isomorphic amino acids in cooling crystallization conducted in water solvent. In most cases, a guest amino acid (an impurity amino acid) whose side chain is longer than that of a host amino acid (a purified amino acid) was incorporated easily in a host amino acid. In this case, a solid solution was formed, and the c-axis of a host crystal structure was extended. Also, the crystal growth was inhibited. On the other hand, when a guest amino acid whose side chain is shorter than that of a host amino acid was incorporated in a host, the lattice length and the crystal morphology of a host amino acid was the same as that of control. From these results, a mutual incorporation model was proposed.

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The optical-response extraction of Au(III) with an azo compound, bis(2,2′-dipyridyl-6-yl)diazene (BDPDA), was studied. The distribution ratio of Au was increased by the configuration change of BDPDA from trans to cis under UV irradiation (340 nm); however, the distribution ratios under UV irradiation were less than 3 times those under VIS irradiation (465 nm). For further improvement of optical-response extraction, the synergistic extraction of Au using octanoic acid as a synergist was tested. Octanoic acid was coordinated mainly with the complex of Au and cis-BDPDA, and effectively enhanced the hydrophobicity of the complex. The distribution ratio of Au under the UV irradiation increased with increasing the concentration of octanoic acid in the organic phase. In the presence of 3 mol/L octanoic acid, the distribution ratio under the UV irradiation reached up to 10 times that under the VIS irradiation.

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We examined a two-step process concept for PLA polymerization with a small amount of catalyst addition to achieve both a high conversion ratio and a small degree of yellowing. First, we developed a calculation program for the chemical reactions. Next, we carried out beaker-scale PLA polymerization experiments to measure the degrees of yellowing. The measured values were compared to amounts of thermal degradation estimated from the calculations simulating the experiments. Then, bench-scale equipment experiments were carried out on the basis of the obtained conditions. The conversion ratios and the degrees of yellowing of the PLA samples obtained from the bench-scale equipment were compared to the numerical simulation results to verify the process concept and conditions. 170°C was good for a first polymerization temperature to avoid a runaway reaction due to heat generation in the ring-opening polymerization. To minimize the degree of yellowing at conversion ratio of 0.9, we chose 5 h as both the first polymerization time at 170°C and the second polymerization time at 190°C. From bench-scale continuous polymerization experiments, we got PLA that had a conversion ratio of 0.92, a weight average molecular weight of 1.96 × 10⁵, and a b-value of 2.42 to verify the concept of the two-step process.

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Oxidation experiments of β-carotene in the presence of α-tocopherol were conducted in a biphasic oil–water system having a definite interfacial area. The induction period in which the β-carotene concentration slowly decreased was about 1.6 times longer than that in the single oil phase system when the initial α-tocopherol concentrations were the same. The existence of the water phase suppressed the α-tocopherol consumption, resulting in a delay in the progress of the β-carotene oxidation. A kinetic model was constructed by modifying the oxidation and antioxidation mechanisms of β-carotene in the single oil phase and incorporating the reaction of the α-tocopherol peroxyl radical with the oxonium ion at the oil–water interface. The model quantitatively described the oxidation behavior of β-carotene in the biphasic system over wide ranges of temperature, initial α-tocopherol concentration and interfacial area.

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Production of a bifidogenic growth stimulator (BGS) by propionibacterial strains was investigated using lactic acid as a carbon source. The maximum concentration (1.9 mg/L) of BGS was obtained in the mono-cultivation of Propionibacterium shermanii using 20 g/L of lactic acid. The co-cultivation, in which lactose was gradually converted only to lactic acid by a homo-fermentative lactic acid bacterium and subsequently the lactic acid was used as a carbon source for BGS production by P. shermanii, resulted in the successful BGS production. The BGS concentration obtained in the co-cultivations of P. shermanii and Lactobacillus casei or P. shermanii and Lactobacillus bulgaricus was 1.8 or 6.4 mg/L, respectively.

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By utilizing the pores of carbonaceous materials as a kind of nanoreactor, nanosized titania (TiO₂) was prepared. The carbon materials acted as a support matrix for obtained titania nanostructures, which were immobilized on the internal surface. The precursor titanium tetraisopropoxide (TTIP) was first adsorbed in the pores of the carrier material. Titania was subsequently formed within the carrier pores by flash pyrolysis. Space confinement of the pores of the carrier was successfully applied to obtain only nanosized titania formed exclusively at the desired place inside the pores. On the other hand, transport resistance in the small pores and rapid heating helped to maximize titania yields because of quickly reaching a temperature regime where the reaction rate of the precursor exceeded its diffusive flux out of the carrier pores. With this method, titania loadings as high as 14 wt% were achieved. Obtained titania existed as monodisperse nanoparticles of 5 to 8 nm in diameter. The nanoparticles were single-crystalline of both anatase and rutile phases. Process parameters were investigated to clarify the optimum operation mode of the nanoreactor for maximum product yields. The titania yield was found to increase exponentially with rising reaction temperature. Rapid heating allowed for improving the titania yield significantly and was crucial to obtain nanoparticles of a good quality, i.e., narrow size distribution and good dispersion. The pore structure of the carrier material had a notable effect on the titania yield, i.e., the yield at very high temperatures in an ordered pore system were higher than in a random pore system. By variation of the precursor loading and changing the reactant, mass transport mechanisms in the pores could be clarified.

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The dependence of water pool pH on the water content of the W/O microemulsions was investigated by using the absorbance ratio of pH-sensitive probe pyranine. The W/O microemulsions were prepared with a mixture of an aqueous solution of pH 1–13 containing pyranine, AOT and isooctane at w₀ = [water]/[AOT] = 10, 20, 30 and 40. The water pool pH was estimated by comparing the absorbance ratios given by the W/O microemulsions and the aqueous solutions of pH 1–13. The experimental results suggest that the water pool pH is kept approximately constant as a buffer regardless of the solution pH 4–11, and that the water pool pH increases with decreasing w₀. As an additive factor to affect the absorbance ratio of pyranine, high Na⁺ counterion concentration in the water pool was focused on because the roughly estimated Na⁺ concentration increases from 1.4 to 5.6 M with decreasing w₀. It was found by the ratio measurements for NaOH aqueous solutions that the ratio increases at NaOH concentration > 5 M, which suggests that the ratio given by the W/O microemulsions is affected by not only pH, but also high Na⁺ concentration in the water pool. It would be correct to assume that the AOT-based W/O microemulsions play a role of the buffer, and that the water pool pH depends on w₀. However, attention should be paid to the possibility that the water pool pH estimated by the absorbance ratio of pyranine may include the effect of high Na⁺ concentration in the water pool.

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Cyclic reaction performances and pore structural change of Ca-solid reactants for the CaO/CO₂ chemical heat pump designed for upgrading and storing high-temperature thermal energy were studied. It was observed that solid reactants prepared using CaCO₃ particles have micro-order pore structure among particles and nano-order pore structure in the particles. With the proposed model, in which the pore structure change during reactions is considered, the numerical analysis suggested that the decarbonation rate was determined by nano-order pore structure change. In experiments of cyclic reaction at 923 K, pore volume change corresponding to the greater part of the total volume change between carbonation and decarbonation was observed in the range from 10 to 30 nm of pore radius.

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A waste incineration atmosphere was simulated as HCl/H₂O/O₂/CO₂/N₂ in order to experimentally study chlorine behavior as temperature ranges from 1173 to 1473 K and residence time varies. The results show that Cl radical, produced by the decomposition of HCl at high temperature mainly recombine to form Cl₂ and HCl at the quenching section. It was found that temperature, residence time, cooling rate and feeding gas composition influence Cl₂ concentration. In addition, thermodynamic equilibrium calculations performed to understand the behavior of chlorine for this reaction system. In spite of the discrepancy existing between experimental and calculation results, similar trends have the capability to describe the behavior of chlorine.

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Reclaimed water for stream augmentation or landscape impound requires low phosphorus contents to avoid eutrophication. A synthetic compressible media filtration system was previously developed for the purpose of wastewater reclamation. However, the filtration system was limited for removal of soluble matters in secondary treated wastewater, such as phosphorus. The objective of this study is to evaluate the optimum coagulation conditions for removal of phosphorus in effluent from a wastewater treatment plant (WWTP) using the filtration system combined with coagulation. Coagulation conditions including selection of coagulant, coagulant dose, mixing conditions were determined through jar-test. Also a field-test with the coagulation–filtration system was conducted to evaluated operation factors such as compression rate of media and periodic backwash. Polyaluminum chloride (PAC) demonstrated the best performance in terms of total phosphorus (TP) removal efficiency and stability of pH among coagulant used in this experiment. Since the change in mixing conditions had little effect on TP removal, in-line coagulant supplying could be feasible for the coagulation–filtration system. Increasing the compression rate of the filter media from 0 to 50% increased the TP removal efficiency within only 10%. This made great changes in the filtration pressure and the flow rate, which is related to operating cost of the system, simultaneously. Compared to the filtration system with no addition of coagulation, the addition of coagulant enhanced the removal of phosphorus along with turbidity, but decreased the operation time between each backwashing cycle. One needs to consider the various operation parameters examined in this study as well as the requirement of phosphorus removal, when operating the coagulation–filtration system. Consequently, the coagulation–filtration system, which requires a small area, can effectively reduce the phosphorus contents of WWTP effluent, and make it suitable for reuse purposes.

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