Constructing S/N-vacancy-and Co/Mo-bimetallic-catalysts for tetracycline degradation through peroxymonosulfate activation: evolution of active substance.

Regulation of the types and content of reactive oxygen species (ROS) in advanced oxidation processes (AOPs) is regarded as a challenging task. Herein, the features of sulfur-vacancy (Sv) and nitrogen-vacancy (Nv), and cobalt (Co)/molybdenum (Mo)-bimetallic constituents were simultaneously incorporated into a novel Co-N@MoS-COOH catalyst through a simple hydrothermal calcination method. The adsorption of oxygen (O) and peroxymonosulfate (PMS) was promoted by Sv/Nv, whereby the generation of superoxide radical (O·) and singlet oxygen (O) species was induced, and the energy barrier for the formation of high-valent cobalt-oxo species (Co(IV)=O) was reduced. The decomposition of PMS was enhanced by a bimetal (Mo/Co) electronic pump and the O·, O, and Co(IV)=O active species degraded tetracycline (TC) together to achieve an efficient degradation rate (initial K = 0.490 min). The degradation intermediates and potential degradation pathways were identified, and the leaching of Co was within the acceptable range of environmental standards. Incorporation of the catalyst into a microfilter membrane achieved a 100 % degradation of TC at an ultra-high membrane flux (1803.4 LMH/bar). This study provided new insights into the types of ROS regulated by bi-vacancy and bimetallic catalysts in AOP systems, with the intention of promoting a more sustainable and resource-efficient treatment technology.