Fenton degradation assisted by cyclodextrins of a high molecular weight polycyclic aromatic hydrocarbon benzo[a]pyrene.

This paper investigates the effect of native beta-cyclodextrin (beta-CD) and its CD derivatives, such as hydroxypropyl-beta-cyclodextrin (HPBCD) and randomly methylated-beta-cyclodextrin (RAMEB), on the solubilization of a high molecular weight polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) and on its degradation by Fenton's reaction. The results show that BaP apparent solubility was significantly increased in the presence of cyclodextrin (CD) in the following order: beta-CD<RAMEB<HPCD. BaP Fenton degradation was strongly dependent on the capacity of cyclodextrin to solubilize BaP. In the presence of a radical scavenger (mannitol), BaP Fenton degradation was inhibited with RAMEB but not in the presence of HPCD. Molecular modelisation was used to visualize the steric complementarity of these host-guest systems. No significant difference of encapsulation between the two modified CDs was observed. Nevertheless, the results suggest a probable existence of a ternary complex HPCD-BaP-iron permitting the generation of hydroxyl radicals in close proximity to BaP. On the basis of these results, it appears that HPCD may be useful for developing targeted BaP degradation system.