PEG Induced Cloud Point Extraction

When an aqueous micelle solution of a nonionic surfactant is at a temperature above its cloud point or in the presence of certain additives, phase separation occurs to form a surfactant-dilute phase and a surfactant-rich phase or coacervate phase. Such a system is called a cloud point system (CPS). The cloud point system has also been utilized as a separated method, which is known as cloud point extraction (CPE). Generally, in order to implement extraction/reaction at a relatively lower temperature, the nonionic surfactant with low hydrophile-lipophile balance (HLB) value is used. However, it's difficult to strip organic compounds from nonionic surfactant with low HLB, which makes it difficult for the product recovery and nonionic surfactant reutilization.A novel PEG induced cloud point system (PEG-CPS) with high molecule PEG and nonionic surfactant with relatively higher HLB has been developed. The experimental results suggest that in PEG-CPS, a CPE can be carried out with a relatively higher HLB (TX-100) value nonionic surfactant at about room temperature. High boiling point 1-naphthol has been used as a model organic solute, and the recovery in nonionic surfactant rich phase of PEG-CPS is 90%. A volume ratio of surfactant rich phase to organic solvent iso-butyl alcohol on 5:3 has been proposed to extract surfactant and solute into Om phase of WinsorⅡ, and the recovery of surfactant and solute are both about 96%. After removal of organic solvent and resolving the residual organic solute and surfactant with water, the solution has been used to WinsorⅠextraction with volume ratio of solution to ethyl ether on 5:12 at 6℃, and the recovery of surfactant and solute are both above 79%.PEG-CPS has been developed as a novel medium for whole cell microbial transformation, and the downstream process has also been researched. The experimental results suggest that in PEG-CPS with 15% hydrophilic TX-100 and 6.4% PEG20000, the yield of product is about 6.38g/L. The microemulsion extraction has been used as the separation technique, i.e., WinsorⅠwith volume ratio of supernatant to ethyl ether on 5:12 at 6℃has been conducted to strip product/substrate from nonionic surfactant/PEG; WinsorⅡwith volume ratio of water phase of WinsorⅡto iso-butyl alcohol on 5:3 at 25℃has been conducted to separate nonionic surfactant and PEG.