It was found that MCM-41 mesostructure can be strengthened by using ethylamine as a mineralizer in our previous study. The addition of ethylamine causes structural changes at the same time. In this report, important factors deciding micelle formation and possible changes in conformation of micelle when small amphiphilic materials co-exist are discussed. Incorporation of short-chain alkylamine in micelle is predicted by the energetical consideration if alkylamine is in neutral state and has an adequately hydrophobic chain part. Ethylamine which is supposed to be neutral in the pH range above pKa is found to incorporate in micelle when alcohol coexists together and increases hydrophobicity of ethylamine by forming complex with it. The same phenomenon takes place even without the addition of alcohol when alkylamine having a longer alkylchain such as propylamine and butylamine is used because of increased hydrophobicity.
The influence of electrolytic conditions on the copper electrowinning was studied in 5.0 kmol m−3 NH3, 1.0 kmol m−3 (NH4)2SO4 and 0.50 kmol m−3 Cu(I) at 293-298 K. Copper deposits potentiostatically obtained on the copper plate electrode at −0.30 and −0.80 V (vs. SHE) for 20 hours were a smooth plate and a crowd of nodules with order of 10 μm in diameter, respectively. Galvanostatic electrolysis was also conducted using the copper plate electrode for 20 hours. The copper deposits were confirmed to be smooth at cathodic current density of 300 A m−2 and a crowd of nodules with order of 100 μm at 700 A m−2. The current efficiency of the electrowinning was estimated to be over 90% at all conditions.
Calcium carbonate powder with high value of whiteness parameter is widely used in various industrial applications such as paper, plastics, glass etc. The value of the whiteness parameter of the powder mainly depends on the whiteness of limestone used as raw material. White limestone is formed through lithological re-crystallization by geological thermal-metamorphism, thus, the reserves of white limestone are limited and regionally maldistributed in Japan. In turn, the production of calcium carbonate products with the high whiteness is viable only in some areas. The native carbon (eg. graphite) as well as sulfide and oxides species, blamed for giving the ordinary limestone a gray color, are not easy to be removed from limestone particles. With this in mind the authors are putting forward a process for production of white calcium carbonate by using ordinary gray colored limestone found in many areas throughout Japan. The process is carried out in two steps: 1. reducing the coloring substances, contained in limestone particles, by heating. 2. covering the surface of limestone particles, mainly calcite, with crystallized white calcium carbonate. The experimental results point out that the whiteness of calcium carbonate particles is considerably increased by using this method, suggesting that the ordinary gray colored limestone can be used to produce high whiteness calcium carbonate products.
Equilibrium experiments were performed between molten lead and PbS-Cu2S mixed sulfide. The PbS-Cu2S system has an eutectic type phase diagram. Experimental temperatures were higher than the eutectic temperature in the range of 823 K to 1073 K. The compositions of PbS-Cu2S corresponded to the two phases of liquid mixed sulfide and solid PbS or liquid mixed sulfide and solid Cu2S at the experimental temperature. After cooling, a lead sample was analyzed for copper and sulfur. A good linear relationship between logarithms of copper concentration and reciprocal values of the absolute temperatures was obtained. In the case of sulfur, the similar tendency was obtained. The experimental values were compared with evaluated values calculated using the solubility of sulfur in the Pb-S binary system and the interaction parameter between copper and sulfur in liquid lead from the literature. The standard Gibbs energy of the following reaction, 2Cu(% in Pb) + S(% in Pb) = Cu2S(s), was evaluated by using the experiment results.
Poly(styrene) samples (MW1C and G100C) were reprocessed in multiple cycles by a single-screw extruder. The reprocessed heat degraded samples were characterized by dynamic viscoelasticity and stress-strain measurement. When the temperatures of heat degradation and the volume velocity of extrusion were particularly selected, the molecular weight (Mη) for the heat degradation samples was expressed by the time (t) required in extrusion without depending on original molecular weight. In blend system, the decrease in Mη was expressed by similar relationship for homo-system, suggesting that the synergy effect of blend on the heat degradation was neglected. Young's modulus (E) obtained from stress-strain curves did not change for both the virgin and the heat degraded samples. It is important to reprocess at temperature (T) as low as possible in order to increase the cycles number (n)
Every year in Japan, approximately 0.7-0.8 million tons of automobile shredder residue (ASR) are generated and most incinerated ASR is landfilled. Since the landfill capacity for industrial and domestic waste is limited, the recycling of ASR is becoming very important. The incinerated ASR contains relatively large amount of non ferrous metals. Neverthless, only a small amount of these metals is recycled, pointing out the need to increase the recycling rate of these metals in order to save resources and reduce the amount of materials to be discarded. In this study, upgrading Cu and Zn from the incinerated ASR ash by means of flotation is described. In order to obtain the optimal condition, the effects of pH, grinding and the addition of reagents were investigated. As a result, it was found that grinding ash to c.a. 10 μm is necessary in order to obtain the optimum grade and recovery of Cu and Zn. Under the optimal conditions (i.e. pH 5; NaHS concentration of 21 kg/t; PAX concentration of 9 kg/t), Cu was upgraded from 3.2wt% to 8.7wt% recovering 49% of Cu. Moreover, Zn was upgraded from 1.4wt% to 2.8wt% recovering 36% of Zn. Cl content in both froth and tailings, on the other hand, was efficiently reduced from 3.3wt% to about 0.1wt%.