RESUMO
Silica gel surface was chemically modified with beta-diketoamine groups by reacting the silanol from the silica surface with 3-aminopropyl-triethoxysilane and 3-bromopentanedione. With this material, copper ions were adsorbed from aqueous solutions. The chemical analysis of the silica-gel-immobilized acetylacetone provided a quantity of 0.67 mmol g-1 of organic groups attached to the support and 0.63 mmol g-1 of copper. This material was used as a stationary phase in IMAC (immobilized metal affinity chromatography), to separate alpha-lactoalbumin from bovine milk whey. The results showed an efficient separation in the chromatographic column. The possibility of reutilization of the stationary phase was also investigated.
RESUMO
[Ru(edta)(H2O)]- is strongly adsorbed on a zirconium(IV) oxide-coated silica gel surface. The immobilized complex showed an electrochemical response due to the Ru(II)/Ru(III) redox couple. By substituting the coordinated water molecule in the adsorbed complex, the midpoint potentials shifted in the order (in mV) water, -290; thiocyanate, -200; pyridine, -180; 4-cyanopyridine, -80; and pyrazine, -50 vs SCE.
RESUMO
Two silica gels, one modified with aminobenzenesulfonic (SABS) groups and the other with phosphate (SZP) groups, were prepared to adsorb some amino acids. Chemical analysis of the modified silica gave 0.65 mmol g-1 aminobenzenesulfonic groups and 0.56 mmol g-1 phosphate groups. The maximum adsorption capacities for amino acids determined by batch experiments for SABS were 1.37, 0.67, 0.76, and 0.59 mmol g-1 for glycine, lysine, histidine, and leucine, respectively, and those for SZP were 0.75, 0.58, 0.44, and 0.75 mmol g-1 for glycine, lysine, histidine, and leucine, respectively. The adsorption capacity of SABS was significantly affected by the solution pH, showing a higher selectivity than SZP. The materials were very stable, allowing their use several times without changes in adsorption capacity.
