The μVT-NEMD method, a combination of the μVT-MC and the boundary-driven NEMD, is used for simulating permeation of pure and mixed gases through slit-shaped carbon membranes with belt-like heterogeneous surfaces under the assumption of local adsorption equilibrium at the membrane entrance. The belt-like heterogeneous surfaces are made by removing carbon atoms of the first layer in a line vertically to the permeate direction. Methane and ethane are used as permeating gases. The values of permeation resistance increase almost exponentially with an increase in the potential barrier; the resistance for ethane is always larger than that for methane. In the case of a binary system, the permselectivity is determined by the adsorption equilibrium at the feed side when the potential barrier is low, while it sharply decreases with increasing potential barrier. This result suggests that the separation mechanism changes from the adsorption equilibrium control to the permeation rate control in the pore. The curve of the molar flux of ethane against temperature has a minimum point where temperature is about 510 K.
A methane hydrate crystal annealed at maximum pressure remembers the compression in the hydrate S-cage until the higher equilibrium temperature for maximum pressure is reached. The hydrate S-cage-like structure in the aqueous solution also remembers the compression until the so-called activation energy is given by heating. Therefore, the hydrate crystal compressed by the maximum pressure is reformed at the equilibrium temperature for the maximum pressure.
This paper investigates the application of a fluidized bed reactor for fast pyrolysis of chlorodifluoromethane (R22) into tetrafluoroethylene (TFE) which is endothermic reaction. Numerical analysis for kinetics of R22 pyrolysis showed that heat supply is critical factor due to higher reaction temperature and shorter reaction time where better TFE yield is obtainable. Then, we proposed microwave-heated fluidized bed as a reactor type instead of a conventional tubular reactor using superheated steam as a major heat source. We examined the fluidized-bed R22 pyrolysis over temperature range of 700–840°Cand could achieve TFE yield more than 80 mol %. It was also expected that the TFE yield can be further enhanced by optimizing fluidizing condition. Hence, the proposed fluidized bed is applicable to R22 pyrolysis as an efficient reactor type. It is demonstrated that the microwave is a promising heating means for the fast reaction since it can achieve high-heat flux for so small reactor volume without overheating the reactor wall.
The influence of the particle size on the thermal decomposition of ε-hexanitrohexaazaisowurtzitane (HNIW) was studied by means of differential scanning calorimetry (DSC). The kinetics and mechanism for the decomposition were evaluated using integral methods. It was found that the thermal kinetic parameters such as activation energy (E) and pre-exponential factor (A) depend little on the particle size of ε-HNIW in the range 4–180 μm, and an A3 model function fits most of the data from the decomposition of the material.
In mixed micellar systems of sodium bis(2-ethylhexyl) sulfosuccinate and long chain alkyl amines, such as tri-n-octylamine and bis(2-ethylhexyl) amine, the extraction of proteins and water are investigated. Extraction of water into the mixed micellar systems, which affects protein extraction, is controlled by pH in the aqueous phase. When the amine concentration is equal to or higher than that of AOT, no extraction of water is observed in the acidic pH range. The pH dependence on water extraction is affected by the basicity of the amines added. Reverse micelles do not form from the mixture of AOT and cationic species of long chain alkyl amines in the acidic pH range. Extraction of proteins, such as low molecular weight lysozyme and higher molecular weight BSA, is also controlled by the formation of the reverse micelles. The formation of aggregates of proteins triggered by the electrostatic interaction with AOT is suppressed in the mixed micellar systems. The proteins extracted into the mixed micellar systems can be successfully back-extracted by destruction of the micelles at acidic pH.
Batch distillation of lactic acid with the simultaneous reactions was studied. Lactic acid was reacted with methanol, and methyl lactate was produced by the esterification reaction. The volatile methyl lactate was distilled simultaneously with the hydrolysis reaction into lactic acid. To recover pure lactic acid through two reactions and distillation, batch distillation system consisted of two condensers, feed vessel, and reboiler was studied. For both reactions of esterification and hydrolysis, the acidic cation exchange resin was used as a solid catalyst. As the concentration of catalyst increased, the yield of recovered lactic acid was increased. As the feed concentration of lactic acid and the reactant molar ratio in the esterification reaction decreased, the recovery yield of lactic acid was increased. The yield of recovered lactic acid was as high as 95%. When impure lactic acid solution obtained from bacterial fermentation was used as feed, highly pure lactic acid solution was obtained with yield of 92% in reboiler.
This study aims to develop an environmentally-friendly resin for boron recovery. To this end, the adsorption characteristics of boron on chitosan resins chemically modified by saccharides are investigated for the purpose of the removal of boron from a boron mine and the desulfurizing equipment in coal-fired steam power stations, and compared with those of a commercial resin (Duolite ES371). First, chitosan derivatives incorporating saccharides were synthesized by reductive N-alkylation, and the products were crosslinked with ethylene glycol diglycidil ether. The resulting products (SMC resins) were found to exhibit dissolubility in acidic and basic solutions. From the adsorption experiment on the resins (SMC and Duolite resins), it is found that the adsorption mechanism is a complex formation between boron which exists as boric acid or borate in an aqueous solution and the vicinal diol groups of the branched saccharide. The apparent adsorption equilibrium constants of boric acid-diol complex and borate-diol salt complex are determined. The adsorption isotherms of boron correlate well with the Langmuir equation, and the order of the saturated adsorption capacity of boron on SMC resins corresponds to that of the degree of substitution on SMC resins.
Protein extraction using reversed micelles is carried out in a packed column. The extracted fraction of lysozyme and the overall capacity coefficient, Kca, are measured for various flow rates and different packing materials. The same column without packings is also used as a spray column. By using a flat interface stirred cell, mass transfer coefficients for the aqueous and the organic phases are measured as well as the protein transfer rate. The results indicate that the resistance of protein solubilization at the interface controls protein transfer from the aqueous into the organic phase. The extracted fraction in the packed column is about three times larger than that for the spray column due to the larger holdup of dispersed phase in the packed column. Since the drops hardly break or coalesce in the packed bed and the protein transfer coefficient is constant, the overall capacity coefficient is controlled by the holdup of dispersed phase. On the assumption that the drop size and the transfer coefficient are constant, the correlation between holdup and flow rates is obtained. Values of Kca and the extracted fraction are calculated from the holdup correlation. Effects of packing materials on the values of Kca are small. A high protein activity is retained in the packed column operation, which indicates that the packed column does little harm to proteins due to moderate mixing.
A novel resin organized from an amidoxime derivative of chitosan is prepared and the adsorption characteristics of metal ions are examined. Metal ions are adsorbed by forming chelates coordinated by nitrogen atoms of primary amino groups and oxygen atoms of oxime groups. The amidoxime chitosan resin (AO-b-1) retards the adsorption of nickel ion compared with that on N-(sulfopropyl)chitosan (PSC), and the maximum adsorption capacity of copper ion on AO-b-1 is 1.6 times as much as that for PSC. The adsorption capacity of copper ion is further enhanced by alkali treatment of the resin. The amidoxime chitosan resin prepared here is found to be an excellent adsorbent with high adsorption capacity and selectivity for copper ions.
The kinetics of aluminum and beryllium extraction by mono(2-ethylhexyl)phosphoric acid (M2EHPA) is studied using a stirred transfer cell. M2EHPA has high surface activity and forms reverse micelles in the organic phase. The formation of a 1:1 complex of the metal ion and the dissociated M2EHPA anion in the aqueous phase is found to be rate-determining. The formation of reverse micelles does not affect the extraction rate, and rapid attainment of the extraction equilibria observed otherwise in the shaking experiments is considered to be caused by the large interfacial area due to the lowering of interfacial tension.
Vertical columns, 1- and 2-m in height, packed with coarse glass spheres or pulverized coke, are used as a cold model for a blast furnace. The effect of bed height on static and dynamic holdups of fines (sieved glass beads, FCC catalyst particles or pulverized coke particles) is investigated using this system. The static holdup of fines is approximately the same in the 1- and 2-m high packed beds. However, the dynamic holdup in the 1-m high packed bed is larger than that in the 2-m high packed bed when glass beads of 65 μm diameter and FCC catalyst particles are used as the fines. The holdup of fine glass beads is then determined at 0.2-m intervals to the axial direction in the 1-m high bed packed with glass spheres. The dynamic holdup is large in the bottom region of the packed bed and approaches a constant value with increasing distance from the bottom, which explains the increase in average dynamic holdup in the shorter packed bed.
A novel method for continuous production of monodispersed oil-in-water (O/W) emulsion is developed using a crossflow-type silicon microchannel plate. On the single crystal silicon plate, a liquid flow path for continuous phase was made, and at each side of the wall of the path an array of regular-sized slits was precisely fabricated. A flat glass plate was tightly attached on the microchannel plate to cover the top of the slits to form the array of microchannels. Regular-sized oil (triolein) droplets were generated by squeezing the oil through the microchannels into the continuous-phase water (0.3 wt% sodium lauryl sulfate solution) flowing in the liquid path. Oil droplet size is significantly dependent on the microchannel structure, which is identified with the microchannel width, height, and the length of the terrace (a flat area at the microchannel outlet). Three types of microchannel plates having different microchannel structures generate monodispersed emulsions of different average droplet sizes, 16, 20, and 48 μm at the water flow rate of 1.4 × 10–2 mL·min–1. For the microchannel plate which generates large droplets of 48 μm, increasing the flow rate causes decreasing droplet size. However, for the microchannel plate which generates small droplets of 16 or 20 μm, the size is not affected by the flow rate within the range from 1.4 × 10–2 to 2.4 mL·min–1. In every case, the droplet size distribution is narrow, and the geometric standard deviation is 1.03 or less.
Traditional analytical methods of determining secondary metabolite levels (e.g., chromatography, spectrophotomety) are based on extraction of the tested tissue and involve its destruction. As a result, it is very difficult to determine such levels in a small localized area. Moreover, because measurements performed in the course of culture necessarily refer to different samples of tissue, levels recorded could reflect variability in the hairy roots themselves, rather than variation as a function of time or morphological location. In this communication we report on a method developed to measure local and overall secondary metabolite levels in a non destructive manner using image analysis and apply it to determine metabolite concentrations in hairy root cultures of Beta vulgaris. To develop the method, after scanning a root under sterile conditions and replacing it in the growth vessel, we converted the image data from red-green-blue to the hue-saturation-intensity coordinate system. Hue and saturation values served respectively for thresholding and determination of pigment level. Root diameter, simulated by thickness of root extract films, was found to be proportional to saturation values, and thus is taken into account when pigment concentration is determined. The data obtained by image analysis were used to determine local and overall accumulation of betacyanin and betaxanthin pigments over time and results were then validated by spectrophotometric analysis. It was concluded that the proposed non destructive method enables accurate determination of changes in local secondary metabolite level at any point in the root, as well as monitoring of changes in overall levels in the entire root system throughout the growth period.
Coal particles contain oxygen functional groups such as hydroxyl, carbonyl, and carboxyl, and mineral matters that contribute surface hydrophilicity. The occurrence of them varies considerably from coal to coal, hence the characteristics of column flotation changes from coal to coal. We expected that the characteristics of column flotation could be simply evaluated by using the area fraction of oxygen functional group sites on the exterior surface of the coal particles. In this work, we conducted column flotation for Shanxi (anthracite), Tyanfu (bituminous), Blair Athol (bituminous), Datong (bituminous), and Illinois (brown coal). The order of carbonaceous materials recovery was found to be Tyanfu > Shanxi > Blair Athol > Datong > Illinois. We also evaluated the area fraction of hydroxyl group on the exterior surface of the coal particles, αex-OH, and that in the coal particles, αin-OH. For Datong coal, the value of αex-OH was larger than that of αin-OH. It means that Datong coal was slightly oxidized. The order of carbonaceous materials recovery was inconsistent with that of αex-OH for the three kinds of bituminous coal. For Shanxi anthracite coal, the flotability is evaluated by considering the wettability of the hydrophobic sites as well as the hydrophilic sites.