Synthesis of hybrid materials, immobilization of lipase in SBA-15 modified with CaO

Mesoporous silica materials (SBA-15) doped with calcium (Ca) at 1, 3 and 5% w/w were synthesized in order to immobilize candida rugosa lipase (CRL), through the adsorption method. It was found that calcium (Ca) is present as CaO, highly dispersed on the surface of SBA-15, the specific area of SBA-15 decreases on incrementing CaO content. The environmental pH influences the adsorption of CRL due to the polarization of positive charges below the isoelectric point (IEP) whereas the Ca-SBA-15 materials present negative charges. The adsorption model proposed for CRL is about the accessible surface of the material, as this has a size of 7 nm and the Ca-SBA-15 present pores at an interval of 3 nm.