EN
The processes of exchange and sorption of orthophosphoric acid on Amberlite IRA-402 were studied. The concentrations of phosphate phosphorus and hydrogen ions were determined in initial and equilibrium solutions. It was found that there is a linear dependence between the amounts of phosphorus exchanged and/or sorbed in the model system tested (Amberlite) and the quantity and concentration of H3PO4. At a certain amount and concentration of H3PO4, the pH of the equilibrium solution containing Amberlite was lower than the pH of the initial solution. The paper provides an explanation of this phenomenon based on appropriate chemical equations of super-stoichiometric ion exchange and super-exchange sorption.