Application of conductometric and pH metric measurements in determining the kinetics and equilibrium parameters of the heterophasic ion exchange: Metal cation-proton

The application possibilities of conductometric and pH metric measurements in the description of the process of heterophasic ion exchange have been analysed, between metal cation (Zn, Cu)-proton, which occurs according to the formula, M+ + HR reversible arrow H+ + MR, where R is an anion permanently bound in the sorbent. Kinetic models of the pseudo-first and pseudo-second order reactions, as well as the Langmuir isotherm model which describes the process equilibrium, have been used in mathematical presentations. It was confirmed that conductometric and pH metric measurements are equally effective in the assessment of such processes' parameters, in comparison with the expensive method of determining metals using atomic absorption spectrometry. Hypogymnia physodes lichens, which are a good natural cations sorbent, were selected for the study. The lichens were saturated with protons for the purpose of the experiment. It was demonstrated that, regardless of the determined variables (metal concentrations, conductivity, pH of the solution), the kinetics and equilibrium parameters of heterophasic ion exchange (metal cation-proton) and the measurements' uncertainty are comparable.