Poly(ethylenimine) coated onto silica gels: Adsorption capacity toward lead and mercury

A series of poly(ethylenimines) (PEI) coated onto silica gels has been test ed for the ability to complex lead and mercury in aqueous solutions. The st udy of the kinetics of metal uptake revealed that all sorbents exhibit a fa st rate of sorption. The saturation capacities of the different systems wer e evaluated according to the Langmuir equation. The influence of different parameters like pH, textural characteristics of silica, and amount of coate d polymer were discussed. Finally, cycles of stripping and sorption for lea d metal were investigated in column system to evaluate the long-term stabil ity of the sorption properties. One striking result was that crosslinking P EI onto silica prevents the desorption of PEI and greatly improves the sorp tion capacity. (C) 1999 John Wiley & Sons, Inc.