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粉体基礎現象研究グループ会の本年度第1回講演会を下記要領で開催いたします。ご参加をご検討いただけますよう、お願いいたします。
■日時: 平成19年9月14日(金)10:30~14:30 ■場所: 岡山大学工学部1号館218室 (岡山市津島中3-1-1) (アクセスはhttp://www.eng.okayama-u.ac.jp/の「交通アクセス」をご参照ください) 【プログラム】 10:30-11:30 Charging behaviour of the oil/water interface in salt solutions George V. Franks (Associate Prof.), Chemical and Biomolecular Engineering, The University of Melbourne The isoelectric point of the pristine oil/water interface is at about pH 4. Evidence supporting the preferential adsorption of hydroxide anion as the mechanism for development of the negative surface charge is presented. Zeta potential measurements of surfactant-free 2 vol% hexadecane-in-water emulsions at pH 9 in the presence of various monovalent salts will be reported. The surface charge density (-5 uC cm^-2 at pH 9) and zeta potential of these emulsions are independent of the identities of the monovalent cations and anions (excepting hydroxide) up to 0.01 M electrolyte concentrations. The magnitude of the negative zeta potentials decrease with the log of the salt concentration between 0.1 and 11 mM, independent of the identity of the anion of the sodium salts of iodide, bromide, chloride, fluoride, perchlorate or iodate, or of the identity of the cation of the chloride salts of Li, Na or Cs. These results imply that neither hydration enthalpies nor ion dispersion potentials are significant in affecting the charge created by the hydroxide ion at the pristine oil/water interface at up to 0.01 M salt concentrations. Zeta potential measurements of oil-in-water emulsions cannot be made at higher salt concentrations because their low magnitude makes the emulsions very unstable such that phase separation results. Anecdotal evidence suggests that at higher salt concentration the behaviour of oil-in-water emulsions depends upon the type of monovalent salt. Macroscopic observations of emulsion behaviour at higher salt concentration such as coalescence and creaming rates, and droplet size measurements as a function of time, may provide evidence of ion specific effects in pure oil-in-water emulsions. This evidence may be able to elucidate the relative influence of ion hydration and ion polarisability. 11:30-12:00 Phase behavior and size variation of W/O microemulsions prepared with Na-AOT and/or H-AOT Jun Oshitani (Associate Prof.), Applied Chemistry, Okayama University An anionic surfactant Na-AOT, having a Na+ counterion and a SO3- polar headgroup, is one of the commonly used surfactants to prepare W/O microemulsions. The properties of the W/O microemulsions have been widely studied. Peculiar characteristics of the water pool, differing from bulk water, have been reported. Counterion’s effect on the properties has been also investigated by using the ion-exchanged AOTs such as Ca-AOT. The interaction between the counterion and the polar headgroup and their hydration are the points of the argument. We focus on the counterion’s screening of the electrostatic repulsion between the polar headgroups in the W/O microemulsions. The counterion would have an important role to form the stable interface by screening the repulsion. There are many papers about the W/O microemulsions prepared with AOT, however, to our knowledge, the screening effect on phase behavior and size of the W/O microemulsions has not been studied. In this study, Na-AOT and H-AOT were used; the CMC measurements indicate that bonding interaction between an H+ and a SO3- group is much weaker than that between a Na+ and a SO3- group. The W/O microemulsions containing Na-AOT and/or H-AOT were prepared with a pure water or NaOH aqueous solutions by changing the ratio [Na+] / [AOT-], at which [Na+] includes total sodium ions from Na-AOT and NaOH. DLS and FT-IR measurements were carried out to examine the size, the phase behavior, the micro structure at the interface and the hydrogen bonding in the water pool respectively. It was found that the size gradually increases with decreasing the ratio from 1.0 until phase separation occurs, whereas the size is almost constant regardless of phase separation when the ratio is increased from 1.0. The phase boundary shifts to the smaller ratio as increasing the amount of NaOH, indicating that H+ from H-AOT is exchanged for Na+ from NaOH. FT-IR spectra relating to -SO3-, C=O and O-H vibration bands indicate that the phase boundary and the size variation result from the fact that the screening effect depends on the amount of the sodium counterion. 12:00-13:30 Lunch 13:30-14:00 Development of industrial scale high performance separation system for removal of Cl-containing plastics from waste plastics by Using Gas-Solid Fluidized Bed Mikio Yoshida (Assistant Prof.), Applied Chemistry, Okayama University Tatsuya Zushi and Yasuo Kubo, Nagata Engineering Co., Ltd. Rotating-type pilot-scale FBMS (fluidized bed medium separation) apparatus that can separate solid waste materials continuously was newly designed and developed in order to achieve the required high efficiency and accuracy of the separation of the waste materials. By using this apparatus, the separation of non Cl-containing plastics (= non Cl-plastics) from the mixture of non Cl-plastics and Cl-containing plastics (= Cl-plastics) was performed under various separation conditions. Waste plastics in shredder residues of electrical and electronic equipments (real waste plastics) and model waste plastics were used as the objects for separation. Unclassified sands were employed as fluidized particles so as to reduce the cost of the separation that is the requirements in practical application of FBMS. Based on the investigation, operating conditions were optimized and high efficiency and accuracy of plastics separation were achieved. 14:00-14:30 Evaluation of adhesion characteristics under high temperature condition by air penetration method Kuniaki Gotoh (Prof.), Applied Chemistry, Okayama University Adhesion characteristic is one of the most important powder characteristics for the designing of unit operation in powder processes or estimation of powder behavior in the operation. Evaluation methods of the adhesion characteristics, therefore, have been investigated by many researches. Many of the popular evaluation methods are, however, difficult to apply to the measurements under high temperature conditions although the characteristic under high temperature condition is required for many processes and operation. Thus, this study is aimed to develop a new adhesion characteristic evaluation method of that is easy to apply to a measurement under high temperature. The newly designed measurement apparatus is based on a fluid penetration method. The apparatus brings the critical pressure drop of penetration air through the test powder bed at which the particle bed is collapsed by the stress induced by the penetrating airflow. From the critical pressure drop, adhesion characteristic value was defined. Measuring operation of this method is only feeding air to the layer. The measuring device required for the method is only the pressure gauge. Then, when the air is heated and a heatproof pressure gauge is employed, the adhesion characteristic under high temperature can be measured easily. In this study, we aimed to develop the apparatus that can be applied to a high temperature measurement of the adhesion characteristic. In addition, the adhesion characteristics of polymer particles was measured by the developed apparatus in the range from room temperature to melting point and the effect of the temperature on the adhesion characteristic was discussed.
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| 2007-09-14 10:30
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