Effect of γ-FeO nanoparticles on the composition of montmorillonite and its sorption capacity for pyrene.

Fe content and distribution on montmorillonite would probably enhance its sorption capacity for hydrophobic organic pollutants. Thus, Fe modified montmorillonites with different ratios of FeSO·7HO and Ca-montmorillonite were prepared. The results indicated that γ-FeO nanoparticles were not only generated at the montmorillonite surfaces, but that the γ-FeO also extended the edges of montmorillonite surfaces. The sorption capacities for pyrene were enhanced and even reached 834.79 μg g with increase in ferrous iron content, but were then suppressed due to aggregation of γ-FeO on montmorillonite surfaces. Furthermore, pyrene was directly observed on γ-FeO-montmorillonite surfaces with a lattice spacing parameter of approximately 0.27 nm, indicating that a new phase that mainly contained pyrene was generated during the sorption process. Additionally, after regenerating the γ-FeO-montmorillonite composites, they could be reused for at least 5 cycles. It is therefore proposed that the prepared γ-FeO-montmorillonite could be exploited as a potential green composite for remediation of hydrophobic organic pollutants in soil and sediment.