Calculation of Protolytic Equilibria Parameters on a Surface of Some Carbon Adsorbents According to Potentiometric Titration Data

An investigation of acid-base characteristics of adsorbents is a matter of practical interest, since they are involved into the technological schemes for separation and concentration of metal ions. It is known that adsorbents synthesized on the basis of natural materials show a high selectivity to individual components during recovery from solutions [1]. We have already shown that the natural oxidized coals of Kuznetsk and Kansk-Achinsk deposits of Siberia are promising to be used as a basis for synthesis of sorbents, which can selectively recover some non-ferrous metal ions and iron (III) from industrial manganese sulfate solutions [2]. That is why the presentation of equilibrium phenomena on a surface of such sorbents is important for investigators. It should be noted that a number of publications related with this question is rather limited [2-4]. A consideration of acid-base characteristics of sorbents is frequently accomplished with data of potentiometric titration of samples by acid and (or) base [5]. The particular values of dissociation constants and of surface concentration of reaction centers (RC) are obtained by a treatment of a potentiometric titration curve within the limits of any model of acid-base equilibrium in the system “solution – sorbent”. For instance, a widespread approach to calculation of RC ionization constants a K .1 a K