In order to develop a hydrometallurgical recycling process for an indium-tin-oxide (ITO) target, it is necessary to remove Sn(IV) ions from solutions containing Sn(IV) and In(III). In this study, therefore, the removal of Sn(IV) ions by galvanostatic electrolysis was examined. Polarization measurements were carried out under a nitrogen atmosphere. In the Sn(IV) solution, the current begins to increase at a cathode potential of −0.26 V vs. SHE, and keeps on increasing with a negative shift of the cathode potential. In the In(III) solution, the current begins to increase at a cathode potential of −0.43 V vs. SHE. In the galvanostatic electrolysis, 52% of Sn(IV) ions were removed and electrodeposited as metallic tin containing less than 1% indium; the current efficiency was close to 100%. After further electrolysis, indium was codeposited with tin.
The discrete element method (DEM) was applied to describe the basic characteristics of particles in an intensive mixer that is expected to grind only the surfaces of particles with a particular agitator and is applied in many industries. Surface grinding experiments using a sample of bauxite particles were also conducted to compare with the simulation. The roles of the pan and agitator were estimated from the DEM simulations and it was revealed that employing only agitator rotation increases the particle mobility in the vertical direction, while employing both pan and agitator rotation increases the mobility in the horizontal direction and stably maintains large mobility in the vertical direction. We also investigated the correlation between the rates of energy dissipation during interparticle contact calculated from DEM simulation results and the abrasion rate estimated from experimental results. The abrasion rate was estimated from the particle size distribution obtained from the surface grinding experiments using an intensive mixer charged with bauxite particles and a population balance model in which two mechanisms of attrition—abrasion and fracture—are considered. The results show that the abrasion rate decreased with an increase in energy dissipation due to friction, which suggests that the energy dissipation of the friction obtained from the DEM simulation results could be used to estimate the abrasion rate in the surface grinding process.
Six hundred thousand tons of beer lees are discharged annually in Japanese breweries. It is well known that purine compounds are one of substances which cause the gout and beer especially contains a lot of purine compounds such as adenosine, adenosine 5’-phosphate and so on, compared with the other alcoholic drinks. The application of activated carbon prepared from beer lees was investigated in order to remove purine compounds in beer. The reuse and recycling of beer lees to activated carbon for removing purine compounds in beer could make a contribution to the zero emission in breweries. In this study, the effect of physical properties of activated carbon derived from beer lees on the adsorption behavior of purine compounds was researched. Adenine, adenosine and adenosine 5’-phosphate, which are one of purine compounds, are selected as an example of model compounds in beer. The size of purine compounds and the pore structure of activated carbon affect the adsorption characteristic of purine compounds. It is found that beer lees can be reused and recycled in breweries by transforming to beer lees activated carbon for removing purine compounds in beer.
The ceramic coatings on metallic materials have attracted by many researchers due to the chemical inertness of ceramic materials. In such aspect, SiC is a promising material to be used as protective coating layer on metallic materials due to its outstanding thermal stability and chemical inertness. In this research, SiC coating was carried out onto Ni-Cr substrate using Cl free preceramic polymers such as polyphenylcarbosilane. 20% of polymethylphenylsilane in cyclohexane solution was coated onto metal by a dip coating method. Thermal oxidation was carried out at 200°C for crosslink of the preceramic polymer and the sample was pyrolysized at 800°C under nitrogen to convert the preceramic polymer to amorphous SiCx film. The microstructure of the SiCx coating after pyrolysis was investigated using a scanning electron microscopy.
This paper describes a study of the immobilization of Pb2+, Cd2+ and Cr3+ by synthetic zeolites formed as a result of the hydrothermal treatment of coal bottom ash (CBA) in alkali-solution after physical separation in below 1.8 specific gravity. The majority zeolite formed at 120°C was a NaP1 species (Na6Al6Si10O32·12H2O) showing gismondine-type appeared in large clusters of tetragonal prisms. The CBA was separated into four kinds depending on specific gravity(S); below 1.8S, 1.8–2.2S, 2.2–2.5S and above 2.5S. NaP1 zeolite could be more synthesized by using the CBA in below 1.8S. The adsorption behavior of hydrothermally treated CBA in 2M NaOH at 120°C after density separation in below 1.8S was studied with respect to Pb2+, Cd2+ and Cr3+ in order to consider its application to purify wastewater. The Langmuir model was found to describe the adsorption process well, offering a maximum adsorption capacity of 15.4 mg/g Pb, 12.7 mg/g Cd and 5.4 mg/g Cr.
Recently, we have successfully demonstrated the photocatalytic activities of strontium tantalate solid solutions by barium doping. However, the detail reason of an increase in the photocatalytic performance by barium doping has not yet verified. In this study, Rietveld analysis of the powder X-ray diffraction data was performed to reveal the structural changes induced by barium doping. The powder samples were prepared by the polymerized complex method with the molar ratio of Sr : Ba : Ta = 1 − X : X : 1. Existing phases in the prepared samples were identified and the mass fraction for each phase was estimated by the result of Rietveld analysis. The photocatalytic activity increases up to X = 0.2, where the sample mostly containing Ba-doped Sr2Ta2O7 exhibits the highest photocatalytic performance, 5700 μmol/hour, to decomposition of H2O into H2. On the other hand, the sample of X = 0.8 including mainly Sr-doped Ba5Ta4O15 shows the next highest activity. The high photocatalytic activities of strontium tantalate solid solutions can be explained in terms of distortion in the crystal lattice based on the result of Rietveld analysis.