We have analyzed the orientational distributions of a nondilute colloidal dispersion composed of ferromagnetic spherocylinder particles subjected to a simple shear flow. We applied the mean-field theory to the system for an external magnetic field parallel to the angular velocity vector of the shear flow in order to understand the effects of the interactions among the particles. We conclude that the interactions suppress the Brownian motion of the particles and, therefore, make the particles incline toward the same direction. Although the interactions of the particles work in the nondilute colloidal dispersion system, the magnetic field and the shear flow dominantly affect the orientational distributions of the system for an external magnetic field parallel to the angular velocity vector of the shear flow. The particles incline toward the magnetic direction as the strength of the magnetic field increases.
Vapor–liquid equilibria of five absorbents were measured using a 1 L equilibrium apparatus. Absorbents tested were 2-Amino-2-methyl-1-propanol (AMP), KS-1 absorbent, monoethanolamine (MEA), methylaminoethanol (MAE), and diethanolamine (DEA). AMP and KS-1 absorbent had good CO2 absorption capacity 0.76–0.80 mol CO2/mol amine and could be easily regenerated at high temperature 0.16–0.23 mol CO2/mol amine. Further, the loading of each absorbent was evaluated in both the absorption and stripping processes. The test data of AMP and KS-1 revealed that the effective CO2 loading is an important index in determining the net CO2 absorption performance in the CO2 recovery process.
A novel ion-exchange method which decreases byproducts and increases purity was developed for purification of amino acids in fermentation broth. The conventional method involves problems such as production of large amounts of byproducts and low purity of the product, since considerable amounts of the eluting agent remain in the effluent and the eluate. The new method employs hydrogen carbonate ions generated by dissolving carbon dioxide gas under pressure as the eluting agent, and this can easily be recovered from the effluent and the eluate after the ion-exchange reaction by releasing the pressure. Experiments were conducted using a strongly basic anion exchange resin (SA10A, Mitsubishi Chemical Corp.) and the fermentation broths of L-phenylalanine and L-glutamic acid as representatives of neutral and acidic amino acid, respectively. In the adsorption process, the ion-exchange reaction successfully proceeded under 0.5 MPa pressure by using compressed air in order to prevent the foaming of the carbon dioxide gas. It was possible to remove most of the hydrogen carbonate ions from the effluent by releasing the pressure and then concentrating the effluent. At the same time, it was also possible to recover the ammonia in the fermentation broth. Carbon dioxide gas dissolved in water or aqueous ammonia under 0.6–0.7 MPa was used for the elution of the amino acid. Almost all of the carbon dioxide gas was recovered by releasing the pressure in the cases of both L-phenylalanine and L-glutamic acid. Therefore, it can be said that in both cases, favorable performances of elution were achieved. The results of this experiment suggest that it is possible to construct a closed system in the amino acid production process.
Experiments to separate nickel and chromium were carried out at 298 K on a porous glass packed-column using nitric acid and citric acid as an eluent. When nitric acid was used as an eluent, both metals were perfectly recovered in the concentration range of 0.02–0.05 mol/dm3, and they were isocratically and perfectly separated at 0.02 mol/dm3. When 0.1 mol/dm3 citric acid was used as an eluent, both metals were perfectly separated in the range of pH 1.7–2.2, and isocratic elution was especially possible at pH 1.7 and at pH 2.2. It was considered that the perfect separation of both metals could be performed in this pH region, since generation of CrOH2+ ion, which was eluted simultaneously with Ni2+ ion, was suppressed. It was found that separation performance was raised, since the retention volume of chromium was increased and that of nickel was hardly changed with decrease in the amount of both metals loaded.
The reversible hydration of CaO to Ca(OH)2, was investigated in open and closed systems. The experimental results were compared with that of the Semi-closed system reported in the previous paper. The pressure for reaction in the open system was higher for hydration and lower for dehydration than in the closed system at the same temperature. The final hydration conversion in the closed system at given reaction temperature was lower than in the open and semi-closed systems. The specific surface area of CaO obtained by the dehydration in the semi-closed system was about 1.2 times greater than that in the closed system. A model previously proposed for Semi-closed system was found to be applicable also to the closed and open systems.
For the removal of acid gases in flue gas from municipal solid waste incineration, simultaneous sorption of HCl and SO2 in CaO fine particles was conducted in the temperature range 473–1073 K, in simulated gas atmospheres comprising mixtures of HCl, SO2, O2, N2, H2O and CO2. The effect of H2O and CO2 on the sorption of HCl and SO2 on CaO was investigated. The maximum capacity of HCl sorption on CaO was found at 873 K in all gas mixtures employed. However, the HCl sorption on CaO was considerably inhibited by the presence of SO2, H2O and CO2 in the HCl–O2–N2 system. The reverse reaction of HCl emission from the reaction product, CaCl2, was considered responsible for a lower HCl sorption on CaO. On the other hand, the capacity of SO2 sorption on CaO was lower in the HCl–SO2–O2–N2 system than the SO2–O2–N2 system. At a higher temperature of 1073 K, the capacity of SO2 sorption on CaO became remarkably higher in the HCl–SO2–O2–N2–H2O system than the HCl–SO2–O2–N2 system. However, SO2 sorption capacity was further decreased by the presence of CO2 in the HCl–SO2–O2–N2–H2O–CO2 system, which might be caused by carbonation of CaO and CaCl2 with CO2.
The partial fraction decomposition method is proposed as a new method for identifying time-delay systems. Many chemical plants include a large or small time-delay factor in their process dynamics. However, it is very difficult to estimate the time-delay exactly by using conventional methods. In the proposed method, a suitable transfer function of the plant is built from operational input-output data with the usual identification method. The transfer function usually includes redundancy, or consists of a characteristic part and a redundant part, because the order of the plant is not known exactly. The redundant transfer function is decomposed into first-order partial transfer functions to extract the characteristic part from the model. Thereby, not only the redundant part but also errors included there in are removed. Consequently, the transfer function of the plant can be rebuilt precisely. The processing algorithm is very simple and calculations are fast and easy. In this paper, two examples are treated to evaluate accuracy for identification. One is to model a process of which the transfer function is well known. The other is to model an industrial distillation column from operational data. Once exact time-delay is estimated, the plant can be expressed with a very simple transfer function.
CHA-type structure silicoaluminophosphate zeolite (SAPO-34) was examined as an AHP adsorbent and the influence of silicon content on its adsorption performance was evaluated. SAPO-34 with silicon content of 7.5 mol% (Functional Adsorbent Material-Zeolite 02; FAM-Z02) was selected for further testing. The water vapor adsorption isotherm of FAM-Z02 was S-shaped and highly dependent on temperature, and a small hysteresis was observed with adsorption/desorption at 363K. No changes were observed in the properties of FAM-Z02 after 100000 cycles of water vapor adsorption-desorption, indicating that FAM-Z02 is suitable durable for practical use. When the AHP was operated under conditions of TL/TM/TH=283 K/313 K/363 K, the adsorption capacity of FAM-Z02 was 4.8 times and 3.8 times those of Y zeolite and silica gel.
To obtain fundamental data for developing an efficient recovery process of heavy metals from various molten fly ashes, chlorination behavior of lead and zinc was investigated for the three types of ash produced from electric resistance, gasification melting and coke bed melting furnaces. Ash samples were heated at terminal temperatures ranging from 873 to 1073 K in a nitrogen stream with a fixed bed reactor. Polyvinyl chloride and carbon derived from phenolphthalein were used as chlorination accelerating agents. The addition of polyvinyl chloride was effective for the release of lead, which was identified as the oxide in every sample. Several zinc compounds such as the oxide, sulfide, carbonate, silicate and aluminosilicate were observed depending on the ash. Zinc originating from oxide and aluminosilicate was volatilized at 1073 K by the addition of polyvinyl chloride, while zinc sulfide and zinc silicate did not react with it. All forms of zinc were released effectively from the three sample ashes by the addition of carbon, and more than 90% of zinc was released at 1073 K.
The inorganic anion exchanger, hydrotalcite (HT) was synthesized by using aluminum dross and MgCl2 waste solution discharged from an Al regeneration factory. The ability of the obtained CO32− type HT and its calcination product to remove various toxic heavy metal ions such as As(III), As(V), Se(IV) and Cr(VI) from aqueous solution was investigated. The amount of As(III) removed with the calcination product of CO32− type HT at 773 K is larger than that with the CO32− type HT. In the removal of As(V), no marked difference was found between the CO32− type HT and calcination product. In the same way, it is possible to remove Se(IV) and Cr(VI) with the CO32− type HT and the calcination product. In using the calcination product for the removal of As(III), As(III) is directly incorporated with HT calcination product in a rehydration process, and the reaction is predominant over the anion exchange reaction between OH− and As(III). About 90% of As(III) removal can be obtained in the initial pH range from 4 to 11. These phenomena are related to the pH buffer effect of HT, by which the equilibrium pH after As(III) removal is adjusted to be about 11. The largest amount of Cr(VI) removal can be obtained with the calcination product at 673 K. The HT derived from the above wastes, which has both anion exchange ability and pH buffer action, can be used as an excellent removal agent of various toxic heavy metal ions.
The effects of magnesite diameter on the magnesite reforming rate were experimentally investigated. When magnesite alone was heated, the reforming rate decreased with increasing magnesite diameter. For mixtures of magnesite with addition of the magnesium nitrate hexahydrate, the magnesite reforming rate constants were similar to those without magnesite nitrate hexahydrate, when the magnesite diameters were greater than 10−3 m, and greater than that without magnesium nitrate hexahydrate when the magnesite diameters were smaller than 10−3 m. In the mixtures with magnesium nitrate hexahydrate, the magnesite reforming rate constant is inversely proportional to the square of the magnesite diameter.