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Some features of 2 and 4-aminopyridines anchored on silica gel: Properties and chemisorption of metal(II) chlorides in non-aqueous solutions

1989; Elsevier BV; Volume: 8; Issue: 24 Linguagem: Inglês

10.1016/s0277-5387(00)86288-9

1873-3719

Afonso S. Gonçalves, Cláudio Airoldi,

Nanomaterials for catalytic reactions

Abstract Silica gel surfaces modified with 2- or 4-aminopyridine groups were used to adsorb MCl 2 (M = Co, Ni, Cu, Zn) from ethanol and acetone solutions at 298 K. The chemisorption isotherms fitted a modified Langmuir equation very well and are similar for all cations. The capacity of anchored 4-aminopyridine (SIL4) in adsorbing the metallic ion is larger than that of the immobilized 2-aminopyridine (SIL2). The maximum retention capacity has the sequence Cu > Co > Zn in acetone for both surfaces, and Zn > Co > Cu > Ni for SIL2, and Zn > Cu > Co > Ni for SIL4 in ethanol. For a given cation, the variation in enthalpy of solvent-solute exchange on the surface is always larger in ethanol. This process seems to be related to the enthalpy of solvation of the cation involved in the exchange.