LaFeO3 and BiFeO3 as nanocatalysts for contaminant degradation

What is it about?

The present study examines the applicability of two iron-containing perovskites, LaFeO3 (LFO) and BiFeO3 (BFO), as nanocatalysts for heterogeneous Fenton-like reactions using phenol and methyl tert-butyl ether (MTBE) as model contaminants. LFO and BFO synthesized according to a sol–gel method using citric acid as complexing agent have a crystallite size of about 60–70 nm with specific surface areas of 5.2 m2 g-1 for LFO and 3.2 m2 g-1 for BFO. In heterogeneous Fenton-like reactions, LFO and BFO showed similar pseudo- first order rate constants for phenol oxidation (k(LFO)= 0.13 h-1 and k(BFO)=0.15 h-1) at pH = 7 when 0.1 g L-1 catalyst and 3.0 g L-1 H2O2 were applied. Degradation efficiency was improved for both perovskites by a factor of approximately three when the pH value was slightly decreased to pH = 5. An increase of the reaction temperature from 20 °C to 60 °C during the BFO-catalyzed reaction led to a significant acceleration of phenol removal of about one order of magnitude k(BFO)=1.9 h-1. High stability and reusability of the BFO particles was confirmed in four successive oxidation batches using MTBE as model contaminant. In addition, the mechanism of the perovskite- catalyzed Fenton-like system was studied by applying compound-specific stable isotope analysis (CSIA). The perovskite-catalyzed oxidation appears to follow a pathway similar to that of the homogeneous Fenton reaction, i.e. OH radicals play a dominant role as primary reactive species.

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