Tadaaki Nishiki

Phenol permeation through liquid surfactant membrane — permeation model and effective diffusivity☆

Abstract A mass transfer model for the permeation of phenol through liquid surfactant membranes is proposed. The model takes account of the internal mass transfer in (W/O) emulsion drop, i.e., the diffusion in the emulsion phase and that through the peripheral thin oil layer, the external mass transfer around the drop, and both the phase and chemical equilibria. According to the model, all parameters required for a computer simulation for the permeation rate of phenol can be estimated from diameters of emulsion drops and internal water droplets. The model satisfactorily predicts the experimental results for the batch permeation of phenol measured under various conditions.

Mass transfer characterization in forward and back extractions of lysozyme by AOT-isooctane reverse micelles across a flat liquid-liquid interface

Abstract The mass transfer rates in lysozyme extraction between an aqueous KCl solution and an bis(2-ethyl)sodium sulfosuccinate (AOT)-isooctane reversed micellar solution were investigated using a stirred cell with a flat liquid-liquid interface. The forward extraction rates from 0.1 kmol m−3 KCl solution of pH 6.5 to a reversed micellar phase are controlled by the diffusion in the aqueous film and the solubilization at the interface. The solubilizing rate constant, kfs, increases from 3.57 × 10−5 to 1.43 × 10−4 m s−1 in proportion to AOT concentration of 0.05 to 0.2 kmol m−3. For the back extraction of lysozyme from the reversed micellar phase to an aqueous solution of higher KCl concentration, the rate-determining step is the release process at the interface. The releasing rate constant, kbd, decreases with an increase of AOT concentration and is also two orders smaller than the kfs values. The back extraction rates are therefore very slow compared to the forward extraction rates.

Batch permeation of metal ions using liquid surfactant membranes

Abstract A mass transfer model, which was proposed for the permeation of phenol through liquid surfactant membranes, has been extended to the permeation of metal ions. Experiments on batch permeation and concentration of copper ion by LIX64N and zinc ion by di-2-ethylhexyl phosphoric acid were carried out under various conditions. The results obtained by using either Span 80 or ECA4360J as surfactant were satisfactorily simulated by the model. It was found that the permeation rate of zinc ion was greatly retarded by the use of ECA4360J.

Development of a Continuous Electric Coalescer of W/O Emulsions in Liquid Surfactant Membrane Process

Abstract The development of an efficient, continuous demulsification apparatus is needed in the industrial separation process utilizing the liquid surfactant membrane technique. A test apparatus for continuous demulsification was constructed in which a pulsed dc high potential is applied to W/O emulsions flowing between parallel copper electrodes of a perforated plate. Efficient demulsification was achieved by an operation in which the demulsified oil phase was absent between the emulsion and the upper electrode. When the feed rate of emulsion was adjusted to be equal to the demulsification rate, the latter value was proportional to the square root of the applied potential and independent of the distance between the electrodes.

Anaerobic Oxidation of Dissolved Hydrogen Sulfide in Continuous Culture of the Phototrophic Bacterium Prosthecochloris aestuarii

The anaerobic oxidation of dissolved H2S to elemental sulfur was studied at 23 degrees C and pH 6.5+/-0.3 in continuous culture of the phototrophic green sulfur bacterium Prosthecochloris aestuarii. The number of cells formed in the cultures was proportional to the amount of H2S oxidized, and the growth yield was independent of light intensity. The specific growth rate was significantly dependent on the dissolved H2S concentration and light intensity. The kinetic data were analyzed with a rate expression as a function of each rate-limiting factor. Under illumination by white fluorescent lamps, the specific oxidation rate of P. aestuarii reached a maximum of 2.02 x 10(-14) mol-H2S.h(-1).cell(-1) when the dissolved H2S concentration was 2.1 mM at 5000 lx. Simultaneous use of near infrared LED (light-emitting diode) and white fluorescent lamps provided a 35% increase in the maximum specific H2S oxidation rate.

A Practicable Process for Phenol Removal with Liquid Surfactant Membrane Permeation Column

A practicable liquid surfactant membrane process for phenol removal is proposed with a stirred countercurrent column used as the liquid membrane contact equipment. The constituents of liquid membranes, such as internal aqueous phase and surfactant, the type of column, and the operating conditions for efficient and continuous performance of the liquid surfactant membrane process, have been examined. When NaOH solution was used as the internal aqueous phase and ECA4360J was used as the surfactant, the W/O emulsion was stable for the duration of column operation. More than 97% phenol could be removed from the feed solution. Nearly complete demulsification was also achieved by gentle agitation with an electrostatic demulsifier.

Mass Transfer Rate in Protein Extraction by Reverse Micelles

Reversed micellar extraction has been noted as an efficient and selective method which has a potential for separating and concentrating proteins continuously and for being scaled up easily. In the practical application of this separation method, it is important to elucidate the mass transfer mechanism for extraction of proteins by reverse micelles.

Permeation of Lanthanum through Supported Liquid Membranes

Abstract The mechanism of lanthanum transport through a supported liquid membrane is presented. The membrane consisted of a Teflon millipore membrane with a kerosene solution of di(2-ethylhexyl) phosphoric acid (HDEHP) as a mobile carrier held within the pores by capillary forces. Interposing the liquid membrane between two aqueous solutions with different pH values, lanthanum was transported and concentrated from the high pH solution to the low pH solution across the liquid membrane. The effects of HDEHP concentration in the membrane solution and of the lanthanum concentration and pH in the aqueous phases on the permeation rates of lanthanum were investigated. It was observed that the permeation rates decrease drastically by the addition of surfactant to the membrane phase. The permeation rates of lanthanum can be explained by a permeation model which includes the extraction and the stripping reaction at the membrane interfaces and the diffusion process of the complex formed between lanthanum and HDEHP t...

Numerical simulation for liquid membrane permeation of metal ions in a continuous countercurrent column

Abstract The objective of our work is to develop a continuous separation process with the liquid surfactant membrane technique. Numerical simulations for the continuous permeation of metal ions in a countercurrent column were performed by applying an axial dispersion model for the continuous phase and a mass transfer model, which was previously proposed for the batch permeation of metal ions, for the dispersed water in oil (W/O) emulsion phase. The effects of operating conditions on the concentration profile of metal ions in the column were investigated.

Liquid Film Thickness in Liquid-Liquid Contact Equipment of Wetted-Wall System

系濡れ壁塔の液膜厚みを, 軽液を静止および向流, 並法に流しについて測定し, 液膜厚みに及ぼす軽液の物性, 流下方向の距び軽液流速などの影響を調べた。その結果, Re1の小さい領域膜厚は流下方向には変化せず, 筆者らの導出した理論式とほぼたが, 波の発生しはじめるRe1以上になると, 膜厚は流下方難によって変化した。また, 本研究で行った軽液流速範囲内で厚は軽液流速の影響をうけなかった。