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Volume 34 (2008)
- Issue 6 Pages 545-
- Issue 5 Pages 493-
- Issue 4 Pages 415-
- Issue 3 Pages 313-
- Issue 2 Pages 205-
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Volume 34, Issue 5
Displaying 1-8 of 8 articles from this issue
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Separation Engineering
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Yuya Sato, Makio TamuraArticle type: Research Papers
Subject area: Separation Engineering
2008 Volume 34 Issue 5 Pages 493-498
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSThis paper concerns improving quality standards of commercial NF membranes by use of tannic acid. Secondly, it considers the way in which tannic acid can reduce oxidative damage in RO membranes. We investigated its effects on separation performance and flux in NF membranes. We found that Chinese gallnut had the highest effect on the separation performance of LES90. Next, we studied the impact of treatment mode, concentration and time in regard to this effect. We found that permeation treatment with pressure was superior to submersion treatment. To improve separation performance, treatment with more than 5 mg/L of tannic acid for 10 minutes was required. Furthermore, this treatment was able to reduce three kinds of oxidative damage in RO membranes. Thus, treatment with tannic acid improved the performance of the commercial RO/NF membranes.View full abstractDownload PDF (321K) -
Yuya Sato, Makio TamuraArticle type: Research Papers
Subject area: Separation Engineering
2008 Volume 34 Issue 5 Pages 499-504
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSThis paper concerns the prevention of oxidative damage in commercial RO/NF membranes by treatment with tannic acid. We investigated the effects of periodic tannic acid treatments on separation performance and flux in membranes with oxidative damage. First, we studied LES90 as an NF membrane. We found that the untreated membrane showed oxidative damage with the increase in flux and decrease in separation performance. Furthermore, the treated membrane showed tolerance to oxidants as stable flux and stable separation performance. We assumed that tannic acid was more likely to react with oxidants than the membrane. Specifically, tannic acid reacted with the oxidants before the membrane. In this way, tannic acid functioned to protect the membrane from oxidative damage. Next, we studied ES10 as an RO membrane. We found that the treated membrane showed tolerance to oxidants. However, the treatment was less effective than in the case of LES90. We supposed that the adsorption level of tannic acid in ES10 was less than in LES90.View full abstractDownload PDF (514K)
Thermal Engineering
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Shogo Tamaki, Yuuko Fujii, Yohsuke Matsushita, Hideyuki Aoki, Takatosh ...Article type: Research Papers
Subject area: Thermal Engineering
2008 Volume 34 Issue 5 Pages 505-512
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSThe effects of an internal heat exchanger in a refrigerant system with carbon dioxide on its cooling capacity and cooling coefficient of performance were numerically investigated. First, experiments were carried out for a refrigerant system with carbon dioxide to obtain volumetric and isoentropic efficiency and to verify numerical accuracy. Second, the effects of varying internal heat exchanger area, environmental temperature, lower side pressure and higher side pressure on cooling capacity and cooling coefficient of performance were numerically investigated. By comparing calculated results with experimental ones, our simulation predicts capacity in the evaporator with +5.1% error, cooling coefficient of performance with +5.2% error, and capacity in the gas cooler with +3.0% error. When the environmental temperature is high and superheat is equal to 0 due to low performance of the evaporator, an internal heat exchanger gives a larger cooling capacity and cooling coefficient of performance. In particular, when the gas cooler exit temperature is close to the critical temperature, the internal heat exchanger gives higher performance.View full abstractDownload PDF (470K) -
Shogo Tamaki, Makoto Igarashi, Yuuko Fujii, Yohsuke Matsushita, Hideyu ...Article type: Research Papers
Subject area: Thermal Engineering
2008 Volume 34 Issue 5 Pages 513-521
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSThe effects of an ejector in a refrigeration cycle with carbon dioxide on its cooling capacity and cooling coefficient of performance were numerically analyzed. The effects of an ejector on the entrainment ratio of vapor mixing in suction flow, pressure difference of the suction chamber, environmental temperature, lower side pressure and higher side pressure were numerically investigated. The cooling coefficient of performance and cooling capacity decrease with an increace in vapor quality in suction flow. Furthermore, the cooling coefficient of performance and cooling capacity increase with an increase in pressure difference of the suction chamber. When the environmental temperature is low, the evaporator inlet pressure is low and the compressor discharge pressure is high, an ejector gives a larger cooling coefficient of performance and cooling capacity.View full abstractDownload PDF (537K)
Environment
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Kazuki Shuku, Norihiro Murayama, Junji ShibataArticle type: Research Papers
Subject area: Environment
2008 Volume 34 Issue 5 Pages 522-526
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSTo develop a recovery process of valuable materials like Ag, Au and polycarbonate from used CD-R and DVD-R, the separation and recovery of Ag and polycarbonate in a CD-R were investigated. Ag leaching from a CD-R was carried out using HNO3 and thiourea solution as a leachant.
The total amount of Ag in the CD-R can be dissolved with over 3.5 mol/dm3 HNO3. In the case of Ag leaching with below 2.0 mol/dm3 HNO3, it is possible to increase both leaching velocity and leaching percentage by increasing the leaching temperature. In this HNO3 concentration range, ultrasonic irradiation also promotes Ag leaching from the CD-R. Ag leaching increases with an increase in the concentration of thiourea solution, but the blue pigment component in the CD-R is not dissolved by thiourea solution. Ag leaching can be improved by increasing the leaching temperature, in leaching with thiourea solution and a lower concentration of HNO3. By this method, the Ag and pigment component in the CD-R can be recovered in the leachant, and the polycarbonate is also obtained as a residue.View full abstractDownload PDF (1196K) -
Hideaki Takahashi, Katsuyasu Sugawara, Risehiro NonakaArticle type: Research Papers
Subject area: Environment
2008 Volume 34 Issue 5 Pages 527-532
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSThe chlorination of indium in the ground powder of liquid crystal displays and selective liquid extraction of volatile components were investigated in order to obtain fundamental data for developing an efficient recovery process of indium from secondary resources. The sample was heated at terminal temperatures ranging from 473–973 K in a chlorine stream with a fixed bed reactor. While indium volatilized by chlorination of the metallic form below 573 K, indium chloride accompanied the volatilization above 573 K according to the carbochlorination reaction of indium oxide in the ground powder. All indium contained in the powder was released by 973 K. Coexistent metals of chromium, iron and titanium in the powder were also released with indium during chlorination. Indium could be concentrated successfully by the temperature control in the cooling zone of the reactor and extraction of volatiles with diethyl ether.View full abstractDownload PDF (987K) -
Tatsuya Ito, Shingo Ando, Naoki Tanahashi, Naoto Mihara, Chouyuu Watan ...Article type: Research Papers
Subject area: Environment
2008 Volume 34 Issue 5 Pages 533-538
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSThe decomposition of chlorobenzene (C6H5Cl) and dry sorption of Cl released from C6H5Cl by CaO and Na2CO3 sorbents were investigated.
In a C6H5Cl–N2 atmosphere without CaO and Na2CO3, it was found that C6H6, C2H2, CH4 and HCl were generated by the thermal decomposition of C6H5Cl at temperatures above 1073 K. Further, the presence of CaO and Na2CO3 sorbents was found to promote the decomposition of C6H5Cl in the temperature range of 673–1273 K. During C6H5Cl decomposition in the presence of CaO or Na2CO3, it was recognized that gaseous Cl compounds formed by the decomposition of C6H5Cl were absorbed on CaO or Na2CO3, producing CaCl2 or NaCl. As for the Cl sorption ratio on CaO and Na2CO3, the highest conversion values of CaO to CaCl2 of 0.23 and Na2CO3 to NaCl of 0.38 were obtained at temperatures of 1073 K and 873 K, respectively.View full abstractDownload PDF (447K) -
Masayuki Shintani, Yuta Naito, Shingo Yamada, Yugo Nomura, Sheng Zhou, ...Article type: Research Papers
Subject area: Environment
2008 Volume 34 Issue 5 Pages 539-544
Published: September 20, 2008
Released on J-STAGE: September 26, 2008
JOURNAL RESTRICTED ACCESSPerfluorooctansulfonate (PFOS) and perfluorooctanoic acid (PFOA), which case concern as persistent organic pollutant compounds, were treated with calcium oxide by a mechanochemical (MC) process. PFOS and PFOA were degraded during MC treatment by the cleavage of C–C and C–F bonds in their molecules, resulting in the formation of calcium carbonate (CaCO3) and calcium fluoride (CaF2) as degradation products. The MC treatment of PFOS/PFOA makes it possible to recover a valuable material such as CaF2. It was found that PFOS had poor degradability in comparison with PFOA because of the difference in physical properties.View full abstractDownload PDF (631K)
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