Surface functionalization of zirconium dioxide nano-adsorbents with 3-aminopropyl triethoxysilane and promoted adsorption activity for bovine serum albumin

Surface functionalization of zirconium dioxide (ZrO 2 ) nano-adsorbents was carried out by using 3-aminopropyl triethoxysilane (APTES) as the modifier. The addition amount of APTES was varied to determine the optimum modification extent, and the bulk ZrO 2 microparticles were also modified by APTES for comparison. Some means, such as TEM, XRD , FT-IR, XPS and TG-DSC were used to character these ZrO 2 particles. The results showed that the APTES molecules were chemically immobilized on the surface of ZrO 2 nanoparticles via Zr O Si bonds, and the nano-ZrO 2 samples showed larger special surface area. In the adsorption of bovine serum albumin (BSA), nano-ZrO 2 samples exhibited enhanced adsorption activity, and APTES modified nano-ZrO 2 with proper APTES content presented the best adsorption property. Under the same adsorption conditions, the equilibrium adsorption capacity of BSA on APTES-ZrO 2 -2 was almost 2.3 times as that on pristine nano-ZrO 2 and 3.0 times as on bulk ZrO 2 microparticles. The increased adsorption capacity of APTES-ZrO 2 nano-adsorbents can be attributed to the chemical interaction between amino and carboxyl groups at APTES-ZrO 2 /BSA interface. The pH-dependent experiments showed that the optimum pH value for the adsorption and desorption was 5.0 and 9.0, respectively, which suggested that the adsorption and release of BSA could be controlled simply by adjusting the solution pH condition.