title: Removal of phenols from aqueous solutions by emulsion liquid membranes.
abstract: The present study deals with the extraction of phenols from aqueous solutions by using the emulsion liquid membranes technique. Besides phenol, two derivatives of phenol, i.e., tyrosol (2-(4-hydroxyphenyl)ethanol) and p-coumaric acid (4-hydroxycinnamic acid), which are typical components of the effluents produced in olive oil plants, were selected as the target solutes. The effect of the composition of the organic phase on the removal of solutes was examined. The influence of pH of feed phase on the extraction of tyrosol and p-coumaric was tested for the membrane with Cyanex 923 as an extractant. The use of 2% Cyanex 923 allowed obtaining a very high extraction of phenols (97-99%) in 5-6 min of contact time for either single solute solutions or for their mixtures. The removal efficiency of phenol and p-coumaric acid attained equivalent values by using the system with 2% isodecanol, but the removal rate of tyrosol was found greatly reduced. The extraction of tyrosol and p-coumaric acid from their binary mixture was also analysed for different operating conditions like the volume ratio of feed phase to stripping phase (sodium hydroxide), the temperature and the initial concentration of solute in the feed phase.
authors.affiliation: Centre for Chemical Processes, Department of Chemical and Biological Engineering, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.
authors.forename: M Teresa A
authors.initials: MT
authors.lastname: Reis
authors.forename: Ondina M F
authors.initials: OM
authors.lastname: Freitas
authors.forename: Shiva
authors.initials: S
authors.lastname: Agarwal
authors.forename: Licínio M
authors.initials: LM
authors.lastname: Ferreira
authors.forename: M Rosinda C
authors.initials: MR
authors.lastname: Ismael
authors.forename: Remígio
authors.initials: R
authors.lastname: Machado
authors.forename: Jorge M R
authors.initials: JM
authors.lastname: Carvalho
mesh_terms: D003373:Coumaric Acids / Q000032:analysis; D004655:Emulsions; D015386:Hazardous Substances; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D019800:Phenol / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000737:chemistry; D010721:Phosphinic Acids / Q000737:chemistry; D011422:Propionates; D012996:Solutions; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*
chemical_list: D003373:Coumaric Acids; D004655:Emulsions; D015386:Hazardous Substances; D008567:Membranes, Artificial; D010636:Phenols; D010721:Phosphinic Acids; D011422:Propionates; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; C011867:4-hydroxyphenylethanol; D019800:Phenol; C495469:p-coumaric acid; D010626:Phenylethyl Alcohol