Recovery of Phenols Using Liquid Surfactant Membranes Prepared with Newly Synthesized Surfactants

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Abstract
Extraction and stripping equilibrium of phenol, p-cresol, and p-chlorophenol were studied with an organic solution containing a newly synthesized surfactant and an aqueous alkaline solution as a stripping phase. A cationic surfactant showed the highest extraction ratio of phenol among several surfactants used in this study. The magnitude of phenol extracted from water was in the order phenol < p- chlorophenol < p-cresol. The stripping of phenol extracted in the organic solution was quantitatively accomplished with an alkaline solution of high concentration except for the case of cationic surfactants. Extraction of phenol and its derivatives by liquid surfactant membranes containing a newly synthesized surfactant as an emulsifier was carried out in a stirred cell. The effects of various parameters (such as a surfactant and alkaline concentration, the kind of surfactant, and the alkali composition) on the extraction efficiency of phenol were examined along with demulsification of W/O emulsions. On the basis of the stability of surfactants against alkaline solutions used as a receiving phase, cationic surfactants which did not involve an ester or amide bond in their molecule appeared to be among the best surfactants available for phenol removal in liquid membrane operations. The efficiency of phenol recovery with sodium hydroxide as a stripping agent was much higher than that with sodium carbonate; however, the demulsification efficiency of the emulsions decreased with an increase in the content of sodium hydroxide in the mixed alkaline solutions of sodium hydroxide and sodium carbonate. In the design of an efficient recovery process of phenols by LSMs, the composition of the alkaline solution was one of the key factors. Under optimal conditions, phenolic derivatives could be recovered in a few minutes.