Performance and mechanisms of sulfadiazine removal using persulfate activated by Fe3O4@CuOx hollow spheres

Mechanism of Sulfate Radical Formation on Activation of Persulfate Using Doped Metal Oxide and Its Role in Degradation of Tartrazine Dye in an Aqueous Solution

Degradation of tartrazine dye (TZD) was performed in this study using sulfate radicals (SO4•-) generated from the activated sodium persulfate (SPS) using Fe3O4@PDA nanoparticles (NPs). The NPs were characterized by Fourier transform infrared (FTIR), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectroscopy (EDX). The average particle size of the NPs was 17.49 nm from XRD analysis. The presence of the C-N group at 1129 cm-1 in FTIR and 2.54% of the nitrogen element identified from the EDX plot was evidence of successful doping of polydopamine (PDA). Superparamagnetic nature with a decrease in the Ms value to 42.015 emu/g after doping was determined. Doping was further confirmed by XPS analysis with binding energies at 399.68 and 400.99 eV. The average particle size from HRTEM analysis was 21.47 nm with a lattice spacing of 0.30 nm. Turnover number (TON) and turnover frequency (TOF) values for Fe3O4@PDA were determined to be 3.72 and 0.0248 min-1 with respect to different systems, respectively. Optimum conditions for the Fe3O4@PDA/SPS system were 50 ppm TZD, 0.9 g/L catalyst, 12 mM SPS, and pH 4 with 94.68% efficiency in 150 min. The inhibition effect of ions in TZD degradation followed the order humic acid Collapse

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Affiliation(s)

Fetcia Jackulin Department of Chemical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam 603 110, Tamil Nadu, India Centre of Excellence in Water Research (CEWAR), Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam 603 110, Tamil Nadu, India
Ponnusamy Senthil Kumar Centre for Pollution Control and Environmental Engineering, School of Engineering and Technology, Pondicherry University, Kalapet, Puducherry 605014, India
Chitra Boobalan Department of Chemical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam 603 110, Tamil Nadu, India Centre of Excellence in Water Research (CEWAR), Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam 603 110, Tamil Nadu, India
Gayathri Rangasamy Department of Civil Engineering, Faculty of Engineering, Karpagam Academy of Higher Education, Pollachi Main Road, Eachanari Post, Coimbatore 641021, Tamil Nadu, India

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Degradation of Remazol Brilliant Blue Dye Using Persulfate Activated by Fe3O4@PDA Nanoparticles: Kinetic Studies, Radical Determination, and Phytotoxicity Test

In the current research work, an advanced oxidation process was applied to the degradation of Remazol brilliant blue dye (RBBD) using a sulfate radical. Fe3O4@PDA nanoparticles were synthesized using coprecipitation and self-polymerization techniques. Nanoparticle formation was confirmed by XRD, FTIR, FESEM-EDX, VSM, and XPS analyses. The crystalline nature of the material showed that it possessed a spherical shape with an Ms value of 58 emu/g. The elemental composition and binding energy from EDX and XPS analyses showed successful doping. Batch studies were conducted, and experimental studies showed that the optimum condition for degradation of 90 ppm of RBBD was 0.3 g/L of nanomaterial, 20 mM PS at pH 3, achieving 91.35% degradation. The kinetic model suitable for this study was a pseudo-second-order kinetic model with R2 value >0.9. From the radical identification tests, sulfate radicals played a dominant role in degradation, and to confirm it, EPR analysis was conducted using DMPO. A stability test was performed for 5 cycles in which the degradation efficiency was reduced appreciably. From XPS, XRD, and EDX analyses, the elemental composition and oxidation state of the recycled material used in the fifth cycle showed variation in a negligible manner when compared to the fresh catalyst used in the first cycle of the degradation experiment. Intermediate identification was done by GCMS analysis, and it disclosed the formation of aliphatic products from the degradation of RBBD with less toxicity. Phytotoxicity analysis was conducted using green grams for 10 days, and it proved that intermediates formed in the solution were nontoxic to the plants. Additionally, TOC and COD removal % were attained to be 80.021 and 80.903%, respectively, which confirm the mineralization efficacy. Hence, this research work proved the efficient performance of the catalyst for RBBD degradation with less formation of intermediates, and therefore, this technique is most suitable for the reduction of water pollution.

Efficient peroxymonosulfate activation by nanoscale zerovalent iron for removal of sulfadiazine and sulfadiazine resistance bacteria: Sulfidated modification or not

Whether it's necessary to extra chemical synthesis steps to modify nZVI in peroxymonosulfate (PMS) activation process are worth to further investigation. The 56 mg/L nZVI/153.65 mg/L PMS and 56 mg/L sulfidated nZVI (S-nZVI) (S/Fe molar ratio = 1:5)/153.65 mg/L PMS) processes could effectively attain 97.7% (with kobs of 3.7817 min-1) and 97.0% (with kobs of 3.4966 min-1) of the degradation of 20 mg/L sulfadiazine (SDZ) in 1 min, respectively. The nZVI/PMS system could quickly achieve 85.5% degradation of 20 mg/L SDZ in 1 min and effectively inactivate 99.99% of coexisting Pseudomonas. HLS-6 (5.81-log) in 30 min. Electron paramagnetic resonance tests and radical quenching experiments determined SO4•-, HO•, 1O2 and O2•- were responsible for SDZ degradation. The nZVI/PMS system could still achieve the satisfactory degradation efficiency of SDZ under the influence of humic acid (exceeded 96.1%), common anions (exceeded 67.3%), synthetic wastewater effluent (exceeded 90.7%) and real wastewater effluent (exceeded 78.7%). The high degradation efficiency of tetracycline (exceeded 98.9%) and five common disinfectants (exceeded 96.3%) confirmed the applicability of the two systems for pollutants removal. It's no necessary to extra chemical synthesis steps to modify nZVI for PMS activation to remove both chemical and biological pollutants.

Dissolved organic matter accelerates microbial degradation of 17 alpha-ethinylestradiol in the presence of iron mineral

Dissolved organic matter (DOM) and iron minerals widely existing in the natural aquatic environment can mediate the migration and transformation of organic pollutants. However, the mechanism of interaction between DOM and iron minerals in the microbial degradation of pollutants deserves further investigation. In this study, the mechanism of 17 alpha-ethinylestradiol (EE2) biodegradation mediated by humic acid (HA) and three kinds of iron minerals (goethite, magnetite, and pyrite) was investigated. The results found that HA and iron minerals significantly accelerated the biodegradation process of EE2, and the highest degradation efficiency of EE2 (48%) was observed in the HA-mediated microbial system with pyrite under aerobic conditions. Furthermore, it had been demonstrated that hydroxyl radicals (HO•) was the main active substance responsible for the microbial degradation of EE2. HO• is primarily generated through the reaction between hydrogen peroxide secreted by microorganisms and Fe(II), with aerobic conditions being more conducive. The presence of iron minerals and HA could change the microbial communities in the EE2 biodegradation system. These findings provide new information for exploring the migration and transformation of pollutants by microorganisms in iron-rich environments.

Research progress of persulfate activation technology

Persulfate-based advanced oxidation processes (PS-AOPs) have been widely investigated by academia and industry due to their high efficiency and selectivity for the removal of trace organic pollutants from complex water substrates. PS-AOPs have been extensively studied for the degradation of pesticides, drugs, halogen compounds, dyes, and other pollutants. Utilizing bibliometric statistics, this review presents a comprehensive overview of persulfate-based advanced oxidation technology research over the past decade. The number of published articles about persulfate activation has steadily increased during this time, reflecting extensive international collaboration. Furthermore, this review introduces the most widely employed strategies for persulfate activation reported in the past 10 years, including carbon material activation, photocatalysis, transition metal activation, electrochemical activation, ultrasonic activation, thermal activation, and alkali activation. Next, the potential activation mechanisms and influencing factors, such as persulfate dosage during activation, are discussed. Finally, the application of PS-AOPs in wastewater treatment and in situ groundwater treatment is examined. This review summarizes the previously reported experiences of persulfate-based advanced oxidation technology and presents the current application status of PS-AOPs in organic pollution removal, with the aim of avoiding misunderstandings and providing a solid foundation for future research on the removal of organic pollutants.

Development of natural attapulgite derived ferromanganese spinel oxides as heterogeneous catalysts for persulfate activation of tetracycline degradation

Ferromanganese spinel oxides (MnFe2O4, MFO) have been proven effective in activating persulfate for pollutants removal. However, their inherent high surface energy often leads to agglomeration, diminishing active sites and consequently restricting catalytic performance. In this study, using Al-MCM-41 (MCM) mesoporous molecular sieves derived from natural attapulgite as a support, the MFO/MCM composite was synthesized through dispersing MnFe2O4 nanoparticles on MCM carrier by a simple hydrothermal method, which can effectively activate persulfate (PS) to degrade Tetracycline (TC). The addition of Al-MCM-41 can effectively improve the specific surface area and adsorption performance of MnFe2O4, but also reduce the leaching amount of metal ions. The MFO/MCM composite exhibited superior catalytic reactivity towards PS and 84.3% removal efficiency and 64.7% mineralization efficiency of TC (20 mg/L) was achieved in 90 min under optimized conditions of 0.05 mg/L catalyst dosage, 5 mM PS concentration, room temperature and no adjustment of initial pH. The effects of various stoichiometric MFO/MCM ratio, catalyst dosage, PS concentration, initial pH value and co-existing ions on the catalytic performance were investigated in detail. Moreover, the possible reaction mechanism in MFO-MCM/PS system was proposed based on the results of quenching tests, electron paramagnetic resonance (EPR) and XPS analyses. Finally, major degradation intermediates of TC were detected by liquid chromatography mass spectrometry technologies (LC-MS) and four possible degradation pathways were proposed. This study enhances the design approach for developing highly efficient, environmentally friendly and low-cost catalysts for the advanced treatment process of antibiotic wastewater.

Sulfadiazine removal efficiency with persulfate driven by electron-rich Cu-beta zeolites

Surface electron transport and transfer of catalysts have important consequences for persulfate (PS) activation in PS system. In this paper, an electron-rich Cu-beta zeolites catalyst was synthesized utilizing a straightforward solid-state ion exchange technique to efficiently degrade sulfadiazine. The X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) results revealed that Cu element substitutes Al element and enters the beta molecular sieve framework smoothly. Furthermore, the X-ray photoelectron spectroscopy (XPS) measurements demonstrated that the Cu-beta catalyst is primarily Cu0. Cu-beta zeolites catalyst can exhibit excellent catalytic activity to degrade sulfadiazine with the oxidant of PS. The optimal sulfadiazine removal performance was explored by adjusting reaction parameters, including sulfadiazine concentration, catalyst dosage, oxidant dosage, and solution pH. The sulfadiazine removal efficiency in the Cu-beta zeolites/PS system could reach 90.5% at the optimal reaction condition ([PS]0 = 0.5 g/L, [Cu-beta zeolites]0 = 1.0 g/L, pH = 7.0) with 50 mg/L of sulfadiazine. Meanwhile, The degradation efficiency was less affected by anionic interference (Cl-, SO4-, HCO3-). The surface electron transport and transfer of the Cu-beta zeolites catalyst were significant causes for the remarkable degradation performance. According to electron paramagnetic resonance (EPR) and quenching studies, the Cu-beta zeolites/PS system was mostly dominated by SO4•- in the degradation of sulfadiazine. Furthermore, two possible pathways for sulfadiazine degradation were proposed according to the analysis of intermediate products detected by the liquid chromatography-mass spectrometry (LC-MS).

Photodegradation performance and mechanism of sulfadiazine in Fe(III)-EDDS-activated persulfate system

In order to overcome the shortcomings in the traditional Fenton process, Fe(III)-EDDS-activated persulfate advanced oxidation process under irradiation is carried out as a promising technology. The photodegradation of sulfadiazine (SD) in Fe(III)-EDDS-activated persulfate system was investigated in this paper. The results showed that SD could be effectively degraded in Fe(III)-EDDS/S 2 O 8 2 - /hv system. The effects of Fe(III):EDDS molar ratio, the concentration of Fe(III)-EDDS, and the concentration of S 2 O 8 2 - on SD degradation were explored. At neutral pH, when Fe(III):EDDS = 1:1, Fe(III)-EDDS = 0.1 mM, S 2 O 8 2 -  = 1.5 mM, the best SD degradation was achieved. The experiment of external influence factors showed that the degradation of SD could be obviously inhibited by the presence of C O 3 2 - , S O 4 2 - , whereas the degradation of SD was almost unaffected by the addition ofCl-. The degradation of SD could be slightly inhibited by the presence of humic acid and NO3-. The effect of pH on SD degradation was investigated, and SD could be degraded effectively in the pH range of 3-9. ESR proved that 1O2, ·OH, S O 4 - , and O2- were produced in the process. S O 4 - and ·OH were identified as the main radicals while O2·- also played non-ignorable role. Eleven intermediate products of SD were analysed. The C = N, S-N, and S-C bonds of SD were attacked by radicals firstly, leading to a series of reactions that eventually resulted in the destruction of SD molecules and the formation of small organic molecules.

Insights into the mechanism of persulfate activation with carbonated waste metal adsorbed resin for the degradation of 2,4-dichlorophenol

Superabsorbent resin (SAR) saturated with heavy metals poses a threat to surrounding ecosystem. To promote the reutilization of waste, resins adsorbed by Fe²⁺ and Cu²⁺ were carbonized and used as catalysts (Fe@C/Cu@C) to activate persulfate (PS) for 2,4-dichlorophenol (2,4-DCP) degradation. The heterogeneous catalytic reaction was mainly responsible for 2,4-DCP removal. The synergistic effect of Fe@C and Cu@C was propitious to 2,4-DCP degradation. Fe@C/Cu@C with a ratio of 2:1 showed the highest performance of 2,4-DCP removal. 40 mg/L 2,4-DCP was completely removed within 90 min under reaction conditions of 5 mM PS, pH = 7.0 and T = 25 °C. The cooperation of Fe@C and Cu@C facilitated the redox cycling of Fe and Cu species to supply accessible PS activation sites, enhancing ROS generation for 2,4-DCP degradation. Carbon skeleton enhanced 2,4-DCP removal via radical/nonradical oxidation pathways and via its adsorption to 2,4-DCP. SO₄˙-, HO˙ and O₂^•- were the dominate radical species involved in 2,4-DCP destruction. Meanwhile, the possible pathways of 2,4-DCP degradation were proposed based on GC-MS. Finally, recycling tests proved catalysts exhibited recyclable stability. Aiming to resource utilization, Fe@C/Cu@C with satisfactory catalysis and stability, is promising catalyst for contaminated water treatment.

Ultrafine ZnCo2O4 QD-incorporated carbon nitride mediated peroxymonosulfate activation for norfloxacin oxidation: performance, mechanisms and pathways

Recently, peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are being actively investigated as a potential technology for water decontamination and many efforts have been made to improve the activation efficiency of PMS. Herein, a 0D metal oxide quantum dot (QD)-2D ultrathin g-C3N4 nanosheet (ZnCo2O4/g-C3N4) hybrid was facilely fabricated through a one-pot hydrothermal process and used as an efficient PMS activator. Benefiting from the restricted growth effect of the g-C3N4 support, ultrafine ZnCo2O4 QDs (∼3-5 nm) are uniformly and stably anchored onto the surface. The ultrafine ZnCo2O4 possesses high specific surface areas and shortened mass/electron transport route so that the internal static electric field (Einternal) formed in the interface between p-type ZnCo2O4 and the n-type g-C3N4 semiconductor could speed up the electron transfer during the catalytic reaction. This thereby induces the high-efficiency PMS activation for rapid organic pollutant removal. As expected, the ZnCo2O4/g-C3N4 hybrid catalysts significantly outperformed individual ZnCo2O4 and g-C3N4 in catalytic oxidative degradation of norfloxacin (NOR) in the presence of PMS (95.3% removal of 20 mg L-1 of NOR in 120 min). Furthermore, the ZnCo2O4/g-C3N4-mediated PMS activation system was systematically studied in terms of the identification of reactive radicals, the impact of control factors, and the recyclability of the catalyst. The results of this study demonstrated the great potential of a built-in electric field-driven catalyst as a novel PMS activator for the remediation of contaminated water.

A Novel Strategy of Combined Pulsed Electro-Oxidation and Electrolysis for Degradation of Sulfadiazine

A combination of the peroxymonosulfate (PMS) electro-activation process and the electro-oxidation process driven by a pulsed electric field (PEF) was used to degrade sulfadiazine (SND) wastewater. Mass transfer is the limiting step of electrochemical processes. The PEF could enhance mass transfer efficiency by reducing the polarization effect and increasing the instantaneous limiting current compared with the constant electric field (CEF), which could benefit the electro-generation of active radicals. The degradation rate of SND after 2 h was 73.08%. The experiments investigated the effects of operating parameters of pulsed power supply, PMS dosage, pH value and electrode inter distance on the degradation rate of SND. The predicted response value of single-factor performance experiments was obtained as 72.26% after 2 h, which was basically consistent with the experimental value. According to the quenching experiments and EPR tests, both SO₄^•- and •OH were present in the electrochemical processes. The generation of active species were significantly greater in the PEF system than that in the CEF system. Moreover, four kinds of intermediate products were detected during the degradation by LC-MS. This paper presents a new aspect for electrochemical degradation of sulfonamide antibiotics.

Kinetics Driven by Hollow Nanoreactors: An Opportunity for Controllable Catalysis

As a novel class of catalytic materials, hollow nanoreactors offer new opportunities for improving catalytic performance owing to their higher controllability on molecular kinetic behavior. Nevertheless, to achieve controllable catalysis with specific purposes, the catalytic mechanism occurring inside hollow nanoreactors remains to be further understood. In this context, this Review presents a focused discussion about the basic concept of hollow nanoreactors, the underlying theory for hollow nanoreactor-driven kinetics, and the intrinsic correlation between key structural parameters of hollow nanoreactors and molecular kinetic behaviors. We aim to provide in-depth insights into understanding kinetics occurred within typical hollow nanoreactors. The perspectives proposed in this paper may contribute to the development of the fundamental theoretical framework of hollow nanoreactor-driven catalysis.

A Review of Persulfate Activation by Magnetic Catalysts to Degrade Organic Contaminants: Mechanisms and Applications

All kinds of refractory organic pollutants in environmental water pose a serious threat to human health and ecosystems. In recent decades, sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted extensive attention in the removal of these organic pollutants due to their high redox potential and unique selectivity. This review first introduces persulfate activation by magnetic catalysts to degrade organic contaminants. We present the advances and classifications in the generation of sulfate radicals using magnetic catalysts. Subsequently, the degradation mechanisms in magnetic catalysts activated persulfate system are summarized and discussed. After an integrated presentation of magnetic catalysts in SR-AOPs, we discuss the application of persulfate activation by magnetic catalysts in the treatment of wastewater, landfill leachate, biological waste sludge, and soil containing organic pollutants. Finally, the current challenges and perspectives of magnetic catalysts that activated persulfate systems are summarized and put forward.

Waste coal cinder catalyst enhanced electrocatalytic oxidation and persulfate advanced oxidation for the degradation of sulfadiazine

Waste coal cinder, a kind of waste cinder discharged from coal combustion of thermal power plants, industrial and civil boilers, and other equipment, was rich in metal oxides with catalytic activity. In this work, waste coal cinder was used to enhance electrochemical coupling peroxymonosulfate (PMS) advanced oxidation degradation of sulfadiazine (SD). The surface morphology, elemental composition, and electrocatalytic activity of waste coal cinder were characterized by various characterization instruments. The results show that compared with simple electrocatalytic oxidation, electrocatalytic oxidation + waste coal cinder and electrocatalytic coupled persulfate oxidation, electrocatalytic oxidation + PMS advanced oxidation + waste coal cinder has the largest removal efficiency (99.95%) and mineralization rates (90.16%) of SD in 90 min, indicating that the introduction of waste coal cinder greatly increases the degradation efficiency. •OH and SO₄^-• were detected during the process of degradation. The optimal degradation process parameters were explored through different voltage, pH, plate spacing, aeration flow rate, potassium peroxymonosulfate sulfate complex salt dose, and Na₂SO₄ dosage. Cycling experiments show waste coal cinder has good structural stability. Through the analysis of triple quadrupole liquid chromatography-mass spectrometry (LC-MS), we put forward three possible ways of SD degradation. This research will provide a novel vision for water treatment.

Application of sulfate radicals-based advanced oxidation technology in degradation of trace organic contaminants (TrOCs): Recent advances and prospects

The large amount of trace organic contaminants (TrOCs) in wastewater has caused serious impacts on human health. In the past few years, Sulfate radical (SO₄^•-) based advanced oxidation processes (SR-AOPs) are widely recognized for their high removal rates of recalcitrant TrOCs from water. Peroxymonosulfate (PMS) and persulfate (PS) are stable and non-toxic strong oxidizing oxidants and can act as excellent SO₄^•- precursors. Compared with hydroxyl radicals(·OH)-based methods, SR-AOPs have a series of advantages, such as long half-life and wide pH range, the oxidation capacity of SO₄^•- approaches or even exceeds that of ·OH under suitable conditions. In this review, we present the progress of activating PS/PMS to remove TrOCs by different methods. These methods include activation by transition metal, ultrasound, UV, etc. Possible activation mechanisms and influencing factors such as pH during the activation are discussed. Finally, future activation studies of PS/PMS are summarized and prospected. This review summarizes previous experiences and presents the current status of SR-AOPs application for TrOCs removal. Misconceptions in research are avoided and a research basis for the removal of TrOCs is provided.

The photodegradation of 17 alpha-ethinylestradiol in water containing iron and dissolved organic matter

17 alpha-ethinylestradiol (EE2) in natural waters can seriously harm ecosystems and human health. Dissolved organic matter (DOM) and iron minerals are ubiquitous in natural waters, and they can shorten the half-life of EE2 in the natural environment. The interaction between dissolved organics and iron affects pollutants' transformation pathways. The mechanism of EE2's adsorption on hematite, magnetite and pyrite was studied. A photo-Fenton system was constructed in which humic acid (HA) and iron minerals degraded EE2 under simulated natural light conditions. Pyrite showed the best adsorption and degradation in acidic conditions (52%) for 5 h. Hydroxyl radical was found to be the main active substance in the photodegradation. The degradation products of EE2 were identified and possible degradation pathways were inferred. These results can contribute to the understanding of the transformation pathways of persistent organic pollutants in natural waters.

Preparation, characterization, and applications of Fe-based catalysts in advanced oxidation processes for organics removal: A review

Fe-based catalysts as low-cost, high-efficiency, and non-toxic materials display superior catalytic performances in activating hydrogen peroxide, persulfate (PS), peracetic acid (PAA), percarbonate (PC), and ozone to degrade organic contaminants in aqueous solutions. They mainly include ferrous salts, zero-valent iron, iron-metal composites, iron sulfides, iron oxyhydroxides, iron oxides, and supported iron-based catalysts, which have been widely applied in advanced oxidation processes (AOPs). However, there is lack of a comprehensive review systematically reporting their synthesis, characterization, and applications. It is imperative to evaluate the catalytic performances of various Fe-based catalysts in diverse AOPs systems and reveal the activation mechanisms of different oxidants by Fe-based catalysts. This work detailedly summarizes the synthesis methods and characterization technologies of Fe-based catalysts. This paper critically evaluates the catalytic performances of Fe-based catalysts in diverse AOPs systems. The effects of solution pH, reaction temperature, coexisting ions, oxidant concentration, catalyst dosage, and external energy on the degradation of organic contaminants in the Fe-based catalyst/oxidant systems and the stability of Fe-based catalysts are also discussed. The activation mechanisms of various oxidants and the degradation pathways of organic contaminants in the Fe-based catalyst/oxidant systems are revealed by a series of novel detection methods and characterization technologies. Future research prospects on the potential preparation means of Fe-based catalysts, practical applications, assistive technologies, and impact in AOPs are proposed.

Constructing electron transfer pathways and active centers over W18O49 nanowires by doping Fe3+ and incorporating g-C3N5 for enhanced photocatalytic nitrogen fixation

A compound constructed from fluffy and porous g-C₃N₅ with OV-rich Fe-W₁₈O₄₉ was employed in the photocatalytic nitrogen fixation. The formation rate of ammonia reached 131.6 μmol g⁻¹ h⁻¹ when Fe-W₁₈O₄₉/g-C₃N₅ was employed as the catalyst.