The Thermodynamics and Kinetics on the Solvent Sublation of Ni

The removal of Ni ion from an aqueous solution was carried out by solvent sublation of Ni-diacetyldioximesodium dodecylbenzensulphonic （sublate） into isopentanol. The ratio of surfactant to Ni-diacetyldioxime complex at 20：1 was most effective for the removal, with over 90% Ni ion removed from the aqueous solution within 1 h. The effects of electrolytes （e.g. NaCl）, non-hydrophobic organics （e.g. ethanol） and pH of the solution upon the process were well studied. The removal rate was enhanced by higher airflow rates but almost independent on the volume of the organic solvent floating on the top of the aqueous column. The process of solvent sublation followed first order kinetics. A characteristic parameter, the apparent activation energy of attachment of the sublate to bubbles, was estimated to be 8.99 kJ/mol. Furthermore, the simulation of a mathematical model with the experiment data on the solvent sublation of Ni-diacetyldioxime-SDS was proved to be validated.

Effect of water droplet in solvent sublation

Aqueous phase layer around bubble and water droplet are two additional processes in solvent sublation. In the dynamic process of mass transfer, they are always neglected, but they are very important in the investigation of thermodynamic equilibrium. In this paper, the effect of water droplet in solvent sublation was discussed in detail, and the previous mathematical model of solvent subaltion was improved. Matlab 6.5 was used to simulate the process of water droplets, and the comparison between the previous hypothesis and the improvement in this paper showed the superiority, especially in the investigation of thermodynamic equilibrium. Moreover, the separation and concentration of the complex compound dithizone-Co（Ⅱ） from aqueous phase to n-octanol by solvent sublation also proved the improved mathematical model was reasonable.

Critical bubble radius in solvent sublation

The complex compound of dithizone-Co（Ⅱ） was separated and concentrated from the aqueous phase to n-octanol by solvent sublation. From the analysis of the coalescence behavior of bubbles on water-organic interface, the conception of critical bubble radius was proposed, and the value of the critical bubble radius in the water-octanol system was obtained： 1.196 × 10^-3 m. The simulation of the mathematical model using CBR and experimental data is completed with perfect results, and the simulation of the mathematical model using CBR is very different with the classic one. The analytical results proved that the critical bubble radius should be adequately considered in mathematical model of solvent sublation.

Nonfoaming Bubble Separation for Recovery of Butyl Acetate from Discharged Wastewater During Penicillin Production

Two nonfoaming bubble separation techniques, air stripping and solvent sublation, are presented and discussed in order to recover butyl acetate (BA) from discharged wastewater after solvent extraction of penicillin. Results show air stripping is not suitable for the recovery of BA from the wastewater. Axial concentration of BA had a noted maximum point along the column. In contrast, solvent sublation is very effective to recover BA from the wastewater. In solvent sublation experiments, axial concentration of BA along the column first increased and then decreased from the bottom to the top because of two primary mass transport processes. One is the transport by adsorption or attachment to ascending bubbles, and the other is by dispersion at water-solvent interface and by water film in organic solvent layer. In order to elucidate the high removal efficiency in solvent sublation, the microstructure of the wastewater was studied with optic microscope, which was showed to be an emulsion of BA in water at large concentration of BA. Solvent sublation can be successfully used in the removal of BA from its emulsion in the wastewater. The surface tension of simulated solution composed of lysozyme and BA was studied to understand mutual effect of biological materials and BA. Results show that lysozyme affects the adsorption of BA at air-water interface and they may form a complex between BA and lysozyme molecules.