Ryuichi Egashira

Thermo-oxidative reactions of Nigerian oil sand bitumen

Abstract The thermal behavior of the Nigerian oil sand bitumen in an oxidizing environment was studied using non-isothermal thermogravimetric analysis (TGA) and differential thermal analysis (DTA). This condition can occur during in situ thermal recovery. The kinetics of the reactions was also determined by Arrhenius plot method. Three regions of weight loss corresponding to low-temperature oxidation, fuel deposition and high temperature oxidation were identified. Increasing the heating rate caused a shift in the reaction regions and peak temperatures to higher temperatures. No effect of gas flow rate was observed on the reactions. The oil sands have lower peak temperatures and activation energies compared with their corresponding bitumen extracts, suggesting a catalytic effect of sand on the reactions. The DTA revealed the exothermic nature of the reactions. The exothermicity increased with increasing heating rate. The results of this study showed that the heating rate and the presence of sand have significant effect on the thermo-oxidative reactions of the bitumen.

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.

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.

Separation of aromatic components from light cycle oil by solvent extraction

ABSTRACT To improve the versatility of light cycle oil (LCO), separation of aromatic compounds from LCO by solvent extraction was investigated. LCO was analyzed to identify 35 components: 19 aromatics and 16 alkanes. The batch liquid–liquid equilibrium extraction of LCO was performed using furfural, sulfolane, and methanol as extraction solvents. In each solvent, the aromatics present in LCO were selectively extracted relative to the alkanes. The separation selectivities of aromatics relative to alkanes were larger in sulfolane than in the other solvents. Among the aromatic components, di- and tricyclic compounds were selectively extracted relative to the monocyclic ones.

Effects of Sterile Ulva sp. Growth Rate on Water Quality Control of Intensive Shrimp Culture Pond in Developing Countries

To control the water quality in the intensive shrimp mariculture pond by uptaking the total ammonia-nitrogen with sterile Ulva sp., the growth rate of sterile Ulva sp. was experimentally measured and the influence of the rate on the water quality control evaluated. The specific growth rate constant of the seaweed increased with the total ammonia-nitrogen concentration, photosynthetic photon flux density and operating temperature. Then the dynamics of ammonia-nitrogen in the modeled culture pond for the intensive shrimp farming in the tropical region were numerically simulated, in which the seaweed was used to uptake ammonia-nitrogen. The seaweed could uptake ammonia-nitrogen effectively during daytime mainly due to the high intensity of sun light, and the total ammonia-nitrogen concentration in the shrimp pond could be kept very low. The required seaweed density to control the total ammonia-nitrogen concentration less than the recommended maximum concentration of 1.0 ⋅ 10 –3 kg N m –3 was estimated to be

Preparative Liquid Chromatography for Macrolide Antibiotics.

マクロライド系抗生物質の分取液体クロマトグラフィー (分取液クロ) に対する操作設計の手法を開発するため以下の検討を行った.エリスロマイシンおよびエチルコハク酸エリスロマイシンをモデル物質および不純物とし, シリカゲル-有機溶媒系におけるラングミュア型吸着等温式および速度式のパラメーターを1成分クロマトグラムのモーメント値より得た.移動相の種類, 組成により吸着等温式のパラメーター値は変化し, 分取液クロにおける分離の程度が異なることを示した.移動相側境膜物質移動係数および固定相内物質移動係数の実験結果を既往の相関式と比較した.マーカム・ベントン型吸着等温式および各パラメーター値を用いて得た2成分クロマトグラムの計算結果は実測結果と良好に一致した.結論として, 本研究の方法で得たパラメーター値を用いてクロマトグラムの計算をすることでマクロライド系抗生物質に対する分取液クロの操作設計が可能になるといえた.

Newly Developed Way to Improve Separation Selectivity in Liquid Membrane Permeation for Hydrocarbon Separation

ABSTRACT The simulation of permeation and separation in an emulsion drop by a Multi-layer liquid membrane model suggested the simple way to improve the separation selectivity of this technique. Batch experiments of permeation confirmed this suggestion.

Energy Requirement for Liquid Membrane Process to Separate Binary Hydrocarbon Mixtures

ABSTRACT The process considered in this work consisted mainly of a multi-staged stirred permeator with extract reflux, a distillation tower with ideal stages and a mechanical demulsifier. The hydrocarbon feeds were binary mixtures of benzene and n-hexane, both of which permeated externally from the internal feed (or raffinate) into the external solvent (or extract) phase through the aqueous emulsified membrane. As an extract solvent, n-octane was selected because the boiling point differences between the solvent and permeates are satisfactorily large to result in easy distillation. Amounts of energy required for several separation problems were estimated under specified stage numbers of the permeator and distillator. Numerical values of volumetric coefficients of permeation were calculated with the aids of results of batch-wise permeation tests conducted by a small scale permeator. Effects of main operation variables, reflux ratios in the permeator and the distillator, on energy requirment are discussed in terms of product purities.

Preparative HPLC of Macrolide Antibiotics

Adsorption isotherms and mass transfer coefficients were measured for one of macrolide antibiotics, erythromycin, with combinations of spherical silica gel and various organic solvents. Measured and simulated chromatorgams agreed well for various combinations and several operating conditions. The effects of equilibrium and rate parameters on the shape of chromatogram were discussed from results of simulation.