Removal of Lead from Contaminated Soils Using Poly(amidoamine) Dendrimers

This study investigated the feasibility of using selected dendrimers for the removal of lead (Pb2+) from three contaminated soils. Lead removal was tested in a fixed-bed column setup, where a prescribed dendrimer solution was passed through a lead-loaded soil bed. Effects of dendrimer generation, concentration, type of the terminal groups, solution pH, and soil type were investigated. In all cases, lower pH increased the removal, lower-generation dendrimers were more effective than higher-generation dendrimers based on the same dose, whereas the effect of terminal groups was minimal. The removal was more effective for sandy soil than for clay soil. A sequential extraction experiment indicated that dendrimer treatment removed primarily (>82%) carbonate-bound Pb2+ cations. Approximately 95% of the spent dendrimers was recovered by nanofiltration, followed by acid regeneration. Approximately 96% of the Pb2+ cations in the solution can be retained by nanofiltration, and 94% of the retained Pb2+ cations can be desorbed upon acid regeneration.