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[Display omitted] • The influence of Cl− on SO 4 −-based AOPs is temperature dependent. • An increase in temperature turns the negative impact of Cl− to positive. • Rate constants of radicals toward Cl− and contaminants at 55 °C were determined. • Increasing temperature promotes Cl–-mediated conversion of SO 4 – to HO. • Cl−/ SO 4 − system is less affected by water matrix at higher temperatures. Using the excess heat in high-temperature industrial wastewater to activate oxidant precursors for organic contaminant degradation would make advanced oxidation processes more sustainable in the context of carbon neutrality, while the salt-mediated radical transformation chemistry in such wastewater is poorly understood. We herein demonstrate that chloride (Cl–) in the range of 0.28–56.34 mM accelerates the degradation of organic contaminants in the heat activated persulfate process in both synthetic and authentic wastewater. We use laser flash photolysis technique together with kinetic modeling to directly determine the bimolecular rate constants of radical–radical (e.g., k S O 4 · - - S O 4 · - = 2.50 × 109 M−1 s−1), Cl–-radical (e.g., k S O 4 · - - C l - = 3.75 × 108 M−1 s−1), and radical-contaminant (e.g., k H O · - B A = 1.02 × 1010 M−1 s−1) reactions at 55 °C, which are substantially higher than those at ambient water temperature (25 °C). We also combine experimental and modelling results to calculate the contribution of different radicals to contaminant removal at 55 °C. The results clearly demonstrate that Cl– in the range of 0.28–56.34 mM promotes the transformation of SO 4 – to HO at 55 °C, with reactive chlorine species involved as the intermediates. The findings improve fundamental understanding of Cl–-mediated radical chemistry in high-temperature water and provide an engineering strategy to recycle the heat in wastewater to enhance contaminant remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni2+ to solid nanorods in casting solution with carbon particles and polyethersulfone. • Film casting cum phase separation directly yields porous catalytic membranes. • NiO to Ni(0) shifts persulfate activation to non-radical and mitigates Ni leaching. • Diclofenac oxidation coupled with adsorption of degradation products within membrane. • Up to 98 % organic carbon removal in flow-through at residence time of only 1.6 s. We introduce a novel all-in-one fabrication method for porous catalytic polyethersulfone (PES) membranes containing NiO nanorods and carbon nanoparticles. This method is based on the sonochemical in situ solidification of a metal salt with NaBH 4 in presence of carbon particles in a PES-containing casting-reaction solution, directly followed by membrane preparation via film casting cum phase separation. In the catalytic flow-through degradation of 20 mg/L aqueous diclofenac with persulfate as oxidant, an as-prepared NiO-carbon-PES membrane achieved a 99 % aromatic content removal degree at a residence time of only 1.6 s. In comparison, NiO and CuO membranes without carbon particles exhibited < 40 % aromatic removal degrees. The high performance was attributed to a degradation-induced adsorption, with a diclofenac removal capacity of 950 mg/g of incorporated carbon particles. We demonstrated that diclofenac is catalytically mineralized in the membrane at incorporated NiO nanorods, followed by adsorption of remaining degradation products at nearby carbon particles. Our data further suggests that reducing NiO to Ni(0) via a membrane pretreatment shifts the catalytic persulfate activation from a radical to a non-radical pathway, and that HCO 3 – can function as sacrificial electron donor for Ni(0). This completely mitigated nickel leaching from the membrane in contact to persulfate. Moreover, even in the presence of NaHCO 3 and NaCl, a Ni(0)–carbon–PES membrane consistently eliminated ∼ 90 % of the total organic carbon (TOC) from a 2 mg/L diclofenac feed containing persulfate in single-pass flow-through mode (continuously for 5 h, respectively for 500 L/m2 permeate volume), with no detectable release of degradation products or any nickel leaching. [ABSTRACT FROM AUTHOR]

[Display omitted] • The involvement of piezopotential in ROS production was discussed. • High carrier production & separation, low recombination, and conversion of Type II to S-Scheme improved ROS generation. • PVDF is the commonly used material for immobilizing piezocatalytic materials. • Scope of Application of Machine learning in piezocatalysis was investigated. Piezocatalysis is an emerging advanced oxidation process (AOP) that converts mechanical energy to chemical form producing reactive oxygen species (ROS) for mineralizing organic pollutants (OPs). Heterojunction-based piezocatalysis has proven to be an excellent way of water remediation due to the increased generation of ROS because of additional piezopotential generated in two catalytic materials. This article systematically reviews the recent developments in piezocatalytic, piezo-photocatalytic, and piezo-electrocatalytic heterojunctions for treating OPs from aqueous media. The mechanism behind improving ROS generation via piezopotential development under different synergistic heterojunctions was deeply analysed. The review found that the enhanced ROS generation in piezo-photocatalytic heterojunctions was attributed to enhanced charge carrier separation, reduced recombination, conversion of the heterojunction from type-II to S-scheme heterojunction, and reducing the Schottky barrier. For piezo-electrocatalysis, the effect of piezopotential on band position, band bending, and Fermi level (F L) was discussed in detail. Furthermore, the review found that adding peroxomonosulphate (PMS) or peroxodisulphate (PDS) into the system enhanced reactive species generation by allowing multiple pathways for reactive species generation in piezocatalytic and piezo-photocatalytic heterojunctions. Apart from the advancements in piezocatalytic heterojunction, the key advancements in piezocatalysis including the immobilization of the piezoelectric materials and the scope of machine learning (ML) in piezocatalysis were also discussed. [ABSTRACT FROM AUTHOR]

• The synthesis strategies for MOFs-based nanofibers are discussed in detail. • The applications of MOFs-based nanofibers for SR-AOPs are summarized. • The advantages of MOFs-based nanofibers for SR-AOPs are analyzed in-depth. Sulfate radical-based advanced oxidation processes (SR-AOPs) show great promise in water purification due to their strong oxidizing properties and high selectivity. The future development of SR-AOPs relies heavily on the advancement of catalysts. Creating catalysts with excellent physicochemical properties, such as stability and high efficiency, is crucial. Metal-organic frameworks (MOFs)-based nanofibers have demonstrated outstanding performance in SR-AOPs. This review provides an overview of the synthesis strategies for MOFs-based nanofibers and their derivatives, discusses their synergistic effects, and explores their potential practical applications in water treatment. It aims to offer a comprehensive understanding and future directions for researchers in the field, thereby facilitating the transition of MOFs-based materials to practical water treatment solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anchoring N and Co species on the aluminum-graphite surface was implemented. • N and Co species promoted the Fenton-like reactivity of Al-Gr-N/Co. • HO•, O 2 •− and 1O 2 can be generated by Al-Gr-N/Co in air purging water. • Efficient degradation of tetracycline was achieved at neutral pH conditions. Molecular oxygen (O 2) activation for reactive species (RSs) production has recently received increasing interest. Reported herein is a novel O 2 activator (Al-Gr-N/Co), synthesized by anchoring N and Co species on the aluminum-graphite (Al-Gr) surface, that could achieve efficient degradation of tetracycline (TC) by activating O 2 in air purging water. RSs, including HO•, O 2 •− and 1O 2 , could be generated in the Al-Gr-N/Co/Air process, achieving 97.8 % of TC degradation at pH 7. This degraded TC can be attributed to the oxidation by 1O 2 and HO•; direct adsorption by Al-Gr-N/Co also contributed to the TC degradation. The N species promoted the H 2 O 2 production during O 2 activation by Al-Gr-N/Co; these produced H 2 O 2 could be further converted to RSs by Co and N species. Demethylation, hydroxylation and dehydration reactions were proposed as the oxidation pathways of TC by Al-Gr-N/Co/Air. TOC result suggests that TC and the oxidized intermediates could be adsorbed by Al-Gr-N/Co or converted to inorganic compounds. Negligible amount of the dissolved metal ions (<0.44 mg/L) was observed after reaction. Highly efficient removal of TC (>82.2 %) in lake water, tap water and MBR secondary effluents suggested that the Al-Gr-N/Co/Air process could be potentially applied in real water systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel oxidative degradation process, FeO x @C/sulfite/UVA, was developed. • Synergy of photo-generated holes and Fe active sites promotes sulfite activation. • Radicals and non-radicals are majorly derived from the crucial SO 5 −. • Both Fe(IV) and 1O 2 are the dominant non-radical species to OFL degradation. • Procedure to realize the remediation of antibiotic-spiked water is proposed. Advanced oxidation processes (AOPs) based on sulfite (S(IV)) activation are gaining recognition as a promising Fenton-like strategy, primarily due to their ability to generate potent radicals (e.g., SO 4 − and HO). However, the existence and role of a non-radical-driven oxidation pathway in the S(IV)-mediated degradation of contaminants remain under debate. Herein, a magnetic iron-carbon composite (FeO x @C) was fabricated using the MOF-templated method and utilized as a stable photocatalyst to activate S(IV) under UVA light, achieving >93.6 % degradation of 20 μM ofloxacin (OFL) with a high degradation rate constant of 0.073 min−1 within 45 min. The catalyst's porous carbon structure facilitated the transport of substrates to active sites and shortened the diffusion distance between reactive species and contaminants. Adsorbed S(IV) donated one electron to photo-generated holes and exposed Fe(III) sites with the formation of SO 5 −, which then followed two distinct pathways to produce radicals (SO 4 −) and non-radicals (Fe(IV) and 1O 2) responsible for OFL degradation. By leveraging the synergy of both radicals and non-radicals, this innovative oxidative system showcased robust anti-interference capacities and exceptional performance in degrading contaminants from complex water matrices. This study provides new insights into the significant role of non-radical species in S(IV)-mediated decontamination processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The modified Bi-MOF displayed outstanding oxidants activation ability. • 100% of BPs removal efficiencies was achieved in Bi-BDC-Fc 0.1 /UVL/oxidants systems. • Differences in mechanism of Bi-BDC-Fc 0.1 /UVL/oxidants systems were clarified. • The toxicity of intermediates during the AOPs were assessed via biotoxicity tests. Peroxymonosulfate (PMS), peroxydisulfate (PDS) and hydrogen peroxide (H 2 O 2)-based advanced oxidation processes are extensively applied for aqueous pollutants degradation. However, few cases reported the comparison the PMS, PDS and H 2 O 2 activation performances of a heterogeneous catalyst. In this work, 1,1′-ferrocenedicarboxylate (Fc) modified Bi-BDC (Bi-BDC-Fc x) with unique electronic structure and strong oxidation ability was synthesized and applied for degrading bisphenols (BPs) via photocatalytic PMS, PDS, and H 2 O 2 activation, respectively. The optimum Bi-BDC-Fc 0.1 exhibited the best photocatalytic PMS, PDS and H 2 O 2 activation performance to degrade various organic pollutants, including BPs, in which the bisphenol A degradation efficiencies followed the order of Bi-BDC-Fc 0.1 /UVL/PMS, Bi-BDC-Fc 0.1 /UVL/PDS and Bi-BDC-Fc 0.1 /UVL/H 2 O 2. The reaction mechanisms of photocatalytic PMS, PDS and H 2 O 2 activation over Bi-BDC-Fc 0.1 were comprehensively clarified by experimental results along with DFT calculations. Also, the toxicity and ecotoxicological impact of the pristine BPs and their intermediates were evaluated by the phytotoxicity experiments and zebrafish early-life stage toxicity test. This work presented a comprehensive investigation of degradation performance and the ecotoxicology assessment of Bi-BDC-Fc x /UVL/PMS, Bi-BDC-Fc x /UVL/PDS, and Bi-BDC-Fc x /UVL/H 2 O 2 systems, providing valuable insights to design and utilize the newly developed catalysts for water purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nickel phosphide/biochar (Ni x P/biochar) is synthesized utilizing phytic acid (PA). • Ni x P/biochar efficiently activates persulfate (PS) for tetracycline removal (94.55%). • The surface-bound radicals are the predominant reactive oxygen species (ROSs). • Biochar alters the catalytic selectivity of Ni x P and electron donations of elements. Exploring efficient and cost-effective heterogeneous persulfate (PS) oxidation systems is meaningful for addressing recalcitrant organic pollutants in wastewater. Herein, nickel phosphide/biochar (Ni x P/biochar) composite, with Ni 12 P 5 as the predominant crystalline phase, is firstly synthesized utilizing a biomass phosphorus source, phytic acid (PA). Ni x P/biochar demonstrates outstanding catalytic capacity in activating PS for removing tetracycline (TC). At 1 mM PS, 0.15 g/L catalyst, and pH 7.0, 94.55 % of TC (20 mg/L) can be removed within 180 min, markedly superior to Fe-, Cu-, and Co-based phosphide/biochar composites. The Ni x P/biochar-PS system exhibits superior catalytic degradation efficiency (>94.00 %) against varying concentrations (1–20 mg/L) of TC and robustly resists interferences from complex water matrices, including sodium humate solution, surface water, anions (>90.00 %). The ideal catalytic efficiency is ascribed to surface-bound radicals (including SO 4 -• and •OH), with •O 2 – and 1O 2 assisting in. Density functional theory (DFT) calculations indicate that due to the electron donations from Ni, P, and C, S 2 O 8 2- may undergo homolysis to produce the surface-bound SO 4 -•, which may induce the generation of other reactive oxygen species (ROSs) through radical chain reactions. Besides, the electronic structures and work functions of Ni x P in Ni x P/biochar composites can be modulated by the biochar, enhancing the catalytic selectivity of NiP, Ni 2 P, and Ni 12 P 5 with Ni as the electron-donating center, while diminishing that of P-centered Ni 3 P. These findings may serve as a reference for the theoretical study of Ni-based catalysts and the practical application of Ni x P in AOPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • CIP and FLO could be degraded effectively by UV 222 /H 2 O 2 and UV 222 /PDS systems. • The dual effects of inorganic anions on UV 222 , UV 222 /H 2 O 2 , and UV 222 /PDS were found. • HCO 3 – was found to generate reactive species under UV 222 irradiation. • UV 222 -AOPs removed antibiotics from reclaimed wastewater better than UV 254 -AOPs. Advanced oxidation processes based on KrCl* excimer lamps (UV 222 -AOPs) have recently received widespread attention in water treatment due to their high radical yields. In this investigation, the degradation of two typical antibiotics, florfenicol (FLO) and ciprofloxacin (CIP), by UV 222 and its combination with hydrogen peroxide (H 2 O 2) or persulfate (PDS) were studied, respectively. The dual effects of inorganic anions on the degradation performance of UV 222 /UV 222 -AOPs were determined. It was found that NO 3 – significantly enhanced the photolysis of CIP, and the degradation rate constants increased from 1.03 × 10-4 mJ−1 cm2 (without NO 3 –) to 2.56 × 10-4 mJ−1 cm2 (with 1 mM NO 3 –). However, NO 3 – markedly inhibited the photolysis of FLO, leading to a decrease in the degradation rate constants from 1.18 × 10-3 mJ−1 cm2 (without NO 3 –) to 5.27 × 10-4 mJ−1 cm2 (with 1 mM NO 3 –). HCO 3 – was found to have a certain promoting effect on the photolysis of FLO and CIP, and SO 4 2- has a negligible effect on the photolysis of both antibiotics. The above three inorganic ions decelerated the degradation of CIP and FLO in UV 222 -AOP, where NO 3 – exerted the most inhibition. Through LC-MS analysis and ECOSAR model, the main transformation products were individually determined and evaluated for toxicity. In addition, the performance of UV 222 -AOPs and UV 254 -AOPs in reclaimed wastewater (RWW) treatment were compared, and the steady-state concentration of radicals was measured. This study provided novel insight into the application of UV 222 -AOPs in RWW treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative wireless nPEC cell uses pulsed light for rapid pollutant degradation. • Si pn photodiode integrates efficient Si-n/Au nanowire and Si-p/mesoporous-NiPt. • The cell achieves > 99 % degradation and > 98 % mineralization of various pollutants. • The cell enhances reaction kinetics even with light intensities 5 times lower than sunlight. • Pulsed light in 100–500 Hz range further improves efficiency, reducing energy input by half. An urgent demand exists for advanced-technologies to efficiently remove persistent organic pollutants from water, while minimizing energy consumption. Here, we introduce an innovative wireless nanophotoelectrochemical (nPEC) cell using pulsed light for the ultrafast degradation/mineralization of organic pollutants. The nPEC cell comprises a nanostructured Si-pn photodiode that monolithically integrates: (i) a Si-n/Au nanowire-based-photocathode for effective light absorption and photovoltage generation, and (ii) a Si-p/mesoporous-NiPt photoanode serving as catalyst to wirelessly amplify the sulfate radical production by low-intensity light without any bias voltage. The efficacy of the nPEC cell was shown by ultrafast degradation (>99 %) and mineralization (>98 %) of three emerging pollutants (tetracycline, levofloxacin and anatoxin-A). Notably, reaction kinetics were boosted by more than one order of magnitude when exposed to light intensities ca. 5-fold lower than sunlight. Remarkably, pulsed light beams in the 100–500 Hz range provided an additional enhancement in the degradation/mineralization efficiencies, reducing energy-input by half, while enhancing the catalyst's oxidation state and durability. [ABSTRACT FROM AUTHOR]

• Significant errors in the kinetics analysis for PMSO degradation was investigated. • Interference and error were negligible under the optimized concentration of terminator. • Calculated the steady-state concentrations of reactive species. • High-valent species is metal dependent. • Fe(IV) is the dominant reactive species in the ZVI-BC/PS system. In this paper, Fe(IV) was analyzed in the zero-valent iron biochar (ZVI-BC) activated persulfate (PS) process with methyl phenyl sulfoxide (PMSO) as the probe compound. Without a reaction terminator, PMSO degradation continued during the sample holding time, resulting in significant errors in the kinetics analysis. When 1 mM NaNO 2 , 1 mM NH 2 OH, 10 mM Na 2 S 2 O 3 , or 10 mM dimethyl sulfoxide were used as terminators, the concentrations of PMSO and its oxidation product, methyl phenyl sulfone (PMSO 2), were effectively maintained without changes during the sample holding period. Furthermore, the terminators did not interfere with PMSO or PMSO 2 analysis by high performance liquid chromatography. In addition to Fe(IV), free radical (i.e. , SO 4 −, OH, O 2 −) and nonradical (i.e. , 1O 2) reactive species were also involved in the ZVI-BC/PS system; however, Fe(IV) was the predominant reactive species. Organic contaminants with electron-donating moieties rapidly reacted with Fe(IV), and the relative contribution of Fe(IV) to overall contaminant degradation decreased as the solution pH was increased. Overall, this study provided new insights into the quantitative analysis of Fe(IV) in the ZVI-BC/PS system and its application to treatment of organic contaminants in solutions with variable water quality. [ABSTRACT FROM AUTHOR]

The complexation confinement and in-situ crystallization strategies realized the effective anchoring of single atom Co in nitrogen-doped hollow carbon nanotubes, close to 100% elimination of tetracycline pollutants while achieving a record mineralization rate of 89.07%. [Display omitted] • Complexation confinement and in-situ crystallization confinement to fabricate single-atom Co. • The removal rate of tetracycline is close to 100% and the mineralization rate reached a record of 89.07% • Multiple perspective reveals the mechanism of ROS production and tetracycline degradation. • Graphite nitrogen regulates cobalt microenvironment to promote activation of PMS. Advanced-oxidation-process (AOPs) based on peroxymonosulfate (PMS) can provide strong reactive oxygen species (ROS) for the elimination of persistent-organic-pollutants (POPs), but the input of highly active environmentally friendly catalysts is the key. Here, confined cobalt was in-situ deposited on natural mineral halloysite nanotubes by Coulomb interaction, which further realizes the introduction of atomically-dispersed cobalt sites in nitrogen-doped hollow-carbon-nanotubes with large specific surface area. The constructed CoNC/NHCNTs-900 material can effectively activate PMS, resulting in the removal rate of tetracycline probe pollutants close to 100%, and the mineralization rate reached a record of 89.07%. Combined with density functional theory calculations, it was proved that the enrichment of graphite nitrogen is beneficial to regulate the microenvironment of Co and promote the adsorption and activation of PMS. In-depth tracking of the formation of ROS and the mechanism of tetracycline mineralization proved that CoNC/NHCNTs-900-driven AOPs degradation of POPs into a low-toxic species has reliability and practical significance. [ABSTRACT FROM AUTHOR]

• An oxygen-coordinated Fe-based single-atom catalyst was successfully designed. • BPA could be removed efficiently by the post-activation pathway of oxidant. • The PMS activation pathway demonstrates high anti-interference performance. • The highest PMS utilization efficiency was achieved in this work. • BPA can be continuously removed in complex water matrices for 20 days. The traditional peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been significantly limited by the high inputs of oxidants. Herein, an oxygen-coordinated Fe-based single-atom catalyst (Fe-N2O1/OCN) was developed as an efficient pathway to activate peroxymonosulfate (PMS). This catalyst allows for a sharp decrease in PMS dosage while avoiding the release of additional sulfate ions into the treated water. The PAPO generates bisphenol-A (BPA) radicals and SO 4 •− species adsorbed onto Fe-N2O1/OCN, triggering a chain reaction for BPA degradation through BPA-initiated PAPO. The excellent performance of this system is attributed to the oxygen-coordinated iron center, which weakens the coordination of PMS on Fe-N2O1 and prevents its pre-activation. Furthermore, this PMS activation pathway demonstrates high anti-interference performance and can be continuously conducted in complex water matrices for 20 days, providing a promising alternative to traditional PMS-AOPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cobalt doped carbon nitride activated peroxymonosulfate effectively, achieving 97% toluene removal rate; • Doped cobalt atoms in carbon nitride significantly improved the production of reactive oxygen species; • Cobalt atoms accelerated the electron transfer during the peroxymonosulfate activation process; • Singlet oxygen was the dominant reactive oxygen species (ROS) in both the degradation and mineralization of toluene. Degradation of gaseous volatile organic compounds (VOCs) under mild conditions is a great challenge. In this work, we doped Co atoms in carbon nitride (CN) to form Co/CN (CCN) catalyst with Co-N configuration. The CCN catalyst exhibited higher toluene degradation efficiency (97 %) than that of the CN/PMS system (27 %) via peroxymonosulfate (PMS) activation, and exhibited high toluene removal efficiency (>90 %) within 7 days. Electron paramagnetic resonance (EPR) and radical quenching tests suggested that singlet oxygen (1O 2) was the dominant reactive oxygen species (ROS) in both the degradation and the mineralization of toluene. Density functional theory (DFT) study indicated that the electron transfer from Co atoms to PMS contributed to the generation of ROS. This work proposed a new perspective on the use of Co doped catalyst in liquid phase advanced oxidation processes (AOPs) for low-temperature VOCs removal technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both laser/chlorine and laser/PS systems could efficiently degrade CBZ. • HO·, Cl· and ClO· were dominant for CBZ degradation in laser/chlorine system. • CBZ degradation in laser/PS system was primarily attributed to HO· and SO 4. -. • The degradation pathways of CBZ were proposed based on DFT analysis. Residual carbamazepine (CBZ) in water is difficult to remove through conventional treatment processes, threatening the safety of drinking water. Ultraviolet-based advanced oxidation processes (UV-AOPs) have shown promise in removing refractory organic pollutants, while the low energy and efficiency of traditional mercury lamps hinder their practical applications. In this study, the performance and mechanism of an intensive-energy light source, UV laser, were systematically explored in UV-AOPs (laser/chlorine, laser/persulfate (PS)). It was found that UV laser exhibited a significantly activating ability for chlorine and PS due to its precise wavelength and high pulse energy. When exposed to UV laser (266 nm, 4.2 mW/cm2) combined with 200 μM chlorine and PS, the kinetic rate constants for the degradation of 10 μM CBZ were determined to be 3.160 × 10-3 and 1.227 × 10-3 s−1, respectively. The degradation of CBZ was dominated by hydroxyl radicals (60.98 %) and sulfate radicals (23.15 %) in laser/PS system, while in laser/chlorine system, hydroxyl radicals (54.90 %), chlorine radicals (27.43 %), and chlorine oxide radicals (13.81 %) were primary reactive species. Furthermore, both the laser/chlorine and laser/PS systems demonstrated compatibility with a wide pH range of 5.0–9.0 and high resistance to anionic interference. Moreover, the electrophilic and nucleophilic sites of CBZ and energy barrier of the initial reaction were calculated based on the density functional theory (DFT). Additionally, the degradation pathways of CBZ and the toxicity of transformation products in laser/chlorine and laser/PS processes were proposed and evaluated. These results demonstrated that the UV laser-based processes exhibited promising prospects in eliminating refractory organic pollutants in water treatment. [ABSTRACT FROM AUTHOR]

Waste graphite from the retired lithium-ion batteries can be designed as peroxymonosulfate activator during reconstruction of porous architecture-based nitrogen-doped graphene using NH 3 ·H 2 O towards sustainable recycling graphite with significantly upcycling recovery strategy. [Display omitted] • Novel strategy for upcycling spent graphite into high value-added PMS activator. • Lower energy consumption compared to direct high temperature regeneration. • The inherent properties in spent graphite provide an advantage for N doping. • The SNGO-2 exhibits enhanced PMS activation behavior than commercial product. • In-depth chemical reaction mechanism is explored for the activation process. The large-scale retirement of lithium-ion batteries (LIBs) has raised increasing concerns about recycling spent graphite with low value-added. However, it remains challenging to design a low energy consumption and high value-added approach for upcycling spent graphite. This study proposes a novel recycling strategy involving the reconstruction of porous architectures through nitrogen-doped graphene using NH 3 ·H 2 O to enhance the deactivation resistance of rhodamine B (RhB) degradation via peroxymonosulfate (PMS) activation. Spent graphite with defects and polar functional groups were used as the feed materials. Specifically, the prepared defective nitrogen-doped graphene can efficiently activate the PMS under a broad pH range and a real water matrix. The analytical and density functional theory calculation results suggested that graphite N plays the dominant role in activating PMS with the formation of reactive oxygen species. The quenching, electron paramagnetic resonance and electrochemical results indicated that the singlet oxygen plays a dominant role, while the free radicals of superoxide radical, sulfate radical and hydroxyl radical work together during the degradation of RhB into CO 2 and H 2 O through demethylation, chromophore cleavage, opening-ring and mineralization. This study proposes a promising strategy for upcycling spent graphite from spent LIBs into environmental functional materials with potential application in effluent treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Combining PM and 3D electrode process showed a remarkable synergy for DCF removal. • GAC and organic contaminants promoted the conversion of MnO 2 and PM to Mn(III) aq. • GAC act as a mediator transferring electrons from organic contaminants to PM. • Mn(III) aq and colloidal MnO 2 mainly contributed to ECs removal. • GAC particles exhibited a stable catalytic performance after 10 cycles. Currently, the electro-activated permanganate (PM) process, as one of the reactive manganese species (RMnS)-based advanced oxidation processes, has shown great potential for environmental remediation. However, the activation efficiency of PM in the electro-activated PM (E-PM) process is limited due to the poor mass transfer and electron transfer efficiency in the two-dimensional (2D) process. In this study, to overcome these drawbacks, granular activated carbon (GAC) was introduced as particle electrodes, establishing an efficient three-dimensional (3D) electrode process (E-GAC-PM), which promoted the generation of RMnS. Comparative experiments exhibited the significant synergy between PM and the 3D electrode process, resulting in the highest diclofenac (DCF) removal (90.2 %) with the lowest energy consumption. Electrochemical impedance spectroscopy and Tafel curve showed that the addition of GAC greatly attenuated the electrochemical impedance, facilitating the activation of PM. Further studies revealed that GAC can serve as an electron mediator, transferring electrons from contaminants to PM, thereby generating Mn2+ and promoting Mn(III) aq formation. Meanwhile, in-situ generated Mn2+ can also be oxidized by the anode and particle electrodes into Mn(III) aq. Besides, the in-situ generated MnO 2 facilitates the performance via oxidation and catalysis effects. Under the protection of the electric field, GAC showed a relatively stable performance which could be regenerated and maintain active after 10 cycles. All these results demonstrated that the E-GAC-PM process was an efficient, energy-saving, and sustainable method for refractory organic contaminants removal, which showed potential for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synergistic effect of natural minerals for persulfate activation were reviewed. • The mechanism of persulfate activation and contaminants degradation were summarized. • We pointed out that the major challenges and direction of mineral-based catalysts. • This review is meaningful for the high-value-added application and functional specialization of minerals. The severity of environmental pollution poses a serious threat to human health, and especially organic pollution is more complex and difficult to treat compared to heavy metal pollution. Nowadays, the persulfate-based advanced oxidation processes receive more and more attention due to high efficiency, strong controllability, easy operation, and economic competitiveness, which is generally employed for the efficient degradation of organic contaminants. Natural minerals possess the characteristics of low-cost, easy availability, environmental friendliness, non-toxic, special structural effects, etc., which have played a critical role and could be the promising alternative to traditional catalysts for persulfate activation. First, this review retrospects the research status of natural minerals and mineral-based catalysts for persulfate activation to degrade organic contaminants, i.e., pyrite, mackinawite, copper sulfide, kaolinite, and montmorillonite. Then, the mechanisms of persulfate activation by natural minerals and mineral-based catalysts to generate the reactive oxygen species including SO 4 •−, •OH, •O 2 −, 1O 2 , and surface reactive complex for contaminants degradation are systematically summarized. Finally, we discussed the further application of natural minerals in activating persulfate as well as the future research frontiers for practical environmental remediation, i.e., the synthesis and characterization of mineral-based catalysts dominated by non-radical pathway, the large-scale application of PDS with low-cost, the surface modification of mineral-based catalysts with amphiphilicity, as well as the more efficient catalysts possessing nano-restricted domain catalytic effect. The development and expansion of novel and efficient mineral-based catalysts with enhanced synergistic effects would provide new opportunities for persulfate activation in environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel enhanced As(III) removal process, MIL-53(Fe)/sulfite, was developed. • As(III) removal was through a combination of oxidation and adsorption. • As(III) oxidation relied on the powerful Fe(IV) and SO 4 •− generated from SO 5 •−. • Oxidation product As(V) was adsorbed by forming monodentate complexes. • Procedure to realize the purification of real arsenic-spiked water was proposed. Iron based metal–organic frameworks (Fe-MOFs) have garnered international interest as a novel and promising category of adsorbent materials for the elimination of arsenic from neutral waters. Nevertheless, their practical implementation is constrained by their inadequate adsorption capacity for aqueous arsenite (As(III)), a prevalent arsenic species found in acidic environments such as acid mine drainage. Herein, a novel oxidation-adsorption process to effectively purify As(III)-contaminated water is constructed by combining the MIL-53(Fe) of high acid resistance with sulfite (S(IV)). Notably, the adsorption capacity of the MIL-53(Fe)/S(IV) process for As(III) at pH 3.5 reached 86.4 mg g−1, surpassing the values achieved by MIL-53(Fe) alone by 21.6 times for As(III) and 1.62 times for As(V) (oxidized As(III)). During the oxidation process, MIL-53(Fe) effectively activated S(IV), leading to the formation of the crucial intermediate SO 5 •−, which then underwent two distinct pathways to respectively generate Fe(IV) and SO 4 •−, accounting for rapid oxidation of As(III). In the adsorption process, the S(IV) activation (i.e., complexation and electron transfer) on the MIL-53(Fe) surface created additional adsorption sites by dredging the pores and altering the electron cloud distribution within the adsorbent. Furthermore, As(V) trended to form monodentate complexes with surface Fe (e.g., Fe O As bond) in the MIL-53(Fe)/S(IV) process. Notably, this oxidative removal process demonstrated reliable performance in complex water matrices and practical arsenic-contaminated waters. Overall, this study presents a promising strategy to enhance the efficacy of Fe-MOFs for the removal of As(III). [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]

[Display omitted] • Prototype plug-flow photocatalytic reactor was applied for degradation of VOCs. • The impacts of operating parameters on reactions kinetics were established. • Ozone in treated air accelerates VOCs oxidation. • Ozone mixed with VOCs is rapidly decomposed photocatalytically. Airborne volatile organic compounds (VOCs) present an increasingly relevant health hazard addressed by the EU directive 2016/2284 requiring 40-% reduction in emissions of non-methane VOCs by 2030 in comparison to 2005. Advanced oxidation processes (AOPs) provide a solution for the VOC problem in industry. Among AOPs, pulsed corona discharge (PCD) and photocatalytic oxidation (PCO) are of particular interest in their synergy complementing each other's strengths in energy-efficient manner. In the present study, air polluted with 2-methoxyethanol (2ME) was treated by using a prototype 21.3 L photocatalytic reactor for the pollutant degradation at its variable concentrations (6–50 ppm), irradiances (65–119 W m−2) and residence times (12–77 sec). Further combination of PCO reactor with forthcoming PCD requires studies in ozone photocatalytic degradation as a standalone byproduct and in combination with 2ME. The analysis of variable conditions resulted in singling out the PCO major restrictive parameters, also demonstrating the degradation enhancement, when both 2ME and ozone were present in air. The PCO treatment combined with ozone resulted in degradation of 2ME and ozone for 40 % and 95 %, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The obtained non-metallic graphitized biochar can effectively degrade QNC in soil. • Degradation mechanism of QNC in soil by WCGBC800 + PMS has been investigated. • QNC is degraded simultaneously by free and non-free radicals in WCGBC800 + PMS system. • WCGBC800 + PMS can repair QNC-contaminated soil and promote rice growth. To explore highly effective and nonmetallic advanced oxidation process system to alleviate the persistent herbicides contamination in agricultural soils is of great importance. In this study, a significantly graphitized biochar with abundant C = O structure is prepared as non-metallic catalyst (WCGBC800). Different from other traditional amorphous pristine biochar, WCGBC800 can accelerate the electron transfer in the system and then effectively activate peroxymonosulfate (PMS) to produce free (OH, O 2 –, SO 4 −, etc.) and non-free radicals (1O 2 , electron transfer, etc.). Consequently, WCGBC800 can degrade 100 % the persistent organic herbicide quinclorac (QNC, with a content of 50 mg·kg−1) in soil within 20 min after PMS addition. The T.E.S.T-QSAR software simulation evidence that the toxicity of degradation intermediates is much lower than QNC. The stress of QNC on rice seedlings was directly described through rice cultivation experiment. The stress of rice seedlings was relieved after WCGBC800 + PMS treatment. The growth experiment of rice seedlings also shows that with an original QNC concentration of 7 mg·kg−1 in soil, the root length, root surface area, leaf length, leaf area, and leaves perimeter of rice increase of 255.30 %, 148.38 %, 207.64 %, 204.19 %, and 63.69 % respectively after detoxification by WCGBC800 + PMS system. This functional material and the WCGBC800 + PMS system provide new solutions for solving the problem of herbicide residues in soil with promising safety. [ABSTRACT FROM AUTHOR]

• La-doped macroporous carbon fibers was prepared by a simple way. • La-HCNFs can effectively catalyse the elimination of tetracycline through persulphate. • Developing reactors with reliable catalytic performance even after multiple cycles. Metal-organic frameworks (MOFs) show substantial potential and impressive development prospects in persulfate-based advanced oxidation (SR-AOPs) due to their exceptional structural advantages. Nevertheless, the structural characteristics, catalytic performance, and catalytic mechanism of lanthanide metal-doped MOFs (La-MOFs) remain unclear. Therefore, we prepared lanthanum-nitrogen co-doped hollow carbon nanofibers (La-HCNFs) through electrospinning and pyrolysis to study the structure, catalytic activity, and mechanism of La-MOFs. Furthermore, we analyzed the physicochemical properties of La-HCNFs with a range of characterisation techniques, and examined the catalytic oxidation mechanism with quenching experiments. Finally, this study clarifies the role of SR-AOPs in La-MOFs and indicates pathways for future research on La-MOFs materials, in order to advance the use of MOFs materials in environmental chemistry and sustainable catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Binder-free growth of active material directly over the conductive substrate for photoelectrocatalysis. • Fabrication of Fe 3 O 4 /NiCo 2 O 4 photoanode for the removal of contaminants by photoelectrochemical degradation process. • Synergistic assistance of reductive H 2 O 2 accompanied Fenton-process for the removal of maximum pollutants. • Efficient treatment of water collected from various resources starting from static water, river water to STP water. Photoelectrocatalytic advanced oxidation processes (PEC AOPs) show great promise for solar-driven water treatment due to their energy efficiency and environmental compatibility. This study focuses on two key aspects: 1) creating an efficient photoanode and 2) utilizing the cathodic process simultaneously to enhance water treatment. Herein, a self-standing photoanode with stemmed nanospikes made from Fe 3 O 4 @NiCo 2 O 4 (FNCO) was developed and seamlessly integrated into a PEC system. FNCO photoanode significantly improves PEC cell performance, using half the energy (12 Wh/g-pollutant) and achieving a four-fold higher rate constant (7.9×10−2 s−1) compared to NiCo 2 O 4 (NCO). The in-situ generation of H 2 O 2 and its Fenton-like activation amplifies the generation of reactive oxygen species (ROS), contributing to the PEC degradation activity. Detailed analysis reveals that the presence of surface-Fe 3 O 4 enhances surface hydrophilicity and contributes to the high density of catalytically active sites in FNCO. We conducted a comprehensive investigation into the in-situ formation and activation pathways of H 2 O 2 molecules through a series of experiments. The designed PEC water treatment system achieved almost 60 % total organic carbon (TOC) removal efficiency with consistent performance across a range of real-world water treatment scenarios, underscoring its versatility and robustness. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergistic effect existed within bimetallic Fe-Cu-CNT catalyst. • CWPO reaction conditions are quantitatively optimized. • Cycling conversions within metallic species are crucial for treatment. • Induction period is shortened with higher Cu content. Treatment of organic wastewater is of great importance and can be carried out by catalysis technologies such as catalytic wet peroxide oxidation (CWPO). A novel bimetallic Fe-Cu-CNT catalyst was first developed by a facile hydrothermal method; Fe species (Fe (Ⅱ) and Fe (Ⅲ)) and Cu species (Cu (Ⅰ) and Cu (Ⅱ)) were used to fabricate the catalyst with the CNTs, which was stable during testing. Methylene blue (MB) was chosen as model compound for the study; the optimization for treatment by the Box-Behnken design indicated that a combination of low pH, high MB concentration and intermediate temperature led to better treatment performance. The CWPO reaction obeyed the 2nd-order kinetic equation and the catalyst activity increased with an increase in the Cu content. The reaction induction period was shortened with decreasing Fe:Cu ratio. The cycling reaction between Fe3+/Fe2+ and Cu2+/Cu+ pairs generated a large number of oxidative radicals and improved the pollutant degradation efficiency. Finally, the reaction rate equation of CWPO over Fe-Cu-CNT was derived, and it was experimentally illustrated that hydroxyl radicals played a crucial role in the treatment. This study demonstrates that the optimized Fe-Cu-CNT has great potentials for treatment of organic wastewater with higher efficiency and lower cost. [ABSTRACT FROM AUTHOR]

[Display omitted] • The crystal phase of cobalt phosphides (Co x P) can be regulated by phytic acid (PA). • Co x P/biochar effectively activates persulfate to produce sulfate radical (SO 4 −•). • The electron transfer composition between the catalyst and persulfate is analyzed. • Biochar changes the electronic structure of Co x P and enhances anion co-catalysis. Effective activation of persulfate (PS) contributes to the efficient degradation of emerging organic pollutants in water matrices. Cobalt phosphides (Co x P) have been testified as promising catalysts in efficiently activating PS, but their applications in water purification are still restricted by hazardous and costly chemical phosphorus sources used in traditional syntheses. Here, the synthesis of Co x P on biochar is regulated by an eco-friendly biomass phytic acid (PA) through low-speed ball milling combined with catalytic pyrolysis. Under the condition of 1 mM PS, 0.2 g/L catalyst, and pH 7, SMX (10 mg/L) can be thoroughly removed within 120 min with a TOC removal efficiency of 52 %. When dealing with low concentrations of SMX (0.25–1 mg/L), the oxidation is completed within 60 min. The simulated complex aqueous matrices (sodium humate solution and surface water) only exert trivial inhibition of SMX removal. Moreover, the leached Co2+ ion concentration is lower than the discharge standard (0.39 mg/L within 180 min). The crucial reactive oxygen species are identified as SO 4 −•, •OH, 1O 2 , and O 2 −•. Density functional theory (DFT) calculations indicate that the most pivotal active site in CoP/biochar is the P ion, while in Co 2 P/biochar is the Co ion. Biochar may potentially influence the electronic structure, thereby altering the oxidation states of ions and significantly enhancing the synergistic catalytic effect of anions in both cobalt phosphides. The more pronounced anion co-catalysis endows CoP/biochar with a better catalytic capacity than Co 2 P/biochar. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flow-through membrane reactors for the photo-Fenton degradation of tetracycline. • Fabrication of NiFe 2 O 4 supported on coffee grounds derived biochar. • Incorporation of NiFe 2 O 4 /biochar catalyst particles into porous polymer membranes. • 5-20x higher turnover frequency in flow-through compared to particles in batch. • Degradation product distribution was controlled by residence time in the membrane. Herein, coffee grounds derived biochar was used as support for the fabrication of NiFe 2 O 4 /biochar composite particles. The composites achieved up to 10x higher turnover frequencies (TOF) in the photo-Fenton degradation of tetracycline (20 mg/L) in batch compared to the pure NiFe 2 O 4 particles. This could be correlated to a decreased agglomeration, lower band gap energy and electronic interaction with the biochar. The hydrophobic support further enabled the incorporation of the NiFe 2 O 4 /biochar powders into porous polyethersulfone (PES) membranes via film casting cum phase separation. The resulting about 150 µm thick porous flow-through membrane reactors achieved high degrees of conversion (95–99 %) at a flux of 100 L/m2h in the continuous photo-Fenton degradation of tetracycline (20 mg/L) in water. We could further show that the TOF values are 5-20x times higher in flow-through the catalytic membranes compared to the NiFe 2 O 4 /biochar catalyst particles used in batch mode. We also demonstrated that our photocatalytic membranes can remove low concentrations of tetracycline (2 and 0.2 mg/L) toward values below the detection limit of the used mass spectrometry analysis. Monitoring the leaching of Ni and Fe from one membrane over 28 h of flow-through revealed that Ni predominantly leaches from the incorporated NiFe 2 O 4 /biochar, which, however, did not lead to any loss of the catalytic activity. Moreover, we found that the residence time in the membrane has a direct influence on the tetracycline degradation pathways and the resulting product profile, which represents a novel approach for tuning Fenton-like reactions towards specific products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfite enhances the degradation of PAHs by ferrate in alkaline conditions. • Sulfite accelerates the production of active species (Fe(V) and SO 4 ●−). • Fe(III) and H 2 O 2 promote Fe(VI) decomposition to generate Fe(IV). • Removal of PAHs efficiency depends on pH and molar ratio of sulfite to ferrate. • High-valent iron and free radicals had different PAHs oxidation pathways. The presence of polycyclic aromatic hydrocarbons (PAHs) in water is a significant environmental concern due to their potential health risks. While sulfite activation of ferrate (Fe(VI)) has shown promise in enhancing the degradation of antibiotics and pesticides in water systems, its applicability to the degradation of PAHs remains largely unexplored. Here, we investigated the efficiency and mechanisms of PAH degradation via sulfite-activated ferrate. The ferrate-sulfite system significantly accelerated PAH degradation, achieving a 1.53 to 3.13-fold rate increase compared to ferrate-only treatment. Key active species involved in PAHs degradation were Fe(V), Fe(IV), and SO 4 ●−. Sulfite accelerated the degradation of PAHs by undergoing a swift reaction with Fe(VI), leading to the formation of Fe(V) and SO 4 ●−. Sulfite accelerated the degradation of PAHs by undergoing a swift reaction with Fe(VI) resulting in the production of Fe(V) and SO 4 ●−. Through the reduction of ferrate species by sulfite, Fe(III) were produced and accelerated the decomposition of residual Fe(VI) into Fe(IV). Sulfite accelerates the degradation of PAHs by ferrate through these two processes. It promotes Fe(V) and Fe(IV) production from ferrate in a different way. Importantly, the toxicity of PAHs degradation intermediates is significantly reduced. Overall, these findings indicate that the ferrate-sulfite combination has significant potential to address environmental and health concerns associated with PAHs in water sources. [ABSTRACT FROM AUTHOR]

• Fe(IV) is the dominant reactive intermediate in the Fe(II)/PMS system at acid pH. • Fe(IV) is also formed at circumneutral pH in the Fe(II)/PMS system. • 18O labeled studies further verified the formation of Fe(IV)-oxo species. • Evolution of Fe(IV) in Fe(II)/persulfates systems was predicted by a kinetic model. • Evolution of Fe(IV) was monitored by a stopped-flow spectrophotometer. Very recently, we have interestingly found that the Fe(II)-activated peroxydisulfate (PDS) process can oxidize methyl phenyl sulfoxide (PMSO) to its oxygen transfer product methyl phenyl sulfone (PMSO 2), suggesting the possible occurrence of a ferryl intermediate (Fe(IV)) rather than long recognized sulfate radical (SO 4 −) in this process. In this work, the formation of PMSO 2 was also observed when PMSO was treated by the Fe(II)/peroxymonosulfate (PMS) system over the pH range of 3–7, and the yield of PMSO 2 (i.e., the molar ratio of PMSO 2 formed to PMSO lost) was quantified to be approximately 100% under acidic conditions, similar to the Fe(II)/PDS system. Moreover, 18O from isotope-labeled water (H 2 18O) was successfully incorporated into PMSO 2 product when PMSO was oxidized by the Fe(II)/PDS and Fe(II)/PMS systems in H 2 18O, likely due to the competitive oxygen exchange of Fe(IV)-oxo species with H 2 18O. Further, Fe(IV) evolution profiles in both systems were predicted by a Fe(IV)-mediated kinetic model, and these results are in good agreement with the experimental data obtained with a stopped-flow spectrophotometer. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new magnetic Cu-Fe oxide (CuFeO) was developed as the photo-Fenton catalyst. • CuFeO/H 2 O 2 /Vis system can work efficiently at slightly basic pH conditions. • The completely removal of 50 mg L−1 of SMZ has been achieved in 30 min. • HO and photoinduced e− are mainly responsible for the degradation of SMZ. Abstract The presence of antibiotics in aquatic environments has attracted global concern. Heterogeneous photo-Fenton process is an attractive yet challenging method for antibiotics degradation, especially when such a process can be operated at neutral pH values. In this work, a new magnetic Cu-Fe oxide (CuFeO) was developed as the heterogeneous photo-Fenton catalyst through a facile two-step method. The obtained CuFeO particles were found to be more efficient to activate H 2 O 2 into radicals (OH and O 2 −) than Cu-Fe Prussian blue analogue (Cu-Fe PBA, the precursor) at near neutral conditions. The removal rate of sulfamethazine (SMZ) in CuFeO/H 2 O 2 /Vis system was much higher than those in CuO/H 2 O 2 /Vis and Fe 3 O 4 /H 2 O 2 /Vis systems. It was observed that nearly complete removal of SMZ from ultrapure water, river water and tap water can be achieved in 30 min in CuFeO/H 2 O 2 /Vis system. The influence of different process parameters on the SMZ degradation efficiency was then examined and the catalytic stability of CuFeO was also tested. The SMZ degradation intermediates during the process were analyzed and the degradation pathway was proposed based on LC–MS results. The mechanisms for H 2 O 2 activation were studied by X-ray photoelectron spectrum analysis, radical scavenging and electron spin-trapping experiments. It is suggested that the synergistic effect among photo-induced electrons, Cu and Fe in CuFeO exhibits excellent performance in the catalytic activation of H 2 O 2. This work is expected to provide useful information for the design and synthesis of bimetallic oxide for heterogeneous photo-Fenton reactions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Influence of bromide ion on the degradation of typical sulfonamides in UV/chlorine process was studied. • The concentration of degradation products and pathways of SAs was proposed using LC-ESI/MS. • The DBPs formation during degradation process was evaluated. • Toxicity change during UV/chlorine process in the presence of Br− was determined. Abstract The degradation of sulfonamides (SAs) in the presence of bromide during the UV/free chlorine process was investigated in this study. The reactions followed pseudo first-order kinetics. With increasing bromide concentrations of 1, 5, 10–20 µM, the degradation rate was gradually raised. The contribution of different reactive species has been calculated. The degradation products and DBPs formed by SAs were determined. The mechanisms of the degradation of SAs in the presence of bromide included hydroxylation, cleavage of the pyrimidinyl group, and bromine and chlorine electrophilic addition. The concentration of brominated disinfection by-products, including DBCM, TBM and DBAN, increased with increasing bromide dosage and degradation time, while 1, 1, 1-TCP and 1, 1-DCP decreased. In an acute toxicity test, the inhibition rate decreased in the first 5–10 min then increased after 10 min degradation when 10 µM Br− was added to the system. The initial decrease may due to the formation of low toxicity substances after the cleavage of the pyrimidinyl group, while the subsequent increase may be attributable to the increased formation of DBPs. [ABSTRACT FROM AUTHOR]

Highlights • 18 PPCPs were decomposed by an advanced oxidation process using UV-LEDs. • The TiO 2 catalyst was immobilized on a porous Ti substrate. • Kinetic rates of PPCPs were explained by factors like charge, solubility, and molecular weight. • Negative PPCPs had the highest removal due to electrostatic attraction to the positive substrate. • Using controlled periodic illumination to decrease the energy usage did not sacrifice PPCP removal performance. Abstract The presence of pharmaceutical and personal care products (PPCPs) in aquatic systems has been a growing cause for concern. Advanced oxidation processes such as UV/TiO 2 (ultraviolet light/titanium dioxide) can break down PPCPs into smaller constituents, reducing the pharmaceutical activity. However, this process is limited by low photonic efficiency under UV systems. Controlled periodic illumination (CPI) is a promising solution to overcome the issues concerning low photonic efficiencies. Using a CPI controlled UV-LED/TiO 2 process, a mixture of eighteen PPCP compounds were analyzed for their degradation removal on porous titanium – titanium dioxide (PTT) substrates. The kinetic rate constants of PPCPs may be analyzed using multiple regression analysis with parameters such as net charge at experimental pH, solubility, and molecular weight. Negatively charged PPCP compounds were found to have the highest removal compared to neutral and positively charged compounds due to electrostatic attraction forces. Decreasing the duty cycle under CPI or the UV-LED illumination period did not significantly change the individual and cumulative PPCP compound removal, suggesting that the CPI controlled UV-LED/TiO 2 processes using PTT substrates were effective in reducing energy requirements without sacrificing removal performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A catalyst of Schiff base copper complex was synthesized on aminated graphene. • The catalyst can effectively activate persulfate to degrade triclosan in water. • SO 4 − and OH are involved in the oxidation of pollutants using persulfate. • Graphene acts as a carrier and protects the active sites of catalyst as well. Abstract Schiff base metal complexes are effective homogeneous catalysts used in oxidation reactions in organic synthesis. However, application of these catalysts in aqueous solution is limited by their effectiveness and stability. In this study, a novel graphene based Schiff base copper complex (Cu(salen)) was developed to effectively activate persulfate (PS) for the removal of organic pollutants in aqueous solution. Aminated reduced graphene oxide (ArGO) was used as a carrier of the heterogeneous catalyst, DArGO-Cu, which was synthesized by the condensation reaction of 3, 5-dibromosalicylaldehyde with ArGO followed by the complexing reaction with copper acetate monohydrate. The surface structure and morphology as well as elemental composition of DArGO-Cu were characterized by SEM, TEM, XPS, FTIR, Raman and elemental analysis. The catalytic performance of DArGO-Cu to activate PS was evaluated with the degradation of triclosan (TCS) in water at room temperature. The mechanism for DArGO-Cu to activate PS was the generation of SO 4 − which was immediately converted to OH to degrade TCS. The role of graphene played in catalysis was not only as a carrier for Cu(salen) but also to build hydrophobic microdomains for the stabilization of the catalytic active sites in the reaction. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • UV/chlorination of diatrizoate (DTZ) follows pseudo first-order kinetics. • UV/chlorination can degrade diatrizoate more effectively than UV alone. • OCl mainly contributes to the degradation of diatrizoate. • The steady-state concentration of OH was very low during UV/chlorination. Abstract The degradation kinetics of the widely used iodinated X-ray contrast medium, namely diatrizoate, was investigated during ultraviolet (UV) photolysis and UV/chlorination. Factors influencing diatrizoate degradation, such as pH, chlorine dosage, and bromide concentration, were also evaluated. Diatrizoate was not degraded during chlorination. However, the degradation of diatrizoate during UV photolysis and UV/chlorination complied with the pseudo-first-order kinetics. At pH 7, the pseudo-first-order rate constant during UV/chlorination was 9.3 times higher than that during UV photolysis. The results of a radical quenching test using excessive tert -butanol suggested that the contribution of Cl, a type of reactive chlorine species (RCS), was limited. The contributions of UV direct photolysis, hydroxyl radicals (OH), and RCS to diatrizoate degradation during UV/chlorination at pH 7 were estimated to be 12.8%, 1.2%, and 85.9%, respectively. Results of further experiment suggested that OCl primarily caused diatrizoate degradation. As the chlorine concentration gradually increased from 25 to 150 μM, the corresponding pseudo-first-order rate constant of UV/chlorination increased from 8.37 (±0.42) × 10−3 to 5.52 (±0.28) × 10−2 s−1. When the pH value was increased from 5 to 9, the rate of diatrizoate degradation reached the maximum at pH 7 and gradually decreased during UV/chlorination; however, the rate of diatrizoate degradation remained stable during UV photolysis. The degradation of diatrizoate was inhibited when the bromide concentration was increased due to the competition for chlorine between bromide and diatrizoate; thus, the generation of OCl was limited. Compared with UV irradiation, UV/chlorination could reduce the formation of iodinated trihalomethanes (I-THM) after chlorination. However, dichloroacetonitrile (C 2 HCl 2 N), which is carcinogenic, was generated during UV/chlorination. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Arsanilic acid was efficiently removed in 15 s by Mn(VII)-S(IV) system. • Reactive species in MnVII-SIV process were supposed to be SO 4 −, OH, and Mn intermediates. • Contribution from each reactive species was related to structures of organic contaminants. • Background water matrices influence the performance of Mn(VII)-S(IV) process. Abstract This work investigated the fast degradation of ASA by a novel advanced oxidation process (permanganate (MnVII)-sulfite (SIV)). The results showed that the combination of Mn(VII) (50 μM) and S(IV) (250 μM) at pH 5.0 triggered near-instantaneous decomposition of ∼71% ASA (5 μM) within 15 s. The reaction parameters, which affected the degradation of ASA, such as pH (4.0–9.0), initial concentration of ASA (1–30 μM), and molar ratio of S(IV)/Mn(VII) (1–20), were systematically investigated. Specifically, sulfate radical (SO 4 −), hydroxyl radical (OH), and Mn intermediates were considered as the important reactive species in Mn(VII)-S(IV) process. Radical scavenging tests showed that both SO 4 − and OH contributed to the removal of ASA, with SO 4 − playing a dominant role. The contributions of reactive radicals, which were excluded in Mn(VI)-S(IV) system by previous researchers, for the degradation of organic contaminants was clarified for the first time. Therefore, our study can be considered as a necessary complement to previous studies about Mn(VII)-S(IV) system. Halide ions inhibited the removal of ASA following a trend of F− < Cl− < Br− < I− due to their competition for reactive radicals with ASA. The degradation products of ASA were identified, and the plausible reaction pathways were proposed, and their toxicity was assessed using luminescent bacteria Vibrio fischeri. Finally, the satisfying performance of Mn(VII)-S(IV) system in a natural water sample indicated it was a promising method for degrading organic contaminants in real water. [ABSTRACT FROM AUTHOR]

Highlights • Application of electrocoagulation in RO brines is advantageous due to high conductivity of brines. • Electrocoagulation effectively removed phosphate, alkalinity and DOM with either Fe or Al anode. • DOM removal resulted more effective with Al than Fe anode due to partial oxidation of iron at pH 5.5. • Electrocoagulation coupled with AOP oxidized micropollutants in brines to a high extent. Abstract The potential of integrating electrocoagulation (EleC) with two-stage reverse osmosis (RO) to enhance desalination of secondary/tertiary effluents through removal of dissolved organic matter (DOM) and scaling salts from brines was studied. EleC appears advantageous due to the high electrical conductivity of RO brines and low residual ions concentration. EleC was performed in batch mode in a flow-through cell with recirculation through a stirred reservoir at 9.4 mA/cm2 current density. Anode was made of Fe or Al as indicated, and cathode of stainless steel. Chemical coagulation (CC) with FeCl 3 was tested as reference. EleC resulted in effective removal of phosphate (>99%), carbonate (88–98%) and DOM (40–50%) at a high Faradaic efficiency (>90%). Fe-EleC resulted less suitable than Al-EleC due to partial Fe(II) oxidation at pH 5.5 required for optimal DOM removal, leaving high Fe content and consequently turbidity in the supernatant, whereas residual Al was negligible. At optimal conditions Al release was 75 mg/L for 1st-stage brines-RO1 (2-fold concentrated) and 300 mg/L for 2nd-stage brines-RO2 (∼8.3-fold concentrated), corresponding to a specific energy consumption of 0.30 and 0.23 kWh/dm 3 mS/cm , respectively. Similar results were obtained with CC, however, its main disadvantage was the considerable increase of chlorides in the supernatant. Since coagulation removes quenching components from brines, coupling EleC with advanced oxidation processes (AOP), either UVA/TiO 2 or UVC/H 2 O 2 , was also evaluated for oxidation of model micropollutants from brines prior to discharge. Either EleC or CC in tandem with AOP increased micropollutants oxidation by 3–4 fold compared to raw brines, achieving practically complete transformation. [ABSTRACT FROM AUTHOR]

In this study, the degradation efficiencies and mechanisms of atrazine, a recalcitrant herbicide, were thoroughly investigated using ferrate (Fe(VI))/peroxymonosulfate (PMS) process. In comparison with Fe(VI) or PMS alone, Fe(VI)/PMS process significantly enhanced the degradation of atrazine, and its degradation efficiency was higher than that of Fe(VI)/persulfate or Fe(VI)/H 2 O 2 process at pH 6.0. Complete degradation of atrazine at an initial concentration of 46.5 µM could be achieved within 20 min at initial concentrations of 6.0 mM Fe(VI), 5.0 mM PMS, pH 6.0, and 25 °C. Fe(VI)/PMS could efficiently degrade atrazine within a wide range of pH values (5–9). NOM concentration lower than 4.0 mg/L was favorable for atrazine degradation. Results of electron spin resonance and quenching studies indicated that both hydroxyl radical and sulfate radical were generated in the Fe(VI)/PMS process, while sulfate radical was the dominant reactive radical responsible for atrazine degradation. The mechanisms of PMS activation were elucidated on the basis of the results of XRD and XPS. In addition, fourteen intermediates from atrazine degradation were identified by LC/MS/MS, and consequently pathways for the degradation were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-atom Fe, Co, and Cu on the supports with similar properties are synthesized. • Single-atom catalysts were efficient in degradation of the pollutants. • The durability of single-atom metal is in an order of Co − N 4 ≈ Fe − N 4 ≫ Cu − N 4. • Co(IV) = O was evidenced to be contribute predominantly to pollutant degradation. Single-atom metal catalyzed peroxymonosulfate (PMS) activation shows great potential in water treatment; and the activity of various metal centers have been explored. The properties of the support contribute significantly to the catalytic performance of the metal centers. The knowledge on the intrinsic distinctions of the elements in single-atom catalyzed PMS activation is, however, relatively in lack. In this work, via a facile one-step method, three representative elements of Fe, Co, and Cu were configured in a metal − N 4 structure and anchored on N-doped carbon matrix with similar composition and structure. The atomic dispersity of the metal centers was experimentally substantiated by electronic microscopic technique in atomic scale and X-ray absorption spectroscopy. All these single-atom metal centers exhibit high activity in PMS activation for selective degradation of the organic pollutants, while the durability of the single-atom metal centers is vastly distinct as examined in continuous flow-mode. The water treatment capacity is in an order of Co − N 4 ≈ Fe − N 4 ≫ Cu − N 4 for the elimination of 0.1 mM 4-chlorophenol from water. Based on the analysis of the qunching effect by various probe molecules and electron spin resonance spectra at various reaction conditions, the high-valent Co(IV) O species is proposed to be the predominant active species for pollutant degradation in Co − N 4 catalyzed PMS activation. The findings in this work sheds light on the desgin of efficent and durable single-atom catalyst for water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D hierarchically porous zero-valent iron (3D-ZVI) was fabricated via 3D printing. • 3D-ZVI showed a catalytic activity comparable to Fe powder with less Fe leaching. • 3D-ZVI retained its excellent catalytic efficiency even after 45 cycles. • The role of high-valent iron-oxo in the 3D-ZVI/PMS system was investigated. Zero-valent iron (ZVI) has emerged as an efficient catalyst for facilitating the decomposition of organic pollutants. However, practical applications of ZVI remain limited owing to its susceptibility towards oxidation and agglomeration. Herein, we utilize 3D printing to fabricate hierarchically porous ZVI (3D-ZVI), which displays a high level of printing precision and superb compression resistance. The 3D-ZVI catalyst can effectively activate peroxymonosulfate (PMS) to degrade a diverse selection of organic contaminants. Notably, while the catalytic activity of 3D-ZVI is comparable to that of Fe powder under similar conditions, the concentration of leached Fe ions of the former is 6.3 times lower than that of the latter. Moreover, 3D-ZVI is capable of maintaining an efficient catalytic performance throughout 45 continuous reactions, which is significantly superior to most previously reported powder catalysts. The high-valent iron-oxo species generated in the 3D-ZVI/PMS system are primarily responsible for contaminant removal, while hydroxyl and sulfate radicals play a lesser role. Additionally, the degradation intermediates and their toxicity levels are investigated. This work provides insight into the practical applications of the ZVI/PMS system, and it also serves as a guide for the rational design of efficient and stable catalysts that can be conveniently recovered from aqueous environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Over 3.5 times improvement in the degradation rate of ATZ via O 3 /PAA process. • An increase in pH significantly enhances the oxidation effect of OH. • More intermediates and pathways are found in O 3 /PAA process. • All the intermediates are less toxic than their parent compound (ATZ). An emerging advanced oxidation process, namely ozone (O 3)/peracetic acid (PAA) process, was systematically investigated for the abatement of atrazine (ATZ) in this research. Compared to O 3 alone, the PAA in O 3 /PAA process significantly promoted the decomposition of O 3 , with a more than 3.5 times increase in the pseudo first-order rate constants (k obs) of the ATZ removal under the tested conditions. The removal of ATZ in O 3 /PAA process was highly pH-dependent and significantly affected by the PAA dose and solution pH, with the best degradation performance achieved at a PAA dosage of 10 mg L−1 and pH of 8. The identification experiments of active species and probe experiments showed that the hydroxyl radical (OH) was the major radical in this process (contribution of 60%−79%), while PAA-specific organic radicals (CH 3 C(O)OO and CH 3 C(O)O) played a minor role (contribution of 16%−35%). In addition, HCO 3 − was observed to inhibit the degradation of ATZ with a reduction of approximately 24% in the k obs , and the removal efficiency of ATZ was inhibited by 31%−48% in the presence of humic acid and the actual water column. Two unique transformation products (TPs) were detected in O 3 /PAA process in comparison to O 3 alone, and the toxicity analysis using ECOSAR software revealed that all the TPs of ATZ were less toxic than their parent compound. In summary, this study demonstrated the outstanding performance of O 3 /PAA process, which can improve the comprehending and implement of this process for the degradation of trace organic pollutants in (waste)water purification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different pore structures were prepared by using almond shells as starting materials. • Catalysts with mesoporous pores can utilize the high mass transfer to activate PMS. • High TOC removal still can be achieved by the mesoporous catalysts. • Low TOC removal in 1O 2 dominated systems can be solved via modulating pore sizes. Biochar was regarded as an effective catalyst for peroxymonosulfate (PMS) activation to eliminate the antibiotic contamination. However, the roles of pores in biochar for PMS activation has rarely been studied. In this study, catalysts with different pore structures were prepared using the almond shells as starting materials, and their structure–function relationships were investigated. The pore structures in the catalysts mainly consisted of microporous and mesoporous. It was found that the pore structure was the key factor for ofloxacin (OFL) degradation, and the pore volume was positively correlated with the activity of the catalysts (R 2 = 0.928). The surface reaction on the microporous materials could trigger the generation of various radicals and nonradical pathways, while the OFL oxidation was dominated by singlet oxygen (1O 2) with tunable electron transfer process. The materials with broad mesoporous pore sizes can utilize their high mass transfer rate to rapidly activate PMS for OFL oxidation. It was also found that the pores with a size of 2–6 nm in the catalyst could shield some external influences and intercept the degradation intermediates inside the pore to maintain the degradation process. As a result, the TOC removal ratio (94.96%) could be achieved by the catalyst, which provided an effective route to solve the low TOC removal in 1O 2 dominated systems. [ABSTRACT FROM AUTHOR]

A Layered g-C 3 N 4 Support Single-Atom Fe-N 4 Catalyst Derived from Hemin to Activate PMS for Selective Degradation of Aromatic Compounds via Singlet Oxygen Species. [Display omitted] • Atomically dispersed Fe-SA sites anchored on layered g-C 3 N 4 were prepared from hemin. • The planar structure of hemin suppressed the curling of g-C 3 N 4 at high temperature. • Singlet oxygen was the major reactive species instead of SO 4 −, HO and FeV = O. • Various electron-rich compounds can be selectively and efficientyl degraded. Single-atom catalysts (SACs) have been widely applied in electrocatalysis, photocatalysis and advanced oxidation processes. However, the synthesis of Fe SACs supported by layered g-C 3 N 4 remains challenging due to the high temperatures required for Fe single-atom (Fe-SA) sites formation, which can lead to the decomposition and curling of g-C 3 N 4. Herein, Fe SACs loaded on layered g-C 3 N 4 (Fe-SA@CN) were synthesized via an one-step pyrolysis using the pre-coordination metal precursor (hemin). The pre-coordinated structure in hemin prevented Fe atoms aggregation, while the planar structure of hemin suppressed the curling of g-C 3 N 4 at high temperature. The structures of the resulting material, including the atomically dispersed Fe-SA sites and its coordination environment (Fe-N 4), were characterized by AC-STEM and XAFS. The doping of Fe-SA sites facilitates the fracture of C-N bonds in pyridinic N and boosts the recombination of C-C bonds, thereby lowering the initial temperature of thermal decomposition of g-C 3 N 4 and improving the quality of the carbonization residue. Experimental tests and DFT calculations demonstrate that Fe-SA sites effectively decrease the adsorption energy of PMS, facilitating electron transfer processes. The Fe-SA@CN, with a Fe loading of 2.03 wt%, performs best in activating PMS for the degradation of aromatic compounds bearing electron-donating groups, which are mainly attacked by 1O 2 generated on Fe-SA sites (above 90% 1O 2 selectivity). This study highlights the role of precursor in the synthesis of single-atom catalysts, and provides insight for developing SACs for advanced oxidation processes. [ABSTRACT FROM AUTHOR]

• Presented influence of key parameters on performance and synergy of hybrid HC-PC system. • Synergy in HC-PC process is likely due to utilisation of re-combined OH through H 2 O 2. • Swirling flow device improves system performance (20%) and synergy (25%) • Synergy was found to decrease with increase in per-pass performance of HC device. A combination of hydrodynamic cavitation and photocatalysis (HC-PC) is a promising water treatment technology for the removal of recalcitrant pollutants. In this work, we investigated influence of key parameters of this hybrid technology such as initial concentration, catalyst loading, pH, re-circulating flow rate and cavitation device/scale on degradation of three model pollutants (coumarin, paracetamol and dichloroaniline). Unlike previous HC-PC studies, the individual and combined systems were investigated for each parameter to determine their effect on system performance and overall synergy. We report a dependence of logK ow for both systems, with highest removal (100% in 20 min with AC-PC, 37% in 120 min, or 350 passes, with HC-PC) and synergy (Synergistic index of 2.8 and 1.2 for AC-PC and HC-PC, respectively) associated with the more hydrophobic compound, dichloroaniline. HC-PC performance increased and synergy decreased with increasing catalyst loading, and the inverse effect was found with initial concentration (C 0 : 17.5 to 70 ppm). Similarly, pH decreased performance but increased synergy and low re-circulating flow rate increased performance but decreased synergy. Detailed analysis of these results indicated the utilisation of in-situ generated H 2 O 2 from recombined OH radicals is the main contributor of the observed synergy, and not physical interactions between cavities and photocatalyst particles. Following this, for the first time, influence of cavitation device type (based on linear flows and swirling flows) and device scale on overall performance of HC-PC system was quantified. Vortex based cavitation device was found to provide a 20% and 25% higher performance and synergy compared to a linear flow based cavitation device like orifice. The results presented here provide valuable insights into the synergy of HC and photocatalytic systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iron phosphide/biochar is highly active in activating persulfate (PS). • Rapid removal (100%) of high and low concentrations of sulfamethoxazole. • High mineralisation rate and low ferric ion leaching are achieved. • The synergy between iron phosphides and biochar in activating PS is studied. The efficient activation of persulfate (PS) is essential for rapidly degrading refractory organic pollutants in water. Traditional metal-based catalysts are limited by defects such as the metal ion redox cycle and secondary pollution, resulting in insufficient catalytic performances. In this research, highly active micron-sized iron phosphides (FeP and Fe 2 P) are in-situ synthesized on biochar, and the primary crystal phase can be switched by adjusting the phytic acid (PA) amount. Under the conditions of 0.15 g/L catalyst, 0.5 mM PS, and pH 7, sulfamethoxazole (SMX) at concentrations of 0.25, 0.50, 1.00, and 10.00 mg/L can be completely oxidized within 3, 5, 15, and 180 min, respectively. The leached ferric ion amount is below 0.020 mg/L. Meanwhile, ideal SMX abatements are achieved in sodium humate solution and surface water matrices, demonstrating the potential of this catalytic system for drinking water and wastewater treatment. Moreover, SO 4 -•, •OH, and 1O 2 are crucial reactive oxygen species for SMX removal. Based on density functional theory (DFT) calculations, it is found that the partially charged Fe ion (≡Feδ+) is the pivotal site for PS activation and ≡Fe2+ regeneration. FeP and Fe 2 P are typically semi-metallic. Biochar can enhance the catalytic efficacies of FeP and Fe 2 P by shifting d-band centers (spin up and down) towards fermi level and reducing band gaps (spin down). Besides, biochar may donate electrons to iron phosphides when activating PS. The enhancement of FeP by biochar is more significant, which is why FeP/biochar is superior to Fe 2 P/biochar in PS activation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new microbial iron reduction activating AOP was applied for sludge conditioning. • The sludge dewaterability was greatly improved by MIR/SPC in full-scale treatment. • Iron source in sludge was re-utilized by microbial iron reduction for AOP activation. • Microbial iron reduction facilitated Fe(II)/Fe(III) redox cycle for enhanced AOP. Sludge conditioning is a critical process to improve sludge dewaterability. This research developed a novel iron-rich sludge conditioning method by microbial iron reduction activating sodium percarbonate (MIR/SPC) treatment. The sludge conditioning parameters were optimized. The results showed that the MIR/SPC treatment could significantly improve the sludge dewaterability. The optimal conditions for sludge conditioning are as follows: 5-day anaerobic MIR treatment, pH 3 and 1 g/L of SPC. Under the optimal condition, the CST value of the conditioned sludge was reduced by over two-thirds, and the moisture content of dewatered sludge was decreased to 51.5% in full-scale application. The critical mechanism of MIR-promoted advanced oxidation process (AOP) in sludge conditioning was explored. The facilitation of iron reduction by MIR under microbial-driven reductive condition promoted the generation of hydroxyl radicals. The improved AOP generate more ROSs to attack floc structure of sludge, modify the EPS properties and cell status, strengthen the hydrophobicity and flocculability of sludge, and propel the release of bound water for enhanced dewaterability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CeO 2 @CNT-NaClO system exhibited a superior removal performance of ARGs. • The performance of CeO 2 @CNT-NaClO system depends on the morphology and crystal surface of CeO 2. • The rectangular CeO 2 -N particles with (2 0 0) and (1 1 1) crystal facets has the highest proportion of O v and Lewis acid sites. • CeO 2 -N particles generated the highest cumulative concentration of •OH and •ClO. • The synergistic effect of •OH and •ClO resulted into the high removal efficiencies of ARGs. The removal of antibiotic resistance genes (ARGs) is important for inhibiting the spread of antibiotic resistance in the aquatic environment. In this study, a series of coupled advanced oxidation-disinfection systems were developed based on a carbon nanotube membrane modified with different CeO 2 nanocrystals and NaClO (denoted as CeO 2 @CNT-NaClO system). The removal performance of ARGs by the CeO 2 @CNT-NaClO systems was tested by treating the simulated water samples containing Pseudomonas sp. HLS-6 with sul1 genes and Escherichia coli TOP10F with tetA genes. The results showed that the CeO 2 @CNT-NaClO system showed the superior disinfection efficiencies compared to using sole CeO 2 @CNT electrified membrane and sole NaClO. After treatment by the CeO 2 @CNT-NaClO system, Pseudomonas sp. HLS-6 and Escherichia coli TOP10F were completely inactivated , and the absolute abundances of sul1 and tetA genes decreased by 4.8 log and 1.8 log, respectively. The probe compounds and quenching experiments showed the synergistic effect of •OH and •ClO is the main contributor to the high removal efficiencies of ARGs by the CeO 2 @CNT-NaClO system. The rectangular CeO 2 particles with (2 0 0) and (1 1 1) crystal facets exhibited the largest amounts of oxygen vacancy and Lewis acid sites, which favored the coupled system to generate the highest cumulative concentration of •OH and •ClO. This led to a synchronous high-efficiency removal of ARGs and antibiotics in the CeO 2 @CNT-NaClO system. [ABSTRACT FROM AUTHOR]

[Display omitted] • A win–win strategy is established for recycling Li and preparing the catalyst. • Waste biomass and spent lithium-ion batteries are used to prepare inexpensive CoO-C catalysts. • CoO-C catalysts show a high turnover frequency value (2.9714 min−1). • The mechanism of catalytic degradation of ciprofloxacin is revealed. • Carbon coating reduces Co leaching rate and improves electron distribution. The functional utilization of transition metals from spent lithium-ion batteries (LIBs) is an essential upcycling way. Herein, we propose a win–win strategy to recover Li and prepare CoO-C catalysts from spent LIBs and waste biomass, and the CoO-C catalyst is used to activate peroxymonosulfate (PMS) to degrade ciprofloxacin (CIP). The interaction between CoO and carbon endows the CoO-C catalyst with a degradation efficiency of 99.99% within 30 min. Both the radical pathway (SO 4 · - and · OH) and the non-radical pathway (surface electron transfer) are involved in the degradation of CIP in the CoO-C/PMS system. The electrostatic potential indicates that the supported carbon improves the electron distribution, showing a particularly high turnover frequency (TOF) value (2.9714 min−1) for CIP. The efficient and stable degradation over a wide range of pH and different aqueous matrices indicates the potential application of CoO-C catalysts. Overall, the pyrolysis reduction upcycles spent LIBs and waste biomass, offering a green way to convert waste to value-added high-performance water remediation catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Ferro-chemistry based advanced oxidation process for LFP recycling. • LFP itself is activated and used as catalyst during advanced oxidation process. • Simultaneous conversion and in-situ recycling of Li and Fe as target products. • In-depth chemical reaction mechanism is explored for the AOPs system. • A green and cost-effective model for the closed-loop of LFP re-fabrication. Increasing application of lithium iron phosphate (LiFePO 4) battery in electric vehicles (EVs) and hybrid electric vehicles (HEVs) is boosting the generation of spent lithium iron phosphate batteries. Sustainable and cost-effective recycling these batteries with less value-added metals is crucial for the fulfillment of circular economy society. Here, in-situ advanced oxidation metallurgy technology was innovatively proposed towards selective extraction of Li from LiFePO 4 by Fenton oxidation, instead of conventional metallurgical processes. Li can be completely liberated without destructing olive type structure of LiFePO 4 with the formation of FePO 4 precursors. Mechanism revealed by DFT calculations and chemical reaction analysis indicates that the oxidation of Fe(II) in LiFePO 4 and release of Li+ is mainly initiated by the rapid attack of a large number of •OH during advanced oxidation process. Liberated Li+ was recovered as Li 2 CO 3 and used with FePO 4 as precursors to re-fabricate LiFePO 4. The recovered LiFePO 4 shows sound electrochemical performances with initial discharge capacity of 138.9 mAh/g at 0.5C and capacity retention of 93.6% after 50 cycles. This study provides a green and efficient alternative for the selective recycling of Li from spent LiFePO 4 battery based on its inherent structure and characteristics of target recycling materials with reduced chemical consumption, high efficiency and simplified recycling process. [ABSTRACT FROM AUTHOR]

When MW is combined with different AOPs, MW promotes the formation of active groups (such as •OH, •SO 4 −, •O 2 − and 1O 2) of the system through thermal or non-thermal effects. Thus, MAOPs have great prospects in removing pollutants from wastewater, wastewater sludge, soil and landfill leachate, etc. [Display omitted] • The advantages of MAOPs based on different AOPs are introduced. • The wide application of MAOPs in different fields is given. • The effect of MW on the AOPs was discussed. • The future research objectives and challenges of MAOPs are presented. Microwave (MW) technology has been widely studied in the field of environmental remediation due to its rapid and uniform heating, "hot spot" effect, and nonthermal effect. MW combined with advanced oxidation processes can mineralize any pollutant. In this article, the theory of MW radiation is introduced, and the latest progress in research on microwave-enhanced advanced oxidation processes (MAOPs, including Fenton/Fenton-like, persulfate, photocatalysis, electrocatalysis, etc.) for degrading organic pollutants in wastewater, sludge, and soil is reviewed, and compares it with traditional treatment methods. We found that MAOPs improved pollutant degradation efficiency. The mechanisms of MAOPs are discussed, MW technology could be combined with AOPs to enhance the production of active species (such as •OH, •SO 4 −, •O 2 −, and 1O 2). However, applications of MAOPs are currently limited to the laboratory scale. Overall, this review may provide insights for the future development of MAOPs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Sulfate radicals produced by ultrasound were applied to waste sludge treatment. • Ultrasound with persulfate pretreatment was most favorable to COD release. • COD consumption by excessive free radicals occurred at high level energy input. Abstract Sulfate radicals produced by ultrasonic activation of persulfate (PS) or sulfate were applied to disintegrate sludge flocs and extracellular polymeric substances (EPSs). The pretreatment facilitated the production of volatile fatty acids (VFAs) and hydrogen from subsequent anaerobic fermentation, yielding a potential method for improving the utilization of sulfate-containing waste-activated sludge (WAS). Sulfate radicals produced using ultrasound (US) in the presence of PS/sulfate showed a synergetic effect of advanced oxidation on WAS pretreatment. Among the three types of pretreatment (US, US + Sulfate, and US + PS), US + PS pretreatment was the most favoured for chemical oxygen demand (COD) solubilization, protein release, and sludge disintegration under a US density of 1.5 W/mL. Tightly bound EPS (TB-EPS) could be effectively disintegrated, and organic compounds were transformed into loosely bound EPS and soluble EPS. Unexpected COD consumption by excessive free radicals was also observed, when increasing the ultrasonic energy input (e.g. to 12 W/mL), towards a positive role for sludge disintegration and subsequent anaerobic fermentation. It was found that small particles (0.1–0.5 μm) from released organics could be preferentially overoxidized. An appropriate low ultrasonic strength initiated attack on the polymeric substances in WAS by the produced radicals, which TB-EPS could be primary target. [ABSTRACT FROM AUTHOR]