Raman scattering and water structure in nonionic amphiphile solutions.
The structure of water in aqueous solutions of polyoxyethylene nonionic amphiphiles ${\mathrm{C}}_{10}$${\mathrm{E}}_{5}$, where ${\mathrm{E}}_{5}$ denotes ${\mathrm{H}}_{21}$(${\mathrm{OCH}}_{2}$${\mathrm{CH}}_{2}$${)}_{5}$OH, is studied by Raman scattering along an isothermal path crossing the isotropic one-phase region from 0 to 1 amphiphile volume fraction \ensuremath{\varphi}. The isotropic OH stretching-vibration spectrum points out a water behavior that depends on the amphiphile concentration. The data analysis is performed using the bond-percolation model developed for water. The interpretation of scattering data leads to the following structural picture for the water in the systems: for \ensuremath{\varphi} lower than 0.75, water is partially bound to the oxyethylene groups of the amphiphile; above \ensuremath{\varphi}=0.75 all water present in the system is bound. Analogously to the behavior of water in confined geometries, the structure of bound water presents a local fourfold-coordinated environment.
Water compressibility in confined spaces
In order to explore the compressibility of water sequestered in droplets surrounded by surfactant molecular films (reverse micelles), we custom-built a high-precision velocimeter. The apparatus comprises two ultrasonic small-sized cells, electronic generators and a computer-controlled digital scope. We carried out a systematic study of the stability and reproducibility of the experimental set-up which yields an accuracy of 10/sup -5/. The ultrasound velocity, the apparent volume, and compressibility of encapsulated water were determined in charged and uncharged molecular films as a function of water concentration. We observed a close relationship between the measured parameters of encapsulated water, the chemical nature of the surfactant molecular film and the number of water molecules in interaction. The values obtained are higher than that reported for bulk water and are assigned to the surfactant-water interactions arising between the head groups and water molecules.
Thermodynamics on the Carbochlorination of Titanium-bearing Ores
The equilibrium compositions of the multi-component, multi-phase and multi-reaction system of carbochlorination of titanium-bearing ores are calculated with HSC, a computational chemistry software. The thermodynamic equilibrium calculation of the reaction system shows that a complete conversion of titanium-bearing ores is feasible at a temperature near 200oC. At temperatures ranging from 800 to 1600oC, the products of the reaction system are all in gaseous phase. Thermodynamic analysis accords with the industrial practice. The simulated results provide reasonable scientific basis for improving suitable technological conditions of the carbochlorination reduction.