Kunio Watanabe

Estimation for size of reverse micelles formed by AOT and SDEHP based on viscosity measurement

Abstract The size of reverse micelles formed by Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) single and AOT-sodium di(2-ethylhexyl) phosphate (SDEHP) mixed surfactants useful in protein separation and enzyme reaction, was estimated from viscosity measurement of surfactant/isooctane solution. Reversed micellar solution was prepared by injection method. At molar ratio of water to surfactant, W O , lower than 2, no reverse micelles of AOT appeared to form in isooctane. AOT reverse micelle size as estimated in this study agrees with published results obtained by other techniques. AOT–SDEHP reverse micelle shape was noted to vary from sphere to ellipsoid and size to decrease with greater molar fraction of SDEHP.

Effects of ion species in aqueous phase on protein extraction into reversed micellar solution

We investigated the effect of cations on the protein extraction into AOT/isooctane reversed micellar solutions using alkaline and alkaline-earth metal ions. Cations greatly influenced the extraction ratio of protein in an order of K+<Rb+<Cs+<Na+<Li+ in monovalent ions and Ba2+<Sr2+<Ca2+ in divalent ones. Besides, the extraction ratio is totally higher in divalent ions than in monovalent ones. This effect of ions can be explained by classifying cations into water-structure forming and water-structure breaking ions. The effect of anions is less than that of cations and is in an order of SCN−<Br−<Cl−, consistent with that of lyotropic series. In addition, the extraction ratio is higher for proteins of higher hydrophobicity and it is supposed that the hydrophobicity and stability of the protein–surfactant complex are related to extraction efficiency.

An easy access to optically pure (R)-malic acid via enantioselective hydrolysis of diethyl malate byRhizopus lipase

SummaryRacemic diethyl malate was enantioselectively hydrolyzed by crudeRhizopus lipase (Saiken) to leave optically pure (≳99% ee) (R)-(+)- malate in c.a. 20% recovery. The combination of dipropyl malate and lipase AY (Amano) also gave (R)-enantiomer with a high ee of ≥97% and about 20% recovery in a short reaction time.

Modeling and simulation of counterflow (W/O) emulsion spray columns for removal of phenol from dilute aqueous solutions

Abstract A simple model for permeation through liquid surfactant membranes in counterflow mode was developed, which is based on the shrinking core model. Mass transfer through the external aqueous boundary film and in (W/O) emulsion phase was examined on the basis of this model, including the effect of backmixing of the continuous aqueous phase in a spray column. From the simulation results for the steady-state axial profile of solute concentration in the column, it was found that the external film resistance is predominant in the membrane permeation as compared with the diffusional resistance in (W/O) drops. The applicability of the model was illustrated by simulating phenol extraction data in literature.

An evaluation of effective diffusivity in (W/O) emulsion drops

Effective diffusivity in a (W/O) emulsion drop was examined in terms of the extraction of ammonia from the inner aqueous droplets phase to external aqueous solution of sulfuric acid in a spray column operation. The experimental values of the effective diffusivity were compared with the values calculated from a cubic model for the permeation taking account of the effect of the surfactant on the diffusion in membrane phase and the interfacial resistance. It was confirmed that the surfactant reduces significantly the diffusivity through the membrane solution and the surfactant layer at the oil-water interface has a significant resistance to the permeation across the liquid surfactant membrane.