Evaluation of the Global S-Entropy Production in Membrane Transport of Aqueous Solutions of Hydrochloric Acid and Ammonia

The results of experimental studies of volume osmotic fluxes ([Formula: see text]) and fluxes of dissolved substances ([Formula: see text]) in a system containing a synthetic Nephrophan(®) membrane (Orwo VEB Filmfabrik, Wolfen, Germany) set in a horizontal plane are presented. The membrane separated water and aqueous HCl or ammonia solutions or aqueous ammonia and HCl solutions. It was found that for the homogeneity conditions of the solutions [Formula: see text] and [Formula: see text] depend only on the concentration and composition of the solutions. For concentration polarization conditions (where concentration boundary layers are created on both sides), [Formula: see text] and [Formula: see text] depend on both the concentration and composition of the solutions and the configuration of the membrane system. The obtained results of the [Formula: see text] and [Formula: see text] flux studies were used to assess the global production of entropy for the conditions of homogeneity of solutions ([Formula: see text]), while [Formula: see text] and [Formula: see text] —to assess the global production of entropy for concentration polarization conditions [Formula: see text]). In addition, the diffusion-convective effects and the convection effect in the global source of entropy were calculated. The concentration polarization coefficient [Formula: see text] was related to modified concentration Rayleigh number, e.g., the parameter controlling the transition from non-convective (diffusive) to convective state. This number acts as a switch between two states of the concentration field: convective (with a higher entropy source value) and non-convective (with a lower entropy source value). The operation of this switch indicates the regulatory role of earthly gravity in relation to membrane transport.