Efficient removal of tetracycline using magnetic MnFe2O4/MoS2 nanocomposite activated peroxymonosulfate: Mechanistic insights and performance evaluation

Abstract

• MnFe 2 O 4 /MoS 2 -X composites exhibited excellent reactivity for PMS activation. • The steady-state concentrations of •OH and SO 4 •− were 8.51×10 −12 M and 5.96×10 −12 M respectively. • •OH, SO 4 •− and nonradical pathway accounted for 31.3 %, 10.5 % and 58.2 % respectively. • The cycles of Mn(III)/Mn(II) and Fe(III)/Fe(II) were accelerated by MoS 2 . In this study, MnFe 2 O 4 /MoS 2 nanocomposite was prepared for activation of peroxymonosulfate (PMS) to remove tetracycline (TC) in aqueous solutions. The results showed that the highest activation efficiency was obtained when the molar ratio of MnFe 2 O 4 to MoS 2 was 1:3 (MnFe 2 O 4 /MoS 2 -3). TC removal efficiency in the MnFe 2 O 4 /MoS 2 -3 (MM3)/PMS system reached 92.9 % in 30 min. Radical identification experiments confirmed that SO 4 •− , •OH and 1 O 2 were the main reactive oxygen species in the MM3/PMS system. The excellent electron transfer capability of MM3 nanocomposite ensured rapid redox cycling of Mn(II)/Fe(II) on the material surface, thus greatly facilitating the production of reactive oxygen species and the degradation of TC. In addition, over 80 % of TC in natural water backgrounds were degraded by the MM3/PMS system. The MM3 maintained its high activity during repeated five cycles. Thus, the synthesized MnFe 2 O 4 /MoS 2 nanocomposite is an ideal PMS activator and can be used to the treatment of refractory pollutants.