JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
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Editorial Note
Physical Properties and Physical Chemistry
  • Jingshu Xu, Yanyu Song, Yunyun Gao, Shihua Sang, Xiaofeng He
    Type: Journal Review
    2019 Volume 52 Issue 10 Pages 783-788
    Published: October 20, 2019
    Released: October 20, 2019
    JOURNALS FREE ACCESS

    The present study investigates the metastable phase equilibria of ternary systems KCl–MgCl2–H2O and MgB4O7–MgCl2–H2O at 273 K by an isothermal evaporation method. The solubility data of the two ternary systems were determined. According to the solubility data, the corresponding metastable phase diagrams were plotted. The equilibrium solid phases of invariant points were identified by X-ray powder diffractometry. The results show that the ternary system KCl–MgCl2–H2O has a double salt KCl·MgCl2·6H2O. Its metastable phase diagram contains three univariate curves, two invariant points and three crystallization areas, which correspond to MgCl2·6H2O, KCl and KCl·MgCl2·6H2O. Compared with the stable phase diagram at 273 K, the unsaturated phase region increases slightly in the metastable phase diagram. The ternary system MgB4O7–MgCl2–H2O is of simple co-saturated type without double salt or solid solution. The metastable phase diagram contains two univariate curves, one invariant point and two crystallization fields, and the corresponding solid phases are MgCl2·6H2O and MgB4O7·9H2O. Comparing the metastable diagram against the stable phase diagram at the same temperature, it can be seen that the solubility of MgB4O7 in the metastable state obviously increased, which means that magnesium borate was significantly supersaturated under the metastable state.

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Thermal Engineering
  • Weraporn Pivsa-Art, Chaiyapop Siraworakun, Sommai Pivsa-Art
    Type: Research Paper
    2019 Volume 52 Issue 10 Pages 789-792
    Published: October 20, 2019
    Released: October 20, 2019
    JOURNALS FREE ACCESS

    The emulsion process is a main method for cosmetic cream manufacturing. For each cream product, the emulsion process is different according to the product properties. Two types of emulsion processes are generally used for cosmetic cream production: oil in water and water in oil techniques. The oil in water process is most extensively used for cosmetic cream production. The reaction is carried out at 80°C. After the reaction is completed, the mixture is cooled to 35°C for the addition of additives to the mixture. The cooling step of a large quantity of cream produced takes a long time of more than 5 h. This slow cooling step limits the cream production cycle. A conventional method to cool the reactor is done by using air blowing from an electric fan, which does not significantly reduce the cooling time of the cream product. To reduce the cooling time while the product quality was controlled, the water cooling system to cream production process was investigated. A water chilling system was designed to produce 5 to 15°C cooling water and the water flow rate could be controlled. The cooling jacket was designed to transfer heat from the cosmetic cream reactor to the cooling water system. The viscosity of the cosmetic cream was measured to verify the cream quality. The synthesis processes were carried out to find the optimal operating system. It was found that the optimal cooling condition of emulsion process was with 8°C cooling water reducing the cooling time of cream product from 80 to 35°C by more than half of the original time.

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Biochemical, Food and Medical Engineering
  • Yoshiki Fukuhara, Takayuki Takei, Takuma Yoshinaga, Hiroto Nishimata, ...
    Type: Research Paper
    2019 Volume 52 Issue 10 Pages 793-798
    Published: October 20, 2019
    Released: October 20, 2019
    JOURNALS FREE ACCESS

    Injectable hydrogels provide the advantage of moldability to fill irregular-shaped wounds compared with pre-formed hydrogels. We previously reported the usefulness of sugar beet pectin (SBP) as an injectable hydrogel material. For application of the SBP hydrogel to wound care, the hydrogel needs to enhance tissue adhesiveness and have an efficacy for promotion of wound healing. To this end, chitosan-gluconic acid conjugate (CG) was incorporated into SBP hydrogel. We showed that the SBP/CG aqueous solution rapidly formed hydrogel (<1 min) via a horseradish peroxidase-mediated oxidative reaction. The tissue adhesiveness of the SBP/CG composite hydrogel was greater than that of a plain SBP hydrogel. The composite hydrogel promoted infiltration of polymorphonuclear leukocytes, which is an important step to promote wound healing. Furthermore, the incorporation of CG enhanced degradation of the hydrogel is promising in the care of ulcers and erosions of digestive system. These results show that the composite hydrogel is useful as an injectable wound dressing.

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Micro and Nano Systems
  • Yuki Mizoguchi, Akinori Muto
    Type: Research Paper
    2019 Volume 52 Issue 10 Pages 799-804
    Published: October 20, 2019
    Released: October 20, 2019
    JOURNALS FREE ACCESS

    The present study examines the use of an electric field to demulsify oil-in-water (O/W) emulsions stabilized using a nonionic surfactant. First, we prepared an O/W emulsion with a low surfactant content and found that the application of an electric field promoted demulsification. The effects of the electric field intensity, droplet size, and organic solvent content on the demulsification efficiency were evaluated. The application of a high electric field was found to lead to the coalescence of droplets in O/W emulsions. However, this technique was only effective for large droplets. As the organic solvent content increased, the droplet size became larger and the demulsification efficiency improved. We investigated a combination of preconcentration and electric-field-based demulsification for wastewater treatment. Preconcentration was found to be effective for enabling the demulsification of dilute O/W emulsions.

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Environment
  • Guanghua Lu, Changsheng Yue, Shiye Liu, Min Guo, Mei Zhang
    Type: Research Paper
    2019 Volume 52 Issue 10 Pages 805-810
    Published: October 20, 2019
    Released: October 20, 2019
    JOURNALS FREE ACCESS

    Thermal desorption has been widely used as an efficient method for remediating Hg-contaminated, whereas the current thermal treatment approach generally needed a high temperature (above 600°C), which negatively affected the soil composition and consumed energy. For the challenge, this study developed a novel Na2S leaching assisting thermal desorption method for thoroughly repairing the severely Hg-polluted (168 mg/kg Hg) soil with a declined temperature (350°C). The results of this study indicate that Hg content could only be reduced from 168 mg/kg to 32.4 mg/kg by directly heating the soil at 550°C for 60 min. However, the Na2S leaching assisting thermal desorption method could realize the low temperature and thorough remediation for highly Hg-polluted soil. When the thermal desorption temperature was reduced to 350°C and the thermal desorption time was kept at 60 min, the Hg content was decreased to 1.0 mg/kg, which was less than the Chinese National Standard. This should be ascribed to the fact that high-temperature volatile Hg compounds in the soil were first removed by Na2S leaching pretreatment. This new collaborative remediation method could not only realize mild thermal desorption but also provide useful guidance for the severely Hg-contaminated soil.

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