Novel polyethylene glycol induced cloud point system for extraction and back-extraction of organic compounds

A novel polyethylene glycol (PEG) induced cloud point system (PEG-CPS) with high hydrophile–lipophile balance (HLB) value nonionic surfactant and high molecular weight PEG had been developed for extraction of organic compounds. The main advantage of this novel system is that the back extraction process of stripping of nonvolatile organic compounds from the nonionic surfactant aqueous solution can be carried out with Winsor I microemulsion extraction. Thus a separation of organic compounds from the nonionic surfactants in aqueous solution become possible, which is potential for cloud point extraction (CPE) or extractive microbial transformation in cloud point system from economical and environmental consideration. With Triton X-100 as a model hydrophilic nonionic surfactant, the phase diagram of PEG-CPS was determined. High boiling point organic compounds, such as phenol, p-nitrophenol and 1-naphthol phenol, were extracted with PEG-CPS. Then the organic compounds in the surfactant rich phase of PEG-CPS were back-extracted with microemulsion.