[Density form of Kedem-Katchalsky equations for non-electrolyte solutions]

A method of transformation of the Kedem-Katchalsky equations from concentration to density form was presented. These equations were applied for mathematical description of the volume flux (J(v)) through polymeric membrane in concentration polarization conditions, i.e. in existence on both sides of the membrane of concentration boundary layers (l(l), l(h)). Obtained model is the cubic equation, in which coefficients contain the membrane transport parameters (L(p), sigma, omega), density of solutions (rho(l), rho(h)), diffusion coefficients in layers (D(l), D(h)) and thicknesses of l(l) and l(h). Assuming that the layers l(l) and l(h) are symmetric (delta(l) = delta(h) = delta) and coefficients D(l) and D(h) are not dependent on concentration, the suitable transformation of model for J(v) the square equation for delta was obtained.