As(V) removal mechanism using Fe(III)-supported ion exchange resins was elucidated by adsorption isotherms and X-ray absorption fine structure spectroscopy. Fe(III) substituted almost all counter ions in the resin at pH 2 during 1-h reaction; the Langmuir exchange capacity was 1.87 mmol Fe/g-resin. The Fe(III)-supported resin comprised ≈65% Fe(III) and ≈35% ferrihydrite. Under pH 3 and arsenic concentration of 10 mg/dm3 conditions, a sorption density of 0.035 mmol As/g-resin was obtained after 1-h reaction, and increased to 0.74 mmol As/g-resin after 120-h reaction. As(V) removal proceeded mainly via surface precipitation of poorly crystalline ferric arsenate via co-precipitation between As(V) and Fe(III); also, some As(V) adsorbed on ferrihydrite.
In the development of mines, risk is latent in a variety of areas. Thus a feasibility study was conducted to determine certain risks. In particular, mineral processing for the recovery of a target mineral constitutes a very large percentage of the cost from the start of a project, and it is an important step in relation to the recovery of funds. In this study, a feasibility study of molybdenum mineral processing is done and comparisons are made between a pilot plant and a commercial plant using the LCCA evaluation method. At the pilot plant, the NPV value of a deterministic approach at five years is $68,984 and the probability that the NPV exceeds 0 is 58.23% according to Monte Carlo simulation done using a probabilistic approach. At the commercial plant, the NPV value with the deterministic approach at five years is –$10,820,473, and it was found that the probability of NPV according to deterministic estimation is 49.91% in a Monte Carlo simulation. As a result, the commercial plant is evaluated as experiencing a loss due to a decrease in the molybdenum concentrate price, whereas a price increase of 20% relative to the current molybdenum concentrate price can meet the margin after five years when the NPV exceeds over 0.
Solvent impregnated resins (SIRs) are an effective means for the separation of metal ions from their mixtures. However, their durability is limited due to dissolution of the extractant from the resin. Our previous studies on the repeated column test using PC88A-SIR in order to remove zinc from the model electroless nickel plating bath showed that zinc adsorption capacity gradually decreased over a few cycles. In this paper, the distribution of PC88A and Cyanex 272 between the aqueous solution and SIR or blank resin was measured batchwise. Then the column experiment was carried out, and the following two methods have been found to be effective: (i) Post-column process in which the feed solution is passed through the PC88A-SIR and then the equal weight of the blank resin (Amberlite XAD7HP) and (ii) replacement of the extractant by weaker acid, Cyanex 272. In the latter, the zinc adsorption ability of the SIR was constant for at least 37 cycles. It is suggested that the combination of these two methods significantly improves the SIR durability.
The objective of this study is to examine the effects of the geological properties of limestone on the synthetic characteristics of precipitated calcium carbonate (PCC) and hydraulic activity. Four groups of limestone samples from eight different limestone deposits according to formation age have been studied. With greater formation age of limestone such as samples from the Paleozoic Ordovician (500~430 million years ago), more calcite twins were presented. Whereas the newest limestone from the Cenozoic Tertiary (65~2 million years ago) had no calcite twins. Furthermore, hydraulic activity and the production yield of aragonite-shaped PCC increased with lower formation age of limestone.
Layered double hydroxides (LDHs) with hydrophobic surface by surfactant modification were prepared using aluminum dross as a raw material, to develop a new recycling method of aluminum dross. The physical properties including crystal structure, surface texture and contact angle were investigated for the LDHs modified with dodecyl sulfate ions (DS–) as a surfactant. The removal tests of dilute toluene in aqueous solution were demonstrated using the DS– type LDHs (DS– LDHs). Organic modification of the LDHs synthesized from aluminum dross can be achieved successfully by an anion exchange with DS–. The toluene in aqueous solution (initial concentration; 10 and 50 mg/dm3) is removed using the DS– LDHs. It was clarified that the DS– LDHs synthesized from aluminum dross can be used as an excellent adsorbent for dilute organic compounds in aqueous solution.
To effectively pre-treat the alkaline inorganic waste by carbonation reaction with CO2, it is necessary to understand a mineralogical change. This is because mineralogical changes serve as an important key to leaching behavior or stabilization of heavy metals, such as Pb, Cu, Cr, and Ni, contained in the inorganic waste, at the point of environmental influence. Therefore, in this study we investigated the chemical composition and mineralogical characteristics of municipal solid waste incineration bottom ash, which is a type of alkaline inorganic waste, and the material changed by the carbonation reaction in bottom ash. In addition, minerals affected by carbonation reactions were identified based on the ternary diagram of Ca-Al-Si in bottom ash. The relationship between mineralogical changes caused by carbonation reactions and stabilization of heavy metals was also examined.
The observation and evaluation of lattice defects such as vacancies, dislocations, and grain boundaries are very important in materials design. Electrical resistivity measurement is superior to electron microscopy for obtaining average microstructural information, including density and type of lattice defects. The purpose of this study was to estimate changes in electrical resistivity during the tensile deformation of commercial-purity (CP) Ti. The electrical resistivity of a cold-rolled Ti sheet was measured at 77 K (ρ77) and 300 K (ρ300) along the rolling direction (RD) using a direct current (DC) four-point method to determine Matthiessen’s empirical relationship, ρ77 = α/(R – 1) + β, R = ρ300/ρ77. Plots of ρ77 versus 1/(R – 1) showed a linear relationship, and the values of α and β were determined to be 0.5266 and –0.0024, respectively. Changes in ρ77 during tensile deformation were estimated by substituting the resistance ratio R into Matthiessen’s empirical relationship. In the elastic deformation region, no remarkable change in the resistivity was observed. Therefore, the dislocation density did not change significantly. However, the resistivity did increase drastically near the yield point.
This study is aimed to find out the most effective way of the information provision which makes more people to take actions for energy saving. The author examined the result of “Home-eco diagnosis” by analyzing the data collected by a questionnaire, and discuss the method for providing effectively the appropriate energy-saving information.