The book describes the physicochemical foundations for the synthesis and modification of neutral and ion-exchange sorbents of a polymer nature. From the standpoint of chemistry of high molecular compounds, the problems of modeling the reactivity of monomers, equilibrium and kinetics of methods for the synthesis and use of ionites are indicated. _ x000D _ Equilibrium of ion exchange and complexation in liquid and solid phases, as well as methods for their description, are considered.