Fe3O4@beta-CD nanocomposite as heterogeneous Fenton-like catalyst for enhanced degradation of 4-chlorophenol (4-CP)

摘要

The magnetic Fe3O4@beta-cyclodextrin (beta-CD) nanocomposites were fabricated via Fe ions and beta-CD in one pot and characterized as a heterogeneous Fenton-like catalyst that may be used for the degradation of 4-chlorophenol (4-CP). The catalytic capacity of Fe(3)o(4)@beta-CD was evaluated on the basis of various parameters, including pH, H2O2 concentration and catalyst loading, with regards to the pseudo-first-order kinetics of 4-CP degradation. In addition, iron leaching, the effect of radical scavengers and reusability of the Fe3O4@beta-CD nanocomposite were also studied. The results showed that Fe3O4@beta-CD exhibited a higher catalytic ability than that Fe3O4 toward 4-CP degradation, the observed rate constants (k(obs)) were 0.0373 min(-1) for Fe3O4@beta-CD, and 0.0162 min(-1) for Fe3O4, which may be ascribed to the construction of a ternary complex (Fe2+-beta-CD-pollutant) that allowed the produced hydroxyl radicals (center dot OH) to directly attack the contaminant and simultaneously enhanced the solubility of the organic pollutant. Fe(3)o(4)@beta-CD also exhibited an enhancement effect for chlorobenzene (CB) degradation with the kobs of 0.0392 min-1 (k(obs) = 0.0099 min(-1) for Fe3O4), which may be due to a synergistic effect in the Fe3O4@beta-CD composite. Furthermore, Fe3O4@beta-CD has an excellent catalytic activity, stable mechanical strength and adequate reusability. A possible reaction pathway of 4-CP degradation dominated by center dot OH was proposed according to analyses of the degradation intermediates and chloride ions. The host-guest interaction between beta-CD and 4-CP were examined with density functional theory (DFT) calculations, expounding the unicity of degraded intermediate owing to the specific spatial selectivity of beta-CD. The findings of this study provide a novel material used in the Fenton-like process for the degradation of contaminants. (C) 2016 Elsevier B.V. All rights reserved.