Recovery of Nitrophenols from Aqueous Solutions by a Liquid Emulsion Membrane System

Abstract
The application of liquid emulsion membrane technology to the extraction of nitrophenols from aqueous solutions is discussed. The effects of various parameters such as hydrophilic lipophilic balance of the surfactants, speed of agitation, water volume fraction in the water-in-oil emulsion, treatment ratio, and the concentration of surfactant on the extraction of p-nitrophenol are studied, and a suitable formulation for a liquid emulsion membrane is developed. The same formulation was used to extract o-nitrophenol and 2,4-dinitrophenol, and the results are compared with those of p-nitrophenol. The swelling of the emulsion during extraction is minimized by the addition of cyclohexanone to the membrane phase. The demulsification of the emulsion phase after extraction is also carried out by a chemical demulsification technique. Acetone is used for demulsification.