Chemical Engineering Journal, Vol.374, 1180-1190, 2019
Mechanism study of nitrilotriacetic acid-modified premagnetized Fe-0/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 H2O2 decomposition (pre-Fe-0/H2O2) 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/ H2O2 process (60 min) and the pre-Fe-0-NTA/H2O2 process (30 min), respectively. The removal rate of SMT in the pre-Fe-0-NTA/H2O2 process was 2.5 times larger than that in the Fe-0-NTA/H2O2 process. Electron paramagnetic resonance signals indicated that more radicals were generated in the pre-Fe-0-NTA/H2O2 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 Fe3O4 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/H2O2, much higher than that in Fe-0/H2O2 (0.73 cm/s), preFe(0)/ H2O2 (1.47 cm/s) and Fe-0-NTA/H2O2 (2.94 cm/s). Pre-Fe-0-NTA/H2O2 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.
Keywords:Premagnetization;Nitrilotriacetic acid;Contact angle;Corrosion rate;Free corrosion potential