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Social development is accompanied by technological progress, which commonly leads to the expansion of pollution As an essential resource of modern medical treatment, antibiotics have become a hot topic in the aspect of environmental pollution. In this study, we first used fish scales to synthesize N, P-codoped biochar catalyst (FS-BC) as peroxymonosulfate (PMS) and peroxydisulfate (PDS) activator to degrade tetracycline hydrochloride (TC). At the same time, peanut shell biochar (PS-BC) and coffee ground biochar (CG-BC) were prepared as reference materials. Among them, FS-BC exhibited the best catalytic performance due to the excellent defect structure (I D /I G = 1.225) and the synergism of N, P heteroatoms. PS-BC, FS-BC and CG-BC achieved degradation efficiencies of 86.26%, 99.71% and 84.41% for TC during PMS activation and 56.79%, 93.99% and 49.12% during PDS, respectively. In both FS-BC/PMS and FS-BC/PDS systems, non-free radical pathways involved singlet oxygen (1O 2), surface-bound radicals mechanism and direct electron transfer mechanism. Structural defects, graphitic N and pyridinic N, P–C groups and positively charged sp 2 hybridized C adjacent to graphitic N were all critical active sites. FS-BC has the potential for practical applications and development because of its robust adaptation to pH and anions and stable re-usability. This study not only provides a reference for biochar selection, but also suggests a superior strategy for TC degradation in the environment. [Display omitted] • SynThesis of a novel N, P co-doped fish scale biochar catalyst. • The degradation efficiency of TC can reach 99.71% in FS-BC/PMS system. • Differences in the activation mechanism of FS-BC on PMS and PDS do not appear. • The activation mechanism only involved non-free radical mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] Mn and N co-doped biochar (Mn-N-TS) was prepared as an effective catalyst to activate peroxymonosulfate (PMS) for ciprofloxacin (CIP) degradation. As opposed to Mn-TS and N-TS, Mn-N-TS had more active sites containing N and Mn, as well as a greater specific surface area (923.733 m2 g−1). The Mn-N-TS exhibited excellent PMS activation ability. In the Mn-N-TS/PMS system, the CIP removal efficiency was 91.9% in 120 min. Mn and N co-doping could accelerate electron transfer between CIP and PMS molecules. Simultaneously, defect sites, graphitic N, pyridinic N, C═O groups, and Mn(II)/Mn(III)/Mn(IV) redox cycles acted as active sites to activate PMS and generate free radicals (OH, SO 4 − and 1O 2). Furthermore, the Mn-N-TS/PMS system could effectively degrade CIP in a wide pH range, background substances, and actual water. Finally, a probable mechanism of PMS activation by Mn-N-TS was proposed. In conclusion, this work gave a novel direction for the rational design of Mn and N co-doped biochar. [ABSTRACT FROM AUTHOR]

• A novel MOF-derived MnFeO X electrocatalyst was prepared. • MD-MnFeO X loaded onto the surface of carbon cloth significantly improves the performance of EC/PS system. • The MD-MnFeO X /CC/EC/PMS system has extremely strong environmental stability. • 1O 2 plays a decisive role in the MD-MnFeO X /CC/EC/PMS system. In this work, metal–organic-framework (MOF) derived MnFeO X (MD-MnFeO X) was loaded onto carbon cloth (CC) formed MD-MnFeO X /CC anode. Subsequently, the ability of MD-MnFeO X /CC anode to electrochemically (EC) activate peroxymonosulfate (PMS) for the degradation of persistent organic pollutants was tested by introducing an electric field. The degradation results indicated that the MD-MnFeO X /CC/EC/PMS system had a degradation ability of 90.20 % for tetracycline (TC) within 20 min at a very low current density of 5 mA/cm2, which was significantly higher than that of CC/EC/PMS (53.75 %) and the reported conventional synthesized double transition metal oxide/EC/PMS electrocatalytic system. In addition, the system had excellent stability and low energy consumption (0.79 kWh/m3). The influencing factors of the degradation efficiency of the system were analyzed, and the degradation ability of the system in actual water bodies was tested. The results demonstrated that the system maintained a stable degradation efficiency in various influencing factors and actual water bodies, proving that the system could degrade organic pollutants in complex water bodies. Mechanistic analysis showed that singlet oxygen (1O 2) played a dominant role in the MD-MnFeO X /CC/EC/PMS system. Finally, the pathway for TC degradation in this system was explored. This experiment provides an economically feasible method to improve the electrocatalytic performance of CC electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous NiCo 2 O 4 nanosheet array is designed using interfacial engineering. • NiCo 2 O 4 -PMS system oxidizes TC efficiently with practicality. • Good morphological and electronic structure enhances mass and electron transfer. • TC oxidization is dominated by 1O 2 and electron transfer process. The rational design of the morphology and structure of bimetallic-based heterogeneous Fenton-like catalyst derived from metal-organic-frameworks (MOFs) for peroxymonosulfate (PMS) activation via a non-radical pathway is attractive but challenging. Herein, a spinel-type 3D hierarchical porous NiCo 2 O 4 nanosheet array for the activation of PMS is rationally designed by surfactant-assisted interfacial engineering. The experimental results showed that the NiCo 2 O 4 /PMS system demonstrated remarkable oxidative degradation of tetracycline (TC) through 1O 2 attack and electron transfer process. In literature, it was thought that the PMS activation process in above system is dominated by radical pathway. In this work, we employ surfactant modified-nanostructure engineering to design hierarchical mesoporous nanosheet array structures and combined them with intrinsic bimetallic synergy to enhance catalytic activity, and interestingly the strategy transformed the PMS activation pathway into a nonradical (1O 2 and electron transfer)-dominated process. This is benefit from the favorable morphological and electronic structure of the designed catalysts to facilitate mass transfer and electron transfer processes. The system also possessed a broad spectrum for degrading other typical contaminants, and was effective in tolerating actual water matrix and pH changes, as well as resisting interference from anions and organic matter. Furthermore, the robust stability of the structure and catalytic activity make it promising for practical water treatment. It can be expected that this proposal will provide insights for the delicate structural design and the understanding of its PMS activation mechanism of bimetallic-based Fenton-like catalysts, as well as for the efficient degradation of emerging organic pollutants. [ABSTRACT FROM AUTHOR]

In the face of the increasingly serious water pollution problem, sulfate radical-based advanced oxidation processes gradually developed due to their remarkable ability to degrade refractory organic pollutants. Spinel ferrite nanoparticles (NPs) and their nanocomposites (NCs) can be used as catalysts to activate peroxymonosulfate (PMS) with great catalytic performance, high stability, and reusability, which has attracted some attention of scholars in recent years. Firstly, the advantages and mechanisms of PMS activation induced by various spinel ferrite NPs and their NCs for organic pollutants removal are reviewed in this paper. Secondly, the influence factors of catalyst performance and PMS activation are discussed. Finally, the challenges of PMS activation induced by spinel ferrite NPs and their NCs are put forward and the direction of improvement is proposed. [Display omitted] • Recent advances of spinel ferrite NPs and their NCs in peroxymonosulfate activation are reviewed. • The frequently-used synthesis methods, activation mechanisms, and influence factors are discussed. • Challenges and the direction of improvement are provided. [ABSTRACT FROM AUTHOR]