Satoru Kato

Permeation rates of aqueous alcohol solutions in pervaporation through Nafion membranes

Abstract Permeation data of methanol-water and 1-propanol-water mixtures in pervaporation (PV) through Nafion membranes with (CH 3 ) 3 NH + as counter ion were obtained. These data showed that water preferentially permeated in PV in spite of the preferential sorption of alcohols. A new permeation model was proposed based on the free volume theory. The model accounted for the effects of solubility and molecular interactions, such as permeant-polymer interactions, on the permeability. Not only the PV data of methanol-water-Nafion and 1-propanol-water-Nafion systems but also those of ethanol-water-nafion and isopropanol-water-Nafions systems listed in the literature supported the validity of the present model.

Extraction of polyunsaturated fatty acid ethyl esters from sardine oil using Ag+-containing o/w/o emulsion liquid membranes

Using silver ion as a carrier in o/w/o type emulsion liquid membranes, batch-wise extraction experiments were performed to separate polyunsaturated fatty acid ethyl esters originating in sardine oil. It was possible to separate polyunsaturated fatty acid (PUFA) esters from the mixture of PUFA and saturated fatty acid esters. The operating conditions for stable liquid membranes were experimentally determined. A new membrane breakage model that successfully describes the membrane stability behavior is proposed.

Recovery of protein from reverse micelles through gas hydrate formation

The recovery of cytochrome c and ribonuclease A from di-2-ethylhexyl sodium sulfosuccinate (AOT) reverse micelles have been examined by the gas hydrate formation. The recovery of cytochrome c depended upon the kind of gas and the water content (w0=[H2O]/[AOT]) of reverse micellar solution containing cytochrome c prepared. Recoveries of cytochrome c and ribonuclease A were more than 80%, when 1,1,1,2-tetrafluoroethane (TFE) was used as a hydrating gas. The activity of cytochrome c recovered from reverse micelles was maintained perfectly.

Enzymatic synthesis of peptide in acetonitrile/supercritical carbon dioxide

SummaryThe peptide synthesis from N-acetyl-L-tyrosine ethyl ester (Ac-Tyr-OEt) and amino acid amides was realized using α-chymotrypsin (CT) in acetonitrile (MeCN) or acetonitrile/supercritical carbon dioxide (SCCO2) containing small amounts of water. In both solvent systems there was an optimum water content for peptide synthesis, above which peptide hydrolysis became more important. After an incubation for 5 hours, the yields of the peptide was 64% in MeCN and 91% in MeCN/SCCO2, respectively.

Increased Thermostability of Cross-Linked Enzyme Crystals of Subtilisin in Organic Solvents

Cross-linked enzyme crystals(CLECs) of subtilisin display the improved thermostability in organic solvents, compared to free subtilisin. CLECs are more stable than the free enzyme in octane with a half life of 200 days at 45°C, while that of free enzyme is 5.4 days. CLECs in octane is more stable than in acetonitrile.

Protease-catalyzed esterification of amino acid in water-miscible ionic liquid

The activity of two proteases in the esterification of N-acetyl-l-phenylalanine with ethanol was examined in the water-miscible ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][Tf]). The activity of subtilisin was not only improved 9-fold by changing from a water-miscible organic solvent, acetonitrile, to [emim][Tf], but also was about three times greater than that in a water-immiscible organic solvent, octane. Likewise, the activity of α-chymotrypsin in [emim][Tf] was more effectively enhanced compared with that in a water-miscible or a water-immiscible organic solvent. The water content in [emim][Tf] affected the activity of subtilisin.

Application of UNIFAC models to partition coefficients of biochemicals between water and n-octanol or n-butanol

Abstract The objective of this work is to examine whether the various UNIFAC models can represent phase behavior of biochemicals in the dilution solution such as partition coefficients (log P i ). Especially, the log P i of a solute in the n -octanol/water system was used as main target for the examination in this work. First, the log P i of common chemical solutes was tested by use of various UNIFAC models. It was concluded that the original model and Larsen et al.s model [B.L. Larsen, P. Rasmussen, Aa. Fredenslund, Ind. Eng. Chem. Res., 26 (1987) 2274–2286] were suitable for the prediction of the log P i . In the next, both models were applied to calculation of log P i of biochemicals such as amino acids, their derivatives, and sugars. In addition, hydrophobicity constants ( π ) of an amino acid side chains were calculated from the log P i of amino acids. From the above results, the performance of the UNIFAC models for log P i and π was discussed.

Extraction of eicosapentaenoic acid ethyl ester from a model media using Ag(I)-containing o/w/o-type emulsion liquid membranes

Abstract Using silver ion as a carrier in oil/water/oil-type emulsion liquid membranes, batchwise extraction experiments were done to separate eicosapentaenoic acid ethyl ester (EPA-Et) from a model mixture consisting of EPA-Et and ethyl laurate. Moderate operating conditions were chosen for the concentration of Ag(I), the type of surfactant, and agitation strength. The emulsion liquid membranes thus formed were stable, and the concentration of Ag(I) and the surfactant types had strong effects on the permeation behavior of EPA-Et. The overall volumetric coefficients of EPA-Et obtained in the present study were equal to or smaller than those of organic solutes obtained with the data available in literature. It was found that the overall volumetric coefficients of these organic solutes increase linearly on a log-log scale, with increasing distribution ratios.

Separation of EPA and DHA from Fish Oil Using Supercritical Extraction with Ag Complex Pretreatment

Supercritical fluid extraction (SFE) of polyunsaturated fatty acid (PUFA) ethyl esters coupled with pretreatment of Ag+ - π-complex formation was studied. PUFA esters such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish oil were selectively dissolved into aqueous AgNO3 solution. After that semi batch SFE was carried out to recover PUFA esters from the pretreated aqueous solution using supercritical (SC) CO2, ethane and ethylene. All the PUFA esters could be recovered by SFE, and extracted products were consist of PUFA esters and Ag free water only. The results of SFE showed that the complex stability affected strongly on the SFE behavior. Selective separation for EPA-Et and DHA-Et was obtained when SC-CO2 and ethane were used, and 90 wt.% of DHA-Et could be produced at the final SFE stage. SC-ethylene has little selectivity for the PUFA esters, however, the extraction rates of PUFA esters were the fastest. This is because ethylene makes 7t-complex with Ag+ ion competitively.

Partition Coefficients of Fatty Acids Between Water and n-Hexane

Some fish oils and vegetable oils include useful long-chain unsaturated fatty acid such as EPA (eicosapentanoic acid) and DHA (docosahexanoic acid). A potential candidate of the purification scheme for these fatty acids consists of separation using liquid-liquid contact operations such as extraction and liquid membrane permeation. The purpose of this study is to examine the artition behavior of fatty acid to elucidate the effect of double bond.