EQUILIBRIUM-THEORY OF EXSORPTION - A GAS-LIQUID-ADSORBENT MASS-TRANSFER OPERATION

A three-phase (gas-liquid-adsorbent) mass-transfer operation, called e xsorption, which may have potential in chemical, biochemical and envir onmental processes, is described. The system of interest consists of a column packed with adsorbent particles through which gas and liquid s treams flow in countercurrent mode. Distributed-parameter models, whic h assume isothermal operation and transfer of a single solute among th e mutually immiscible phases, are presented for the two different wett ing states of adsorbent particles. Equilibrium theory of exsorption is established on the basis of the distributed-parameter models of the s ystem. The equilibrium theory predicts various aspects of propagation dynamics of concentration waves and reveals individual-relative effect s of concentration dependence of gas-liquid, liquid-adsorbent and gas- adsorbent equilibrium isotherms. Based on the characteristics of the e quilibrium isotherms, criteria for the development of sharpening, spre ading, and stagnant concentration waves can be obtained directly from the equilibrium propagation velocity of the system. The equilibrium th eory of exsorption is compared with the equilibrium theories of fixed- bed adsorption and countercurrent gas-liquid mass-transfer operations.