STEADY-STATE THERMODYNAMICS OF TRANSFER THROUGH A GAS-LIQUID INTERFACE, TREATED AS A LIMITING CASE OF THERMO-OSMOSIS

The flux of a gas through a gas-liquid interface has been calculated b y applying Onsager's theory to a system which evolves continuously thr ough the following stages: (1) a system in which thermo-osmosis of a g as takes place through a horizontal membrane located between two semi- infinite gas reservoirs, (2) a system similar to ( 1) except that the gas in the lower reservoir has undergone a continuous transition to li quid via the critical point, and (3) a system similar to (2) except th at the pores in the membrane have been allowed to expand to the point where the membrane has been replaced by a stagnant layer of gas. The r esulting expression, which agrees with one obtained previously, shows that the gas flux through the interface depends on the gradients of bo th temperature and partial pressure at the liquid surface.