Combined microwave-induced and photocatalytic oxidation using zinc ferrite catalyst for efficient degradation of tetracycline hydrochloride in aqueous solution

• We report a novel combined microwave-induced and photocatalytic process. • ZnFe 2 O 4 has both microwave-catalytic and visible-light photocatalytic activities. • little O 2 −• active species generates in MW/MEDL/ZnFe 2 O 4 system. In this research, ZnFe 2 O 4 was employed as heterogeneous catalyst for the degradation of tetracycline hydrochloride (TCH) by a novel combined microwave-induced (MW-induced) and photocatalytic oxidation. The ZnFe 2 O 4 catalyst was synthesized using co-precipitation method, and characterized by XRD, TEM, BET and UV–Vis DRS. A microwave electrodeless discharge lamp (MEDL) was introduced to this process as a light source. 91.6% of TCH degradation was obtained in MW/MEDL/ZnFe 2 O 4 system in 4 min. ZnFe 2 O 4 catalyst had both microwave-catalytic and visible-light photocatalytic activities. The operation parameters, such as microwave output, catalyst dosage, initial pH and recycle runs, showed different influence on TCH degradation. The analysis of degradation mechanism indicated that h + was the main active species for TCH degradation and little O 2 −• active species generated in MW/MEDL/ZnFe 2 O 4 system. The decomposition intermediates of TCH were identified by LC-MS.