Junjiro Kawasaki

Surface modification of adsorbents by dielectric barrier discharge

Granular activated carbon was treated by oxygen non-thermal plasma to improve its adsorbability for metal ions. The plasma was produced by dielectric barrier discharge under atmospheric pressure. The results of characterization of activated carbon showed that its surface area was decreased, and the concentrations of acidic functional groups at the surface were increased by the treatment. Adsorbability was examined changing the initial pH of the solution containing a metal ion. The saturated adsorption amount of Cu and Zn ion was increased considerably by the treatment. The plasma treatment of activated carbon was concluded as an effective method for improvement of adsorbability.

A novel method improving low separation performance for W/O/W ELM permeation of erythromycin

The permeation of erythromycin, macrolide antibiotics, into a W/O emulsion globule was simulated with the multi-layer liquid membrane model and the formation of the unfavorable concentration profile in an emulsion globule, this would cause the low separation performance. It was, therefore, proposed that to control the formation of the concentration profile, the feed phase and emulsion should be contacted as the dispersed and continuous phases, respectively, in a spray column contactor. A series of permeation experiments were conducted by both batch and continuous operations with a spray column (height: 0.5 m, i.d.: 0.027 m). In the cases of batch permeation runs, erythromycin permeated through the membrane phase and was concentrated in the stripping phase. By the new contacting method, the improvement in the separation performance was achieved, also the stability of the emulsion membrane improved, specifically mechanical entrainment. Finally, a theoretical evaluation of the permeations with respect to the dispersion in the column is discussed.

Recovery of erythromycin by a liquid membrane

Abstract A supported liquid membrane technique was applied for extraction of erythromycin A from its dilute slightly alkaline aqueous solutions. 1-decanol was used as an intermediate (membrane) phase and a buffered acidic aqueous solution to strip the organic membrane. The antibiotic distribution coefficient between the membrane used and the feed was found to be 122, providing relatively high solute fluxes across the membrane, although the transfer resistance remains in the filled membrane pores. It was shown that due to existing equilibrium between the protonised and non-protonised forms of the solute, the antibiotic can be completely transferred and concentrated in the receiving, low pH solution.

A SCALE-UP OF STIRRED TANK CONTACTORS FOR THE LIQUID MEMBRANE PERMEATION OF HYDROCARBONS

The scale-up of stirred tank contactors on the drop size of emulsion-solvent dispersion and the mass transfer coefficient of hydrocarbon in oil-in-water O/W emulsions (dispersed phase) are discussed. Correlative equations to estimate the drop sizes and the mass transfer coefficient are proposed without regard to tank size and material systems. The consumption of power created by stirring one unit of liquid tank volume is an applicable scale-up standard for the drop size of O/W emulsion and the mass transfer coefficient of hydrocarbons in the emulsion.

Permeation and concentration of compactin by a liquid membrane technique

Abstract A liquid membrane technique proved to be a possible method for the recovery process of compactin (ML-236B), a highly effective pharmaceutical compound for the treatment of hyperlipidemia, from its dilute aqueous solution. The kinetics and the mechanism for the transport process were discussed, and the effects of the operating parameters on the liquid membrane permeation could be quantitatively demonstrated. The distribution equilibrium of compactin was measured between the aqueous and the oil phases, in which toluene and mesitylene (1,3,5-trimethylbenzene) containing di-n-octylamine, a complexing agent, were used as the oil phase. The dissociation constant, the distribution coefficients and the reaction equilibrium constants were determined experimentally. A simple transport model was proposed that compactin molecules should permeate through two pathways: the physical diffusional permeation and the ion-pair complex permeation. Supported liquid membrane (SLM) experiments were conducted by adjusting pH values in the aqueous phases and the carrier concentration, and the individual mass transfer coefficients of the species were evaluated according to the proposed model. The overall mass transfer resistance was expressed as the sum of the local resistances in feed, membrane and stripping phases. With the increase of the carrier concentration, the resistance in the membrane phase became less important and the overall transfer rate was controlled by the diffusion in the aqueous layer, implying that an excessive carrier would be no longer effective. The work performed provides us the suggestion for setting the reasonable carrier concentration for the liquid membrane system concerned.

COMPUTATIONAL STUDIES OF THE COUNTERCURRENT MULTISTAGE EXTRACTION-COUPLED ESTERIFICATION PROCESS OF OLEIC ACID WITH METHANOL USING EXCESS METHANOL AS EXTRACTANT

A new process has been suggested for the esterification of oleic acid with methanol catalysed by a cation exchange resin, in which water is removed by simultaneous extraction with excess methanol as the extractant, and an algorithm for the simulation of countercurrent multistage extraction-coupled reaction processes has been proposed. The algorithm was applied to the new process and was proved to have good convergence. The calculated results showed that methyl oleate product with high yield and high purity could be obtained in the multistage countercurrent extraction-coupled esterification process. It was found that both yield and purity of methyl oleate product increase with the increase in the feed ratio of methanol/oleic acid as well as in the number of stages. A feed ratio more than six (in mole base) is required to obtain the purity and/or the yield higher than 95%. Purity of 99% and yield of 99% can be achieved in a four to nine stage process with a feed ratio of more than 8.5–16 when using 100% pure raw methanol.

Separation and Recovery of Bicyclic Aromatic Components in the Light Cycle Oil

There are a lot of valuable aromatic components in light cycle oil (LCO). Among them, 2,6-dimethylnaphthalene is focused as the elementary raw material for engineering plastic (PEN plastic) and polymer liquid crystal, etc. We investigated the separation and recovery of valuable aromatic components (bicyclic aromatic components: carbon number 10–12) in LCO by solvent extraction method. Sulfolane, dimethylsulfoxide (DMSO), diethyleneglycol, and dimethylformamide were used as extraction solvents to measure distribution equilibrium. It was found that DMSO was a promising extraction solvent based on the distribution coefficient of bicyclic aromatic component and selectivity for n-Nonane. The effect of operation factors on extraction performance for bicyclic aromatic components in LCO using DMSO as extraction solvent was also studied. With increasing moisture content of solvent, the distribution coefficient of bicyclic aromatic components decreased and selectivity increased. Increasing operation temperature resulted in decreasing the distribution coefficient and selectivity. The lower the carbon number, the higher the distribution coefficient and selectivity of bicyclic aromatic components. Because boiling temperature of DMSO overlapped with that of component, it was difficult to recover extract component of extract phase. Benzene, toluene, m-xylene, n-hexane (HX), and n-octane were used as secondary solvents, and the distribution equilibrium between extract phase (re-extraction feed) and secondary solvent was measured. It was found that HX was a promising solvent for recovering bicyclic aromatic components. To examine the effect of operation factors on recovering bicyclic aromatic components, HX was used as a re-extraction solvent. The distribution coefficient of bicyclic aromatic components decreased smoothly while increasing the mass ratio of solvent to re-extraction feed and operation temperature. The higher the carbon number, the higher the distribution coefficient of bicyclic aromatic components. To examine the process of separation and recovery for dimethylnaphthalene mixture with 10 structural isomers in the LCO, the experiment result obtained from equilibrium extraction and equilibrium re-extraction were used.

Separation of Hydrocarbons by Liquid Surfactant Membrane with a Batch Stirred Vessel

Extraction experiments on liquid membrane permeation were conducted in a batch stirred vessel to separate aromatics from an aromatics-nonaromatics binary mixture as an inner oil phase in the emulsion. The investigations were conducted under various material systems (hydrocarbon feeds, aqueous membrane phases) and the mass transfer coefficient in the emulsion (dispersed phase) was measured. Independently of the system of hydrocarbon feed and aqueous membrane solution, the mass transfer coefficient of the dispersed phase could be correlated with the dimensionless stirring time and the solubility of the aqueous membrane phase. The batchwise results agree fairly well with previous results reported for continuous operation.

Mechanical Entrainment in W/O/W Emulsion Liquid Membrane

Abstract An experimental study of mechanical entrainment in W/O/W emulsions is conducted. W/O/W emulsions are stirred for various stirring times under the conditions that mechanical entrainment solely occurs, and changes in volume of the W/O emulsions and size distribution of the internal water droplets are measured. The rate of change in number of the water droplets entrained is found to be proportional to the volume fraction of W/O emulsions. Based on this result, a new model for mechanical entrainment is developed. The calculated change in W/O emulsion volume with time agrees with the observed ones except in the region near phase inversion. Then, phase inversion is discussed.

Solid‐Liquid Extraction of Taxane Compounds from Yew Needle

Abstract Solid‐liquid extraction of the taxane compounds in yew needles is carried out with methanol. The concentration of each component in the raffinate is estimated from the observed concentration in the extract and material balance equations with a solvent‐permeation model that solvent permeates the solid. The obtained distribution coefficient is found to be independent of the particle size. It suggests a possibility that the extract is in equilibrium with the liquid solution in the raffinate. Based on the experimental results, the effect of operating conditions on separation performance of countercurrent‐multistage extraction is studied by using the ideal stage calculation.