The role of static diffusion during storage in the immediate breakthrough of activated carbon bed cyclically exposed to vapour

A rising concern is addressed to occupational safety and health administrations for evaluation of the risk of respiratory cartridge reuse exposed to organic vapour. Immediate breakthrough upon reuse has been experimentally demonstrated by several studies, but mathematical model is still lacking. An experimental reuse procedure also reported significant immediate breakthrough for acetone, acetonitrile and dichloromethane in PICA activated carbon bed column. This phenomenon is caused by so called static diffusion which is the transport of adsorbed molecules in the adsorbent bed during the period of storage. In this work, a static diffusion model is proposed. Intraparticle mass transfer is described by a pore diffusion model involving surface diffusion following Higashi model, and measured by the perturbation chromatography method. The model sheds the light on a kinetics parameter D_S0 from the Higashi model for surface diffusion, which can be a relevant indicator of the risk of immediate breakthrough upon reuse and permits to distinguish fast diffusing species and slower diffusing species for a given activated carbon adsorbent.