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 by applying Onsager's theory to a system which evolves continuously through the following stages: (1) a system in which thermo-osmosis of a gas 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 liquid via the critical point, and (3) a system similar to (2) except that the pores in the membrane have been allowed to expand to the point where the membrane has been replaced by a stagnant layer of gas.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 resulting expression, which agrees with one obtained previously, shows that the gas flux through the interface depends on the gradients of both temperature and partial pressure at the liquid surface.