Equations to describe the amount and rate of sorption

The partition of materials that react with soil between the solid and solution phase, how this changes time, can often be described by a simple equation: S = cb1tb2 where is amount sorbed, c concentration, t time contact, a, b1 b2 are parameters. However, when range values for sorption large, it apparent both increase decreasing sorption. At low sorption, approaches 1, plots nearly linear. These observations consistent mechanistic model in which postulated heterogenous sites. As decreases, heterogeneity occupied sites decreases. This why increases. Because there sites, rates subsequent reaction. proportional to fractional index time. It better describe effects way than using several first-order equations.