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[Display omitted] • Abundant electron-rich Co centers generated by Mg doping enhanced PMS activation. • MCO@PES membrane/PMS system achieved instant contaminants elimination. • The highly accessible SO 4 −, OH, and 1O 2 were the responsible reactive species. • Catalyst recovery and enhanced mass transfer in membrane provided the application value. The practical application of heterogeneous Fenton-like processes in wastewater treatment is limited by inadequate catalyst recovery and limited mass transfer in traditional batch mode. Consequently, a catalytic membrane composed of inert magnesium (Mg)-doped Co 3 O 4 spinel (MCO) was crafted to activate peroxymonosulfate (PMS) for the elimination of organic contaminants. The incorporation of the less electronegative Mg induced electronic polarization on the MCO surface, resulting in the generation of sufficient electron-rich Co centers, thereby amplifying its electron-donating properties in PMS activation and enhancing the inherent catalytic activity of the spinel. Regarding the catalytic membrane, the stacked porous structure of the MCO layer achieved reactive sites exposure, mass transfer enhancement, and reactive species availability. Remarkably, the MCO@polyethersulfone (PES) membrane/PMS system instantaneously activated PMS, displaying an elimination kinetic constant of 0.039 ms−1 for tetracycline. The MCO@PES membrane exhibited exceptional catalytic performance and stability in long-term operational studies. Mechanistic investigations elucidated that the highly accessible SO 4 −, OH, and 1O 2 within the catalytic membrane facilitated the immediate elimination of contaminants. This study serves as a valuable reference for the application of transition metal spinel-based catalytic membranes in wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • La 2 (CO 3) 3 /CoFe 2 O 4 /biochar (LCB) was synthesized by a hydrothermal process. • LCB/PMS system was established to remove P(III) in one step. • LCB/PMS exhibited satisfactory removal rate of P(III) in a wide pH range. • SO 4 •- played a critical role in the oxidation process. • Different types of phosphorus could be rapidly removed by LCB/PMS. Phosphite [P(III)], an emerging eutrophication pollutant, has attracted limited attention in recent years. Owing to the higher solubility and resistance to biotransformation of P(III), oxidation of P(III) to phosphate [P(V)] is considered to be necessary to enhance P(III) removal. Herein, an efficient and regenerable magnetic La 2 (CO 3) 3 /CoFe 2 O 4 /biochar composite (LCB) was constructed through a facile one-pot hydrothermal method to treat phosphite-laden wastewater. LCB coupled with peroxymonosulfate (PMS) exhibited satisfactory P(III) removal performance through a one-step process for simultaneous oxidation and adsorption of P(III). The adsorption capacity of LCB/PMS for P(III) (71.94 mg/g) was much higher than that of LCB. LCB/PMS system showed high P(III) removal efficiency of 96.62 %, wide pH ranging from 4.0 to 9.0, and good reusability. It also worked well in the existence of anions and humic acid. The quenching experiments and electron spin resonance tests (ESR) revealed the critical role of SO 4 •- in the P(III) oxidation process. Characterization results demonstrated that electrostatic attraction and ligand exchange were responsible for P(III)/P(V) adsorption. Moreover, LCB/PMS system presented desirable performance in eliminating a series of typical organic and inorganic phosphorus. The LCB/PMS system provides a promising and sustainable technology for the purification of P(III)-contaminated water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Peroxymonosulfate could be efficiently activated by piezo-catalysis (PE) with hydraulic mixing. • The energy consumption of hydraulic PE-PMS process was only 2.56% and 22.87% of ultrasonic PE-PMS and traditional E-PMS processes, respectively. • BaTiO 3 as piezoelectric material maintained performance without valence and crystal phase changes after 10 cycles. • There was an optimal hydraulic gradient (7.72 s−1) in hydraulic PE-PMS process. • ·OH played a critical role in the hydraulic PE-PMS process for CBZ degradation. Although peroxymonosulfate (PMS) coupling with ultrasonic piezo-catalysis (PE) or electrolysis (E) exhibited satisfactory efficiency of organics degradation by generating more reactive species, the relatively high energy consumption restricted their application. Hydro-energy, as a clean energy resource, is available in water treatment and transportation processes. Herein, a hydraulic-driven PE-PMS process was proposed, using barium titanate as piezoelectric material for carbamazepine (CBZ) degradation. Results showed that CBZ was efficiently degraded (76.17%, 180 min) in the PE-PMS process with a pseudo-first-order rate constant of 8.15 × 10−3 min−1. Moreover, the degradation ratio of CBZ was still up to 64.19% after 10 cycles without valence and crystal phase changes. Importantly, the energy consumption of the hydraulic PE-PMS process (428.65 kWh m−3 order−1) was only 2.56% and 22.87% of ultrasonic PE-PMS and traditional E-PMS processes, respectively. Finite element method and electrochemical measurement were performed to understand the influence of the hydraulic gradient (G). A positive correlation between G and piezo-potential/current was found in the hydraulic PE-PMS process. However, there was an optimal G value (7.72 s−1) for CBZ degradation. Further studies showed that ·OH played a major role in CBZ degradation during the hydraulic PE-PMS process. Various refractory organics could be effectively degraded in this process, while a satisfactory degradation of CBZ was observed in the actual water matrices. Therefore, the hydraulic-driven PE-PMS system might be an efficient, sustainable, and energy-saving process for water treatment by the potential utilization of residual hydro-energy in water transportation. [ABSTRACT FROM AUTHOR]

• Co 3 O 4 nanoparticles were successfully confined in the internal cavity of CNTs. • Co 3 O 4 @CNT was effective for catalytic activation of PMS to degrade norfloxacin. • Co 3 O 4 nanoparticles filling is a strategy to lower Co leaching. • Non-radical 1O 2 was the major function of norfloxacin degradation. • DFT calculation results confirmed Co 3 O 4 @CNT had high electronic activity. In this work, the tube-filled nanocomposites Co 3 O 4 @CNTs were successfully prepared and applied for the first time in the permonosulfate (PMS) system to degrade norfloxacin (NX). Characterization results showed that Co 3 O 4 nanoparticles served as independent templates and were randomly distributed onto the surface of the internal cavity of CNTs. After five cycles, the removal rate of NX decreased by only 4.5%, indicating its high catalytic activity and stability. This study also proposed a potential mechanism based on Co 3 O 4 @CNT/PMS system catalysis in which 1O 2 was the main cause of NX degradation. DFT calculation results confirmed that the electronic activity of Co 3 O 4 filled CNTs increased, and that the Co 3 O 4 nanoparticles filled in the tube were the main catalytic sites of Co 3 O 4 @CNTs for NX degradation. This work provided the first insight into the effects of metal nanoparticles in the confined structure of CNTs on PMS activation. [ABSTRACT FROM AUTHOR]

• Novel nitrogen-doped carbon fiber aerogel (N-CFA) was obtained by carbonization of cotton and urea in one-step. • 1O 2 instead of radicals was the predominant reactive oxidant species in N-CFA/PMS process. • CBZ degradation pathways mainly by 1O 2 were firstly proposed. • CBZ was removed in different water matrices with a satisfactory efficiency in N-CFA/PMS process. Nitrogen-doped carbon as metal-free catalysts exhibited exceptionally catalytic activities in environmental remediation fields. Herein, a novel nitrogen-doped carbon fiber aerogel (N-CFA), which was conveniently prepared using cotton and urea by a direct high temperature carbonization in one-step, was used to activate peroxymonosulfate (PMS) for the degradation of carbamazepine (CBZ) in water. Characterization results demonstrated that the key active sites (pyridinic N, pyrrolic N, and graphitic N) were formed in the process of nitrogen doping into the carbon fiber aerogel. More importantly, singlet oxygen (1O 2) instead of conventional OH and SO 4 − was suggested as the predominant reactive oxygen species (ROS) during N-CFA/PMS process based on the scavenger inhibition tests, and confirmed by molecular probe and liquid-phase electron paramagnetic resonance (EPR) experiments. It was speculated that nitrogen-containing functional groups played a key role in inducing the non-radical pathway. Moreover, CBZ degradation pathways mainly by 1O 2 were firstly proposed based on intermediates. The N-CFA/PMS system could achieve a CBZ degradation rate of 100% within 50 min, which was significantly higher than the catalytic effect of several carbon materials (ACF, GAC, and GO) and even higher than the catalytic effect of various metal-based catalysts including Co 3 O 4 , CuO, Fe 3 O 4 , and Fe 2 O 3. It was also noted that the CBZ was removed with a satisfactory efficiency in different water matrices with inorganic anions (HCO 3 –, Cl−, H 2 PO 4 −, SO 4 2−, and NO 3 –) and humic acid (HA). Thus, this study proposed a benign and highly efficient oxidation technology, which would exhibit wide potential for environmental restoration. [ABSTRACT FROM AUTHOR]