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Graphical abstract Highlights • Reduced graphene oxide and N-doped graphene were prepared by microwave irradiation. • Surface engineered graphene exhibited high catalytic ozonation activity. • Microwave reduction created more edging sites and graphitic nitrogen species. • Diverse reactive species, O 2 −, OH and 1O 2 , were possible for 4-nitrophenol degradation. Abstract N-doped graphene has demonstrated exceptional activities in versatile metal-free catalytic processes. In this study, reduced graphene oxide (rGO) and N-doped rGO were synthesized by a facile approach via microwave reduction with a low energy input and short reaction time. The activities of the derived carbocatalysts were evaluated by catalytic ozonation of 4-nitrophenol (4-NP). Compared with thermally annealed rGOs in argon atmosphere, microwave treated rGO demonstrated a better performance in catalytic oxidation, and N-doping would further improve the catalytic activity. It is discovered that microwave irradiation not only gave rise to more edging sites and dangling bonds in rGO, making higher catalytic potentials for ozone decomposition than that from thermal annealing, but also resulted in a higher concentration of N dopants. XPS studies revealed that more graphitic N species were incorporated into the carbon basal plane during the microwave reduction processes. The reactive oxygen species (ROS) in 4-NP oxidation were evaluated and identified by liquid-phase electron spin resonance (ESR) and radical scavenging tests, which indicated the generation of O 2 −, OH and 1O 2 for 4-NP degradation. This study provides a facile protocol for fabricating advanced nanocarbon materials for green oxidation and enables new insights in catalytic ozonation with state-of-the-art carbocatalysis. [ABSTRACT FROM AUTHOR]

Three simple structured nitrogen heterocyclic compounds (NHCs), namely indole (ID), benzopyrazole (BP) and benzotriazole (BT), were degraded via wet air oxidation (WAO) in an autoclave-type reactor. The elimination of target pollutants became significant only above 220 °C. The reactivity order of the three substrates was ID > BP > BT. The chemical oxygen demand (COD) removal levels were lower than 70%. Many partial oxidation intermediates were produced, as detected by electrospray ionization–mass spectrometry (ESI-MS). The presence of different anions, such as CO 3 2− , SO 4 2− , and PO 4 3− , had a detrimental effect on the removal performances. On the other hand, Cl − and NO 3 − had a beneficial effect on the WAO of the target pollutants. By combining quantum chemistry calculations and ESI-MS analysis, detailed degradation pathways of ID, BP, and BT could be proposed. It was concluded that ring breakage occurred on both the benzene and heterocyclic ring in the initial stage of WAO for all three substrates. [ABSTRACT FROM AUTHOR]

• Persulfate combined wet air oxidation (PWAO) is proposed to deep remove benzothiazole. • OH is firstly detected by electron paramagnetic resonance in wet air oxidation process. • OH plays a very important role in the PWAO process. • High COD removal is achieved with a large amount of microsphere polymers recycling. • The PWAO process has a lower operating cost than WAO in COD removal. Wet air oxidation (WAO) has an obvious advantage in treating wastewater with high concentration of organics, but harsh reaction conditions are required and the treatment efficiency has not reached a satisfactory level. Herein, we developed a low dosage of persulfate promoted WAO process (PWAO) to remove a model heterocyclic pollutant benzothiazole (BTH). The addition of persulfate remarkably enhanced the elimination of benzothiazole (BTH) and COD from water via degradation and polymerization. Under optimized operation condition (with 11.1 mM K 2 S 2 O 8 addition into WAO), about 65.0% of BTH converted into microsphere polymers and more than 94.6% COD was eliminated from water after polymers separation. Electron paramagnetic resonance (EPR) analysis and quenching experiments revealed that OH was effectively generated in a wide range of reaction temperature and it played the key role in BTH degradation and polymerization, while SO 4 − was detected at low temperature for its fast decomposition at high temperature. Quantum chemical calculation together with ultra-performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS) analysis confirmed that the degradation and polymerization of BTH mainly started from the heterocyclic ring, followed by further oxidation or polymerization. Comparing with normal WAO process, the PWAO technology had an advantage in lower operating cost in removing per unit COD and carbon resource recycle, which indicates a promising prospect in treating wastewater with high concentration of heterocyclic compounds. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • δ -MnO 2 and γ -MnO 2 showed different APAP removal kinetics at different pH. • Strong acidity largely promoted the APAP removal by MnO 2 , especially for γ -MnO 2. • Low pH values promoted nucleophilic addition and dimerization of APAP by MnO 2. • Dimerization and hydrolysis-oxidation were two major APAP transformation pathways by MnO 2. • Low pH values largely decreased the environmental risk of APAP transformation products by MnO 2. Abstract Manganese dioxides (MnO 2) govern the polymerization of phenolic and anilinic pollutants in nature water body. The studies on the chemistry of different phases of MnO 2 was relatively limited. Here we compared two MnO 2 , layer δ -MnO 2 and tunnel γ -MnO 2 , on their reaction kinetics and removal pathways with acetaminophen (APAP) as model compound. We found the kinetics of acetaminophen transformation by MnO 2 were largely influenced by pH values and MnO 2 structures. In neutral systems, APAP removal by δ -MnO 2 was faster than by γ -MnO 2. This was attributed to the higher catalytic potential of δ -MnO 2. In acidic systems, APAP removal by γ -MnO 2 was faster than by δ -MnO 2. This was attributed to the larger surface area and weaker electrostatic repulsion of γ -MnO 2 to APAP in acidic conditions. Furthermore, the pathways of acetaminophen transformation were influenced by pH values. Dimerization and hydrolysis-oxidation were the two major APAP transformation pathways by both MnO 2 in neutral and acidic systems. Low pH values induced the nucleophilic addition between quinoneimine (the product of hydrolysis-oxidation) and anilines (e.g. , APAP and its dimers). Low pH values also promoted the dimerization degrees of APAP. The hydrophilicity of APAP transformation products by MnO 2 were significantly reduced by low pH values. This work reconsidered the significances of acidity in the pollutants transformation by MnO 2 , and provided new perspectives to study the pollutants transformation by different phases of MnO 2. [ABSTRACT FROM AUTHOR]

Effective recycling of spent graphite from lithium-ion batteries (LIBs) has a strong application potential. In this research, anode scrap of spent LIBs is efficiently recovered and reused as high-performance cathode in electro-Fenton system. Role of different recovery processes in the reuse of anode scrap powder in electro-Fenton system is focused, including Anode raw powder (RP), acid leaching (AL), acid and alkali leaching (AAL) residual powder. The results indicate functional groups of anode powder are changed by different leaching processes, which can significantly affect the subsequent reuse in electro-Fenton system. According to evaluation by electrochemical characterization, the AAL has a higher hydrogen peroxide (H 2 O 2 ) selectivity and yield than RP and AL due to highly active two - electron reduction of oxygen (O 2 ). Interestingly, when anode powder is reused in electro-Fenton system, the AL electrode achieves 100% bisphenol A (BPA) removal in 70 min and 87.4% COD removal in 240 min, showing the best degradation efficiency. The reason can be attributed to higher carboxylic group content (35.83%) of AL powder than that of AAL (7%). Thus, part of iron ion in solution can be adsorbed on the surface of AL cathode, forming a partial heterogeneous iron oxidation-reduction. Furthermore, the reusability of AL electrode is evaluated. Compared with other carbon cathode, the AL cathode with a low current density still maintains 100% BPA removal after 10 reuse cycles. Since it is inherent with high reusability and environmental friendliness comparing with traditional cathode materials, this research demonstrates a potentially new approach to cooperatively treat pollutants from solid waste and waste water. [ABSTRACT FROM AUTHOR]

The effective V(V) and Cr(VI) separation is very difficult due to their similarity in physiochemical properties. In this research, almost completely separation of V(V) and Cr(VI) with primary amine N1923 was firstly demonstrated by employing multistage countercurrent extraction (MCE) with annular centrifugal contactors (ACCs). The optimum operation conditions of single-stage extraction with ACC were determined by systematic experiments, and best conditions of the rotor speed, the flow rate and the flow ratio of organic phase to aqueous phase were obtained. The loaded-organic phase can be reused for extraction process after stripping with ammonia/sodium hydroxide. Vanadium, in the leaching/aqueous solution with the initial pH of 6.1, was reached to extraction equilibrium by three-stage countercurrent extraction with ACCs. V(V) and Cr(VI) were separated through 21 stages of countercurrent extraction with ACCs. 95.1% of vanadium and almost none of chromium were extracted, with the separation factor approaching infinity. Through the mechanism of hydrogen bond association and different species of two metals in the leaching/aqueous solution, an in-depth analysis to correlate the results obtained and the chemical reactions with ACCs has been made in order to establish a firm conclusion with aim of the guidance in industrial application. [ABSTRACT FROM AUTHOR]

Microbial electrolysis cell (MEC) coupled with sulfate-reducing bacteria (SRB) was used to degrade sulfate-rich wastewater which was deficient in electron donors. Results confirmed that SRB could trigger vigorous synergy with an applied current. An applied electrical field of 1.5 mA (R1) resulted in the highest sulfate removal, which was 14.9% higher than that of the control reactor (R0). In addition, organic-substance consumption decreased with the increase of applied current. The concentration of lactic dehydrogenase (LDH), an indicator of cell rupture, increased by 3.59 times at 2.5 mA; that of ATP, an indicator of cell metabolism, sharply decreased under 2.5 and 3.5 mA. This finding indicated that high current led to plasmatorrhexis, low growth rate, and metabolic activity, subsequently reduced sulfate-reduction efficiency. Conversely, a proper current resulted in the enhancement of extracellular secretion, which was conducive to biofilm formation as further confirmed by detection through SEM. Electrochemical impedance spectroscopy (EIS) illustrated the SRB in the biofilm could accelerate the rate of direct electron transfer to cathode. Genus-level results further revealed that the dominant bacterium Desulfovibrio , an SRB, was richer in the cathode biofilm and R1, compared with R0. [ABSTRACT FROM AUTHOR]

[Display omitted] • The influences of 31 nucleophiles on the removal of dichlorobenzoquinones (DCBQs) was studied. • Degradation kinetics, pathways and toxicity evolution of DCBQs were characterized. • Fast removal and detoxification of DCBQs was achieved with the presence of thiol compounds. • Role of amino acids in promoting DCBQs hydrolyzation was revealed. • Relationships among nucleophilic structures, transformation pathways and products were found. Halobenzoquinones (HBQs), a metabolism of pentachlorophenol, arouse increasing concern for their high toxicity. This paper systematically studied the influences of 31 extracellular nucleophiles on the removal of dichlorobenzoquinones (DCBQs). The results showed that at pH 6.0–8.0, the transformation of DCBQs followed a pattern of pseudo first-order reaction. With the presence of different thiol compound (ratio 1:1), the apparent rate constant of 25DCBQ and 26DCBQ was between 0.028 and 0.204 min−1 and 0.061–0.156 min−1, respectively, which was 6.6–48.3 times faster than direct hydrolysis and 1.9–23.4 times of that with histidine, a typical amino acid. This was attributed to the different transformation pathways of DCBQs with thiol or amino groups. According to the MS spectrum and transition state theory, thiol compounds was stably incorporated into DCBQs via Michael addition or substitution, which also decreased the oxidative stress of DCBQs by 35.5–86.4% and cytotoxicity of hydrolyzed DCBQ by 44.9–100%, respectively. Conversely, amino acids promoted the hydrolysis of DCBQs by forming unstable AA-DCBQ intermediates that can be further hydrolyzed to OH-DCBQs, leading to an increased selectivity of OH-DCBQs, and increased the oxidative stress of 25DCBQs by 0.2–31.2% and cytotoxicity of hydrolyzed 25DCBQ by 42.0–52.7%. Such difference was inherently related to the nucleophilicity of different atoms. Moreover, it was revealed that the maximum condensed local nucleophilicity index of nucleophiles (N k, max) can joint describe the relationship among nucleophilic structures, transformation pathways and toxicity of DCBQs. This paper provided a comprehensive perspective on the fast removal and detoxification of HBQs in extracellular environment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Higher numbers of basic sites on AC benefited the oxalate ozonation. [•] Pyridine groups on AC possibly decreased the surface oxidation of oxalate. [•] Pyrrole groups on AC may enhance HO generation in bulk solution. [•] Basic oxygen-containing groups and basal planes on AC enhanced surface oxidation. [•] Basicity of AC indirectly contribute to the weakened HO oxidation in bulk solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning analysis identifies catalyst's key role in Me 2 SiCl 2 selectivity. • MeSiCl 2 -SiCl 2 Me and MeSiCl 2 -SiClMe 2 are main compositions of industrial HBRs. • MeSiCl 2 -SiClMe 2 prefers to produce MeSiCl 3 and Me 2 SiHCl based upon DFT insights. • Challenges & suggestions for upgrading HBRs to Me 2 SiHCl has been analyzed. Recently, the growing capacity of silicone monomers directly lead to a large accumulation of associated high-boiling residues (HBRs), which has become an urgent issue for limiting the sustainably development in industry. Dimethyldichlorosilane (M2) is an essential intermediate in silicone industry, which have been extensively applied in kinds of fields like architecture, electronics, new energy, medicine, transportation and plastic rubber. Consequently, the catalytic cracking of HBRs to produce value-added M2 is considered a promising strategy. However, most cracking catalysts exhibit low M2 selectivity in batch reactors. In this perspective, we initially provide an overview of the HBRs current cracking system. Moreover, the influence factors of M2 selectivity during HBRs-catalytic cracking system through machine learning (ML) methods are systematically calculated and analyzed. The latest findings regarding the actual components of HBRs feeding and their effluxes of HBRs-tri-n-butylamine cracking system are presented, as well as their distribution of final products. Finally, the existing challenges and suggestions for HBRs to M2, are given with the aim of providing novel research ideas and stimulating inspiration to drive toward a sustainable development for minimizing pollution and enhancing cost-effectiveness. [ABSTRACT FROM AUTHOR]

• High phenolic compound removal efficiency is achieved in DBD. • All possible reactive species in DBD were explored. • Influence of the organic structure in pollutants removal in DBD were founded. • EPR was applied to detect Hydroxyl radical in the system. • A plasma-catalyst combination technique is proposed. The degradation of a series of phenolic compounds in a novel dielectric barrier discharge (DBD) plasma reactor was studied in this paper. The effect of various parameters, such as applied voltage, water flowrate, initial concentrations of organics, solution conductivity and pH, was investigated to achieve a high removal efficiency for phenolic compounds. The complete degradation of p-CH 3 could be achieved within 32 min, and the highest energy yield was about 3.5 g/kWh. Electron paramagnetic resonance analysis and radical quenching experiment indicated that OH played an important role in phenols degradation, along with ozone molecules. O 2 − and 1O 2 also possibly contributed to phenols degradation. Substituted phenols were more easily degraded, especially nitrophenol with strong electron withdrawing groups, originating from OH and O 2 − attack. The intermediates of different phenolic compound generated in the degradation process were identified by Mass spectroscopy (MS) and the corresponding mechanism were proposed to strengthen the understanding of mechanism. A DBD plasma and activated carbon combined technique is further proposed to promote the conversion of oxygen into ROS (reactive oxygen species) and enhance the mineralization rate of substituted phenols. [ABSTRACT FROM AUTHOR]

Electro-peroxone process utilizes the in-situ generated H 2 O 2 by electro-reduction of O 2 to react with ozone molecule to produce hydroxyl radical, and achieves high efficiency in the wastewater treatment. However, detailed reaction mechanism in this process is still deficient. In this paper, a three-electrode system was adopted in the electro-peroxone process, and the origin of the synergy was revealed with the aid of the rotating ring disk electrodes. It was found that besides the main reaction between O 3 and H 2 O 2 , O 3 is also electro-reduced to O 3 − and then transformed into OH. Meanwhile, O 3 electro-reduction on the cathode can also possibly generate O 2 and promote H 2 O 2 production. Higher concentration of OH − near the cathode originated from O 2 and O 3 reduction may also react with O 3 to produce H 2 O 2 . These two pathways contributed to the higher amount of H 2 O 2 than the system with O 2 bubbling only, and ultimately contributed to produce more OH. All these reactions are synthetically responsible for the higher degradation rate of sodium oxalate in the electro-peroxone process than those in O 3 -electrolysis and ozonation processes, respectively. Though this system was quite different from normal electro-peroxone process, the conclusions are useful for understanding the practical reactions possibly happened on electrodes in the electro-peoxone process. [ABSTRACT FROM AUTHOR]

The recent thrust in utilizing microbial electrolysis cell (MEC) has led to accelerated attention in environmental decontamination. One key factor that governs this process is electron transfer efficiency. In this study, neutral red (NR) is involved as electron transfer mediator to investigate whether it could contribute to MEC performance. Afterwards, influence of electrode material selection on NR addition system was also studied. The results indicate MEC with NR shows better electrochemistry activity, which means sulfate-reducing bacteria (SRB) can response to electron transfer mediator NR. Further study reveals graphite felt triggers a better synergy with NR to facilitate electron utilization efficiency of the system subsequently maintains bacteria metabolic activity for a longer time. Sulfate removal in this reactor reaches 79.0% with electron utilization efficiency of 54.2%. To explore the mechanism, electrode bioelectrochemical property, microorganism activity and community were investigated. Electrode morphology analysis confirms graphite felt affords abundant space for the growth of electroactive microorganisms especially SRB and promotes electron exchange through cooperating with NR, which fits in with electrochemical impedance spectroscopy (EIS) analysis. High-throughput sequencing analysis confirms improved reactor can fortify the population dominant of SRB in the community which greatly raises electron utilization efficiency of SRB. [ABSTRACT FROM AUTHOR]

The high-efficient extraction of vanadium using primary amine and its application in the utilization of the chromium-bearing vanadium slag (V–Cr slag) were studied in this work. The extraction mechanism and the possible difficulties in the application were both considered. From the results, the extraction percentage of vanadium using free primary amine with the hydrogen bond association mechanism is higher than that in the acidic environment by primary amine salts. The inorganic ions and other impurities existing in the system were all considered to research for the continuous operation of the extraction. Furthermore, the viscosities of the fresh organic phase and the recycled organic phase were determined using the extractant not only N1923 but also LK-N21, where the viscosity of the latter system increased slightly during the recycled process of the extractant. Based on the above results, the pilot and the commercial experiment were carried out. In the large-scale experiment, the vanadium was extracted and the product of 99.5 wt.% vanadium pentoxide was obtained, and the mass loss of the extractant was only 0.1%. [ABSTRACT FROM AUTHOR]

• A novel strategy of utilization of impurity in waste-derived V 2 O 5 was provided. • Recycled vanadium oxides show high surface areas, and low work function values. • The Cr-doped V2O5 delivers high capacities and excellent long cycle stability. To meet the urgent requirement of sustainable energy storage technologies, it is essential to incorporate efficient waste management into designing energy storage materials. Herein, we report an environmentally responsible pathway to utilize the recycled V 2 O 5 from V-Cr slag leaching solution. Because of the fact that trace Cr are existed in the recycled V 2 O 5 from initial leaching solution. Therefore, the Cr-doped V 2 O 5 with different content of Cr was successfully synthesized and the effect of Cr on the structure and electronic characteristics of V 2 O 5 was systematically investigated. The date arising from spectral analyses informs us that the trace Cr doping can result in an expansion of the V 2 O 5 lattice, and lead to the decreasing of the work function values, so aiding in enhancing the electrochemical performance. Owing to the trace Cr doped into V 2 O 5 lattice, the recycled V 2 O 5 shows a high specific capacity of 405.5 mAh g−1 and excellent cycling stability over 2000 cycles. A detailed electrochemical reaction mechanism of Cr-doped V 2 O 5 cathode is investigated through a series of in-depth analyses. Different from conventional recycled strategy, we use the impurity element Cr, which is very difficult to separate from V, and realize the enhancement of the electrochemical performance of the recycled V 2 O 5. Moreover, the practicability of recycled V 2 O 5 is exemplified by fabricating a flexible, quasi-solid-state zinc batteries, and the cell operates well upon deformation. This work provides a new strategy for recycling wasted materials into high value materials for sustainable battery systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detailed evolution mechanism of O 3 into ROS on the doped graphene was revealed. • O ads produced from O 3 decomposition was a vital intermediate to generate other ROS. • Types and efficiency of the formed ROS from O ads depended on the doped heteroatoms. • CDD was a useful descriptor for carbonaceous catalyst design based on QSAR model. The detailed evolution mechanism of O 3 into Reactive oxygen species (ROS) is of paramount importance but remains elusive in catalytic ozonation. Herein, we report a density functional theory study to comprehensively reveal the specific evolution processes of O 3 into ROS on the B-, N-, P-, and Si-doped graphene, including the adsorption, decomposition and ROS generation. In contrast to some previous reports that O 3 would directly decompose into effective ROS on catalysts, our results indicate that after O 3 adsorption, the decomposition products are ground state O 2 and the adsorbed oxygen species (O ads). The O ads is more likely to act as a crucial intermediate for generating other ROS instead of directly attacking the organics. The type of the ROS and generation efficiency vary with the doped heteroatoms, and the heteroatoms of B, P and Si, or the neighboring C of N, would serve as active sites for O 3 adsorption and decomposition. The N- and P-doped graphene are predicted to have the superior performance in ROS generation and catalytic stability. Finally, twenty representative descriptors were adopted to build the quantitative structure–activity relationship (QSAR) with the activation energy barrier of O 3 decomposition. The result indicates that condensed dual descriptor (CDD) could be useful for preliminarily selecting the modified graphene catalysts, since it shows a very good linear relation with the activation energy barrier. This contribution provides an alternative way to gain fundamental insights into the mechanism of catalytic ozonation at the molecular level, and could be helpful for designing more-efficient catalysts in environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The paired electrolysis reduces energy consumption in the recycling of spent LIBs. • Synchronously recovering Co2+ as cobalt metal and synthesizing persulfate. • Simultaneous desalting in the recycling process of spent LIBs. The application of electrochemical methods on the recycling of valuable metals from spent lithium-ion batteries, and the removing of pollutant from wastewater by persulfate have attracted widespread attention in recent years. However, high energy consumption resulting from side electrochemical reactions constrains its application. Herein, a paired electrolysis method was designed to achieve the recycling of valuable metals from the spent LIBs and the synthesis of persulfate synchronically. In the process, high purity cobalt metal (>99.9%) was obtained from the leachate (catholyte) of the spent LIBs, and valuable persulfate were synchronically synthesized anolyte through a diaphragm electrolyzer. The prepared persulfate was directly thermally activated for pollutant degradation. Two important synthesis process are conducted in one step. About 30% energy consumption is reduced through paired electrolysis to produce valuable products of equal quality and the cathodic current efficiency is also enhanced about 4% compared with the single cobalt electrolysis system at same stage. Additionally, Li+ is recycled as Li 2 CO 3 through precipitation from the electrolyte. As a green method, paired electrolysis will own a wide application prospects in the waste recycling and other hydrometallurgical fields because of low energy consumption and high valuable products. [ABSTRACT FROM AUTHOR]

• Global softness of the NHCs was employed to correlate with the ozonation efficiency. • Higher global softness of NHCs resulted in a greater degradation efficiency. • Fewer N atoms in heterocyclic ring generated more OH from ozone dissociation. • Reactive sites for both O 3 and radical attack were located by FO theory. • Combined DFT and TOF-MS results were used to identify the hydroxylation products. Nitrogen-containing heterocyclic contaminants (NHCs) have aroused intense environmental issues in waterbody because of their high toxicity and strong recalcitrance against natural degradation. In this study, ozonation degradation on four typical NHCs - benzotriazole (BTA), benzimidazole (BMZ), indazole (IDZ), and indole (IDO) was carried out to investigate the effects of N atoms on degradation efficiency. Global softness of the NHCs was calculated by density functional theory (DFT) and correlated with ozonation efficiency. It was discovered that higher global softness of the NHCs resulted in the greater degradation efficiency. Mineralization results together with the quenching tests results suggested that NHCs with ortho-positioned N atoms in heterocyclic ring are easier to be mineralized, while the presence of para-positioned N atoms increased the recalcitrance for destruction. Apart from hydroxyl radicals, superoxide radicals and singlet oxygens were also identified by electron paramagnetic resonance (EPR) spectra. Condensed Fukui index was employed to probe the potential active sites for both direct ozone oxidation and radical-based attack. Single point energies were further calculated among these active sites to seek the initial-stage hydroxylation intermediates. Combined the calculation results with the identified intermediates from time-of-flight mass spectroscopy (TOF-MS), degradation routes of the NHCs were proposed. This study discovered structure-dependent behavior of NHCs on ozonation efficiency and envisaged a more accurate strategy for establishing the degradation pathway. [ABSTRACT FROM AUTHOR]