Constructing Directional Electrostatic Potential Difference via Gradient Nitrogen Doping for Efficient Oxygen Reduction Reaction.

Nitrogen doping has been recognized as an important strategy to enhance the oxygen reduction reaction (ORR) activity of carbon-encapsulated transition metal catalysts (TM@C). However, previous reports on nitrogen doping have tended to result in a random distribution of nitrogen atoms, which leads to disordered electrostatic potential differences on the surface of carbon layers, limiting further control over the materials' electronic structure. Herein, a gradient nitrogen doping strategy to prepare nitrogen-deficient graphene and nitrogen-rich carbon nanotubes encapsulated cobalt nanoparticles catalysts (Co@CNTs@NG) is proposed. The unique gradient nitrogen doping leads to a gradual increase in the electrostatic potential of the carbon layer from the nitrogen-rich region to the nitrogen-deficient region, facilitating the directed electron transfer within these layers and ultimately optimizing the charge distribution of the material. Therefore, this strategy effectively regulates the density of state and work function of the material, further optimizing the adsorption of oxygen-containing intermediates and enhancing ORR activity. Theoretical and experimental results show that under controlled gradient nitrogen doping, Co@CNTs@NG exhibits significantly ORR performance (Eonset = 0.96 V, E1/2 = 0.86 V). At the same time, Co@CNTs@NG also displays excellent performance as a cathode material for Zn-air batteries, with peak power density of 132.65 mA cm-2 and open-circuit voltage (OCV) of 1.51 V. This work provides an effective gradient nitrogen doping strategy to optimize the ORR performance.

Aldehyde group pendant-grafted pectin-based injectable hydrogel.

Periodate oxidation has been the widely accepted route for obtaining aldehyde group-functionalized polysaccharides but significantly influenced the various physicochemical properties due to the ring opening of the backbone of polysaccharides. The present study, for the first time, presents a novel method for the preparation of aldehyde group-functionalized polysaccharides that could retain the ring structure and the consequent rigidity of the backbone. Pectin was collected as the representative of polysaccharides and modified with cyclopropyl formaldehyde to obtain pectin aldehyde (AP), which was further crosslinked by DL-lysine (LYS) via the Schiff base reaction to prepare injectable hydrogel. The feasibility of the functionalization was proved by FT-IR and 1H NMR techniques. The obtained hydrogel showed acceptable mechanical properties, self-healing ability, syringeability, and sustained-release performance. Also, as-prepared injectable hydrogel presented great biocompatibility with a cell proliferation rate of 96 %, and the drug-loaded hydrogel exhibited clear inhibition of cancer cell proliferation. Overall, the present study showed a new method for the preparation of aldehyde group-functionalized polysaccharides, and the drug-loaded hydrogel has potential in drug release applications.

Super-twisting sliding mode control for neutral point voltage of three-phase four-wire inverter based on SiC/Si hybrid switch.

The three-phase four-wire voltage source inverter (3P4W VSI) is widely used in applications like uninterrupted power supply (UPS) and bidirectional onboard charger. The increasing power density demand requires higher switching frequency and lower switching loss. To fulfill the conflicting objectives, two-fold methodology is proposed in this paper: 1) SiC/Si hybrid switches (HyS) together with recently reported gate trigger are reported for the first time in the 3P4W VSI; 2) the natural point voltage is controlled to track a sinusoidal voltage with the frequency equal to 3 times of fundamental frequency in order to achieve higher DC-bus voltage utilization rate, and further reduce the switching loss. The traditional PI controller is very hard to achieve desired performance due to both the nonlinearity and the variant reference of the natural point voltage control system. Thereby, the super-twisting sliding mode control (ST-SMC) is proposed in this paper to achieve desired tracking performance and fast dynamic response. The effectiveness and superiority of the system are verified by both simulation and experiment comparison with the existing methods using a 5 kW prototype.

Transformation of ZIF-67 Nanocubes to ZIF-L Nanoframes.

Investigating the process of crystalline transformation in metal-organic frameworks (MOFs) has significant implications in advancing our understanding of the growth mechanisms and design of innovative materials. This study achieves a theoretically impossible transformation direction from three-dimensional (3D) zeolitic imidazolate nanocubes (ZIF) to two-dimensional (2D) ZIF nanoframes through the Marangoni effect in droplets. This transformation challenges the established belief that only a transition from 2D ZIF-L to 3D ZIF-67 is possible, which neglects the reverse process. Finite element analysis indicates that the conversion from 3D ZIF to 2D ZIF is feasible when uniform mass distribution and heat transport are guaranteed under Marangoni flow. This research not only demonstrates an alternative pathway for MOF crystalline transformation but also provides a fresh perspective on the construction of MOF nanoframes.

Bimetallic metal-organic framework as a high-performance peracetic acid activator for sulfamethoxazole degradation.

A novel 3D bimetallic metal-organic framework (MOF(Fe-Co)) was successfully prepared and its performance on sulfamethoxazole (SMX) removal in advanced oxidation process (AOP) based on peracetic acid (PAA) was evaluated. MOF(Fe-Co) exhibited an efficient catalytic performance on PAA activation for SMX degradation under neutral condition. Increasing PAA concentration could enhance SMX removal, while the variation of MOF(Fe-Co) dosage from 0.05 to 0.2 g/L had an inappreciable effect on SMX removal. According to the results of inductively coupled plasma mass spectrometry analyses and X-ray photoelectron spectroscopy, catalytic reactions mainly occurred on the surface of MOF(Fe-Co). Organic radicals (i.e., CH3C(O)OO• and CH3C(O)O•) were demonstrated to be the predominant reactive radicals for SMX degradation by MOF(Fe-Co)/PAA through radical quenching experiments. The presence of Cl- could enhance the degradation of SMX by MOF(Fe-Co)/PAA, while HCO3- and natural organic matter inhibited SMX degradation severely. Five identified degradation products were detected in this system and four possible SMX transformation pathways were proposed, including amino oxidation, S-N bond cleavage, coupling reaction and hydroxylation.

Hydroxylamine promoted degradation of organic contaminants using peroxydisulfate activated by Fe-alginate.

To overcome the shortcomings of Fe(Ⅱ)/peroxydisulfate (PDS) system including the limited working pH range and large iron sludge production, a Fe-doped alginate (Fe-Alg) catalyst was prepared and combined with hydroxylamine (HA) to continuously activate PDS for the removal of organic pollutants in neutral condition. Due to the strong reductive capability of HA, it could significantly enhance the catalytic capability of Fe-Alg for PDS. The results of characterization suggested that Fe(Ⅲ)/Fe(Ⅱ) was evenly distributed in Alg through its complexation with carboxyl groups, and the reduction of Fe(Ⅲ) to Fe(Ⅱ) initiated by HA enabled Orange G (OG) to be continuously degraded in the Fe-Alg/HA/PDS system. The results of quenching experiments suggested that SO4∙- and HO• played a dominant role for OG removal in the Fe-Alg/HA/PDS process. The effect of influence factors (e.g. initial pH, HA concentration, Fe-Alg dose and PDS concentration) and water matrix components (i.e. SO42-, NO3-, Cl-, HCO3- and dissolved organic matters (DOM)) on the performance of Fe-Alg/HA/PDS system was systematically investigated. Other refractory organic contaminants, including diclofenac (DCF), sulfamethoxazole (SMX), oxytetracycline (OTC) and bisphenol AF (BPAF) were also efficiently eliminated in Fe-Alg/HA/PDS system, suggesting the feasibility of this system for the treatment of organic pollutants. This work provides a method to optimize Fe(Ⅱ)/PDS system and a novel process applied to degrade refractory pollutants.

Degradation of organic pollutants through activating bisulfite with lanthanum ferrite-loaded biomass carbon.

The removal of methylene blue (MB) in water is a challenging task due to its toxicity, carcinogenicity and resistance to biodegradation. Accordingly, a novel composite catalyst (BC@LF) was prepared by loading lanthanum ferrite (LaFeO3) on biomass carbon (BC) to activate bisulfite (BS) for methylene MB removal in this study. Characterization via scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) indicated that LaFeO3 was successfully loaded on BC. X-ray photoelectron spectroscopy (XPS) analysis suggested that [triple bond, length as m-dash]Fe(iii) was the main active site for BS activation. It was found that 99.4% MB was removed within 60 min in BC@LF/BS system. Sulfate radical (SO4˙-) and hydroxyl radicals (HO˙) were proved to be responsible for MB removal in the BC@LF/BS system and SO5˙- might also be involved in MB removal. The degradation efficiency of MB in the BC@LF/BS system decreased with increasing pH, while the adsorption efficiency of BC@LF for MB improved with increasing pH. Additionally, BC@LF exhibited good reusability for BS activation in successive uses. The BC@LF/BS system exhibited favorable removal effect for various organic compounds, indicating that it has good applicability in the treatment of organic wastewater.

Heat induced superfast diclofenac removal in Cu(II)-activated peracetic acid system: Mediation from non-radical to radical pathway.

A Cu(II)/heat coactivated peracetic acid (PAA) system for enhancing diclofenac (DCF) degradation was proposed in this work. The superiority of this synergetic activation strategy for PAA, working reactive species, catalytic mechanism and effects of reaction parameters on DCF elimination in this system were simultaneously investigated. Based on our results, the DCF loss rate in Cu(II)-heat/PAA process at pH 8.0 was about 49.3 and 4.2 times of that in Cu(II)/PAA and heat/PAA processes, respectively. Increasing the reaction temperature to 60 оC not only motivated the conversion of Cu(II) to Cu(I) but also facilitated the one-electron transfer between Cu(I) and PAA, boosting the generation of radicals. Organic radicals (mainly CH3C(O)O• and CH3C(O)OO•) were evidenced to be the core oxidizing substances dominating in the destruction of DCF while hydroxyl radical (•OH) made a minor contribution in this system by electron paramagnetic resonance (EPR) method together with scavenging experiments. This study broads the eyes into enhanced PAA activation initiated by homogenous Cu(II), providing a simple but efficient tool to degrade micropollutants.

High Crystallinity 2D π-d Conjugated Conductive Metal-Organic Framework for Boosting Polysulfide Conversion in Lithium-Sulfur Batteries.

The catalytic performance of metal-organic frameworks (MOFs) in Li-S batteries is significantly hindered by unsuitable pore size, low conductivity, and large steric contact hindrance between the catalytic site and lithium polysulfide (LPSs). Herein, the smallest π-conjugated hexaaminobenzene (HAB) as linker and Ni(II) ions as skeletal node are in situ assembled into high crystallinity Ni-HAB 2D conductive MOFs with dense Ni-N4 units via dsp2 hybridization on the surface of carbon nanotube (CNT), fabricating Ni-HAB@CNT as separator modified layer in Li-S batteries. As-obtained unique π-d conjugated Ni-HAB nanostructure features ordered micropores with suitable pore size (≈8 Å) induced by HAB ligands, which can cooperate with dense Ni-N4 chemisorption sites to effectively suppress the shuttle effect. Meanwhile, the conversion kinetics of LPSs is significantly accelerated owing to the small steric contact hindrance and increased delocalized electron density endued by the planar tetracoordinate structure. Consequently, the Li-S battery with Ni-HAB@CNT modified separator achieves an areal capacity of 6.29 mAh cm-2 at high sulfur loading of 6.5 mg cm-2 under electrolyte/sulfur ratio of 5 µL mg-1 . Moreover, Li-S single-electrode pouch cells with modified separators deliver a high reversible capacity of 791 mAh g-1 after 50 cycles at 0.1 C with electrolyte/sulfur ratio of 6 µL mg-1 .

Phosphate enhanced Cu(II)/peracetic acid process for diclofenac removal: Performance and mechanism.

Since limitedly existing researches suggested Cu(II) had deficiently catalytic ability to PAA, in this work, we tested the oxidation performance of Cu(II)/PAA system on diclofenac (DCF) degradation under neutral conditions. It was found that overwhelming DCF removal could be obtained in Cu(II)/PAA system at pH 7.4 using phosphate buffer solution (PBS) compared to poor loss of DCF without PBS, and the apparent rate constant of DCF removal in PBS/Cu(II)/PAA system was 0.0359 min-1, 6.53 times of that in Cu(II)/PAA system. Organic radicals (i.e., CH3C(O)O• and CH3C(O)OO•) were evidenced as the dominant contributors to DCF destruction in PBS/Cu(II)/PAA system. PBS motivated the reduction of Cu(II) to Cu(I) through chelation effect, and then the activation of PAA by Cu(I) was facilitated. Besides, due to the steric hindrance of Cu(II)-PBS complex (CuHPO4), PAA activation was mediated from non-radical-generating pathway to radical-generating pathway, leading to desirably effective DCF removal by radicals. The transformation of DCF mainly experienced hydroxylation, decarboxylation, formylation and dehydrogenation in PBS/Cu(II)/PAA system. This work proposes the potential of coupling of phosphate and Cu(II) in optimizing PAA activation for organic pollutants elimination.

Ruthenium doping: An effective strategy for boosting nitrite electroreduction to ammonia over titanium dioxide nanoribbon array.

Electrochemical reduction of nitrite (NO2-) not only removes NO2- contaminant but also produces high-added value ammonia (NH3). This process, however, needs efficient and selective catalysts for NO2--to-NH3 conversion. In this study, Ruthenium doped titanium dioxide nanoribbon array supported on Ti plate (Ru-TiO2/TP) is proposed as an efficient electrocatalyst for the reduction of NO2- to NH3. When operated in 0.1 M NaOH containing NO2-, such Ru-TiO2/TP achieves an ultra-large NH3 yield of 1.56 mmol h-1 cm-2 and a super-high Faradaic efficiency of 98.9%, superior to its TiO2/TP counterpart (0.46 mmol h-1 cm-2, 74.1%). Furthermore, the reaction mechanism is studied by theoretical calculation.

Oxygen-Rich Carbon Nitrides from an Eutectic Template Strategy Stabilize Ni, Fe Nanosites for Electrocatalytic Oxygen Evolution.

Functionalized porous carbons are central to various important applications such as energy storage and conversion. Here, a simple synthetic route to prepare oxygen-rich carbon nitrides (CNOs) decorated with stable Ni and Fe-nanosites is demonstrated. The CNOs are prepared via a salt templating method using ribose and adenine as precursors and CaCl2 ·2H2 O as a template. The formation of supramolecular eutectic complexes between CaCl2 ·2H2 O and ribose at relatively low temperatures facilitates the formation of a homogeneous starting mixture, promotes the condensation of ribose through the dehydrating effect of CaCl2 ·2H2 O to covalent frameworks, and finally generates homogeneous CNOs. As a specific of the recipe, the condensation of the precursors at higher temperatures and the removal of water promotes the recrystallization of CaCl2 (T < Tm = 772 °C), which then acts as a hard porogen. Due to salt catalysis, CNOs with oxygen and nitrogen contents as high as 12 and 20 wt%, respectively, can be obtained, while heteroatom content stayed about unchanged even at higher temperatures of synthesis, pointing to the extraordinarily high stability of the materials. After decorating Ni and Fe-nanosites onto the CNOs, the materials exhibit high activity and stability for electrochemical oxygen evolution reaction with an overpotential of 351 mV.

Tuning the Coordination Environment of Carbon-Based Single-Atom Catalysts via Doping with Multiple Heteroatoms and Their Applications in Electrocatalysis.

Carbon-based single-atom catalysts (SACs) are considered to be a perfect platform for studying the structure-activity relationship of different reactions due to the adjustability of their coordination environment. Multi-heteroatom doping has been demonstrated as an effective strategy for tuning the coordination environment of carbon-based SACs and enhancing catalytic performance in electrochemical reactions. Herein, recently developed strategies for multi-heteroatom doping, focusing on the regulation of single-atom active sites by heteroatoms in different coordination shells, are summarized. In addition, the correlation between the coordination environment and the catalytic activity of carbon-based SACs are investigated through representative experiments and theoretical calculations for various electrochemical reactions. Finally, concerning certain shortcomings of the current strategies of doping multi-heteroatoms, some suggestions are put forward to promote the development of carbon-based SACs in the field of electrocatalysis.

Construction of the comprehensive evaluation system of waterbody pollution degree and the response of sedimentary microbial community.

This study proposed and established a comprehensive evaluation system for the pollution degree of the waterbody by taking overlying water and sediment as a whole. By dividing different sampling points into three gradients according to the pollution degree, the changes in sedimentary microbes under various pollution gradients were compared. The results showed that microbial diversity, abundance and specific OTUs decreased significantly with the increase in pollution degree. Meanwhile, Firmicutes, Bacteroidota and Caldiseriota increased in the severely polluted group, while Chloroflexi and Acidobacteriota decreased. Spearman correlation analysis and co-occurrence network revealed that COD, pH in overlying water, and Mn, Fe in sediments were the most significant pollution degree evaluation indicators affecting sedimentary microorganisms, which drove the sedimentary microbial communities dominated by Proteobacteria and Firmicutes. FAPROTAX functional prediction indicated that increased pollution levels led to the weakening of functional genes related to nitrogen metabolism and sulfur metabolism and the increase of functional genes related to carbon metabolism in sediment microorganisms. This study not only provided new insights into waterbody pollution evaluation but also verified the feasibility of this evaluation method by the response of sedimentary microbial communities to different pollution degrees.

Heat-activated peracetic acid for degradation of diclofenac: kinetics, influencing factors and mechanism.

ABSTRACTHeat-activated peracetic acid (PAA) was used to degrade diclofenac (DCF) in this study. Electron paramagnetic resonance and radical scavenging experiments proved that organic radicals (i.e. CH3C(=O)O• and CH3C(=O)OO•) were the primary active species for DCF removal in the heat/PAA process. The degradation efficiency of DCF increased with the increase of temperature or initial PAA concentration in the heat/PAA process, and the optimal reaction pH for DCF removal was neutral. The presence of NO3- or SO42- insignificantly affected DCF degradation, while Cl- was favourable for DCF removal in this process. In contrast, an obvious inhibition on the removal of DCF was observed with the addition of natural organic matter, which might be responsible for the lower DCF removal in real waters. Finally, dechlorination, formylation, dehydrogenation and hydroxylation were proposed to be four degradation pathways of DCF in the heat/PAA system based on the five detected transformation products.

Efficacy of the Chinese herbal medicine Jintiange capsules in the postoperative treatment of osteoporotic vertebral compression fractures: a systematic review and meta-analysis.

Background: In traditional Chinese medicine, Jintiange capsules are frequently used to treat metabolic bone diseases and strengthen bones and tendons. The main component of Jintiange capsules is bionic tiger bone powder. However, the active ingredients and proteins are derived from other animal bones, with chemical profiles similar to that of natural tiger bone. This study aimed to explore the efficacy of Jintiange capsules, a Chinese herbal medicine, in the postoperative treatment of osteoporotic vertebral compression fractures (OVCFs). Methods: In this systematic review, literature was retrieved using PubMed, the Cochrane Library, the Chinese National Knowledge Infrastructure, the Web of Science, the Wanfang Database, the Chinese Biomedical Literature Database, and the Chinese VIP Database from inception to July 2023. The primary outcome measures were the bone mineral density (BMD) and effective rate. The secondary outcome measures were the visual analog pain score (VAS), Oswestry disability index (ODI), Cobb's angle, serum osteocalcin, serum alkaline phosphatase, and adverse events. RevMan 5.4 and STATA 17.0 software were used for data analysis. Results: We enrolled randomized controlled trials (RCTs) focusing on 1,642 patients in the meta-analysis. The meta-analysis illustrated that Jintiange capsules significantly increased the BMD of the lumbar spine (p < 0.00001), femoral neck (p = 0.0005), and whole body (p = 0.01). The subgroup analysis of Jintiange capsules combination therapy showed that the BMD of the lumbar spine and whole body was significantly improved with Jintiange capsules (p < 0.00001). The test for the overall effect showed that Jintiange capsules had a significantly higher effective rate than the control groups (p = 0.003). Additionally, the overall effect test showed that Jintiange capsules decreased the VAS and ODI (p < 0.00001) and Cobb's angle (p = 0.02), and improved serum OC and ALP (p < 0.00001) compared with the controls. Furthermore, the pooled analysis of adverse reactions showed no serious impacts on the treatment of OVCFs. Conclusion: Jintiange capsules demonstrate high safety and efficacy in the treatment of OVCFs, including increasing BMD, the lift effect rate, serum OC levels, and pain relief, decreasing the ODI, serum ALP levels, and adverse events, and improving Cobb's angle. Additional research is required to validate the efficacy of Jintiange capsules for the postoperative treatment of OVCFs.Systematic review registration: https://www.crd.york.ac.uk/PROSPERO.

Rapid degradation of sulfamethoxazole by permanganate combined with bisulfite: efficiency, influence factors and mechanism.

In this study, permanganate combined with bisulfite (PM/BS), a novel advanced oxidation process, was used for rapidly removing sulfamethoxazole (SMX) from contaminated water. The results showed that 80% SMX was removed within 10 s in the PM/BS system, while no obvious SMX degradation was observed in the PM or BS alone system within 300 s. Reactive manganese species (RMnS, Mn(III), Mn(V) and Mn(VI)), sulfate radical (SO4•-) and hydroxyl radical (HO•) formed in the PM/BS system all played a role in accelerated degradation of SMX. Due to the loss of RMnS, SMX degradation was significantly inhibited with the increase in pH. The best [BS]:[PM] ratio for SMX removal was 7.5:1-10:1. The presence of Cl-, HCO3- or natural organic matter (NOM) significantly inhibited the degradation of SMX, while SO42- and NO3- had little impact on SMX removal. Based on the detected transformation products, two degradation pathways of SMX by PM/BS, namely N-S bond cleavage and amino oxidation, were proposed.

Activated peracetic acid by Mn3O4 for sulfamethoxazole degradation: A novel heterogeneous advanced oxidation process.

In this study, a novel peracetic acid (PAA)-based advanced oxidation process using Mn3O4 as a catalyst was proposed. A thorough sulfamethoxazole (SMX) removal could be achieved within 12 min in Mn3O4/PAA system at neutral pH. The characterization results of fresh and used Mn3O4 suggested that ≡Mn(II), ≡Mn(III) and ≡Mn(IV) on Mn3O4 were the Mn species for PAA activation, constituting the redox cycles of ≡Mn(II)/≡Mn(III) and ≡Mn(III)/≡Mn(IV) simultaneously. Organic radicals (i.e., CH3C(O)O• and CH3C(O)OO•) were verified to be the dominant reactive species responsible for SMX degradation in Mn3O4/PAA system by radical scavenging experiments. The neutral condition was the most favorable pH for SMX removal in Mn3O4/PAA system and the increase of PAA or Mn3O4 dosage could enhance SMX degradation. Presence of HCO3- and natural organic matter (NOM) could inhibit SMX degradation, while Cl-, NO3- and SO42- had a negligible effect on SMX removal. The thorough SMX removal in successive experiments and characterization results of used Mn3O4 suggested the good reusability and stability of Mn3O4 for PAA activation. Based on six detected transformation products of SMX, hydroxylation, nitration, bond cleavage and coupling reaction were proposed to be its degradation pathways in Mn3O4/PAA system.

Two-dimensional activated carbon nanosheets for rapid removal of tetracycline via strong π-π electron donor receptor interactions.

Two-dimensional carbonaceous materials have sparked extensive attention in organic pollutants adsorption due to their unique structure to facilitate the formation of the physical or chemical bonding. Herein, natural two-dimensional porous activated carbon nanosheets with ultra-high specific surface area (2276.44 m2 g-1) are prepared by alkaline immersion-assisted circulating calcination techniques from corn straw piths. The prepared nanosheets exhibit rapid tetracycline adsorption capacity (633 mg g-1 within 5 min) and high equilibrium adsorption capacity of 804.5 mg g-1. Significantly, the nanosheets can adapt to a wide range of pH (at least between pH = 3-10) and are almost unaffected by coexisting ions. Mechanism studies and theoretical calculations demonstrate that the rapid and high-efficient adsorption of tetracycline mainly depends on the π-π electron donor receptor interactions. In addition, hydrogen bonding and pore filling was also responsible for tetracycline adsorption. This work provides important guidance for the development of the biobased high-performance adsorbents from agricultural waste.

Effect of bicarbonate on nitrate-induced photosensitive degradation of sulfamethoxazole under UV irradiation.

In this study, the influence of HCO3- on NO3--induced photosensitive degradation of sulfamethoxazole (SMX) under UV irradiation was investigated. It was found that the removal of SMX by UV in the presence of NO3- improved significantly compared to its photolysis, which was confirmed to be due to the role of hydroxyl radical (HO•) formed through UV-activated NO3-. However, the addition of HCO3- in UV/NO3- system could further enhance SMX degradation, which was verified to be ascribed to the formed carbonate radical (CO3•-) through the reaction of HCO3- with HO•. The second-order rate constant of CO3•- with SMX was determined to be 2.58 × 108 M-1 s-1. In UV/NO3-/HCO3- system, the reactive species for SMX removal were HO• and CO3•-, and the contribution of CO3•- to SMX degradation might be much higher than that of HO•. The concentration of NO3- was almost unchanged after reaction in UV/NO3- and UV/NO3-/HCO3- systems because of its regeneration. Based on the detected four transformation products, the possible degradation pathways of SMX in UV/NO3-/HCO3- system were proposed including hydroxylation, amino-oxidation and bond cleavage.