Sorption of Binary Mixtures of Toluene 1 Lower Aliphatic Alcohols C 1 –C 6 in Low-Density Polyethylene A. Randova ´, 1 L. Bartovska ´, 1 S ˇ . Hovorka, 1 P. Iza ´k, 2 K. Friess, 1 J. Janku ˚ 3 1 Department of Physical Chemistry, Institute of Chemical Technology, 166 28 Prague 6, Czech Republic 2 Institute of Chemical Process Fundamentals, 165 02 Prague 6, Czech Republic 3 Department of Agroecology and Biometeorology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, 165 21 Prague 6, Czech Republic Received 25 August 2009; accepted 27 May 2010 DOI 10.1002/app.32878 Published online 23 August 2010 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Sorption gravimetric and volumetric techni- ques performed at 25  C and at atmospheric pressure were employed to study the preferential and total sorptions from binary liquid mixtures of toluene þ lower aliphatic alcohols (C 1 –C 6 ) in a high-pressure low-density polyethylene mem- brane and the volume of the swollen membrane. Toluene was preferentially sorbed in all six systems. The total sorbed amount increased from pure alcohol to pure toluene. The ex- perimental volume of the swollen membrane was compared with that calculated under the assumption that interactions between the polymer and liquid mixture were negligible. The composition of the binary liquid mixture sorbed in the polymer as a function of the composition of the bulk solu- tion surrounding the membrane is presented. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1781–1787, 2011 Key words: swelling; polyethylene (LDPE); membrane; phase diagrams; selectivity INTRODUCTION Mixtures of aromatic hydrocarbons (e.g., toluene) with aliphatic alcohols have wide use in the pharma- ceutical industry 1 and are important in the fuel industry, 2,3 where they are often used in fuels (alka- nols are used as fuel additives and toluene repre- sents original hydrocarbon fuel without additives 2 ) and for verification of solution theories. 4 Therefore, some physical properties of the binary toluene þ ali- phatic alcohols mixtures have been intensively stud- ied. A thermodynamic study based on light scatter- ing was published by Munk et al. 5 and calorimetric data on excess calorimetric properties was reported by Mrazek, 6 Hwa and Ziegler, 7 and by Cobos et al. 8 Vapor-liquid equilibria important for describing the distribution of compounds between vapour and liq- uid equilibrium phases at distillation and extraction separation processes can be found in 4,9 (see compre- hensive literature survey for limiting activity coeffi- cients data presented by Vrbka et al. 4 ). Distillation and extraction can be costly (extraction due to neces- sity of purification of extraction solvent); therefore, it is important to consider cost-effective membrane sepa- ration processes. Nonequilibrium and equilibrium physical properties for transport of toluene þ aliphatic alcohols have been studied. Mandal and Pangarkar 1 measured the dependence of the permeate composi- tion on the feed content for pervaporation of methanol þ benzene and methanol þ toluene mixtures in the steady state through eight types of polymer mem- branes. Villaluenga et al. 7 measured pervaporation characteristics for binary toluene þ alcohol (methanol, ethanol or propan-1-ol) mixtures in linear low-density polyethylene (LDPE) membranes. Gagnard et.al. 3 reported the total permeation fluxes for toluene þ methanol vapour mixtures in four polymer mem- branes. Data on the total mass uptake of pure toluene by LDPE were published by Makitra et al. 10 and Cor- bin et al., 11 the total mass uptake of pure aliphatic alcohols by LDPE was reported by Makitra et al. 10 (ethanol, propan-1-ol, pentan-1-ol) and Cunha et al. 12 The aim of this work was to extend the data avail- able for binary tolueneþ(C 1 –C 6 alkan-1-ols) mix- tures in contact with LDPE membranes. Measure- ments of preferential and total equilibrium sorption and equilibrium volumetric swelling were per- formed and are being reported for the first time. EXPERIMENTAL Studied properties The behavior of polymers in contact with various organics and the separation of organic mixtures Correspondence to: A. Randova ´ (randovaa@vscht.cz). Contract grant sponsor: Czech Science Foundation; contract grant number: 104/08/0600. Contract grant sponsor: Ministry of Education of the Czech Republic; contract grant number: MSM 6046137307. Journal of Applied Polymer Science, Vol. 119, 1781–1787 (2011) V C 2010 Wiley Periodicals, Inc.