Electrokinetic potential measurements showed that pHiep i e

Fig. 4. Kinetics of the LSZ adsorption on the Cr2O3 surface.Figure optionsDownload full-size imageDownload as PowerPoint slide
Fig. 5. Adsorption isotherms of LSZ on the Cr2O3 surface at various BMS 195614 values (CNaCl = 0.01 M, tads = 5 h; Ce – the LSZ equilibrium concentration).Figure optionsDownload full-size imageDownload as PowerPoint slide
Kinetic measurements of LSZ adsorption on the chromium(III) oxide surface showed that without a buffer (which corresponds to pH of about 5) the examined system reaches equilibrium after approximately 3–5 h. To ensure, that all adsorption data were collected after equilibration of the system the amount of macromolecules adsorbed was determined after 5 h. On the other hand, under pH conditions of oral cavity (i.e. in the presence of phosphate buffer, at pH close to 7) the equilibrium is reached after 8–10 h. Moreover, the adsorbed amount is greater. The increase in adsorption is a consequence of the pH increase (therefore, less positive charge of the surface) and ionic strength. As it is shown in this paper – both result in greater adsorption values. The slower rate of adsorption can be identified with close to zero surface charge, i.e. limiting steps are diffusion and short-range interactions rather than relatively strong electrostatic forces.