Cloud-Point Extraction of Organic Compounds from Aqueous Solutions with Nonionic Surfactant

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Abstract
Cloud-point extraction of organic compounds from aqueous solutions by using the nonionic surfactant PONPE10 has been investigated for phenol and three pyridines to clarify the effect of operating factors on its extractability. Phase separation of the surfactant solutions is attained at temperatures above the cloud point, and it is improved by adding NaCl or phenol. Phenol is extracted successfully in a wide pH range from acidic to neutral solutions with and without NaCl, where the extraction efficiency increases with an increase in the surfactant concentration. Backextraction of phenol from the surfactant-rich phase was found to be possible with alkaline solutions. Three pyridine derivatives can also be extracted from the solution under neutral and alkaline conditions, although the efficiencies are somewhat low compared with phenol. Moreover, selective separation of the pyridines from each other could be accomplished because of the difference in their hydrophobicities.