Absorption of methanol and butanol vapours into droplets and its potential for decontamination: A fundamental approach

Abstract

The use of small droplets to decontaminate atmospheres from organic vapours (VOCs) is a very attractive prospect. Surprisingly this simple yet promising idea has not been extensively explored in literature. Fundamental aspects of this process and mass/heat transfer are investigated in this study. We demonstrate that sessile droplets in contaminated atmospheres with Methanol and Butanol organic vapours can be a very effective way of absorbing these latter. Very small volumes of liquid droplets are shown to absorb many times their initial volume of vapour from the surrounding atmosphere. The dynamics of absorption and droplets profile evolution is quantified experimentally. A theoretical approach allowed a satisfactory interpretation of the observed trends. The coupling in mass transfer between absorption and evaporation is analysed and formulated. The droplets are found to show a volume growth before exhibiting a peak followed by a monotonous very slow decline. The trends are dependent on the initial composition of the droplets as well as the nature of the organic vapour in the atmosphere. Vapours which are more soluble in the liquid, have led to the largest volumes increase recorded. Furthermore droplets initially containing organics tend to absorb less vapour. The proposed analysis can provide a valuable approach for the implementation of this phenomenon in decontamination applications. Moreover the proposed model can be used as a tool to optimise the absorption process and the removal of the organic vapours from the atmosphere.