Studies on adsorption property of novel composite adsorption material PEI/SiO2 for uric acid

Polyethyleneimine (PEI) was grafted onto the surface of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP), the composite adsorption material PEI/SiO2 with strong adsorption action for uric acid was prepared. Static adsorption experiment results show that macromolecules of PEI grafted onto silica particles have very strong adsorption ability by right of strong physical adsorption induced by the hydrogen bond interaction between PEI and 2,6,8-trihydroxypurine which is a tautomer of uric acid, and chemical adsorption of a certain extent caused by Schiff base reaction. The isothermal adsorption fits to Freundlich equation, and the maximum adsorption amount reaches 84.9 mg/g. The pH value of the medium influences greatly the sorption, in neutral solution (pH = 6–7), PEI/SiO2 displays strong adsorption ability for uric acid, whereas in acidic and basic solution, the adsorption is weak. Temperature also has some influence on the adsorption property of PEI/SiO2, and the adsorption capacity increases with rising temperature.