Predispersed solvent extraction (PDSE) is a new method for separating solutes from aqueous solution by solvent extraction and one which has shown promise for extraction from extremely dilute solution very efficient and very quick. The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer and low interfacial mass transfer areas in solvent extraction process. In present paper, colloidal liquid aphrons are successfully generated using kerosene as a solvent, tributyl phosphate(TBP) as an extractant, sodium dodecyl benzene sulphate(SDBS) as surfactant in aqueous phase and Tween-80 in oil phase. Extraction of phenol from dilute solution was studied by using colloidal liquid aphrons and colloidal gas aphrons in a semi-batch extraction column. It has been found that the PDSE process is more suitable for extraction of dilute solutions. It has also been discovered that the PDSE process has a great advantage over traditional single-stage extraction process.
Predispersed solvent extraction (PDSE) is a new extraction technique in which one of the two phases (usually the oil phase) is predispersed into minute droplets. The essential part of this novel technique is the use of colloidal liquid aphrons (CLA) together with colloidal gas aphrons (CGA). The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer etc. In this paper, PDSE process, CLA and CGA are systematically reviewed and the potential applications of CLA, CGA and PDSE for the various areas of separation as well as the latest development in this area are discussed.
Wang Yundong, Huang Yingyi and Dai Youyuan (State Key Laboratory of Chemical Engineering---Solvent Extraction Laboratory, Department of Chemica Engineering, Tsinghua University, Beijing 100084)
This paper presents a method of separation of fine particles, of the order of a few microns or less, from aqueous media by flotation using colloidal gas aphrons (CGAs) generated in aqueous solutions. More than 150 experiments were conducted to study the effects of surfactant type, surfactant concentration, CGAs flow rate, and particle concentration on the removal efficiency (fine particles of polystyrene were used as a target compound). The results indicate that CGAs, generated from cationic surfactant of hexdecyltrimethyl ammonicum bromide (HTAB) and anionic surfactant of sodium dodecylbenzne sulfonate (SDBS), are an effective method for the separation off ine particles of polystyrene from wastewater. The flotation yields are higher than 97%.
