Carbon framework-encapsulated copper oxide particles to activate peroxymonosulfate for the efficient degradation of tetracycline

Abstract CuO particles encapsulated by an irregular polyhedral carbon framework (CuO@C) were prepared via a one-pot polymerization method. The prepared CuO@C exhibited a highly enhanced performance in the activation of peroxymonosulfate (PMS). Our results indicated that the rate constant of tetracycline (TC) degradation was significantly increased by more than 85%, i.e., from 0.021 to 0.147 min−1, compared with the corresponding value for the bare CuO. TC elimination was completely achieved within 40 min, with the mineralization rate reaching 75.3% in 1 h. In addition, the CuO@C/PMS system exhibited an excellent performance in complex water matrixes containing various inorganic ions. Based on the use of scavengers and spin-trapping electron paramagnetic resonance technology, reactive species including ·OH, SO4·−, and 1O2 were proposed to be the main oxidants of the CuO@C/PMS system, and the possible intermediates were also fully investigated. Moreover, a catalytic cycle involving Cu+/Cu2+/Cu3+ was proposed. It was also demonstrated that the highly stable CuO@C can be easily recycled and reused. The present study therefore embodies the conceptual design of an excellent catalyst with a persistent stability for the activation of PMS, which may serve as a versatile platform for wider environmental applications.