Functional dendrimeric "nanosponges" for the removal of polycyclic aromatic hydrocarbons from water

A series of poly(propylene imine) dendrimers functionalized with long aliphatic chains has been prepared and characterized. The property of these dendrimers to encapsulate polycyclic aromatic hydrocarbons from water down to a few ppb level has been established. The inclusion formation constants are orders of magnitude higher than those reported for activated carbon (from 1.4 x 10(4) to 3.4 x 10(5) M-1) or cyclodextrins (10-10(3) M-1) while they are comparable to those of cyclodextrin polymers (from 1 x 10(8) to 5 x 10(9)). Furthermore, the loading capacities depend on polycyclic aromatic compounds and the type of alkylated dendrimeric derivatives, that is, 6-19 mg/g for fluoanthrene, 44-67 mg/g for phenanthrene, and 34-57 mg/g for pyrene. Regeneration is also feasible using nonpolar solvents.