The Wheeler-Jonas equation: A versatile tool for the prediction of carbon bed breakthrough times

This paper gives an overview of the recent developments in the use of the Wheeler-Jonas equation. Extensive experimental work has been done by measuring breakthrough times of different types of activated carbon beds, under different experimental conditions, for a large variety of gases and vapours. This includes the use of activated carbon fibre beds, the presence of moisture on the carbon and in the air stream, non-constant flow patterns and adsorption of chemisorbed species. In all cases the applicability of the Wheeler-Jonas has been demonstrated, i.e. one can use this equation to extrapolate single laboratory breakthrough results by simply varying the independent variables of the equation (amount of adsorbent, flow rate, inlet and breakthrough concentrations). In most cases it is even possible to perform ab initio breakthrough calculations for a well-defined carbon bed. To achieve this new supporting equations had to be derived to allow the estimation of the dependent variables, W_e (the equilibrium adsorption capacity) and k_v (the overall mass transfer coefficient), under different circumstances. In conclusion, the scope of the Wheeler-Jonas (or Reaction Kinetic) equation extends largely beyond its commonly accepted boundaries. This is primarily due to its apparent simplicity: the combination of a single capacity term and an overall kinetic effect strongly enhances its applicability to different adsorption circumstances. In this way it is far more potent than many of the more modern equations that require the exact knowledge of several, not readily available, input parameters.