ADSORPTION OF 2,2'-DIPYRIDYL ONTO SILICA MODIFIED BY CU2+ IONS

The dependences of dipyridyl adsorption from solutions onto highly dis persed silica modified by Cu2+ ions on pH and dipyridyl concentration were studied. The data obtained were used for the determination of the compositions and stabilities of the ternary surface complexes which a re formed in this system. Two methods were used for the calculations: one is based on material balance equations and the other is analogous to Bjerrum's method. The equilibrium constant of the reaction of the f irst dipyridyl molecule binding with Cu2+ ions on the surface (K-1) is greater than that of the second dipyridyl molecule (K-2), as is usual ly observed for complex formation in solutions. The difference between K-1 and K-2 depends on the concentration of Cu2+ ions on the surface.