The kinetics and mechanism of carbamazepine (CBZ) degradation in a neutral pH range by a modified Fenton-like reaction using ferric-nitrilotriacetate (FeIII-NTA) complexes and in a heterogeneous nano-magnetite (Fe3O4) system with NTA will be presented. The results for the aqueous system indicate that CBZ degradation by FeIII-NTA/H2O2 can be described by pseudo first-order kinetics and mainly attributed to hydroxyl radical (�OH) attack. The steady-state concentration of �OH was strongly dependent on the concentration of FeIII, the initial pH, and H2O2:FeIII and NTA:FeIII molar ratios. Optimal conditions of [FeIII], [H2O2:FeIII]and [NTA:FeIII] were obtained for the degradation of CBZ at neutral pH (7.0) and ambient temperature (25 oC); the corresponding degradation rate constant of CBZ, kapp, was 0.0419 (�0.002) min-1. The value of kapp increased with increasing pH from 5.0 to 9.0 due to the strong pH-dependence of FeIII-NTA complexes; FeIII(NTA)(OH)22- was the most likely active iron species to activate H2O2 to produce �OH. Ten intermediates were identified during the degradation process, and a potential mechanism for the formation of �OH by FeIII-NTA/H2O2 and possible degradation pathways of CBZ are proposed. In addition, the effects of nano-Fe3O4 dosage, H2O2 concentration, NTA concentration and initial pH on the degradation kinetics of CBZ in the heterogeneous system by the modified Fenton-like reaction with nano-Fe3O4 and NTA have also been investigated. More than 99.5% of CBZ was degraded after 2 h reaction time in the presence of NTA, much faster than the reaction in the absence of NTA (> 12 h). The mechanism of this improved CBZ degradation rate has been elucidated: a heterogeneous Fenton-like reaction on the Fe3O4 nanoparticle surface and a modified homogeneous Fenton-like reaction by FeIII-NTA complexes in the aqueous phase. This method using biodegradable NTA would provide an efficient approach for the remediation of emerging contaminants in the environment.

Kinetics and mechanism of CBZ degradation at neutral pH by an NTA modified Fenton reaction in solution and by a heterogeneous Fenton reaction with nano-magnetite and NTA

246th National Meeting (2013)

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