Determination of liquid diffusivities of VOC (paraffins and aromatic hydrocarbons) in phthalates

An investigation relative to a regenerative absorption-based process for removal of volatile organic compounds (VOC) in high-boiling solvents, namely phthalates, is presented here, discussing largely the influences of the type of VOC (linear paraffins, iso and/or cyclic paraffins or aromatic hydrocarbons), of the phthalate and of the temperature parameter. In a previous paper was published the solubility study of VOC in phthalates. The aim of this work is the determination of the liquid diffusion coefficients of VOC into phthalates. Absorption experiments were achieved in a wetted-wall column characterized by a co-current contact mode between gas and liquid phases. The temperature range (10–40 °C) was investigated. Liquid diffusivities were determined by an indirect method requiring the adequate simulation of the absorption test runs which has to fit the experimentally measured VOC concentrations of the exit gas. Orders of magnitude of estimated parameters are here discussed and attempts at correlations are presented.