Determination of partition coefficients of three volatile organic compounds (dimethylsulphide, dimethyldisulphide and toluene) in water/silicone oil mixtures

The main objective of this work was to propose a model able to predict the partition coefficient of odorous or toxic gaseous pollutants (dimethylsulphide, dimethyldisulphide and toluene) in water/silicone oil mixtures. Experimental measurements using a static headspace method were carried out for pure water ( H voc,water), for pure silicone oil ( H voc,solvent) and for mixtures of varying composition ( H voc,mixture). The dramatic decrease in the partition coefficient ( H voc,mixture) with oil addition clearly showed a deviation from linearity, which was more pronounced for increasing H voc,water/ H voc,solvent ratios. Moreover, experiments using a dynamic absorption method underlined that the absorption capacity of a biphasic water/silicone oil mixture can be classed as the absorption capacity of a pseudo-homogeneous phase whose physical properties (molecular weight and density) can be calculated from the physical properties of water and solvent, and balanced using the “equivalent absorption coefficients” H voc,mixture/ H voc,water and H voc,mixture/ H voc,solvent. An “equivalent absorption capacity” concept is then proposed, which should be useful to design absorption units using two-phase liquid mixtures for the treatment of industrial air loaded with volatile organic compounds.