Mechanism study of nitrilotriacetic acid-modified premagnetized Fe0/H2O2 for removing sulfamethazine

Sulfamethazine (SMT) is extensively used as growth promoters and antibacterial drugs. In this study, premagnetized Fe 0 was used to catalyze H 2 O 2 decomposition (pre-Fe 0 /H 2 O 2 ) in the presence of nitrilotriacetic acid (NTA) to remove SMT at neutral pH conditions. In all, 30.3% and 99.8% of SMT were removed by the pre-Fe 0 /H 2 O 2 process (60 min) and the pre-Fe 0 -NTA/H 2 O 2 process (30 min), respectively. The removal rate of SMT in the pre-Fe 0 -NTA/H 2 O 2 process was 2.5 times larger than that in the Fe 0 -NTA/H 2 O 2 process. Electron paramagnetic resonance signals indicated that more radicals were generated in the pre-Fe 0 -NTA/H 2 O 2 system. SMT and NTA and their degradation by-products adsorbed on pre-Fe 0 reduced the contact angle of the particle and prevented the formation of Fe 3 O 4 on the particle surface, thus accelerating Fe 0 corrosion. Tafel scan images confirmed the enhancement of Fe 0 corrosion in the presence of NTA and magnetic field. The Fe 0 corrosion rate (10 9 ) after 20 min of reaction was 6.61 cm/s in pre-Fe 0 -NTA/H 2 O 2 , much higher than that in Fe 0 /H 2 O 2 (0.73 cm/s), pre-Fe 0 /H 2 O 2 (1.47 cm/s) and Fe 0 -NTA/H 2 O 2 (2.94 cm/s). Pre-Fe 0 -NTA/H 2 O 2 could also keep the fast SMT removal with eight consecutive runs without the addition of pre-Fe 0 and NTA and presented high efficiency for SMT removal in real municipal wastewater .