Enhanced heterogeneous and homogeneous Fenton-like degradation of carbamazepine by nano-Fe3O4/H2O2 with nitrilotriacetic acid

Abstract The influence of a biodegradable agent, nitrilotriacetic acid (NTA), on the degradation of the model compound carbamazepine (CBZ) by the nano-Fe 3 O 4 /H 2 O 2 system was investigated. The results showed that the presence of NTA can provide better performance of the nano-Fe 3 O 4 /H 2 O 2 system for CBZ degradation at reduced usage of H 2 O 2 and nano-Fe 3 O 4 . The optimal concentration of NTA was determined to be 0.5–1.0 mM. The first-order rate constant, k app , for CBZ degradation by 1.0 g L − 1 of nano-Fe 3 O 4 and 100 mM of H 2 O 2 in the presence of 0.5 mM of NTA at an initial neutral pH was determined to be 4.32 × 10 − 2  min − 1 , which was 80 times larger than that in the absence of NTA. In addition, the k app value increased with the increase in nano-Fe 3 O 4 concentration from 0.1 to 3.0 g L − 1 , and the H 2 O 2 concentration increased from 5 to 600 mM. The initial pH of CBZ solutions over a range of pH 5.0–9.0 did not affect the k app value of CBZ ( p  = 0.08). A decrease in the initial concentration of CBZ from 6.35 × 10 − 2 to 1.06 × 10 − 2 mM resulted in an increase of the k app value from 4.32 × 10 − 2 to 1.51 × 10 − 1  min − 1 . Moreover, the results indicated that the degradation intermediates were generated by the attack of OH. The degradation mechanism of CBZ included both an enhanced heterogeneous Fenton-like reaction on the Fe 3 O 4 nanoparticle surface and an enhanced homogeneous Fenton-like reaction in the aqueous phase by Fe-NTA complexes.