Pyrolysis Of Urea Research Articles

(Ag–NiO)/g-C3N4 with enhanced photocatalytic activity for hydrogen evolution under simulated sunlight

g-C3N4 is a promising metal-free photocatalyst for hydrogen production, whose application is difficult due to the low mobility of charge carriers and rapid electron-hole recombination. Here we propose a new route to improve its response to simulated sunlight and prevent electron-hole recombination by grafting mixed Ag–NiO (1:1 nominal Ag/NiO weight ratio) materials, as an alternative to platinum group metal co-catalysts. g-C3N4 was prepared by urea pyrolysis, whereas Ag–NiO was prepared by a co-precipitation method, and then the composites were prepared by physical mixing using sonication-grinding. The presence of Ag–NiO on the surface plays a key role in accepting excited electrons and enhancing their lifetime for a subsequent reduction of protons to hydrogen. Hydrogen production was carried out from the photoreforming of ethanol under simulated sunlight. The results revealed that 2% (Ag–NiO)/g-C3N4 is effective among others with 5.2 times higher H2 production than unmodified g-C3N4. The percentage of ethanol in the ethanol/water ratio is very important as we have found that with increasing its quantity, the evolution of hydrogen becomes significant.

Ammonia-Cyanuric Acid Co-Production in Boiler Denitrification System.

In response to the issues of poor economic efficiency and high CO2 emissions in the urea-to-ammonia technology of thermal power plants, this paper innovatively proposes a new ammonia production process for thermal power plants. This process utilizes the waste heat of thermal power plant boilers and conducts urea pyrolysis through two-stage heating to prepare ammonia and cyanuric acid. From this, the prepared ammonia can be used in the denitrification process of thermal power plants, and the prepared cyanuric acid can bring additional benefits to thermal power plants. The optimal process scheme was determined through orthogonal experiments of urea pyrolysis. And with the help of Aspen Plus software, a whole-process modeling analysis of urea pyrolysis experiments was carried out to investigate the influences of the melting temperature, melting time, reaction temperature, and reaction time on the process. The results show that when the melting temperature was 160 °C, the melting time was 45 min, the reaction temperature was 240 °C, and the reaction time is 20 min, which was the best scheme, 18.45% ammonia and 52.35% cyanuric acid could be obtained. Through the combined analysis of the Aspen Plus simulation and urea pyrolysis experiments, it was found that the melting temperature should be controlled within 160-167 °C, the melting time should be controlled within 40-45 min, the reaction temperature should be controlled within 240-245 °C, and the reaction time should be controlled within 15-20 min. Compared with the existing urea-to-ammonia process, this process has the advantages of nearly zero emissions and good economic benefits, thus providing reliable research data support for future industrialization.

Self-catalysed breakdown of titanate nanotubes by graphitic carbon nitride resulting in enhanced hydrogen production

Efficient design of a photocatalyst is an important step in realizing real world applications. In this work, using in-situ catalysis we have prepared and investigated a titanate nanotube (TiNT)/ graphitic carbon nitride nanocomposite, which after optimization shows excellent hydrogen production efficiency of 2.3 mmolg−1h−1, much improved compared to GCN, which achieved a rate of 0.56 mmolg−1h−1. We can conclude that pyrolysis of urea to carbon nitride also self catalyses the breakdown of TiNT into anatase TiO2 nanoparticles, resulting in a nanocomposite material comprising TiO2 and heterojunctions with GCN. After heating and modification the TiO2 shows a conduction band edge with a more negative potential than the H+/H2 potential, which along with the ideal position of the GCN CB edge facilitates hydrogen production under light irradiation. This novel method can be viewed as a general method for improving catalysis synthesis and design, whilst simultaneously reducing the complexity and energy footprint of active catalyst synthesis.

Enhanced La(III) adsorption performance and mechanism of urea-modified dolomite composite adsorbent

Dolomite, a prevalent mineral in rock formations, often coexists with various minerals, impacting their properties and typically being discarded as waste in the extraction process of other minerals. This research introduces a straightforward and effective technique for co-calcining urea with natural dolomite at 550℃, yielding a novel composite adsorbent designated as CN/xDO, where ‘x’ denotes the proportion of dolomite incorporated. During the preparation, urea promotes the conversion of dolomite to nano calcite, and the gas produced by urea pyrolysis during the calcination process has a cavitation effect on the material, enhancing its surface properties. BET analysis reveals that the specific surface area and total pore volume of CN/xDO notably surpass those of pure dolomite, with CN/0.6DO achieving 2.9479 m2/g and 0.0382 cm3/g, respectively. CN/0.6DO demonstrates an adsorption capacity of 237.91 mg/g for La(III) within 360 min at 298 K, which is 16.9 times greater than that of untreated dolomite (14.05 mg/g). The maximum adsorption capacity of CN/0.6DO for La(III) (C0 = 500 mg/L) reaches 382.94 mg/g at 308 K, exceeding the majority of adsorbents documented in the literature. The comparative analysis of batch adsorption experiments and material characterization before and after the adsorption process reveals that the mechanisms adsorption of La(III) adsorption by CN/xDO include physical adsorption, cation-π interactions, ion exchange, and complexation with oxygen-containing functional groups, especially −OH, CO32-. This study broadens the application of dolomite in adsorption and introduces a new strategy for the efficient recovery of rare earth elements from wastewater, consistent with the principles of sustainable development.

One-step synthesis of g-C3N4/TiVCTx MXene electrodes for lithium-ion batteries and supercapacitors

The wide-ranging application of lithium-ion batteries (LIBs) is currently restricted by their slow ion dynamics and low capacity, which hinders the development of innovative electrode materials. Herein, the graphitic carbon nitride (g-C3N4)/TiVCTx composite was fabricated through in situ pyrolysis of urea to generate g-C3N4 nanosheets on the surface of TiVCTx nanosheets. The as-prepared g-C3N4 protective layer can reduce the degree of oxidation of TiVCTx MXene, restrain the re-stacking of TiVCTx nanosheets and minimize the risk of undesirable side reactions. As expected, the g-C3N4/TiVCTx electrode exhibits remarkable specific capacity of 1025.3 mAh/g after 150 cycles at 0.1 A/g and 558.3 mAh/g after 1000 cycles at 1.0 A/g for LIBs and a high specific capacitance of 508.9F g−1 in 0.5 M Na2SO4 electrolyte at 1.0 A/g after 7000 cycles for supercapacitors (SCs). Furthermore, the assembled g-C3N4/TiVCTx-30//LiFePO4 full cell presents stable specific capacity of 505.5 mAh/g at 0.1 A/g after 100 cycles and 255.2 mAh/g at 0.1 A/g along with a Coulombic efficiency of 97.9 % after 50 cycles at − 20 °C, demonstrating excellent low temperature tolerance. Density functional theory (DFT) calculation results indicated that the g-C3N4/TiVCTx-30 exhibits strongest adsorption capacity for Li+ with an adsorption energy of −3.85 eV. The introduction of g-C3N4 improves the insertion and extraction kinetics of Li+, effectively reducing the diffusion barrier. Consequently, the g-C3N4/TiVCTx-30 electrode exhibits potential application prospects in high-performance electrochemical energy storage devices. Our work provides valuable insights and significant research implications for improving the specific capacity and stability of TiVCTx MXene in the field of energy storage.

Synthesis of N-doped porous biochar from chemical pollutant for efficient sulfadiazine degradation: Performance, mechanism and bio-toxicity assessment

Turning chemical wastes into valuable materials presently is a key challenge. Therefore, a facile method was employed upon synthesis of an N-doped porous biochar (NPBC) catalyst via pyrolysis of chemical pollutant (reactive red 2, RR2), urea, and NaHCO3. Using NaHCO3 activation, the NPBC/PMS system exhibited excellent catalytic efficiency for sulfadiazine (SDZ) degradation, which was attributed to the porous structure with abundant active species of graphitic C/N, C=O, –COOH, and C–S–C. Significantly, the NPBC displayed excellent environmental suitability, catalytic universality for the decomposition of common organic pollutants (i.e. bisphenol A, ciprofloxacin, tetracycline, and sulfamethoxazole) and catalytic recycling stability. In addition, free radical quenching and mechanism inspection demonstrated that 1O2 is the dominating reactive oxygen species (ROS) in the NPBC/PMS system. The most probable degradation pathway and mechanism are proposed. Finally, the biotoxicity of SDZ before and after degradation was evaluated by ECOSAR analysis and the germination tests of wheat seeds. This study not only provides a rational method for the facile synthesis of valuable materials from chemical pollutants, but also presents a direction for discovering metal-free catalysts with remarkable activity for water decontamination in the future.

Enhanced photocatalytic activities of FCNO nanoparticles on graphitic carbon nitride

Efficient charge separation and broadened light absorption are of crucial importance for photocatalytic environmental remediation, and graphitic carbon nitride (g-C3N4) is a very promising photocatalyst for this purpose. Herein, the synthesis of FCNO nanoparticles embedded within graphitic carbon nitride (g-C3N4) by hydrothermal route assisted with pyrolysis of urea was presented. The g-C3N4 was obtained from an abundantly available precursor urea and the synthesis process played double role. Urea reacted with metal salts to convert them into metallic oxides and yielded g-C3N4. The experimental results revealed the in-situ fabrication of FCNO nanoparticles and formation of g-C3N4. The band gap narrowing made it possible that the samples were able to show a wide range of visible light absorption which made them suitable for photocatalytic activity studies. Thus, the materials were utilized for the visible light-based photocatalytic degradation of methylene blue dye. Photocatalytic degradation efficiency with ~93 % was achieved by the composite FCNO/g-C3N4 (50:50). The present approach for the synthesis of materials was proved to be cost-effective and time saving which enabled their use as recyclable photocatalyst.

Chemical reaction process and dynamic characteristics of urea pyrolysis products in inhibiting gas explosion

During the coal mining process, gas explosions pose significant hazards, causing casualties and property losses. In order to develop new types of inhibitors for gas explosions, this paper explores the reaction mechanisms of urea pyrolysis products NH3 and HNCO inhibiting gas explosions based on density functional theory (DFT), transition state theory, and grand canonical ensemble Monte Carlo method (GCMC). It analyzes the reaction processes and kinetic characteristics of urea pyrolysis products with key radicals and gas molecules involved in explosions from a microscopic dynamic perspective. The results show that urea pyrolysis products exhibit good inhibition effects on active radicals involved in explosion reactions·NH3 and HNCO show stronger van der Waals forces in electrostatic attraction towards O2 and *H, respectively, and faster rate advantages in reaction rate constants. The lower Gibbs free energy barrier indicates higher reaction activity of pyrolysis products, thereby diluting the concentration of key radicals involved in explosion reactions and effectively inhibiting explosion key elementary reactions (R32, R38, R53, R57, R156, and R170). This study provides new insights into the microscopic inhibition mechanism of urea pyrolysis products on gas explosions, offering a new approach for designing more targeted modified inhibitors, which helps reduce the hazards of gas explosions during coal mining and provides scientific support and technical guidance for safe coal mining production.

Introducing Br, K, and cyano group into carbon nitride for efficient photocatalytic hydrogen peroxide production then in situ tetracycline mineralization

In this work, Br, K-doped and cyano group-rich carbon nitride (CN) were prepared via pyrolysis of molten urea and 6-Bromopyridine-3-carbaldehyde, followed by re-calcination with potassium thiocyanate. The hydrogen peroxide (H2O2) evolution and in situ tetracycline (TC) mineralization performances of the prepared samples were studied. The optimal sample could produce 9127 μmol g–1 h–1 H2O2 from 10 vol% ethanol solution and air atmosphere, which was 10.9 times higher than that of pristine CN. With addition of 4 mg L–1 Fe2+ ions, 97.2% of TC (10 mg L–1) and 98.7% of total organic carbon were removed in 30 min under the actions of holes, hydroxyl and superoxide radicals. The high H2O2 yield and TC mineralization ratio were attributed to the increased light absorption, efficient electrons-holes separation, enhanced surface O2 adsorption (0.3878 mmol g−1), and accelerated conversion from Fe3+ to Fe2+ ions. Meanwhile, the system possessed good reusability in H2O2 evolution and TC removal. It is expected that this work can provide new ideas to design CN-based photo-Fenton system to treat wastewater.

N-doped Bi2S3 nanoflower as an efficient supercapacitor electrode based on the highly concentrated salt electrolyte

As a low-cost and environmentally friendly new energy storage device, supercapacitors suffer from a low energy density, significantly restricting their potential applications. Hence, exploring supercapacitors with elevated energy density and wide potential windows has become a key research focus. Metal sulfides are receiving notable interest for their benefits, such as superb electrical conductivity, efficient charge storage, and cost-effectiveness. This study utilized ultrasonic methods to rapidly prepare Bi2S3 nanoflowers, followed by the synthesis of N-doped Bi2S3 through urea pyrolysis. And its supercapacitor behavior of N-doped Bi2S3 in 10 M NaNO3 electrolyte was studied. The assembled N–Bi2S3//N–Bi2S3 symmetric capacitor exhibited a high energy density of 112 Wh kg−1 when power density is 7828 W kg−1. The study provides a new scientific avenue for exploring the design of supercapacitors with high capacity and wide potential windows.

Microwave Synthesis of (g‐C3N4)−BiVO4: Selective Adsorption and Photocatalytic Activity Towards Dye Degradation

AbstractPhotocatalytic degradation of pollutants has been extensively studied. Among the investigated photocatalysts, BiVO4 has emerged as a very promising material. BiVO4 is known for its narrow band‐gap energy suitable for solar‐driven reactions; however, it is subjected to challenges such as charge recombination and slow electron transfer kinetics. Combining BiVO4 with g‐C3N4 proves promising, aligning energy levels and leveraging unique charge transport properties to enhance dye degradation under visible light. This study reports a novel synthesis of g‐C3N4−BiVO4 heterojunction through in‐situ urea pyrolysis, ensuring homogeneous dispersion. While maintaining the monoclinic structure of BiVO4, the heterojunction exhibits increased surface area and a more negative zeta potential, influencing catalyst‐substrate to be degraded interactions. Adsorption studies reveal distinct behaviors with cationic dyes (MB and RhB) forming multilayers, hindering light absorption, and reducing photocatalytic efficiency. Conversely, the heterojunction performs efficiently with the anionic MO dye. Photoelectrochemical studies show that the heterojunction has succeeded in promoting the separation of photogenerated charges. The study lays the groundwork for optimizing synthesis methods and designing nanocomposites with superior photocatalytic activities.

Clozapine-laden carbon dots delivered to the brain via an intranasal pathway: Synthesis, characterization, ex vivo, and in vivo studies

Clozapine, which is widely used to treat schizophrenia, shows low bioavailability due to poor solubility and high first-pass metabolism. The study aimed to design clozapine-loaded carbon dots (CDs) to enhance availability of the clozapine to the brain via intranasal pathway. The CDs were synthesized by pyrolysis of citric acid and urea at 200 °C by hydrothermal technique and characterized by photoluminescence, transmission electron microscopy (TEM), X-ray Photoelectron Spectrometer (XPS), and Fourier transform infrared spectrum (FTIR). The optimized clozapine-loaded CDs (CLZ-CDs-1:3–200) showed a quasi-spherical shape (9–12 nm) with stable blue fluorescence. The CDs showed high drug solubilization capacity (1.5 mg drug in 1 mg/ml CDs) with strong electrostatic interaction with clozapine (drug loading efficiency = 94.74%). The ex vivo release study performed using nasal goat mucosa showed sustained release of clozapine (43.89%) from CLZ-CDs-1:3–200 for 30 h. The ciliotoxicity study (histopathology) confirmed no toxicity to the nasal mucosal tissues using CDs. In the rat model (in vivo pharmacokinetic study), when CDs were administrated by the intranasal route, a significantly higher concentration of clozapine in the brain tissue (Cmax = 58.07 ± 5.36 μg/g and AUCt (µg/h*g) = 105.76 ± 12.31) was noted within a short time (tmax = 1 h) compared to clozapine suspension administered by intravenous route (Cmax = 20.99 ± 3.91 μg/g, AUC t (µg/h*g) = 56.89 ± 12.31, and tmax = 4 h). The high value of drug targeting efficiency (DTE, 486%) index and direct transport percentage (DTP, 58%) indicates the direct entry of clozapine-CDs in the brain via the olfactory route. In conclusion, designed CDs demonstrated a promising dosage form for targeted nose-to-brain delivery of clozapine for the effective treatment of schizophrenia.

Anti-perovskite Co4N nanowhisker rooted on nickel foam to activate peroxymonosulfate for robust degradation of p-nitrophenol via non-radical dominant pathway

The fabrication of metal-nitrogen functional centers that possess features of easy recovery and high performance for degrading organic pollutants through activating peroxymonosulfate (PMS) represents a significant challenge. In this study, we present the synthesis of an anti-perovskite Co4N architecture in a granular nanowhisker form rooted on three-dimensional nickel foam (Co4N/NF) using a hydrothermal method followed by thermal nitridation with ammonia from urea pyrolysis. The resulting Co4N/NF exhibits exceptional efficiency in degrading p-nitrophenol (PNP), achieving a degradation efficiency of 97.8 % and a rate constant of 0.204 min−1 within 20 min. The unique nanostructure of granular nanowhisker Co4N on NF provides abundant surface sites for activating PMS and enhances mass/electron transport, contributing to its excellent degradation capabilities. Additionally, the Co4N/NF material exhibits outstanding stability, easy separation and recovery features, maintaining a degradation efficiency of 90.2 % within 20 min even after five cycles. This study lays the groundwork for developing advanced anti-perovskite nitrides on a 3D substrate to activate PMS for environmental contaminant remediation.

Controllable introducing C, N-defects and oxygen-doping on carbon nitride to tune electronic structure and boost photocatalytic hydrogen evolution

In this work, one-step pyrolysis of molten urea and formaldehyde was adopted to introduce O atom, C and N defects in polymeric carbon nitride (CN) for tuning its electronic structures. Results confirmed that the introduced C, N-defects and O dopant could increase the light absorption (440–640 nm) and suppressed the photogenerated charge recombination of CN. The calculated free energies for H* adsorption revealed that the intrinsic H2 evolution activity of C, N-deficient and O-doped CN increased. Accordingly, the optimal sample exhibited an excellent photocatalytic H2 evolution rate (HER) of 18.95 mmol g−1 h−1 in 10% triethanolamine solution under visible light irradiation (1% Pt as a cocatalyst), which was 6.7 times higher than that of traditional CN (2.83 mmol g−1 h−1). In addition, the HER and yield of benzaldehyde were 1.04 and 4.20 mmol g−1 h−1, respectively in 5% benzyl alcohol solution. This work provides a simple and effective strategy to tune the heptazine and electronic structure of CN for large increasing its photocatalytic activity.

Coaxial nickel cobalt selenide/nitrogen-doped carbon nanotube array as a three-dimensional self-supported electrode for electrochemical energy storage.

Herein, we propose a one-step urea pyrolysis method for preparing a nitrogen-doped carbon nanotube array grown on carbon fiber paper, which is demonstrated as a three-dimensional scaffold for constructing a nickel cobalt selenide-based coaxial array structure. Thanks to the large surface area, interconnected porous structure, high mass loading, as well as fast electron/ion transport pathway of the coaxial array structure, the nickel cobalt selenide/nitrogen-doped carbon nanotube electrode exhibits over 7 times higher areal capacity than that directly grown on carbon fiber paper, and better rate capability. The cell assembled by a nickel cobalt selenide/nitrogen-doped carbon nanotube positive electrode and an iron oxyhydroxide/nitrogen-doped carbon nanotube negative electrode delivers a volumetric capacity of up to 22.5 C cm-3 (6.2 mA h cm-3) at 4 mA cm-2 and retains around 86% of the initial capacity even after 10 000 cycles at 10 mA cm-2. A volumetric energy density of up to 4.9 mW h cm-3 and a maximum power density of 208.1 mW cm-3 are achieved, and is comparable to, if not better than, those of similar energy storage devices reported previously.

Electrochemical and colorimetric dual-channel biosensor based on B and N co-doped carbon nanotubes

Rational design of efficient metal-free doped carbon nanotubes to construct dual-channel sensing platforms remains a challenge. In this study, B and N co-doped carbon nanotubes (BNCNTs) were designed and produced by one-step pyrolysis of P123, boric acid and urea, in which P123 could act as a structural guide to promote the generation of nanotubes. The synergistic effect of B and N doping can modulate the electronic structure of the skeleton, where B can reduce the valence band and the N could excite the conduction band. This can promote electron transport and create more active sites. As a result of the hollow tubes and the synergistic effect of B and N doping, the BNCNTs are an excellent electrocatalyst which could be candidates for electrode modification materials. In addition, the BNCNTs also exhibit excellent peroxidase activity. Therefore, BNCNTs were employed conduct an electrochemical and colorimetric dual channel sensing platform for the detection of uric acid in the range of 2–400 μM and 5–200 μM, with the detection limits of 0.078 μM and 4.52 μM, respectively. This work presents a method for the preparation of metal-free doped carbon nanotubes as multifunctional catalysts for applications in nanozymes, sensing, clinical diagnostics, and other fields.

Porous pie-like nitrogen-doped biochar as a metal-free peroxymonosulfate activator for sulfamethoxazole degradation: Performance, DFT calculation and mechanism

Design and development of low-cost, high-efficient, metal-free persulfate heterogeneous catalysts was a hot research topic. Herein, porous pie-like nitrogen-doped biochar (NBC) was prepared by one step high temperature pyrolysis of rape straw, urea and ZnCl2 mixture, and applied for peroxymonosulfate (PMS) activation toward sulfamethoxazole (SMX) degradation. Among these as-prepared catalysts, the NBC2.0 sample presented the best catalytic activity, with the 99.8 % SMX degradation efficiency in 5 mins and the 81.7 % total organic carbon (TOC) removal rate in 30 mins. Additionally, it could realize an excellent SMX degradation in the wide pH range of 3.0 to 9.0, and possessed the high degradation efficiency in presence of various organic pollutants or in real water environments, indicating its good pH adaptability, universality and practicality. Mechanistic investigations disclosed that the NBC2.0/PMS/SMX system involved both radical and non-radical degradation pathways, with singlet oxygen (1O2) and the direct electron transfer mechanism being the main contributors. The main active reaction sites of NBC were graphitic N, pyridinic N and C = O group, as corroborated by density functional theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) measurement. The possible SMX breakdown routes were determined by intermediate identification. This work provides a promising metal-free persulfate catalyst for environment remediation.

Efficient treatment of actual glyphosate wastewater via non-radical Fenton-like oxidation

Compared to radical oxidative pathway, recent research revealed that non-radical oxidative pathway has higher selectivity, higher adaptability and lower oxidant requirement. In this work, we have designed and synthesized Cu2O/Cu nanowires (CuNWs), by pyrolysis of copper chloride and urea, to selectively generate high-valent copper (CuIII) upon H2O2 activation for the efficient treatment of actual glyphosate wastewater. The detailed characterizations confirmed that CuNWs nanocomposite was comprised of Cu0 and Cu2O, which possessed a nanowire-shaped structure. The electron paramagnetic resonance (EPR) analysis, in situ Raman spectra, chronoamperometry and liner sweep voltammetry (LSV) verified CuIII, which mainly contributed to glyphosate degradation, was selectively generated from CuNWs/H2O2 system. In particular, CuI is mainly oxidized by H2O2 into CuIIIvia dual-electron transfer, rather than simultaneously releasing OH• via single electron transfer. More importantly, CuNWs/H2O2 system exhibited the excellent potential in the efficient treatment of actual glyphosate wastewater, with 96.6% degradation efficiency and chemical oxygen demand (COD) dropped by 30%. This novel knowledge gained in the work helps to apply CuNWs into heterogeneous Fenton-like reaction for environmental remediation and gives new insights into non-radical pathway in H2O2 activation.

Microwave synthesized N-doped carbon dots for dual mode detection of Hg(II) ion and degradation of malachite green dye

One of the most intriguing materials today is carbon dots, which offer a variety of possible uses owing to their distinct photophysical and chemical characteristics. The current study examines the electrochemical and photochemical aspects of carbon dots produced in a single pot for environmental sustainability. Domestic microwave-assisted pyrolysis of urea and glucose yielded chemically synthesized nitrogen-doped carbon dots (microwave synthesized N-doped carbon dots (M-NCDs)) with blue fluorescence and a quantum yield of 14.9 %. High water dispersibility, stability, and biocompatibility were the significant attributes of synthesized M-NCDs. Customarily fluorescent carbon dots were initially used for sensing studies. Fluorescent and electrochemical studies manifest the excellent stability, sensitivity, and selectivity of M-NCDs for mercuric ions. Both methods' Hg (II) procure detection limits of 3.5 nM and 6.1 nM. In addition to sensing traits, the subsequent section deals with the potential of M-NDCs to bring about the exhaustive degradation of malachite green (MG) dye. Within 60 min, 98 % of the dye was catalytically degraded by M-NCD by first-order kinetics based on the Langmuir-Hinshelwood model. This is the first time reporting the catalytic degradation of malachite green dye utilizing carbon dot in its natural form rather than being doped with any metal atom or converted to any composite form.

Enhanced activation of peroxymonosulfate by Fe/N co-doped ordered mesoporous carbon with dual active sites for efficient removal of m-cresol

The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method. During the preparation of the Fe-NC catalyst, the complexation of N elements in urea could anchor Fe, and the formation of C3N4 during urea pyrolysis could also prevent migration and aggregation of Fe species, which jointly improve the dispersion and stability of Fe. The FeN4 sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation, while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process, which together promote catalytic degradation of m-cresol by PMS activation. Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO4-· and ·OH, and partially based on ·OH as the active components, and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed. This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.