Nanocatalysts for the Degradation of Refractory Pollutants

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (15 May 2023) | Viewed by 19530

Special Issue Editors

State Key Laboratory of New Textile Materials and Advanced Processing Technology, Wuhan Textile University, Wuhan, China
Interests: preparation and application of green environment catalytic and adsorption materials; treatment of refractory textile/dye wastewater with 3D printing materials
Special Issues, Collections and Topics in MDPI journals
School of Environment, Nanjing Normal University, Nanjing 210023, China
Interests: advanced oxidation process; photocatalysis; water splitting; H2 production; CO2 reduction
Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450052, China
Interests: photocatalysis; environmental catalysis; water splitting; H2 production; CO2 conversion; electrochemical catalysis; density functional theory

Special Issue Information

Dear Colleagues,

The rapid development of industrialization has led to excessive emissions of hazardous pollutants into our water and air resources, which has a negative impact on health and the environment. Therefore, adequate contaminant management is required, such as adsorption, biological oxidation, chemical oxidation and incineration. Yet, the efficiency of these processes is limited by diffusive mass transport, and external means of agitation are required for enhancing the yields. In parallel, the rapid growth of nanotechnology has added a new dimension to environmental remediation processes. Due to their nanoscale size, nanoparticles show unique physical and chemical properties such as large surface-area-to-volume ratios or high interfacial reactivity. Up to now, more and more nanoparticles have been proven to interact specifically with pollutants in water, gas and even soil, which brings hope for exciting novel and advanced environmental technologies.

We welcome submissions to this Special Issue, “Nanocatalysts for the Degradation of Refractory Pollutants”, in the form of original research papers, reviews, or communications that highlight recent progress and advance of nanocatalysts and their applications in water treatment and air purification.

The proposed scope of this Special Issue includes:

1. Synthesis of novel nanocatalysts;
2. Physicochemical characterization of nanocatalysts;
3. Degradation of refractory inorganic and/or organic pollutants;
4. Theoretical and experimental studies of nanocatalysts.

Dr. Sheng Guo
Dr. Yazi Liu
Dr. Jun Li
Guest Editors

Manuscript Submission Information

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Keywords

  • environmental catalysis
  • advanced oxidation processes (AOPs)
  • photocatalysis
  • nanomaterial
  • nanotechnology
  • water treatment
  • environmental remediation
  • catalyst characterization
  • VOC degradation
  • emerging contaminants
  • non-biodegradable organic contaminants

Published Papers (12 papers)

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Research

11 pages, 2874 KiB  
Article
Facile Synthesis of Ni-Doped WO3-x Nanosheets with Enhanced Visible-Light-Responsive Photocatalytic Performance for Lignin Depolymerization into Value-Added Biochemicals
by Hao Wang, Yuan Li and Xintong Xiao
Catalysts 2023, 13(8), 1205; https://doi.org/10.3390/catal13081205 - 12 Aug 2023
Viewed by 886
Abstract
Lignin is the only renewable resource composed of aromatic hydrocarbons in nature that can be used as raw materials for preparing chemicals. However, due to the existence of stable C–O bonds and C−C bonds in the lignin, the high-value resource utilization of lignin [...] Read more.
Lignin is the only renewable resource composed of aromatic hydrocarbons in nature that can be used as raw materials for preparing chemicals. However, due to the existence of stable C–O bonds and C−C bonds in the lignin, the high-value resource utilization of lignin is still challenging work. Herein, we reported efficient lignin depolymerization using a Ni-doped WO3-x nanosheet photocatalyst that was prepared via the two-step hydrothermal treatment. The optimized catalyst (Ni-doped WO3-x) successfully depolymerized sodium lignosulfonate to vanillic acid and guaiacol under visible-light irradiation. The active radicals of photocatalytic depolymerization of sodium lignosulfonate were superoxide radicals, photogenic holes, and hydroxyl radicals under visible-light irradiation. Furthermore, the introduction of Ni significantly decreased the activation energy barrier for selective cleavage of the C−C bond, which was the essential step to promote lactic acid production. This work presented an effective and promising strategy for lignin depolymerization and value-added biochemical production. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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14 pages, 2991 KiB  
Article
Self-Assembly of Porous Hierarchical BiOBr Sub-Microspheres for Efficient Aerobic Photooxidation of Benzyl Alcohol under Simulated Sunlight Irradiation
by Zhigang Wang, Cheng Liu, Fengxi Chen and Rong Chen
Catalysts 2023, 13(6), 958; https://doi.org/10.3390/catal13060958 - 1 Jun 2023
Viewed by 1129
Abstract
Semiconductor photocatalytic performances can be modulated through morphology modification. Herein porous hierarchical BiOBr microspheres (BiOBr-MS) of ~3 μm was firstly self-assembled without the assistance of a template via a facile solvothermal synthesis in triethylene glycol (TEG) at 150 °C for 3 h. KBrO [...] Read more.
Semiconductor photocatalytic performances can be modulated through morphology modification. Herein porous hierarchical BiOBr microspheres (BiOBr-MS) of ~3 μm was firstly self-assembled without the assistance of a template via a facile solvothermal synthesis in triethylene glycol (TEG) at 150 °C for 3 h. KBrO3 was exploited as a bromine source, which slowly provided bromide ions upon reduction in TEG and controlled the growth and self-assembly of primary BiOBr nanoplates. The addition of PVP during solvothermal synthesis of BiOBr-MS reduced the particle size by about three-fold to generate BiOBr sub-microspheres (BiOBr-sMS) of <1 μm. BiOBr-sMS exhibited significantly higher photocatalytic activity than BiOBr-MS for aerobic photooxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) under simulated sunlight irradiation (conversions of BzOH (50 mM) over BiOBr-sMS and BiOBr-MS were, respectively, 51.3% and 29.6% with 100% selectivity to BzH after Xenon illumination for 2 h at 25 °C). The photogenerated holes and ·O2 were found to be main reactive species for the BzOH oxidation over BiOBr spheres by scavenging tests and spin-trapping EPR spectra. The higher photocatalytic activity of BiOBr-sMS was attributed to its more open hierarchical structure, efficient charge separation, more negative conduction-band position and the generation of larger amounts of ·O2. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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13 pages, 3880 KiB  
Article
The Effect of Different g-C3N4 Precursor Nature on Its Structural Control and Photocatalytic Degradation Activity
by Xiuhang Liu, Xiaoye Xu, Huihui Gan, Mengfei Yu and Ying Huang
Catalysts 2023, 13(5), 848; https://doi.org/10.3390/catal13050848 - 7 May 2023
Cited by 7 | Viewed by 1787
Abstract
Due to its good visible-light photocatalytic activity and environmental friendliness, g-C3N4 has attracted much attention. The relationship between precursor type and the properties of obtained catalysts is interesting to investigate. In this work, target catalysts were prepared via the thermal [...] Read more.
Due to its good visible-light photocatalytic activity and environmental friendliness, g-C3N4 has attracted much attention. The relationship between precursor type and the properties of obtained catalysts is interesting to investigate. In this work, target catalysts were prepared via the thermal polymerization of different precursors, melamine, a mixture of urea and melamine, and a mixture of melamine and cyanuric acid. The prepared g-C3N4 were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), and scanning electron microscopy (SEM). Through the characterization and analysis, the adjusting of precursors could result in the change of the microstructure. The maximum BET surface area was 98.04 cm3g−1 through precursor controlling, more than eight times that of MCN (11.15 cm3g−1) using melamine as precursor. The thermal decomposition process was also analyzed to discuss the interaction and polymerization with precursor controlling. The introduction of melamine and cyanuric acid with melamine as precursors led to the formation of a special nanotube structure and additional function groups on the surface of g-C3N4 to increase the photocatalytic activity. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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15 pages, 4246 KiB  
Article
Nitrogen-Rich Porous Carbon Nanotubes Coated Co/Mo2N Composites Derived from Metal-Organic Framework as Efficient Bifunctional Oxygen Electrocatalysts
by Shiang Li, Yuehong Xie, Chao Feng, Afaq Hassan and Jide Wang
Catalysts 2023, 13(5), 801; https://doi.org/10.3390/catal13050801 - 25 Apr 2023
Cited by 2 | Viewed by 1301
Abstract
Noble metal catalysts such as Pt/C and RuO2 are the most efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts and show excellent activity. However, their high costs, scarcity, single function, and weak durability impede their large-scale practical application. Therefore, [...] Read more.
Noble metal catalysts such as Pt/C and RuO2 are the most efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts and show excellent activity. However, their high costs, scarcity, single function, and weak durability impede their large-scale practical application. Therefore, it is paramount to design bifunctional electrocatalysts with high activity, long durability, and low cost. In this work, we used the functionalized modification and hierarchical porous structure of MOFs and adjusted the ratio of Co/Mo atoms to prepare uniformly dispersed nanospheres. The uniform porous nitrogen-doped carbon nanotubes coated with Co/Mo2N composites were obtained by trapping the volatile CNx during high-temperature pyrolysis via a vapor deposition strategy. The physical and chemical properties of the materials were analyzed by various characterization methods such as XRD, XPS, TEM, SEM, Raman, and BET. Notably, CoMoN@NCNTs-700 exhibited excellent ORR/OER bifunctional electrocatalytic activity in alkaline conditions due to the synergistic effect of porous nitrogen-doped carbon nanotubes and the unique heterostructure of Co/Mo2N. In 0.1 M KOH, its ORR half-wave potential was E1/2 = 0.78 V, with a limiting current density even reached to 5.3 mA cm−2 and its operating potential was 1.60 V at a current density of 10 mA cm−2. At the same time, CoMoN@NCNTs-700 also showed better stability and methanol resistance than the commercial catalysts. This work provides a valuable reference for the design and construction of inexpensive non-noble metal bifunctional electrocatalysts. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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13 pages, 4640 KiB  
Article
Facile Synthesis of a Bi2WO6/BiO2−x Heterojunction for Efficient Photocatalytic Degradation of Ciprofloxacin under Visible Light Irradiation
by Hongzhong Zhang, Zhaoya Fan, Qingqing Chai and Jun Li
Catalysts 2023, 13(3), 469; https://doi.org/10.3390/catal13030469 - 23 Feb 2023
Cited by 6 | Viewed by 1657
Abstract
In this work, a Z-scheme Bi2WO6/BiO2−x heterojunction was successfully prepared using a self-assembly strategy. Various characterization techniques demonstrated that the formation of the heterojunction not only accelerated the separation of photoinduced carriers but also weakened the recombination rate [...] Read more.
In this work, a Z-scheme Bi2WO6/BiO2−x heterojunction was successfully prepared using a self-assembly strategy. Various characterization techniques demonstrated that the formation of the heterojunction not only accelerated the separation of photoinduced carriers but also weakened the recombination rate of photogenerated electron–hole pairs-. The Bi2WO6/BiO2−x composites had a wider absorption edge than Bi2WO6 in the range of 200–800 nm, which improved the photocatalytic performance of ciprofloxacin (CIP) degradation under xenon lamps. As a result, the Z-scheme heterojunction Bi2WO6/BiO2−x composite exhibited excellent photocatalytic activity. Catalyzed by the optimal 20% Bi2WO6/BiO2−x (0.5 g/L), the removal rate of CIP (10.0 mg/L) was 91.8% within 2 h irradiated by visible light, which was 2.37 times that of the BiO2−x catalyst. This work will provide a fresh perspective on the construction of visible-driven Z-scheme photocatalysts for wastewater treatment. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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13 pages, 2489 KiB  
Article
Efficient Combination of Carbon Quantum Dots and BiVO4 for Significantly Enhanced Photocatalytic Activities
by Chenyan Hu, Qingdi Chen, Maosheng Tian, Weiwen Wang, Junxia Yu and Lianguo Chen
Catalysts 2023, 13(3), 463; https://doi.org/10.3390/catal13030463 - 22 Feb 2023
Cited by 5 | Viewed by 1616
Abstract
The development of highly efficient and stable photocatalysts is of critical importance for the removal of environmental pollutants, such as paraben preservatives. In this work, carbon quantum dots (CQDs) were used to modify bismuth vanadate (BiVO4) through a hydrothermal reaction. Regarding [...] Read more.
The development of highly efficient and stable photocatalysts is of critical importance for the removal of environmental pollutants, such as paraben preservatives. In this work, carbon quantum dots (CQDs) were used to modify bismuth vanadate (BiVO4) through a hydrothermal reaction. Regarding the as-formed CQDs/BiVO4 composite, TEM, XPS, and Raman spectra analysis demonstrated the strong interaction between CQDs and BiVO4, possibly leading to the elevated energy level of the composite. As compared to pristine BiVO4, CQDs/BiVO4 showed an increase in light harvesting, and significantly enhanced visible-light activities in degrading the typical paraben pollutant—benzyl paraben (BzP)—where the maximum 85.4% of BzP was degraded in 150 min. After four cycle reactions, the optimum sample 0.6%CQDs/BiVO4 still degraded 78.2% of BzP, indicating the good stability and reusability of the composite. The notably higher photocurrent and smaller arc in Nyquist plot were measured by CQDs/BiVO4, unveiling the improved photocharge separation and lowered interfacial charge transfer resistance by CQDs modification. Meanwhile, due to the promoted energy level, CQDs/BiVO4 practically produced •O2 species and thereby contributed to the BzP degradation, while they had no ability to produce •OH. This was contrary to the BiVO4 system, where •OH and h+ played the dominant roles. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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15 pages, 3699 KiB  
Article
Biochar Derived from Palm Waste Supported Greenly Synthesized MnO2 Nanoparticles as a Novel Adsorbent for Wastewater Treatment
by Amel Taha and Samah Daffalla
Catalysts 2023, 13(2), 451; https://doi.org/10.3390/catal13020451 - 20 Feb 2023
Cited by 2 | Viewed by 1820
Abstract
Water pollution with dye effluents from different industries is a broadly established environmental and health problem that needs serious attention. In this study, making use of Acacia nilotica seed extract, greenly synthesized MnO2 nanoparticles were loaded on the surface of biochar derived [...] Read more.
Water pollution with dye effluents from different industries is a broadly established environmental and health problem that needs serious attention. In this study, making use of Acacia nilotica seed extract, greenly synthesized MnO2 nanoparticles were loaded on the surface of biochar derived from palm waste (MnO2/PF), with specific surface areas of 70.97 m2/g. Batch experiments were adopted, aiming to evaluate the performance of palm fronds, biochar, and the MnO2/PF adsorbents in methyl orange (MO) removal from an aqueous solution. The feedstock and synthesized biochars were comprehensively characterized using XRD, SEM-EDX, FTIR, and BET surface area techniques. Moreover, the influences of the modification of palm fronds, initial dye concentrations, pH, and adsorbent dosage on MO uptake were examined. The results demonstrated that MnO2/PF biochar nanocomposite led to an increase in the removal efficiency by 6 and 1.5 times more than those of palm fronds and biochar, respectively. In addition, it was found that the second-order kinetic model presented the kinetic adsorption very well. This paper demonstrates that the depositing of greenly synthesized MnO2 nanoparticles on the date palm waste biochar forms a novel adsorbent (MnO2/PF) for the removal of MO from aqueous solutions. Furthermore, this adsorbent was easy to synthesize under moderate conditions without the need for chemical capping agents, and would thus be cost-effective and eco-friendly. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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13 pages, 3038 KiB  
Article
Three-Dimensionally Printed Zero-Valent Copper with Hierarchically Porous Structures as an Efficient Fenton-like Catalyst for Enhanced Degradation of Tetracycline
by Sheng Guo, Meng Chen, Yao Huang, Yu Wei, Jawad Ali, Chao Cai and Qingsong Wei
Catalysts 2023, 13(2), 446; https://doi.org/10.3390/catal13020446 - 19 Feb 2023
Cited by 4 | Viewed by 1482
Abstract
Three-dimensionally printed materials show great performance and reliable stability in the removal of refractory organic pollutants in Fenton-like reactions. In this work, hierarchically porous zero-valent copper (3DHP-ZVC) was designed and fabricated via 3D printing and applied as a catalyst for the degradation of [...] Read more.
Three-dimensionally printed materials show great performance and reliable stability in the removal of refractory organic pollutants in Fenton-like reactions. In this work, hierarchically porous zero-valent copper (3DHP-ZVC) was designed and fabricated via 3D printing and applied as a catalyst for the degradation of tetracycline (TC) through heterogeneous Fenton-like processes. It was found that the 3DHP-ZVC/H2O2 system could decompose over 93.2% of TC within 60 min, which is much superior to the homogeneous Cu2+/H2O2 system under similar conditions. The leaching concentration of Cu2+ ions in the 3DHP-ZVC/H2O2 system is 2.14 times lower than that in the Cu powder/H2O2 system in a neutral environment, which could be ascribed to the unique hierarchically porous structure of 3DHP-ZVC. Furthermore, 3DHP-ZVC exhibited compelling stability in 20 consecutive cycles. The effects of co-existing inorganic anions, adaptability, and pH resistance on the degradation of TC were also investigated. A series of experiments and characterizations revealed that Cu0 and superoxide radicals as reducing agents could facilitate the cycling of Cu(II)/Cu(I), thus enhancing the generation of hydroxyl radicals to degrade TC. This study provides new insights into employing promising 3D printing technology to develop high-reactivity, stable, and recycling-friendly components for wastewater treatment. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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19 pages, 3777 KiB  
Article
Integrated Photocatalytic Oxidation and Adsorption Approach for the Robust Treatment of Refinery Wastewater Using Hybrid TiO2/AC
by Ihtisham Ul Haq, Waqas Ahmad, Imtiaz Ahmad, Amjad Shah, Muhammad Yaseen and Taj Muhammad
Catalysts 2023, 13(1), 193; https://doi.org/10.3390/catal13010193 - 13 Jan 2023
Cited by 2 | Viewed by 1927
Abstract
This study reports the removal of hydrocarbon (HC) pollutants from petroleum refinery wastewater by integrated photocatalytic oxidation and adsorption using a TiO2/AC hybrid material. The hybrid adsorbent/catalyst was prepared by the impregnation of TiO2 over AC and characterized by FTIR, [...] Read more.
This study reports the removal of hydrocarbon (HC) pollutants from petroleum refinery wastewater by integrated photocatalytic oxidation and adsorption using a TiO2/AC hybrid material. The hybrid adsorbent/catalyst was prepared by the impregnation of TiO2 over AC and characterized by FTIR, SEM, EDX, and XRD analyses. Under the optimized reaction conditions of pH 3, 30 °C, and 1000 mg TiO2/AC per 500 mL of sample in 50 min, the integrated photocatalytic oxidation-adsorption achieved a net percentage removal of benzene, toluene, aniline, and naphthalene of 91% from model HC solutions. Under these conditions, for the treatment of real refinery wastewater, TiO2/AC caused a 95% decrease in chemical oxygen demand (COD). The integrated photocatalytic oxidation and adsorption using TiO2/AC showed a clear advantage over the individual adsorption and photocatalytic oxidation using AC and TiO2, whereby about the same level of removal of model HCs and a decrease in the COD of refinery wastewater was attained in 105 min and 90 min, respectively, utilizing larger adsorbent/catalyst dosages. GC-MS analysis revealed that during the integrated process of adsorption-photocatalytic oxidation, all the parent HCs and oxidation byproducts were completely removed from the refinery wastewater. Based on the outstanding performance, cost-effectiveness, and environmental greenness, the newly designed TiO2/AC via the integrated adsorption-photocatalytic oxidation can be counted as an effective alternative route for the large-scale processing of refinery wastewater. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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12 pages, 3218 KiB  
Article
Ni-Pd-Incorporated Fe3O4 Yolk-Shelled Nanospheres as Efficient Magnetically Recyclable Catalysts for Reduction of N-Containing Unsaturated Compounds
by Dong Wang, Yi Li, Liangsong Wen, Jiangbo Xi, Pei Liu, Thomas Willum Hansen and Ping Li
Catalysts 2023, 13(1), 190; https://doi.org/10.3390/catal13010190 - 13 Jan 2023
Cited by 35 | Viewed by 2601
Abstract
The use of metal-based heterogeneous catalysts for the degradation of N-containing organic dyes has attracted much attention due to their excellent treatment efficiency and capability. Here, we report the synthesis of heterometals (Ni and Pd)-incorporated Fe3O4 (Ni-Pd/Fe3O4 [...] Read more.
The use of metal-based heterogeneous catalysts for the degradation of N-containing organic dyes has attracted much attention due to their excellent treatment efficiency and capability. Here, we report the synthesis of heterometals (Ni and Pd)-incorporated Fe3O4 (Ni-Pd/Fe3O4) yolk-shelled nanospheres for the catalytic reduction of N-containing organic dyes using a facile combination of solvothermal treatment and high-temperature annealing steps. Benefiting from the magnetic properties and the yolk-shelled structure of the Fe3O4 support, as well as the uniformly dispersed active heterometals incorporated in the shell and yolk of spherical Fe3O4 nanoparticles, the as-prepared Ni-Pd/Fe3O4 composite shows excellent recyclability and enhanced catalytic activity for three N-containing organic dyes (e.g., 4-nitrophenol, Congo red, and methyl orange) compared with its mono metal counterparts (e.g., Ni/Fe3O4 and Pd/Fe3O4). In the 4-nitrophenol reduction reaction, the catalytic activity of Ni-Pd/Fe3O4 was superior to many Fe3O4-supported nanocatalysts reported within the last five years. This work provides an effective strategy to boost the activity of iron oxide-based catalytic materials via dual or even multiple heterometallic incorporation strategy and sheds new light on environmental catalysis. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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15 pages, 3462 KiB  
Article
Design of BiOCl/WO3@Polyaniline Organic–Inorganic Nanocomposite Photocatalyst for the Efficient Decontamination of 2-Chlorophenol from Wastewater
by Rajeev Kumar, Md. Abu Taleb, Mohamed A. Barakat and Bandar Al-Mur
Catalysts 2023, 13(1), 175; https://doi.org/10.3390/catal13010175 - 11 Jan 2023
Cited by 3 | Viewed by 1525
Abstract
Advanced photocatalysts that can utilize solar energy for water purification applications are always needed. The present article reports a facile fabrication of tungsten oxide (WO3)/bismuth oxychloride (BiOCl) immobilized on polyaniline (PAn) (BiOCl/WO3@PAn) heterojunction nanocomposite photocatalyst. The designed nanocatalyst was [...] Read more.
Advanced photocatalysts that can utilize solar energy for water purification applications are always needed. The present article reports a facile fabrication of tungsten oxide (WO3)/bismuth oxychloride (BiOCl) immobilized on polyaniline (PAn) (BiOCl/WO3@PAn) heterojunction nanocomposite photocatalyst. The designed nanocatalyst was tested for 2-chlorophenol (2-CP) decontamination from the aquatic system. Synthesized WO3, BiOCl, and BiOCl/WO3@PAn nanocomposites were distinguished via UV-DSR, photoluminescence, SEM, TEM, XRD, and XPS analysis. The combination of PAn with WO3 and BiOCl showed a synergistic impact on the photocatalytic efficiency of the BiOCl/WO3@PAn nanocomposite. The synthesized BiOCl/WO3@PAn nanocomposite showed higher visible light absorption behavior and bandgap energy reduction than the WO3 and BiOCl. The obtained data shows that 2-CP photocatalysis by the BiOCl/WO3@PAn is controlled by degradation time, pH, and pollutant amount in the solution. The highest photocatalytic degradation of 2-CP (99.7%) was recorded at pH 5 and 25 mg/L concentration within 240 min. The photocatalysis mechanism and active radical scavenging study discovered that O2 and OH, were responsible for the 2-CP mineralization onto the BiOCl/WO3@PAn nanocomposite. The BiOCl/WO3@PAn nanocomposite showed enhanced decontamination properties over pristine catalysts. The reusability of the synthesized BiOCl/WO3@PAn nanocomposite was evaluated. It found that the photocatalyst could be recycled for up to four cycles for 2-CP degradation without significantly losing the photocatalytic properties. The fabricated BiOCl/WO3@PAn nanocomposite catalyst presented exceptional catalytic and recycling properties, indicating an effective method for scavenging hazardous organic contaminants under solar irradiation and green technology for wastewater purification. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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12 pages, 3937 KiB  
Article
Catalytic Wet Peroxide Oxidation of Anionic Pollutants over Fluorinated Fe3O4 Microspheres at Circumneutral pH Values
by Fengxi Chen, Huaixiang Lv, Wu Chen and Rong Chen
Catalysts 2022, 12(12), 1564; https://doi.org/10.3390/catal12121564 - 2 Dec 2022
Cited by 3 | Viewed by 1095
Abstract
Fluorinated Fe3O4 microspheres with 7.1 ± 1.4 wt% of fluoride (F-Fe3O4-1) were prepared via glycothermal synthesis. Fluorination significantly enhanced the activity of F-Fe3O4-1 in catalytic wet peroxide oxidation of anionic dyes (including [...] Read more.
Fluorinated Fe3O4 microspheres with 7.1 ± 1.4 wt% of fluoride (F-Fe3O4-1) were prepared via glycothermal synthesis. Fluorination significantly enhanced the activity of F-Fe3O4-1 in catalytic wet peroxide oxidation of anionic dyes (including orange G (OG) and congo red) at pH ~7. However, the promotional effect of fluorination became less obvious for amphoteric rhodamine B and was not observed for cationic methylene blue. After reacting with H2O2 (40 mM) for 2 h at pH 6.5 and 40 °C, the decolorization rates of OG (0.1 mM) and the pseudo-first-order rate constant were 96.8% and 0.0284 min−1 over F-Fe3O4-1 versus 17.6% and 0.0011 min−1 over unmodified Fe3O4. The effects of reaction parameters (initial H2O2 concentration and pH value and reaction temperature) on OG decolorization with H2O2 over F-Fe3O4-1 were investigated. The reusability of F-Fe3O4-1 was demonstrated by OG decolorization in eight consecutive runs. Fluorination increased the isoelectric point of F-Fe3O4-1 to 8.7 and facilitated the adsorption and degradation of anionic dyes on the surface of F-Fe3O4-1 at pH ~7. Scavenging tests and EPR spectra supported that hydroxyl radicals were the main reactive species for the OG decolorization over F-Fe3O4-1. Full article
(This article belongs to the Special Issue Nanocatalysts for the Degradation of Refractory Pollutants)
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