Spinel MnFe 2 O 4 nanoparticles activating bicarbonate/hydrogen peroxide for the degradation of tetracycline: Revealing the influence of temperature and raw water and developing countermeasure

Bicarbonate/hydrogen peroxide (BHP) activating is expected to treat antibiotic wastewater effectively, but it has been rarely studied at different temperature and raw water conditions. Based on their MnFe bimetallic sites and photothermal property, spinel MnFe 2 O 4 nanoparticles were investigated as catalysts to activate BHP for tetracycline treating in variable temperature and raw water environments. At 23±2°C, impressive activity was observed on MnFe 2 O 4 nanoparticles for BHP activating to achieve the degradation of tetracycline regardless of in distilled, municipal tap and natural lake water. Meanwhile, spinel MnFe 2 O 4 nanoparticles had high durability to activate BHP for tetracycline degradation, no obvious activity attenuation was found in 10 cycles of reuse. The apparent activation energy of tetracycline degradation with MnFe 2 O 4 /BHP was found to be 38.73 kJ mol -1 , having temperature dependent feature. Accordingly, the activity of MnFe 2 O 4 /BHP for tetracycline degradation was proportional to temperature, and MnFe 2 O 4 /BHP had low activity at 3±2°C and 13±2°C. Under simulated sunlight irradiation, the activity of MnFe 2 O 4 /BHP for tetracycline degradation at 3±2°C and 13±2°C can be obviously improved by means of the photothermal property of spinel MnFe 2 O 4 nanoparticles to rise temperature. In a 15 L of continuous reactor with intake solution rate range of 2.4 to 9.6 L h -1 , MnFe 2 O 4 /BHP showed good operational performance for tetracycline degradation in municipal tap water. Active species detections revealed that tetracycline degradation with MnFe 2 O 4 /BHP was co-initiated by °O 2 - , °OH and °CO 3 - which are mainly produced from spinel MnFe 2 O 4 activating BHP reactions.