Shigeno Matsumoto

First-Principles Calculations for Chemical Reaction between Sodium Diethyldithiocarbamate and Transition-Metal (Cr) atom to Produce Cr(DDC)3 and Cr(DDC)2ODDC

We investigate the chemical reaction between a Cr transition-metal atom and sodium diethyldithiocarbamate (NaDDC), a complexing agent used to detect and extract Cr in human blood samples. Using density-functional-theory-based calculations, we determine their stable structures of Cr(DDC)2ODDC and Cr(DDC)3 complexes and obtain their dissociation energies. We found dissociation energies of -10.66 and -3.24 eV for Cr(DDC)2ODDC and Cr(DDC)3 complexes, respectively. Hence, on the basis of dissociation energies, we have verified that the reaction of NaDDC with Cr produces Cr(DDC)2ODDC as a major product.

Solvent Extraction of Copper from Chloride Solution for Environmentally Friendly Copper Hydrometallurgical Process.

The present refining of copper from sulfide copper ores by pyrometallurgical process is lack for the environmental concerns, that is, generation of harmful SO2 gas and high energy consumption. Considering our environmental aspect and saving the energy, we directed our attention to recover Cu by using the more advantageous L-SX=EW (Leaching-Solvent Extraction-Electrowinning) method. This hydrometallurgical L-SX-EW method can be designed as a closed system and lessen the wastes from the process. Based on the investigation we have already reported with respect to the extraction mechanism of Cu2+ with EHO (2-ethylhexanal oxime), in this study the separation of Cu2+ was examined from the leached solution obtained after leaching copper sulfide ores with ferric chloride solution, and the realizability of the environmentally friendly hydrometallurgical process was also investigated. The extractant EHO is very effective to separate Cu2+ from the leached solution containing Fe2+, Fe3+ and Zn2+. Cupric ions are selectively extracted in the organic phase at chloride ion concentration, 3～5 mol/dm3, while Fe3+ and Zn2+ are not transferred into the organic phase. The stages and phase ratio (A/O) required to attain the desired Cu2+ recovery are estimated to be 2-stage countercurrent extraction with the phase ratio (A/O) of 1.5. In order to strip Cu with water from the organic phase, 6-stages countercurrent stripping with the phase ratio (O/A) of 1.8 are required. By the extraction and stripping operation, 10 g/dm3Cu2+ is purified and concentrated to 25 g/dm3 Cu2+.

Dispersion Behavior of Magnetic Iron Oxide in Organic Slurry Containing Fatty Acids.

Dispersion of magnetic iron oxide powder, γ-Fe2O3 in the mixture of toluene and cyclohexane was studied to decrease the viscosity of the slurry and prepare the stable slurry in the presence of some saturated fatty acids with a straight chain as dispersing agents. The dispersion of γ-Fe2O3 is controlled by the steric hindrance of the dispersing agent adsorbed on it. Therefore, the viscosity and dispersion of the slurry significantly depend on the carbon number and the amount of the fatty acids. Since water content of γ-Fe2O3 greatly influences the control of the viscosity and dispersion degree, low water content is required to get lower viscosity and more stable dispersed state. The four measurements to evaluate slurry flow characteristics, namely viscosity, yield stress, sedimentation volume and particle size measurements, can become a standard method to estimate the degree of flocculation and dispersion of particles in solvents.