Viscosities of the ternary mixture cyclohexane + 1-3-dioxolane + 1-butanol and the binary mixtures cyclohexane + 1-butanol and 1-3-dioxolane + 1-butanol have been measured at normal pressure at 298.15 and 313.15 K. Viscosity deviations for the binary and ternary mixtures were fitted to Redlich-Kister’s and Cibulka’s equations respectively. The group contribution method proposed by Wu has been used to predict the viscosity of binary and ternary mixtures.
In this paper, it is verified that the difference in mixing state between both lower and upper zones of a bubble column exists even in the shallowest bed with a clear liquid height L0 equal to 0.56 m. From the time-dependent QM profiles, the following conclusions are obtained: The tracer concentration is relatively uniform in the lower and upper zones, but the mixing properties of both zones are different, except for the earliest and latest stages of the mixing process. This is valid in the range of superficial gas velocities from 0.0178 m/s to 0.0305 m/s, provided that the clear liquid height is kept constant at 0.56 m. The mixing state of one zone is more advanced than that of the other zone when the superficial gas velocity is set as high as 0.0381 m/s, except for the earliest and latest stages of the mixing process. This tendency is independent of column height. It is also proven that the operating time at which the concentration homogeneity is attained throughout the column is predictable and equal to the mass transfer (saturation) time τMTexp. For that purpose, Miller’s (1974) method should be employed to correct the kL value derived by Higbie (1935). The authors propose the characteristic time τMTexp to be adopted as a routine column shut-down time.
The flow properties of whipped cream were measured by means of a rheometer under atmospheric pressure. A rheological model to predict the non-Newtonian viscosity of whipped cream is proposed. This model is the modification of a suspension rheology model previously proposed by one of the authors of this study. The inter-particle bonding energy for minimum sized fat particles is determined from the viscosity measurement results. Assuming that both air bubble and fat particle are solid particles, it is demonstrated that the model is able to predict the non-Newtonian behavior of whipped cream under atmospheric pressure. The whipped cream was forced to flow in 5 mm dia. tube under pressurized conditions. The flow rate and the local pressure distribution were measured. These experimental data enable us to determine the apparent viscosity of whipped cream at the wall shear rate under pressurized condition. Assuming that the ideal gas law can be applied to the air bubble suspended in whipped cream the above mentioned rheology model is applied for a pressurized system. The prediction is in good agreement with the apparent viscosity experimentally determined. Thus, we conclude that the apparent viscosity of whipped cream can be predicted by the suspension rheology model proposed in this study.
The effect of nozzle contraction angle on air entrainment rate by a vertical plunging liquid jet was investigated. The surface roughness of the jet increases with increasing nozzle contraction angle up to about 40°, and then levels off. The volumetric air entrainment rate increases in proportion to (sinθ)0.21, corresponding to the increased surface roughness of the jet. The air entrainment rate is correlated with empirical equations, which cover a wider range of the nozzle geometries and operational conditions. The relationship between the air entrainment rate per power consumption and nozzle contraction angle was also investigated. The power efficiency for air entrainment is found to be almost independent of the nozzle contraction angle.
Gas hold-up in water and Castor oil, which were agitated separately by four disc type impellers, is compared on the basis of equal specific power dissipation (PG/V). It is noted that unlike in water, gas hold-up in Castor oil is time dependent, and also strongly influenced by impeller design. Further, the gas hold-up values in Castor oil are generally higher than those observed in water, and unlike in water, decrease with increasing (PG/V). These observations, which appear anomalous in the context of some earlier publications, are explained by considering the hold-up in Castor oil in terms of contributions from large and tiny bubbles.
Some primary alcohols, different in alkyl chain lengths ranging from C4 to C8, were anodically esterified by using I+/I– as a mediator while the alcohols were emulsified in water by ultrasonic irradiation. Concurrently, for comparison, they were similarly esterified while emulsified with surfactant addition. The irradiation increased alcohol conversion and ester yield, although the values were less than the maxima obtained by surfactant addition. Further the conversion and yield varies through maxima against change in the alkyl chain length. The increase in the conversion and ester yield is explained in terms of an increase in interfacial area of the dispersed alcohol phase. The variation in the conversion and ester yield with the alkyl chain length is regarded as being caused from changes in the physico-chemical properties of the alcohols, such as solubility in water and viscosity. Superimposition of ultrasonic irradiation to surfactant addition increases further the conversion and yield at lower and higher surfactant concentrations. However, it did not make the conversion and yield exceed their maxima attained by surfactant addition alone.
The velocity profile, temperature distribution, and the slowest heating point of a canned liquid food containing fibers or particles were calculated numerically by using fundamental equations that take account of the effect of free convection in the can at an unsteady state under the assumption of imaginary fluid with apparent physical properties. To check these calculated results, the temperature distribution in the can was measured experimentally under the same operating conditions as those of the theoretical analysis. The calculated results agree closely with the experimental ones. Adaptable ranges of present numerical analysis and the positional characteristics of the slowest heating point are shown.
The axial distribution of gel beads suspended completely in a bubble column was measured by sampling the three-phase dispersion through a vertical pipe located at any height of the column axis under various operating conditions of superficial gas velocity UG, average gel beads holdup εS and unaerated slurry height HD. The gel beads used were prepared by entrapping glucose oxidase as well as fine palladium particles within calcium alginate gel to catalyze the air oxidation of glucose for efficient production of calcium gluconate. The conventional sedimentation-diffusion model, which includes the gel beads dispersion coefficient EP and their settling velocity vP to describe the axial distribution, is found to give unreasonable EP values being at least twice as high as than those predicted from the published correlations, and also twice as high as the estimated values of the liquid dispersion coefficient EL in the three-phase bubble column. This was assumed to be ascribed to the reduced apparent values of vP, since the intrinsic EP value should be nearly equal to the EL value. In view of the fact that the gel bead has almost the same density as the liquid phase and the size is comparable to the mean bubble size, the model was modified by introducing an additional parameter, the rise velocity of the gel beads swarm um representing an effect of rising air bubbles on settling gel beads. The values of um were determined from the observed axial distributions by assuming that the EP values are given by the reported correlation of EL in suspension of the inert calcium alginate gel beads, and empirically correlated with UG and εS. The axial distributions calculated from the modified model well agreed with the observed ones for the different HD.
Char combustion is investigated in the temperature range of 559–1273 K and pressure range of 0.1–1.6 MPa in a 0.5th-order reaction (a lignite coal char) and a first-order reaction (a bituminous coal char). The intrinsic combustion constant kv and the reaction order n do not vary with pressure, but the char combustion initial rate varies with the pressure in the chemical kinetics control and the internal diffusion influence regimes. The variation of initial rate with pressure was also sensitized to the reaction order n. In the chemical kinetics control regime, the char combustion initial rate was proportional to Pn with the exponent n, the reaction order. In the internal diffusion influence regime, the apparent dependency of char combustion initial rate on pressure changed with the exponent range from n to n/2. The reaction initial rate in the external diffusion control regime was invariant with pressure. A rate expression was developed for predicting the initial rate of nth-order char combustion under elevated pressure.
Thiazolium ion catalyst was immobilized on a cation-exchange resin, and the formose reaction was carried out with the resin. As a result, the use of this resin turned out to be useful for the formose reaction in an organic solvent, similar to the free thiazolium catalyst. Interestingly, the catalytic activity of this resin decreases after washing with an organic solvent, but recovers after washing with water. This result suggests that water molecules have an influence on the catalysis in this system.
Dissections of solid samples partially reacted under different conditions were examined to determine the control region of the reaction between titanium pellet and nitrogen gas. The thickness of the pellet studied was varied from 0.0012 to 0.00638 m while temperature was varied from 1, 173 to 1, 473 K. Experimental results indicate that the system is in the chemical reaction control region as the pellet thickness is 0.0012 m for all temperatures studied. The system is in the gas-pore-diffusion control region when the thickness is 0.00638 m and the temperature is 1, 373 or 1, 473 K. For other cases, the system is in both control region.
The two-dimensional distribution of liquid flow is measured in a gas-liquid concurrent downflow trickle bed, where trilobe particles are packed with three different methods, i.e. random, convex and concave packing. The effects of shape and orientation of particles on the liquid flow rate distribution are examined. The particle orientation has a significant effect on the liquid flow in the trickle bed. The liquid is distributed toward the wall when the trilobe particles are packed in the convex structure, but is converged into the center of the bed packed in the concave structure.
Mechanochemical solid-phase reactions for hydroxyapatite (Ca10(PO4)6(OH)2, HAp) from different kinds of constituent powder mixture were investigated. HAp monophase can be produced from the three sets of powder mixtures of Ca(H2PO4)2H2O-CaO, Ca(H2PO4)2H2O-Ca(OH)2, and Ca(H2PO4)2H2O-CaCO3 (Ca/P atomic ratio: 1.67) by dry grinding using a planetary ball mill at room temperature. All the solid-phase reactions for HAp from the starting mixtures were almost completed within 60 min of grinding. Among them, Ca(H2PO4)2H2O-Ca(OH)2 mixture is the most suitable one for the preparation of HAp. The amount of free H2O released during mechanochemical treatment plays a key role in these synthesis reactions. The formation of HAp is improved as grinding progresses. The completion of synthesis reactions is confirmed by measuring the equilibrium pH of powder suspensions of ground mixtures.
A distillation column with an adjustable slope horizontal rectification section was constructed. A rotating screw brush was inserted into the section, which could be rotated from 0 to 600 rpm with an external motor. Distillation experiments were carried out using the system cyclohexane-heptane at total reflux at slopes of 0 (horizontal), 5 and 10 degrees. Separation efficiency for the horizontal column was the highest of the three orientations, and was obtained as HETP from 0.04 to 0.16 m at F-factor of 0.05 to 0.4 m/s(kg/m3)1/2 in the range of 100 to 600 rpm. The HETP for each slope was roughly constant at a rotation speed of more than 300 rpm. The values of the pressure drop were found to be equivalent to those of one seventh to one fifth of conventional packed columns.
Tannin gel particles that have extremely high adsorption capacity for hexavalent chromium Cr(VI) have been developed by controlling gelation of Mimosa tannin extracted from the bark of plants. The gelation process is composed of two stages; partial gelation of Mimosa tannin by reaction with formaldehyde (cross-linking agent) and granulation by dispersing the partially gelated solution into a liquid mixture of decalin and a polyether nonionic surfactant with vigorous stirring. The structure of the tannin gel particles is controlled by a combination of operating conditions such as reaction time and temperature at both stages. The water content of the tannin gel particles that reflects their structure can be widely changed from 40 to 79% (wet basis), even for a constant composition of 23 g Mimosa tannin and 6 ml formaldehyde (37 wt%). It is found that it is very important to increase the water content without losing mechanical strength and supply a large amount of protons during adsorption for achievement of high adsorption capacity. The maximum adsorption capacity, 540 mg-Cr(VI)/(g-dry tannin gel) is obtained at a water content of 77.6% with an acidic solution of pH ≈ 2.0. Based on this knowledge, we propose a new system that generates little waste in removing and recovering hexavalent chromium.
Continuous rotating annular chromatography with partial recycling of the effluent (CRAC-PRE) was used for the separation of a ternary mixture of amino acids. A mathematical model describing the separation process was constructed to find the optimized operating conditions. The effectiveness of the CRAC-PRE for the separation of a ternary mixture was experimentally and theoretically elucidated by comparison to conventional CRAC. A recycling loop which gives reasonable separation was successfully arranged on the basis of the numerical simulation result. A combination of CRAC-PRE with the step elution method was applied to the complete separation of a ternary mixture of amino acids.
Reverse micellar extraction of various proteins of large molecular weight and oligomeric proteins, as well as small ones, was carried out using conventional AOT reverse micellar extraction systems at various pH values. The conformational change of the proteins by electrostatic interaction with AOT was also measured using a CD spectrum. Extraction behavior and conformational change of the proteins were discussed from their electric charge properties and electrostatic interaction between protein and AOT. Most of the proteins were effectively extracted into the reverse micellar phase at around zero surface net charge. Formation of aggregates and denaturation of proteins were observed in the region of positive net charge higher than 10.
Dry grinding of a powder mixture composed of talc and magnesium carbonate was conducted using a tumbling ball mill to investigate formation of forsterite in bodies sintered from the ground mixture and their bending strengths. The grinding causes a structural change in the starting materials from a crystalline state to an amorphous one. The amorphous mixture leads to the formation of single-phase forsterite at relatively low sintering temperature, at which the bending strength of the sintered bodies reaches the maximum value. The maximum bending strength increases with increasing grinding time for the mixture. The sintering temperature providing the maximum bending strength becomes low as grinding progresses. Dry grinding for the mixture is favorable for production of forsterite ceramics.
Dry grinding a mixture composed of kaolinite, talc, and aluminum hydroxide was conducted using a tumbling ball mill to investigate its effect on formation of cordierite in a sintered body prepared from the ground product and its mechanical and thermal properties. The grinding enables us to induce structural changes in the raw materials, namely into amorphous state with good homogenization. Prolonged grinding of about 192 h leads to the formation of single-phase α-cordierite from the ground product at relatively low sintering temperature. Grinding for 192 h and sintering at 1573 K allows us to produce dense α-cordierite in the sintered body, having high Vickers hardness (700 Hv) and a low linear thermal expansion coefficient of 0.6 × 10–6/K (298–1173 K).
The elutriation of fine powders (group C or group A powders in Geldart’s classification) from a fluidized bed of fine-coarse particle mixtures in a steady state is investigated. FCC and alumina particles of 12 μm to 91 μm in diameter (group C and group A powders) were used as fines. Alumina particles of 69 μm to 650 μm in diameter (group A and group B particles) were used as coarse particles. The effects of the weight fraction of powder in the bed, superficial gas velocity, size of fine powder, size of coarse particle, and mean diameter of bed particles on the elutriation rate constant were investigated. The following results are obtained. The elutriation rate constant of group A particles is affected by the properties of the elutriated particles and gas and by operating conditions such as gas velocity. However, the elutriation rate constant of group C powders is not only affected by the above conditions, but also by the weight fraction of the elutriated powder in the bed and sizes of both coarse particles and elutriated powder in the bed, that is, the mean diameter of the bed particles. The elutriation rate constant of group C powders decreases with increases in the mean diameter of bed particles and with decreases in the size of group C powders under the condition of a constant superficial gas velocity. This finding is quite different from that of elutriation of group A or group B particles.
The effects of the urea concentration and methods of addition on refolding efficiencies were studied by use of lysozyme and carbonic anhydrase to attain high refolding efficiencies at high protein concentrations. Depending on the protein concentration to be refolded, a suitable urea concentration exists. Thus, by selecting such a urea concentration for formation of a so-called loosely folded state of protein molecules without aggregate formation in renaturation mixtures, high refolding efficiencies above 80% were obtained in both lysozyme and carbonic anhydrase. A method of addition of denatured protein solutions to refolding buffers in fed-batch manner was devised to adjust the urea concentration in renaturation mixtures to follow the best trajectory for high refolding efficiencies through the course of refolding. By fed-batch addition of a denatured lysozyme solution to the refolding buffer containing 2.5 mol/L urea, a refolding efficiency of 85% was attained even at a lysozyme concentration of 7.3 kg/m3. Urea in renaturation mixtures could be removed by dialysis without loss of the enzyme activities. These results are useful to attain a high efficiency at a high protein concentration in refolding processes.
In order to develop a high temperature heat storage and temperature upgrading system using the CaO/CaCO3 reaction, decarbonation of CaCO3 has been carried out with thermogravimetry in the ranges of 1073–1193 K and 3–55 kPa. Calcium carbonate virtually did not decompose under the condition where the partial pressure of CO2, P, is higher than half of the equilibrium decomposition pressure of CaCO3, Pe. It implies that the present heat storage system has to be operated in pressure regions lower than half of Pe. Most decarbonation occurred during the chemical reaction-controlling period. A rate expression, employing a fractional pressure term, (Pe – P)/Pe, is proposed for the reaction-controlling period by assuming the presence of a reaction intermediate. It is found that the dependency of pressure on reaction rate is non-linear, and the reaction is strongly influenced by the change in P.