Power consumption was measured in a cylindrical mixing vessel with a helical coil, for which data have not yet been published. It was found that the power number of the paddle impeller with the coil on the vessel wall corresponded to that of a vessel with a single baffle of which the ratio of baffle width to coil diameter was 0.25, and the power number of the vessel with a draft tube type coil corresponded to that of a vessel with a baffle of which the ratio of baffle width to vessel diameter was 0.05.
Power consumption was measured for a rectangular eccentric mixing vessel with a paddle impeller. The power number of both rectangular and cylindrical eccentric mixing vessels was correlated with the equations of Kamei et al. for paddle impellers by taking the number of baffles as unity and the baffle width as the eccentric length of the mixing shaft.
A thickener-modeled dry dense medium separator using a gas-solid fluidized bed was developed in which materials of different specific gravity float or sink in the bed and can be withdrawn by overflow or underflow. This system is expected to allow high-speed separation and low-maintenance operation compared with a conventional dry dense medium separator, because there are no moving parts for withdrawing floats and sinks from the bed. The effects of overflow/underflow rate and sample feed rate on the performance of the separator were investigated using silica sand as a fluidized bed medium and 20-mm diameter spheres of various specific gravities as samples for separation. It was found that when the overflow/underflow rate was 0.44 or less, the float-sink boundary was smaller than when there was no overflow and no underflow, but float-sink sharpness was maintained. On the other hand, when the overflow/underflow rate was 0.64 or more, the float-sink boundary was similar to that in the case of no flow, but separation sharpness deteriorated. Furthermore, when the overflow/underflow rate was 0.44 and the feeding rate was 0.035 kg/s (=2.2 m3-object/(m2·h): volume-based separation speed per fluidized bed area) or less, Newton efficiencies were more than 0.9. Compared with conventional apparatus, the separation speed of the present apparatus was 3.4 times higher. Hence, this withdrawing system can be valuable for increasing separation speed and reducing the need for maintenance.
Membrane permeation characteristics of formic, acetic, propionic, and butyric acids were studied over a wide range of operating conditions in the electrodialysis. These mono-carboxylic acids permeated through an anion-exchange membrane, but did not permeate through a cation-exchange membrane. The flux of each mono-carboxylic acid in the single-acid system was significantly affected by solution pH: The flux increased rapidly at pH about 2, after which was kept constant. In the experiments of binary, and ternary acids systems, the order of the flux was formic acid>acetic acid>propionic acid>butyric acid. All the experimental results were analyzed with a mathematical model which considered dissociation equilibrium of mono-carboxylic acids, electroneutrality in the solution, ion-exchange between the solution and the ion-exchange membranes, and ionic flux in the ion-exchange membranes based on the Nernst-Planck’s equation. The model successfully explained the permeation behavior of single, binary, and ternary mono-carboxylic acids systems.
Chemical process problems should be solved by a systematic approach in which simulation plays an important role. Simulation software permits the saving of time in problem solving by skipping part of the process of learning model knowledge. However, if the part skipped includes information that is important to understanding the problem, then simulation software obstructs valuable discussion. The object of this paper is to propose a method to clarify the model knowledge of which the learning process is skipped by simulation software. The model knowledge is expressed by a structural graph based on cause-and-effect relationships between process variables. The usefulness of this method is shown for the case of particle settling simulation.
This study focused on a 1500 L fixed-bed anaerobic ammonium oxidation (anammox) reactor (effective volume: 1563 L), which was developed using malt ceramics (MC) produced from carbonized spent grains as the biomass carriers for anammox sludge. Start-up time for the 1500 L reactor was reduced to 105 d by using effluent from a 400 L fixed-bed anammox reactor as seeding anammox microorganisms. In the 1500 L reactor, stable nitrogen removal rates of 1.98–4.12 kg-NH4-N/m3/d were obtained though the continuous treatment of real wastewater containing synthetic inorganic wastewater with an HRT of 3.0 h at room temperature (25°C) for 120 d.
The influence of the amount of thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), on the anion-exchange properties of PNIPAM/mesoporous silica composite was examined. The structure of synthesized composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), elemental analysis, and nitrogen adsorption measurement. The amount of PNIPAM immobilized on the mesoporous silica, which was calculated from the weight loss measured by thermogravimetry, ranged from 1.0 to 51.2 wt% depending on the amount of NIPAM monomer and crosslinking agent. The adsorption–desorption behavior of methyl orange (MO) ions was affected by the temperature of aqueous solution: the MO ions were adsorbed and desorbed reversibly and repeatedly depending on the pH of the solution at 25°C, while the amount of adsorbed MO ions remained nearly constant at 0.03–0.04 mmol/g regardless of the pH of the solution at 40°C. Also, the amount of PNIPAM immobilized on the mesoporous silica affected the adsorption rate of MO ions. The results indicated that 1 wt% of amount of immobilized PNIPAM is sufficient to produce a rapid response to the temperature change quickly and rapid adsorption of ions.
Lead-free glasses with a low glass transition temperature, low coefficient of thermal expansion, high fluidity and high durability against water are desirable for sealing of electrical devices. In this study, V2O5, H2WO4, and KPO3 were used to develop a novel sealing glass. We investigated the glass transition temperature, softening temperature, glass crystallization temperature, coefficient of thermal expansion and ratio of weight loss of glasses after waterproof testing. Amorphous glasses were obtained by melting of mixtures of V2O5 (10–60 mol%), H2WO4 (10–50 mol%), and KPO3 (30–70 mol%). Two types of glass (40 mol% V2O5–20 mol% H2WO4–40 mol% KPO3 and 40 mol% V2O5–10 mol% H2WO4–50 mol% KPO3) had low glass transition temperature and good fluidity. Addition of Sb2O3 (2.5, 5 or 10 wt%) to the glasses enhanced their durability against water. The coefficient of thermal expansion of the glass composed of 39.0 mol% V2O5–9.7 mol% H2WO4–48.7 mol% KPO3–2.6 mol% Sb2O3 was lowered by incorporation of Zr2(WO4)(PO4)2, a low-thermal-expansion ceramic filler. The glass showed comparable bonding strength with a commercial lead glass.
This study aimed to develop sustained-release microspheres that can be dispersed on agricultural land using conventional sprayers and thus reduce labor required for pesticide application. Acetamiprid-loaded microspheres of less than 100 µm in diameter were first prepared through suspension polymerization of pentaerythritol tetraacrylate (PETEA), but were found to release more than 90% of the loaded pesticide within 3 h in water. However, addition of hydrophobic polystyrene to the microspheres decreased the release rate without increasing the microsphere diameter. These results demonstrate that the acetamiprid-loaded polyPETEA/polystyrene microspheres are promising for further reduction of labor due to the controlled release of acetamiprid.
Poly(p-phenylene) derivatives with pendant-type side chains of various lengths were synthesized in order to investigate the effect of side chain structure on properties such as sulfonation, thermal stability, mechanical strength, water uptake, dimensional stability, proton conductivity, and polymer electrolyte fuel cell (PEFC) properties. The sulfonation reactions were affected by the electron density of side chains. All sulfonated polymers showed thermal stabilities up to 240ºC, which is sufficient for polymer electrolyte membranes used in PEFC. Although the glass transition temperatures were about 200ºC regardless of the side chain structure, the mechanical strength was influenced by the side chain length. The number of adsorbed water molecules per sulfonic acid group (λ) decreased with increasing side chain length, resulting in a lower swelling ratio. The proton conductivity increased with an increase in ion exchange capacity and λ, and S-P1(2.79), which has the shortest side chain, showed the highest proton conductivity. All the sulfonated polymer membranes exhibited sufficient cell performance, but S-P2(2.27) showed the highest performance, revealing a different order of performance among the membranes from that of proton conductivity. It is suggested that the higher water uptake of S-P1 provides not only higher proton conductivity but also lower carrier density, resulting in increased membrane resistance in fuel cell tests.
Moisture adsorbent was prepared from fly ash treated by heating (FA, FA300, FA500, and FA700) or alkaline hydration (FA48, FA60, and FA72). Ash content, specific surface area, pore volume, mean pore diameter, X-ray diffraction, and scanning electron microscopy of the adsorbents were investigated. Among the adsorbents, FA60 had the highest specific surface area (85.7 m2/g) and the highest amount of moisture adsorbed/desorbed, which indicated that adsorption mechanism was related to the specific surface area, the pore volume, and hydrophilicity or hydrophobicity of adsorbent. Adsorption/desorption isotherms of moisture were fitted to the BET equation. FA60 had a humidity control capacity of 116.8 mg/g and was usable for repeated adsorption/desorption of moisture. The results suggest that moisture adsorbent prepared from fly ash has the potential for practical application.
Nylon felts used in the paper manufacturing process are constructed of Nylon-6 and Nylon-6,6 and most of the 1100 t/year of felt produced is disposed of. In this study, a new process was proposed for regeneration of Nylon-6 and Nylon-6,6 from Nylon felts discarded by the paper mill industry. The process consists of dissolution-separation of Nylon into a solvent, reprecipitation of Nylon using a non-solvent, and recycling of waste solvent from the above two steps by distillation. The mixed solution of methanol with calcium chloride dihydrate (CaCl2–MeOH solution) used in the previous work was again used as solvent for dissolution of Nylons. The experimental results on the selective separation of Nylon-6 or Nylon-6,6 showed that both were possible by adjusting the concentration of calcium chloride dihydrate in the solvent. The results of X-ray diffraction analysis suggested that the solubility of Nylons was affected by their crystalline structures. The experimental results on solvent recovery indicated that methanol, water and calcium chloride dihydrate could be recycled by double distillation. By the proposed process, Nylons were regenerated in a high recovery rate 92.8% from felt wastes, and the purities of Nylon-6 and Nylon-6,6 were almost 100% and 81.4% respectively. This process is thus considered applicable for regeneration of Nylon-6 and Nylon-6,6 from Nylon wastes in chemical industries.
Contaminated soils were prepared by impregnating four soils of different origins with heavy metals, Cd, Cu and Pb, to concentrations of 300 mg/kg-dry soil. The effects of pH on the dissolution of heavy metals from the contaminated soils in aqueous solution were investigated. For all soils, the heavy metal dissolution increased markedly when the initial pH of the solution was 2 or below. In the range of initial pH of 4–10, the dissolution of heavy metals was low and almost constant. The pH buffering actions of the soils varied with their place of origin. When soils with high contents of humic substances or other organic matter were immersed in solutions with an initial pH of 12–14, the amount of dissolved Cu increased due to complexation by the dissolved organic compounds. Stabilization experiments were carried out by adding zeolite synthesized from coal fly ash to soil in a mixing tank, and by making pellets of soil and zeolite. The amount of heavy metals in the solution was decreased by the cation exchange action of zeolite and by increasing the solution pH. In the mixing tank, the addition of zeolite showed a stabilizing effect on Cd, Cu and Pb, compared with the absence of zeolite. With pellets of soil and zeolite, the amounts of Cd, Cu and Pb in the solution decreased to less than 2 mg/dm3. Thus the stabilization of heavy metals in contaminated soil can be achieved by addition of zeolite.
As an alternative for noble metals such as platinum that are included in three-way catalysts for exhaust purification in gasoline automobiles, an electrically heating alumite plate catalyst supporting iron–cerium–carbon was synthesized, and its properties in purification of automobile exhaust were examined. It was found that carbonization treatment at 800°C produced a Fe3C phase in the catalyst. Catalysts treated by carbonization at 800°C for 2 h °C showed favorable purification of automobile exhaust and good durability, suggesting their potential for application as under-floor catalysts in automobiles.
Among the basic strategies for promotion of cooperation in innovation among industry, universities and the government, MEXT has proposed the establishment of an innovation ecosystem. Innovation is holistic, and in establishing such a system, it is necessary to take a holistic approach to research and to manage research and development. To support such an approach, the present study examined the introduction of Project & Program Management (P2M) and a supporting system for research planning using the Logic Model and the Balanced Scorecard. Four years after this system was introduced to support engineering research in university, its effectiveness was evident in increases in research achievements such as the numbers of research presentations and research papers. These results also suggested that the Logic Model and the Balanced Scorecard are two tools that can play important roles in integration of multiple technologies and coordination of interests among stakeholders in collaborative research among industry, universities and the government.