Volumetric mass transfer coefficients characterising VOC absorption in water/silicone oil mixtures

The physical absorption of three Volatile Organic Compounds (dimethyldisulphide (DMDS), dimethylsulphide (DMS) and toluene) in “water/silicone oil” systems at a constant flow rate for mixtures of different compositions (ϕ = 0%, 5%, 10%, 15%, 20%, and 100%) was investigated using a dynamic absorption method. The results indicate that silicone oil addition leads to a dramatic decrease in KLa which can be related to the change in the partition coefficient (Hmix). They confirm the results obtained for styrene absorption using another measurement technique [15]. The interpretation of the results using dimensionless ratios KLa(ϕ)/KLa(ϕ=0%) and KLa(ϕ)/KLa(ϕ=100%) versus ϕ also confirms the importance of the partition coefficient ratio mR = Hwater/Hoil in the KLa change. Moreover, the results obtained for toluene absorption in “air/water/silicone oil” systems (ϕ = 10%, 15%, and 20%) suggest that the mass transfer pathway is in the order gas → water → oil for these operating conditions.

► The absorption of three VOCs in water/silicone oil systems was investigated.
► Silicone oil addition leads to a dramatic decrease in KLa.
► This drop is due to the change in the partition coefficient value (Hmix).
► This result is valid for dimethyldisulphide, dimethylsulphide and toluene.
► For toluene, a mass transfer pathway in series gas → water → oil was identified.