Fig. 2. Graphic representation of model calculations. Circles represent sorption points, triangles desorption points, and squares corresponding hysteresis indices. (a) Linear desorption with different irretrievable fractions b at C (C^S)^–1 = 0; (b) single desorption point (triangle) originating from different points (circles) along the sorption isotherm. The term C is the solute concentration, q is the sorbed concentration, and the superscript S represents the sorption state from which desorption is initiated.