Language：English   Publisher：Japan Society on Water Environment  

This study focused on the removal of arsenic from simulated groundwater by batch adsorption using iron-modified rice husk carbon (RH-Fe). The results showed that RH-Fe was very effective in the removal of arsenic not only at low and moderate initial concentrations of arsenic (1.42 and 2.77 mg/L) but also at very high initial concentrations of arsenic (4.61 and 7.38 mg/L). The arsenic adsorption by RH-Fe was dependent on pH and varied with arsenic initial concentration and adsorbent dose. Langmuir isotherm could describe the adsorption equilibrium and the adsorption capacity was found to be 2.24mg/g. The pseudo-second order kinetic model gave the best fit with the experimental data.

DOI： 10.2965/jwet.2009.43

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DOI： 10.3107/jesss.3.19

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Language：English   Publisher：Japan Society on Water Environment  

Groundwater is one of the most important sources for drinking water. Arsenic (As) contamination of groundwater is a serious problem worldwide, especially in Bangladesh, India and South East Asia. Adsorption using appropriate and readily available adsorbents is a promising method for the removal of arsenic with applicability in rural areas. This work aims to study the removal of arsenic from synthetic groundwater using an adsorption column by sequential combination of laterite (LA) and iron-modified activated carbon (AC-Fe) as adsorbents. The effect of ratio LA/AC-Fe, flow rate, initial arsenic concentration and pH to the breakthrough time were investigated. Adsorption equilibrium and adsorption kinetics were also studied through batch experiment. The result was found to be an efficient and feasible approach for arsenic treatment from groundwater for ready applicability in rural areas.

DOI： 10.2965/jwet.2008.43

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DOI： 10.1007/BF03175333

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Language：English   Publisher：TAYLOR & FRANCIS INC  

Experimental and numerical studies on liquid-liquid extraction of taxane compounds that are extracted from yew needles by solid-liquid extraction are carried out. In the treatment, the materials are classified to three components, and separation of component C from components A and B is discussed. In experiments, distribution coefficients and selectivities of those components are measured with various solvents. Based on the experimental results, numerical simulation of the countercurrent multistage liquid-liquid extraction process for separating the components is carried out with various operating conditions. Then, the fractional countercurrent multistage liquid-liquid extraction process is examined, and the effect of reflux operation on separation performance of the fractional liquid-liquid extraction process is studied. Based on the numerical results, it is found that the fractional countercurrent multistage liquid-liquid extraction with reflux is superior to the other extraction processes for separating taxane compounds.

DOI： 10.1080/00986440701555456

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Language：English   Publisher：Japan Society on Water Environment  

Groundwater is one of the most important sources for drinking water. Arsenic (As) contamination of groundwater is a serious problem worldwide, especially in Bangladesh, India and South East Asia. Adsorption using appropriate and readily available adsorbents is a promising method for the removal of arsenic with applicability in rural areas. This work aims to study the removal of arsenic from synthetic groundwater using an adsorption column by sequential combination of laterite (LA) and iron-modified activated carbon (AC-Fe) as adsorbents. The effect of ratio LA/AC-Fe, flow rate, initial arsenic concentration and pH to the breakthrough time were investigated. Adsorption equilibrium and adsorption kinetics were also studied through batch experiment. The result was found to be an efficient and feasible approach for arsenic treatment from groundwater for ready applicability in rural areas.

DOI： 10.2965/jwet.2008.43

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DOI： 10.1007/BF03175333

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Language：English   Publisher：TAYLOR & FRANCIS INC  

For the purpose of capturing CO2 from flue gas the absorption Of CO2 into an aqueous solution of monoethanolamine was measured by using a column packed with a novel packing, Super Mini Ring (SMR). The SMR gave a higher absorption performance relative to pall ring packing due to a larger effective surface area and also reduced the frictional pressure gradient. The absorption mechanism was observed to be mainly gas phase controlling. It was concluded that for the treatment of flue gas the SMR packing could reduce the height of the absorption column by 20% relative to a pall ring packed column.

DOI： 10.1080/01496390601174075

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Language：English   Publisher：TAYLOR & FRANCIS INC  

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.

DOI： 10.1080/01496390600636892

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Language：English   Publisher：ELSEVIER SCIENCE BV  

Compactin (ML-236B) is an effective ingredient for production of anti-hypolipidemia medicine called mevalotin (Sankyo Pharmaceutical Co. Ltd.). Conventional liquid-liquid extraction is now applied in the commercial process of purification and concentration of compactin. In this study, we investigated compactin extraction process from aqueous solution to organic solvent of ethyl acetate using a microporous membrane-based flat interface contactor. Teflon (polytetrafluoroethelene; PTFE) membranes with 0.1 mu m pore size with either hydrophilic or lipophilic surface were utilized under the study. The extraction experiments were conducted at 298 K. The main objective of this study was to investigate mass transfer characteristics of compactin extraction by different types of membranes at the same operating conditions. Our previous work showed that water and ethyl acetate transferred simultaneously with compactin during the extraction. Therefore, the study of mass transfer in a binary mixture of two solvents was indispensable. Local mass transfer coefficients of extraction could be estimated from the mass transfer of binary mixture, and mass transfer models for membrane extraction were developed. These mass transfer coefficients and models can be applied to any operating conditions. We found that extraction of compactin by lipophilic membrane has better performance than the extraction with hydrophilic membrane due to the faster transfer of ethyl acetate relative to water. (C) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.seppur.2005.04.010

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Language：English   Publisher：ELSEVIER SCIENCE SA  

Equilibrium partitioning of compactin in water-ethyl acetate system was measured at 298 K. The extraction pH showed strong influence on the partitioning ratio: the partitioning ratio decreased with pH. The dissociation constant and distribution coefficients of compactin were determined by treating equilibrium data with numerical approach. Distribution coefficient of compactin in water-ethyl acetate system was treated as a variable and a function of compactin concentration in aqueous solution. The estimated values of dissociation constant and distribution coefficient were compared with the values of water-toluene system. The mutual solubility of ethyl acetate and water was also measured at the same temperature when compactin concentration was varied. The investigation found that increasing compactin concentration increased mutual solubility of water in organic phase as well as of ethyl acetate in aqueous phase. The increasing mutual solubility caused the change of solute composition in aqueous solution and affect equilibrium distribution of compactin. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cep.2003.11.006

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Language：English   Publisher：ELSEVIER SCIENCE BV  

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. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0376-7388(02)00528-8

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DOI： 10.11491/scej.2003f.0.99.0

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Language：English   Publisher：ELSEVIER SCIENCE BV  

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. (C) 2002 Published by Elsevier Science B.V.

DOI： 10.1016/S0376-7388(02)00179-5

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Language：English  

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. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(02)00030-5

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Language：English   Publisher：ELSEVIER SCIENCE SA  

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. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(02)00030-5

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DOI： 10.1016/S0376-7388(02)00179-5

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Language：English   Publisher：ELECTROCHEMICAL SOC JAPAN  

Electroless copper deposition on the wall of the blind via holes was numerically simulated by solving a conventional diffusion equation with the reduction reaction of copper(II) on the wall. Highly non-uniform copper deposition was ascribed to the small rate of copper (II) transport to the inmost part of the hole in comparison with the rate of the copper deposition, particularly in the cases of the aspect ratios of two or greater. According to the preliminary runs of the copper deposition, an application of the ultrasonic vibration at the deposition step improved the uniformity substantially but not very significantly. Having been expected the enhanced transfer of copper(II) in the hole, temperature gradient along the axis of the hole was applied in the simulation of the copper deposition which results suggested more uniform copper deposition than in the isothermal condition. Experimentally, copper deposited preferentially rather at the inmost part of the hole under the conditions of 298 Kat the hole opening and 338 Kat the bottom. It was found that the temperature gradient copper deposition on the wall of the blind via holes provides us with the uniform layer of copper.

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DOI： 10.1627/jpi1958.42.136

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DOI： 10.1627/jpi1958.42.136

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Language：English   Publisher：SOC CHEMICAL ENG JAPAN  

Erythromycin, a macrolide antibiotic, permeates through liquid membranes without a carrier. The contribution of local resistances to the overall permeation resistance is conceived from the permeation mechanism.
According to measured distribution equilibria of erythromycin between aqueous and oil phases and previously reported dissociation equilibrium of erythromycin in the aqueous phase, the distribution coefficient of free erythromycin is constant for each oil phase and independent of proton concentration.
In a supported liquid membrane, a high degree of concentration is attained in the case of a 1-decanol membrane. Not only the membrane phase but also the two aqueous phases contribute to overall resistance. For the heptane membrane, the controlling step is predicted to be in the membrane phase.
An emulsion liquid membrane also concentrates erythromycin in the stripping phase, however, it gives a low degree of concentration which is ascribed to undesirable reduction of the overall permeation coefficient. For a m-xylene membrane, the controlling resistance is in the membrane and stripping phases, and for the heptane membrane, it is in the membrane phase.

DOI： 10.1252/jcej.31.47

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DOI： 10.1627/jpi1958.40.107

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DOI： 10.1627/jpi1958.40.107

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