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Volume 71, Issue 5
Displaying 1-10 of 10 articles from this issue
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Comprehensive Papers
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Development of Polymer Membranes and Membrane Separation Techniques for Concentration of Bio-EthanolTadashi URAGAMI2014 Volume 71 Issue 5 Pages 169-186
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSIn order to concentrate ethanol from a dilute aqueous solution produced by bio-fermentation, two kinds of hydrophilic and hydrophobic polymer membranes were prepared. Hydrophilic membranes, such as quarternized chitosan (q-Chito) membranes cross-linked with glutaraldehyde and hybridized q-Chito membranes with tetraethoxysilane, showed very high water/ethanol selectivity and high permeation rate for the dehydration of ethanol/water azeotropes using pervaporation (PV) and evapomeation (EV). On the other hand, hydrophobic poly[1-(trimethylsilyl)-1-propyne] (PTMSP) and poly(dimethylsiloxane) (PDMS) membranes were used to directly concentrate ethanol from dilute bio-ethanol. When the surface of the PTMSP membrane was treated with a polymeric surface modifier, the ethanol permeselectivity improved remarkably. The DMS phase forms the continuous phase in microphase separated DMS-g-MMA membranes. We could show that this significantly increases ethanol permselectivity. Dense PTMSP and PDMS membranes for temperature-difference controlled evapomeation (TDEV) showed higher ethanol permselectivity than those used in PV. Furthermore, porous PDMS membranes showed both higher permeation rate and ethanol permselectivity in TDEV compared to dense PDMS membranes.View full abstractDownload PDF (2326K) -
Shuichi SATO, Shinji KANEHASHI, Kazukiyo NAGAI2014 Volume 71 Issue 5 Pages 187-201
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSPoly(lactic acid) (PLA) is an environmentally-friendly biodegradable polymer. It is often used in packages, in automobiles, and for electronics. We can even expected that PLA replaces petroleum-based plastics. PLA crystallization can be controlled by cooling and heating, organic solvents, and vacuum ultraviolet irradiation. This paper focuses on controlling the crystalline structure by thermal-, solvent-, and photo-induced crystallization. The effect of the crystalline structures on PLA membranes on gas transport properties was systematically investigated. Interestingly, unlike common crystalline polymer membranes, the permeability through a crystalline PLA membrane was larger than that through an amorphous PLA membrane. PLA is an interesting polymer, whose gas permeability is not significantly affected by its isomer ratio and crystallinity in the L:D-donor ratio range of 98.7:1.3–50:50 and in the crystallinity range of 0–25%.View full abstractDownload PDF (1783K) -
Ikuo TANIGUCHI, Teruhiko KAI, Shuhong DUAN, Shingo KAZAMA, Hiroshi JIN ...2014 Volume 71 Issue 5 Pages 202-210
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSPoly(amidoamine) (PAMAM) dendrimers display quite high specificity toward CO2, and incorporation of the dendritic molecules in a polymer matrix has been investigated to fabricate CO2 separation membranes. Especially, photopolymerization of poly(ethylene glycol) dimethacrylate (PEGDMA) in the presence of the dendrimers allows forming macroscopically homogeneous membranes. The resulting membranes show excellent CO2 separation from H2 under high humidity, depending on the dendrimer concentration and fabrication. The morphology is studied in detail by various real-space and Fourier-space methods. For example, a laser-scanning confocal microscope observation reveals the formation of a bicontinuous phase structure of the dendrimer-rich and PEG-rich phases upon polymerization-induced phase separation on a couple of microns scale. The macrophase-separated structure is related to the CO2 separation performance. The mechanism of preferential CO2 separation is elucidated. CO2 partially turns into bicarbonate ions in the membrane under humid conditions, which would be the major migrating species, while the rest of the CO2 forms carbamate with primary amines of the PAMAM dendrimer to form a quasi-crosslinking, which would suppress the H2 permeation by a so-called “CO2-selective Molecular Gate”.View full abstractDownload PDF (899K) -
Kyoichi SAITO2014 Volume 71 Issue 5 Pages 211-222
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSTo remove and recover targeted ions and molecules at a high rate, inorganic compounds, enzymes, and extractants were immobilized onto a commercially available 6-nylon fiber by radiation-induced graft polymerization and subsequent chemical modifications. Fibrous supports with a smaller diameter provide a larger external interface area with liquids. Modified fibers are fabricated into various shapes such as wound filter and braid according to application sites. First, insoluble cobalt ferrocyanide-impregnated fiber was prepared via precipitation by immersing ferrocyanide ion-bound anion-exchange fiber in cobalt chloride solution. Cobalt ferrocyanide impregnated onto the polymer chain grafted onto the fiber specifically captured cesium ions in seawater. Similarly, sodium titanate impregnated onto a cation-exchange fiber selectively captured strontium ions in seawater. Second, urease was bound by an anion-exchange graft chain, followed by enzymatic cross-linking among urease molecules with transglutaminase. The bed charged with the urease-immobilized fiber exhibited a quantitative hydrolysis of urea at a high space velocity of urea solution. Third, an acidic extractant (HDEHP, bis(2-ethylhexyl) phosphate) was impregnated onto a dodecylamino-group-containing polymer chain grafted onto the 6-nylon fiber. Distribution coefficients of the HDEHP-impregnated fiber for neodymium and dysprosium agreed well with those in n-dodecane.View full abstractDownload PDF (1589K) -
Masakazu YOSHIKAWA2014 Volume 71 Issue 5 Pages 223-241
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSIn membrane separation, permselectivity and flux (throughput) are two of the important factors. It is a relatively easy task to enhance permselectivity by applying molecular imprinting or alternative molecular imprinting to the preparation process of membranes. However, a trade-off relationship is often observed in membrane separation; in other words, it is difficult or seems to be impossible to simultaneously enhance both permselectivity and flux. Membranologists are expected to enhance flux without a concurrent reduction in permselectivity at least. To this end, molecularly imprinted nanofiber membranes were fabricated from candidate polymers by simultaneously applying alternative molecular imprinting and electrospray deposition. Molecularly imprinted nanofiber membranes thus fabricated gave high flux without reduction of permselectivity. The emergence of molecularly imprinted nanofiber membranes could solve the trade-off relationship in membrane separation.View full abstractDownload PDF (1776K)
Original Papers
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Ayumi IKEDA, Yukiko TOKUNAGA, Jun-ya SASANOMA, Emi MATSUYAMA, Naofumi ...2014 Volume 71 Issue 5 Pages 242-248
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSAn organic-inorganic hybrid gel having a joint-rod structure was prepared by using the Ashby-Karstedt catalyst. 1, 3, 5, 7-tetramethylcyclohexane is one of siloxane compounds that was employed as a joint molecule. 1, 5-Hexadiene is one of α, ω-uncoupling dienes that was employed as a rod molecule. Porous γ-alumina substrates having pores of 4 nm were coated with this gel to obtain toluene permselective membranes. Toluene is one of VOC components. Toluene/N2 permeance ratio was 850 with toluene permeance of 1.55×10−6 mol m−2 s−1 Pa−1. The permeation through this gel membrane is discussed using a novel permeation model. The permeation model consists of two permeation pathways. One is permeation through the thin gel layer, and the other is that through the gap between the gel clusters. Optimum membrane structures can be found through a novel transmission mechanism and by variation of the model parameters.View full abstractDownload PDF (773K) -
Ryotaro KIYONO, Yukito AOYAMA, Masashi SEKIGUCHI, Takahumi MASUDA, Sho ...2014 Volume 71 Issue 5 Pages 249-254
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSComposite membranes of polydimethylsiloxine (PDMS) and carbon nanofiber (CNF) were prepared. The properties of the membranes (contact angle, degree of swelling in solvent and mechanical strength) and the vapor permeation of n-hexane and water were measured. The contact angle of water on the membrane surface and mechanical strength of the membrane increased with an increase in the CNF content while the degree of swelling in n-hexane solution decreased. The water vapor permeation (Pwater) across the membranes decreased with increasing CNF content due to the increase in hydrophobicity of the membrane surface. The n-hexane permeation (Pn-hexane) increased with increasing the CNF content until 3% CNF content, however, it decreased at more than 3%. The ratio of Pn-hexane/Pwater for composite membrane containing 3% CNF was twice as large as that for PDMS membranes.View full abstractDownload PDF (807K)
Notes
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Tamotsu HASHIMOTO, Takero MINOWA, Daichi OHASHI, Michio URUSHISAKI, To ...2014 Volume 71 Issue 5 Pages 255-257
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSGas permeability of ionene polymers (PTIs) containing poly(tetrahydrofuran) [PTHF] soft-segment blocks (the molecular weight of PTHF block: 1100 and 2300) and viologen hard ionic segments (counter anion: Cl−, Br−, and I−) were investigated. The gas permeability coefficients of carbon dioxide (PCO2) and the CO2 and N2 separation factor (PCO2/PN2) of PTI having the 2300-PTHF block molecular weight and Cl− counter anion were 201 barrer and 30, respectively, indicating that PTI is a good candidate for CO2 separation membrane polymer.View full abstractDownload PDF (435K) -
Toshikazu SAKAGUCHI, Fumiya KATSURA, Tamotsu HASHIMOTO2014 Volume 71 Issue 5 Pages 258-260
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSNovel poly(vinyl ether)s with tetraethylene glycol and methacrylate side groups [poly(TetraEGMVE-VEEM)] were synthesized by the copolymerization of TetraEGMVE with VEEM. The free-standing membranes of poly(TetraEGMVE-VEEM)s were prepared by thermal crosslinking between the methacrylate units. Membranes of poly(TetraEGMVE-VEEM) with 2:1 composition ratio showed high CO2 permeability and CO2/N2 selectivity, whose PCO2 and PCO2/PN2 were 250 barrer and 52, respectively. The PCO2 of membranes of poly(TetraEGMVE-VEEM) with 4:1 composition ratio was 320 barrer, which is larger than that with 2:1 composition ratio. This difference is caused by the number of crosslinking points in the polymer matrix. The CO2 permeability of poly(TetraEGMVE-VEEM) is higher than that of poly(vinyl ether) having diethylene glycols as a side chain. This high permeability originates from the high diffusivity of CO2 in the membranes.View full abstractDownload PDF (431K)
Erratum
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Toshiro WASHIZAKI, Toshihisa KAJIWARA, Yasuya NAKAYAMA2014 Volume 71 Issue 5 Pages 261
Published: May 25, 2014
Released on J-STAGE: May 23, 2014
JOURNAL FREE ACCESSDownload PDF (107K)
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