Teruhiko Hoshino

Electro-ultrafiltration bioreactor for enzymatic reaction in reversed micelles

Electro-ultrafiltration (EUF) was applied to separate the Aerosol OT (AOT) reverse micelles containing lipase from isooctane, and the effect of electric field on the rejection of reverse micelles and the permeation flux was examined experimentally. It could be said from the experimental results that EUF was effective for separation of the reverse micelles containing the enzyme and that the motive forces for the negatively charged reverse micelles were electrophoretic and dielectrophoretic.

Membrane Separation of Supercritical Fluid Mixture

The ceramic membrane as well as the polymer membrane were used to examine the possibility of membrane separation of the supercritical fluid mixture. The permeation rate of carbon dioxide exhibited a maximum peak near the critical pressure when it was measured at a constant temperature with change of pressure. Polyethylene glycol 400(PEG 400), PEG 600 and triolein were used as the model solutes with the maximum concentration of 1%. The rejection was negative in the composite polymer membrane(NTGS-2100) and approached zero with increase in the permeation flux. The rejection of PEG 400 was from 0.5 to 0.8 at 40°C and 20 MPa in the thin porous silica membrane with the average pore size less than 0.6 nm.

Effect of Freezing Conditions on Vapor Permeability of Freeze-Dried Foods

The soybean proteins solution was freeze-dried by conductive heating the frozen sample conductively from the bottom of the vessel (back-face heating). The drying rate was analyzed by the uniformly retreating ice front (URIC) model to evaluate the vapor permeability in the dried layer. The vapor permeability was affected by the rate of freezing and the levels of supercooling since they could control the structure of ice crystals, that is, the channels of vapor flow after the sublimation of ice crystals. The vapor permeability was inversely proportional to the square root of the freezing rate when the freezing was accompanied by the weak supercooling.

Adsorption Isotherms for Supercritical Carbon Dioxide on Proteins and Polysaccharides

The adsorption isotherms for CO2 on several proteins and polysaccharides were measured at pressures of 0-29.4 MPa by two different microbalances, gravimetric and piezoelectric. The adsorption isotherms measured gravimetrically all exhibited the maximum peak near the critical pressure Pc and remained constant at the higher pressure, the level differing each others. The piezoelectric microbalance using the quartz crystal (9 MHz, At-cut) could measure the “absolute” amount of fluid sorbed in the adsorbent which was larger especially at the high pressure than the “surface excess” adsorption measured gravimetrically. The density of adsorbed layer was calculated using the data of the surface excess and the absolute adsorption isotherms.