Surface Ion Exchange Capacity Research Articles

Zirconium Phosphate and Modified Zirconium Phosphates as Supports of Lipase. Preparation of the Composites and Activity of the Supported Enzyme

Biocomposites with enzymatic activity were obtained by adsorption of lipase from Candida rugosa on the surface of different layered zirconium phosphates and phosphonates such as α-zirconium hydrogenphosphate, solid dispersions of zirconium phosphate in silica, zirconium carboxyethanephosphonate, zirconium phosphate-carboxyethanephosphonate, zirconium benzenephosphonate, and zirconium phosphate-benzenephosphonate. All the supports were characterized for chemical composition, BET specific surface area, surface ion exchange capacity, and X-ray diffraction patterns. The adsorption process at 4 °C was studied as a function of time of equilibration of the support with the lipase solutions (0.5 mg/mL) and as a function of the amount of protein present in the equilibrating solution. The activities of biocomposites with the different supports, at different protein loadings, were obtained by determining the amount of acetic acid produced by catalyzed hydrolysis of p-nitrophenylacetate. The best results in terms of ...