Activation of peroxydisulfate using N-doped carbon-encapsulated Ni species for efficient degradation of tetracycline

Abstract

• N-doped carbon-embedded NiN x was prepared in activating PDS for removal of TC. • Catalytic system exhibits wide pH adaptation, durability, anti-interference ability. • O 2 − and 1 O 2 generated in Ni@NC/PDS system was the dominant ROSs to oxidize TC. • NiN x -mediated electron transfer and dissolved oxygen-derived ⋅O 2 − can degrade TC. In this study, N-doped porous carbon materials embedded with NiN x species (Ni@NC) were fabricated via the pyrolysis of Ni-doped zeolitic imidazolate frameworks-8 (ZIF-8) at the temperature of 900 °C. The obtained Ni@NC-1 catalyst exhibited excellent activity in activating the peroxydisulfate (PDS) that was used for removing tetracycline (TC). The catalytic system exhibited good stability, wide pH adaptation, and high resistance to the operational environment. It was supposed that NiN x species could attach to PDS and act as electron acceptors to receive the electrons for activating the PDS, thus generating highly reactive superoxide radicals (⋅O 2 − ) and singlet oxygen ( 1 O 2 ) species for rapid degradation of TC. The electron transfer and dissolved oxygen-derived ⋅O 2 − were also responsible for the degradation of TC. In addition, the Ni@NC-1/PDS system exhibited high efficiency for removing oxytetracycline, ciprofloxacin, or levofloxacin. The results of this study would promote the design of other MOFs-derived carbon-encapsulated metal species for efficiently activating persulfate to remove antibiotics from the wastewater.