Preparation Of Seven Kinds Of Amino Bonded Silica Gels And Their Adsorption To Heavy Metal Pb2+

Seven kinds of amino bonded silica gels were prepared. They were aminopropyl bonded silica gel ( SiO2-N), ethylenediamine-N-propyl bonded silica gel ( SiO2-2N), diethylenetriamine bonded silica gel ( SiO2-3N), triethylenetetramine bonded silica gel ( SiO2-4N), tetraethylene pentamine bonded silica gel ( SiO2-5N), pentaethylene hexamine bonded silica gel ( SiO2-6N) and polyvinylimide bonded silica gel ( SiO2-nN). The densities of the bonded amino groups in SiO2-N and SiO2-2N prepared by a one. step method were up to 2. 07 mmol / g and 1. 71 mmol / g, respectively. The density of the bonded amino groups in SiO2-nN with ethylene imine units prepared by a two. step method, was 0. 02 mmol / g. The densities of the bonded amino groups in the other silica gels were similar, about 0. 50 mmol / g. The synthesized silica gels were used to investigate the adsorption of the heavy metal ion Pb2+ which commonly exists in aqueous solutions. About 20 mg of the silica gel was added to 10 mL of 400 mg / L Pb2+, at pH 5 and 30. The results indicated that the adsorption capacity reached the maximum value after 10 h. The adsorption process was fit to the Freundlich isothermal equation. The adsorption capacities of SiO2-N, SiO2-2N, SiO2-3N, SiO2-4N, SiO2-5N, SiO2-6N and SiO2-nN to Pb2+ were 131. 28, 138. 98, 85. 37, 75. 22, 61. 87, 79. 12 and 114. 06 mg / g, respectively, indicating the potential utility of these amino. functionalized silica gels for the adsorption of Pb2+.