Multiple roles of hydroxylamine for degradation of tetracycline in HA/Fe-Al₂O₃/O₃ process

Hydroxylamine (HA) and a heterogeneous catalyst Fe-Al2O3 prepared by the soak-calcination method were induced in the oxidation of tetracycline (TC) by ozone. The maximum 75.2% removal efficiency of total organic carbon (TOC) was achieved after 30 min of reaction at O-3 flow rate 0.2 L/min, HA concentration 0.9 mM, dosage of Fe-Al(2)O(3)6.6 g/L, and initial pH 4.8. The results indicated that TC was mainly degraded by ozone oxidation catalyzed with HA and Fe-Al2O3, where HA played multiple vital roles. HA not only catalyzed the oxidation of ozone, but also reduced Fe(III) to enhance the removal of pollutant. However, HA could also exhibit an inhibiting effect by consuming center dot OH when initial pH was above 4.5. The catalysis of Fe3+/Fe2+, Fe-Al(2)O(3)adsorption, and ozone direct oxidation also contributed to the degradation of TC. The electron paramagnetic resonance (EPR) result showed that center dot OH was the main active substance in the HA/Fe-Al2O3/O-3 system. In addition, the possible degradation pathways were proposed. The acute toxicity of wastewater treated with the HA/Fe-Al2O3/O-3 system was less than the untreated wastewater. Overall, this study illustrates combination of HA and Fe-Al2O3 to catalyze ozonation is an efficient method to treat antibiotic wastewater.