Synthesis of second generation dendrimere PPI (G2) functionalized with 4-hydroxycoumarin effective for the removal of chromium (VI) by adsorption

We report here the preparation of a second generation PPI dendrimer (G2) functionalized by 4-hydroxycoumarin based on the Manich reaction and its use for chromium (VI) removal. The literature review has shown that dendrimers are types of polymer defined by regular branches of a central monomer, which give it a tree molecular structure.  Their ends carry functional groups whose arrangement gives rise to cavities that are able to receive other molecules as part of host-guest chemistry. To increase the generation or modify peripheral groupings it is possible to manipulate the properties during the synthesis of the dendrimer.

Coumarins are a set of molecules with multiple beneficial properties including antioxidant, anti-inflammatory, anticancer, antibacterial, antiviral properties. It has also been shown that these molecules are good metal ion chelators and are able to modulate the activity of metrix metalloproteinases (MMPs).

The study of adsorption, on a PPI dendrimer functionalized with Coumarin (C2), trivalent chromium and hexavalent chromium, shows that the kinetics are carried out in two steps with a significant removal efficiency for Cr VI (38.26%) and zero for Cr III.

During this study, we kept the initial chromium concentration, pH, stirring rate, contact time and temperature constant and with the same amount of adsorbent (30 mg).