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• Co 1.1 Mn 1.9 O 4 exhibited excellent activity to activate PAA for SMX degradation. • CH 3 C(O)OO● was evidenced as the dominant reactive oxidizing species. • Significant role of Mn in intensifying the activity of Co sites was revealed. • Co 1.1 Mn 1.9 O 4 /PAA process had great potential in high-salinity wastewater treatment. Activation of peracetic acid (PAA) to generate powerful oxidizing species has become a promising advanced oxidation processes (AOPs) in wastewater treatment, yet the development of low-cost and high-performance activators is still a primary challenge. Herein, a range of Co–Mn spinel oxides (Co 3-x Mn x O 4) with varying levels of Co and Mn were successfully elaborated, in which Co 1.1 Mn 1.9 O 4 exhibited remarkable performance in PAA activation, outperforming most reported heterogeneous catalysts. Extensive quenching experiments and electron spin resonance (ESR) analysis indicated that acetylperoxyl radical (CH 3 C(O)OO●) was the predominated oxidizing species responsible for sulfamethoxazole (SMX) degradation. Density functional theory (DFT) calculations revealed that doping with Mn not only promoted the electron transfer and accelerated reduction of Co(III) to Co(II), but also lowered the energy barrier for PAA activation. Moreover, the prominent chemisorption and activation of PAA with Co 1.1 Mn 1.9 O 4 was also benefitted from the significant role of Mn in optimizing the distribution of bonding and antibonding states on Co 3d orbitals. Unexpectedly, high levels of Cl−greatly facilitated SMX degradation due to the mass production of HOCl from the chain reactions of various radicals with Cl−. This work provides new insights into bimetallic activation of PAA, and the knowledge obtained will further advance the application of PAA-based AOPs. [Display omitted] [ABSTRACT FROM AUTHOR]

Nickel phosphide (Ni 2 P) is an emerging efficient catalyst for the hydrogen evolution and water splitting. Herein, we report that Ni 2 P is also a promising catalyst for enhancing electrochemical dechlorination of chlorinated disinfection byproducts (DBPs). Amorphous Ni 2 P (ANP) mini-nanorod arrays were in-situ fabricated on nickel foam (NF) via a facile phosphidation process, and then used as a binder-free cathode for electrochemical dechlorination of trichloroacetic acid (TCAA). Results showed that ANP exhibited superior performance on electrochemical dechlorination of TCAA than other metal cathodes (e.g., NF and Pd/C). Scavenging experiments and electron spin resonance (ESR) technique indicated that atomic H* was generated from water reduction through ANP catalysis, and primarily contributed to TCAA dechlorination. Indeed, the superhydrophilic surface of ANP favored electrocatalyst/electrolyte contact, and its low impedance further afforded rapid electron transport from the electrode to water or protons for atomic H* generation. The kinetic modelling and mass balance evaluation revealed the transformation mechanism of TCAA dechlorination. This study is among the first to develop ANP as a binder-free cathode for electrochemical dechlorination, and have important implications for eliminating chlorinated DBPs in water. Image 1 • ANP, a noble metal-free cathode, exhibited superior efficiency than Pd/C. • The atomic H* was primarily responsible for TCAA dechlorination. • Superhydrophilic surface of ANP accelerated H* formation in a wide pH range. • Stepwise and concerted pathway accomplished dechlorination of TCAA to AA. • ANP showed high reusability for dechlorination. [ABSTRACT FROM AUTHOR]