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Innovative Catalytic and Photocatalytic Systems for Environmental Remediation
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Innovative Catalytic and Photocatalytic Systems for Environmental Remediation

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

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 51848

Special Issue Editors

Dr. Vincenzo Vaiano

E-Mail Website
Guest Editor
Department of Industrial Engineering, University Salerno, Via Giovanni Paolo 2 132, I-84084 Fisciano, Salerno, Italy
Interests: photocatalysis for sustainable chemistry; photocatalytic and photo-fenton processes for pollutants removal in wastewater; catalytic combustion of sewage sludge; decomposition and oxidative decomposition of H2S; hydrolysis of COS in the liquid phase
Special Issues, Collections and Topics in MDPI journals
Dr. Olga Sacco

E-Mail Website
Guest Editor
Department of Chemistry and Biology "A.Zambelli", University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, SA, Italy
Interests: synthesis and characterization of catalytic materials; phosphors-based nanomaterials; nanostructured photocatalysts and supports; photocatalysis for the removal of pollutants from water and wastewater; membrane separation processes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Today, water and air pollution are issues of great concern, due to the adverse effects that pollution has on the environment and human health. Therefore, cost-effective and appropriate air-pollution-control and water-treatment technologies must be explored and implemented. Many different approaches have been investigated and, in particular, catalytic processes may play a central role. For this reason, the design of new catalytic systems for the mitigation of environmental pollution is strongly necessary. This Special Issue is focused on “Innovative Catalytic and Photocatalytic Systems for Environmental Remediation”, featuring the state-of-the-art of this field. Research papers related to the synthesis and characterization of novel nanomaterials or nanocomposites and their uses in the removal of pollutants from liquid and gaseous phases are welcome in this Special Issue. Moreover, innovative structured catalysts for different purposes will also be considered.

Prof. Vincenzo Vaiano
Dr. Olga Sacco
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanomaterials
  • Zero-valent iron (ZVI)
  • Nanostructured photocatalysts
  • Heterostructures
  • Structured catalysts
  • Water and wastewater treatment
  • Gaseous streams treatment

Published Papers (15 papers)

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Research

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18 pages, 41287 KiB  
Article
Effect of Different Catalyst Supports on the Quality, Yield and Morphology of Carbon Nanotubes Produced from Waste Polypropylene Plastics
by Helen Uchenna Modekwe, Messai Adenew Mamo, Kapil Moothi and Michael Olawale Daramola
Catalysts 2021, 11(6), 692; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11060692 - 30 May 2021
Cited by 19 | Viewed by 4662
Abstract
The role of the effect of the support on the reactivity of heterogeneous catalysts cannot be over-emphasized. Therefore, the study documented in this article investigated the effect of different metal oxide supports (MgO, CaO and TiO2) and mixed oxide supports (CaTiO [...] Read more.
The role of the effect of the support on the reactivity of heterogeneous catalysts cannot be over-emphasized. Therefore, the study documented in this article investigated the effect of different metal oxide supports (MgO, CaO and TiO2) and mixed oxide supports (CaTiO3) on the performance of a bimetallic NiMo catalyst prepared via the sol–gel method during the catalytic growth of carbon nanotubes (CNTs) from waste polypropylene (PP). Waste PP was pyrolyzed at 700 °C in a single-stage chemical vapor deposition reactor and off-gas was utilized in-situ as a cheap carbon feedstock for the growth of CNTs under similar conditions for all the prepared NiMo catalysts (supported and unsupported). The structures of the prepared catalysts and deposited carbon were extensively characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), etc. The catalytic performance of NiMo supported and unsupported catalysts was evaluated in terms of the yield, purity, and morphology of synthesized CNTs. The results revealed that the stabilizing role of supports is fundamental in preventing nanoparticle agglomeration and aggregation, thereby resulting in improved yield and quality of CNTs. Supported NiMo catalysts produced better aligned graphitic and high-quality CNTs. The NiMo/CaTiO3 catalyst produced the highest carbon of 40.0%, while unsupported NiMo produced low-quality CNTs with the lowest carbon yield of 18.4%. Therefore, the type of catalyst support and overall stability of catalytic materials play significant roles in the yield and quality of CNTs produced from waste PP. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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12 pages, 2601 KiB  
Article
Synthesis of an Ag3PO4/Nb2O5 Photocatalyst for the Degradation of Dye
by Nur Syazwani Osman, Siti Norhasimah Sulaiman, Ernee Noryana Muhamad, Hayati Mukhair, Sin Tee Tan and Abdul Halim Abdullah
Catalysts 2021, 11(4), 458; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040458 - 01 Apr 2021
Cited by 15 | Viewed by 2033
Abstract
In this work, the photocatalytic performance of Ag3PO4, Nb2O5 and Ag3PO4/Nb2O5 hybrid photocatalysts to degrade methyl orange dye, MO, in an aqueous solution under visible light irradiation was evaluated. [...] Read more.
In this work, the photocatalytic performance of Ag3PO4, Nb2O5 and Ag3PO4/Nb2O5 hybrid photocatalysts to degrade methyl orange dye, MO, in an aqueous solution under visible light irradiation was evaluated. The Ag3PO4 and Ag3PO4/Nb2O5 photocatalysts, with various Ag to Nb molar ratios, were prepared using a facile precipitation method. The photocatalysts were characterized by X-ray diffraction, UV–Visible, X-ray Photoelectron, and Photoluminescence spectroscopies. Upon the addition of Ag3PO4, the band gap energy of Nb2O5 decreased from 3.0 eV to 2.7 eV, indicating the possible use of the Ag3PO4/Nb2O5 hybrid photocatalysts under visible light irradiation. All of the prepared Ag3PO4/Nb2O5 catalysts exhibited higher photocatalytic performance than Ag3PO4 in degrading methyl orange dye under 23-watt visible light irradiation. The Ag3PO4/Nb2O5 catalyst, with a mole ratio of 2:1, exhibited the fastest MO degradation rate of 7.3 × 10−2 min−1, which is twice faster than that of Ag3PO4. The catalyst also shows better stability, as it is reusable for up to six experimental cycles while maintaining its photocatalytic activity above 60%. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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15 pages, 2370 KiB  
Article
Biochar Derived from Agricultural Wastes as a Means of Facilitating the Degradation of Azo Dyes by Sulfides
by Qilin Han, Yadong Yang, Ruofan Wang, Kai Zhang, Na Liu and Mei Hong
Catalysts 2021, 11(4), 434; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040434 - 29 Mar 2021
Cited by 11 | Viewed by 1941
Abstract
Dyes are common contaminants, some of which are teratogenic, carcinogenic, and causative of ecological damage, and dye wastewater often contains toxic sulfides. Biochar has been widely used for the adsorption and catalysis degradation of pollutants, including dyes and sulfides, due to its abundant [...] Read more.
Dyes are common contaminants, some of which are teratogenic, carcinogenic, and causative of ecological damage, and dye wastewater often contains toxic sulfides. Biochar has been widely used for the adsorption and catalysis degradation of pollutants, including dyes and sulfides, due to its abundant surface functional groups and large specific surface area. Therefore, the simultaneous treatment of dyes and sulfides with biochar may be a feasible, effective, and novel solution. This study sought to utilize low-cost, environmentally friendly, and widely sourced biochar materials from agricultural wastes such as corn stalk, rice chaff, and bean stalk to promote the reduction of dyes by sulfides. Through the action of different biochars, sulfides can rapidly decompose and transform oxidizing dyes. The RCB800 (rice chaff biochar material prepared at 800 °C) was observed to have the best effect, with a degradation rate of 96.6% in 40 min and 100% in 50 min for methyl orange. This series of materials are highly adaptable to temperature and pH, and the concentration of sulfides has a significant effect on degradation rates. Compared with commercial carbon materials, biochars are similar in terms of their catalytic mechanism and are more economical. Scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption and desorption characterization results indicated that biochar contains more pores, including mesopores, and a sufficient specific surface area, both of which are conducive to the combination of sulfides and dyes with biochar. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy showed that there are oxygen-containing functional groups (examples include quinones and carboxyl groups) on the surface of biochar that promote the reaction of sulfide and dye. The formation of active polysulfides also potentially plays an important role in the degradation reaction. This article outlines a new method for improving the degradation efficiency of azo dyes and sulfides via biochar materials derived from widely sourced agricultural wastes. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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23 pages, 4537 KiB  
Article
Degradation Kinetics of Methyl Orange Dye in Water Using Trimetallic Fe/Cu/Ag Nanoparticles
by Masaku Kgatle, Keneiloe Sikhwivhilu, Gebhu Ndlovu and Nosipho Moloto
Catalysts 2021, 11(4), 428; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040428 - 26 Mar 2021
Cited by 44 | Viewed by 7072
Abstract
The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was [...] Read more.
The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was coupled with copper and silver to make trimetallic Fe/Cu/Ag nanoparticles, in order to enhance the degradation of MO and increase reactivity of the catalyst by delaying the rate of oxidation of iron. The synthesis of the trimetallic nanoparticles (Fe/Cu/Ag) was carried out using the sodium borohydride reduction method. The characterization of the particles was performed using XRD, XPS, EDX, and TEM. The analyses confirmed the successful synthesis of the nanoparticles; the TEM images also showed the desired structures and geometry of the nanoscale zerovalent iron particles. The assessment of the nanoparticles in the degradation of methyl orange showed a notable degradation within few minutes into the reaction. The effect of parameters such as nanoparticle dosage, initial MO concentration, and the solution pH on the degradation of MO using the nanoparticles was investigated. Methyl orange degradation efficiency reached 100% within 1 min into the reaction at a low pH, with lower initial MO concentration and higher nanoparticle dosage. The degradation rate of MO using the nanoparticles followed pseudo first-order kinetics and was greatly influenced by the studied parameters. Additionally, LC-MS technique confirmed the degradation of MO within 1 min and that the degradation occurs through the splitting of the azo bond. The Fe/Cu/Ag trimetallic nanoparticles have proven to be an appropriate and efficient alternative for the treatment of dye wastewater. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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13 pages, 4810 KiB  
Article
Green Synthesis of Silver and Gold Nanoparticles via Sargassum serratifolium Extract for Catalytic Reduction of Organic Dyes
by Beomjin Kim, Woo Chang Song, Sun Young Park and Geuntae Park
Catalysts 2021, 11(3), 347; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11030347 - 08 Mar 2021
Cited by 47 | Viewed by 3529
Abstract
The green synthesis of inorganic nanoparticles (NPs) using bio-materials has attained enormous attention in recent years due to its simple, eco-friendly, low-cost and non-toxic nature. In this work, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized by the marine algae extract, Sargassum [...] Read more.
The green synthesis of inorganic nanoparticles (NPs) using bio-materials has attained enormous attention in recent years due to its simple, eco-friendly, low-cost and non-toxic nature. In this work, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized by the marine algae extract, Sargassum serratifolium (SS). The characteristic studies of bio-synthesized SS-AgNPs and SS-AuNPs were carried out by using ultraviolet–visible (UV–Vis) absorption spectroscopy, dynamic light scattering (DLS), high-resolution transmission electron microscope (HR-TEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Phytochemicals in the algae extract, such as meroterpenoids, acted as a capping agent for the NPs’ growth. The synthesized Ag and Au NPs were found to have important catalytic activity for the degradation of organic dyes, including methylene blue, rhodamine B and methyl orange. The reduction of dyes by SS-AgNPs and -AuNPs followed the pseudo-first order kinetics. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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15 pages, 4863 KiB  
Article
Zirconium-Doped Chromium IV Oxide Nanocomposites: Synthesis, Characterization, and Photocatalysis towards the Degradation of Organic Dyes
by Zahir Muhammad, Farman Ali, Muhammad Sajjad, Nisar Ali, Muhammad Bilal, Mohammed Rafi Shaik, Syed Farooq Adil, Mohammed A.F. Sharaf, Emad Mahrous Awwad and Mujeeb Khan
Catalysts 2021, 11(1), 117; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010117 - 14 Jan 2021
Cited by 23 | Viewed by 3202
Abstract
Degradation of organic dyes and their byproducts by heterogeneous photocatalysts is an essential process, as these dyes can be potentially discharged in wastewater and threaten aquatic and xerophyte life. Therefore, their complete mineralization into nontoxic components (water and salt) is necessary through the [...] Read more.
Degradation of organic dyes and their byproducts by heterogeneous photocatalysts is an essential process, as these dyes can be potentially discharged in wastewater and threaten aquatic and xerophyte life. Therefore, their complete mineralization into nontoxic components (water and salt) is necessary through the process of heterogeneous photocatalysis. In this study, Zr/CrO2 (Zirconium-doped chromium IV oxide) nanocomposite-based photocatalysts with different compositions (1, 3, 5, 7 & 9 wt.%) were prepared by an environmentally friendly, solid-state reaction at room temperature. The as-prepared samples were calcined under air at 450 °C in a furnace for a specific period of time. The synthesis of Zr/CrO2 photocatalysts was confirmed by various techniques, including XRD, SEM, EDX, FT-IR, UV-Vis, and BET. The photocatalytic properties of all samples were tested towards the degradation of methylene blue and methyl orange organic dyes under UV light. The results revealed a concentration-dependent photocatalytic activity of photocatalysts, which increased the amount of dopant (up to 5 wt.%). However, the degradation efficiency of the catalysts decreased upon further increasing the amount of dopant due to the recombination of holes and photoexcited electrons. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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12 pages, 3759 KiB  
Article
Bismuth Oxyhalides for NOx Degradation under Visible Light: The Role of the Chloride Precursor
by Francesca Tessore, Federico Galli, Dalma Schieppati, Daria C. Boffito, Alessandro Di Michele, Francesco Demartin, Giuseppina Cerrato and Claudia L. Bianchi
Catalysts 2021, 11(1), 81; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11010081 - 08 Jan 2021
Cited by 4 | Viewed by 2244
Abstract
Photocatalysis is a green technology for tackling water and air contamination. A valid alternative to the most exploited photocatalytic material, TiO2, is bismuth oxyhalides, which feature a wider bandgap energy range and use visible radiation to attain photoexcitation. Moreover, their layered [...] Read more.
Photocatalysis is a green technology for tackling water and air contamination. A valid alternative to the most exploited photocatalytic material, TiO2, is bismuth oxyhalides, which feature a wider bandgap energy range and use visible radiation to attain photoexcitation. Moreover, their layered structure favors the separation of photogenerated electron–hole pairs, with an enhancement in photocatalytic activity. Controlled doping of bismuth oxyhalides with metallic bismuth nanoparticles allows for further boosting of the performance of the material. In the present work, we synthesized Y%Bi-doped BiO(Cl0.875Br0.125) (Y = 0.85, 1, 2, 10) photocatalysts, using cetyltrimethylammonium bromide as the bromide source and varying the chloride source to assess the impact that both length and branching of the hydrocarbon chain might have on the framing and layering of the material. A change in the amount of the reducing agent NaBH4 allowed tuning of the percentage of metallic bismuth. After a thorough characterization (XRPD, SEM, TEM, UV-DRS, XPS), the photocatalytic activity of the catalysts was tested in the degradation of NOx under visible light, reaching a remarkable 53% conversion after 3 h of illumination for the material prepared using cetylpyridinium chloride. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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16 pages, 4952 KiB  
Article
Photocatalytic Degradation of the Light Sensitive Organic Dyes: Methylene Blue and Rose Bengal by Using Urea Derived g-C3N4/ZnO Nanocomposites
by Fahad A. Alharthi, Abdulaziz Ali Alghamdi, Hamdah S. Alanazi, Amjad Abdullah Alsyahi and Naushad Ahmad
Catalysts 2020, 10(12), 1457; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10121457 - 13 Dec 2020
Cited by 47 | Viewed by 4079
Abstract
In this study, we report the fabrication of graphitic carbon nitride doped zinc oxide nanocomposites, g-C3N4/ZnO, (Zn-Us) by using different amount of urea. They were further characterized by X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman, UV-vis, Scanning electron [...] Read more.
In this study, we report the fabrication of graphitic carbon nitride doped zinc oxide nanocomposites, g-C3N4/ZnO, (Zn-Us) by using different amount of urea. They were further characterized by X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman, UV-vis, Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) techniques. The prepared nanocomposites were used as photocatalysts for the mineralization of the light sensitive dyes Methylene Blue (MB) and Rose Bengal (RB) under UV light irradiation, and corresponding photo-mechanism was proposed. Benefiting from these photocatalytic characteristics, urea derived g-C3N4/ZnO photocatalysts have been found to have excellent photodegradation activity against the MB and RB for 6 h and 4 h, respectively. Under the given experimental conditions, the degradation percentage of fabricated Zn-Us were shown ~90% for both model dyes. Compared to cationic MB dye, anionic RB dye is more actively degraded on the surface of prepared photocatalysts. The results obtained can be effectively used for future practical applications in wastewater treatment Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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19 pages, 1725 KiB  
Article
Modeling the Mineralization Kinetics of Visible Led Graphene Oxide/Titania Photocatalytic Ozonation of an Urban Wastewater Containing Pharmaceutical Compounds
by Fernando J. Beltrán, Manuel Checa, Javier Rivas and Juan F. García-Araya
Catalysts 2020, 10(11), 1256; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10111256 - 30 Oct 2020
Cited by 5 | Viewed by 2039
Abstract
In a water ozonation process, dissolved organics undergo two reactions at least: direct ozone attack and oxidation with hydroxyl radicals generated from the ozone decomposition. In the particular case of urban wastewater contaminated with pharmaceuticals, competition between these two reactions can be studied [...] Read more.
In a water ozonation process, dissolved organics undergo two reactions at least: direct ozone attack and oxidation with hydroxyl radicals generated from the ozone decomposition. In the particular case of urban wastewater contaminated with pharmaceuticals, competition between these two reactions can be studied through application of gas–liquid reaction kinetics. However, there is a lack in literature about kinetic modeling of ozone processes in water specially in photocatalytic ozonation. In this work, lumped reactions of ozone and hydroxyl radicals with total organic carbon have been proposed. Urban wastewater containing a mixture of eight pharmaceutical compounds has been used to establish the kinetic model that simulates the mineralization process. The kinetic model is based on a mechanism of free radical and molecular reactions and the knowledge of mass transfer, chemical reaction rate constants, and radiation transfer data. According to the model, both single ozonation and photocatalytic ozonation present two distinct reaction periods characterized by the absence and presence of dissolved ozone. In the first period (less than 10 min), pharmaceuticals mainly disappear by direct ozone reactions and TOC variation due to these compounds has been modeled according to gas–liquid reaction kinetics through a lumped ozone-pharmaceutical TOC fast second order reaction. The corresponding rate constant of this reaction was found to change with time from 3 × 105 to 200 M−1 s−1 with Hatta values higher than 0.3. In the second period (nearly 5 h), competition between direct and hydroxyl radical reactions takes place and a kinetic model based on a direct and free radical reaction mechanism is proposed. Main influencing parameters to be known were: Direct ozone reaction rate constant, catalyst quantum yield, and hydroxyl radical scavengers. The first two take values of 0.5 M−1 s−1 and 5 × 10−4 mol·photon−1, respectively, while a fraction of TOC between 10% and 90% that changes with time was found to possess hydroxyl radical scavenger nature. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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19 pages, 5214 KiB  
Article
Kinetics and Nanoparticle Catalytic Enhancement of Biogas Production from Wastewater Using a Magnetized Biochemical Methane Potential (MBMP) System
by Emmanuel Kweinor Tetteh and Sudesh Rathilal
Catalysts 2020, 10(10), 1200; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10101200 - 16 Oct 2020
Cited by 21 | Viewed by 3057
Abstract
This study presents magnetized nanoparticles (NPs) as a catalyst to accelerate anaerobic digestion (AD) potential for clean and ecofriendly energy (biogas) from wastewater settings. The effects of iron oxides (Ms) and aluminum sulphate (Alum) were investigated using two chronological experiments: (i) the Jar [...] Read more.
This study presents magnetized nanoparticles (NPs) as a catalyst to accelerate anaerobic digestion (AD) potential for clean and ecofriendly energy (biogas) from wastewater settings. The effects of iron oxides (Ms) and aluminum sulphate (Alum) were investigated using two chronological experiments: (i) the Jar test technique to generate residue slurry as organic fertilizer potential and (ii) a magnetized biochemical methane potential (MBMP) system for biogas production at mesophilic conditions for 21 days. X-ray diffraction and Fourier Transform Infrared spectroscopy were carried out to establish the Ms Crystallite and active functional groups respectively. Scanning electronic microscopy coupled with energy dispersive X-ray spectrometer and elemental analysis were used to track and confirm NPs inclusion after the post-AD process. Coagulation at 50 mg/L and magnetic exposure time of 30 min showed above 85% treatability performance by Ms as compared to 70% for Alum. Owing to the slow kinetics of the AD process, additional NPs content in the digesters coupled with an external magnetic field improved their performance. Cumulative biogas yields of 1460 mL/d > 610 mL/d > 505 mL/d for Ms > Control > Alum respectively representing 80% > 61% > 52% of CH4 were attained. The modified Gompertz model shows that the presence of NPs shortens the lag phase of the control system with kinetics rate constants of 0.285 1/d (control) to 0.127 1/d (Ms) < 0.195 1/d (Alum). Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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13 pages, 753 KiB  
Article
Deactivation of a Vanadium-Based SCR Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation
by Johanna Englund, Sandra Dahlin, Andreas Schaefer, Kunpeng Xie, Lennart Andersson, Soran Shwan, Per-Anders Carlsson, Lars J. Pettersson and Magnus Skoglundh
Catalysts 2020, 10(5), 552; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10050552 - 16 May 2020
Cited by 4 | Viewed by 3124
Abstract
We have investigated how the exhaust gases from a heavy-duty Euro VI engine, powered with biogas impact a vanadium-based selective catalytic reduction (SCR) catalyst in terms of performance. A full Euro VI emission control system was used and the accumulation of catalyst poisons [...] Read more.
We have investigated how the exhaust gases from a heavy-duty Euro VI engine, powered with biogas impact a vanadium-based selective catalytic reduction (SCR) catalyst in terms of performance. A full Euro VI emission control system was used and the accumulation of catalyst poisons from the combustion was investigated for the up-stream particulate filter as well as the SCR catalyst. The NOx reduction performance in terms of standard, fast and NO2-rich SCR was evaluated before and after exposure to exhaust from a biogas-powered engine for 900 h. The SCR catalyst retains a significant part of its activity towards NOx reduction after exposure to biogas exhaust, likely due to capture of catalyst poisons on the up-stream components where the deactivation of the oxidation catalyst is especially profound. At lower temperatures some deactivation of the first part of the SCR catalyst was observed which could be explained by a considerably higher surface V4+/V5+ ratio for this sample compared to the other samples. The higher value indicates that the reoxidation of V4+ to V5+ is partially hindered, blocking the redox cycle for parts of the active sites. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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21 pages, 6636 KiB  
Article
Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity
by Magaly Y. Nava-Núñez, Eva Jimenez-Relinque, Maria Grande, Azael Martínez-de la Cruz and Marta Castellote
Catalysts 2020, 10(2), 226; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10020226 - 14 Feb 2020
Cited by 19 | Viewed by 3933
Abstract
The use of new photocatalysts active under visible light in cement-based building materials represents one interesting alternative to improve the air quality in the urban areas. This work undertakes the feasibility of using BiOX (X = Cl and I) as an addition on [...] Read more.
The use of new photocatalysts active under visible light in cement-based building materials represents one interesting alternative to improve the air quality in the urban areas. This work undertakes the feasibility of using BiOX (X = Cl and I) as an addition on mortars for visible-light-driven NOx removal. The interaction between BiOX photocatalysts and cement matrix, and the influence of their addition on the inherent properties of the cement-based materials was studied. The NO removal by the samples ranking as follows BiOCl-cem > BiOI-cem > TiO2-cem. The higher efficiency under visible light of BiOCl-cem might be ascribed to the presence of oxygen vacancies together with a strong oxidation potential. BiOI-cem suffers a phase transformation of BiOI in alkaline media to an I-deficient bismuth oxide compound with poor visible light absorbance capability. However, BiOI-cem showed considerably higher nitrate selectivity that resulted in the highest NOx global removal efficiency. These results can make its use more environmentally sustainable than TiO2 and BiOCl cement composites. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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9 pages, 1060 KiB  
Communication
Electrospinning a Dye-Sensitized Solar Cell
by Sophia Kohn, Daria Wehlage, Irén Juhász Junger and Andrea Ehrmann
Catalysts 2019, 9(12), 975; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9120975 - 21 Nov 2019
Cited by 19 | Viewed by 3148
Abstract
Dye-sensitized solar cells (DSSCs) offer new possibilities to harvest solar energy by using non-toxic inexpensive materials. Since they can generally be produced on flexible substrates, several research groups investigated possibilities to integrate DSSCs in textile fabrics, either by coating full fabrics with the [...] Read more.
Dye-sensitized solar cells (DSSCs) offer new possibilities to harvest solar energy by using non-toxic inexpensive materials. Since they can generally be produced on flexible substrates, several research groups investigated possibilities to integrate DSSCs in textile fabrics, either by coating full fabrics with the DSSC layer structure or by producing fiber-shaped DSSCs which were afterwards integrated into a textile fabric. Here we show a new approach, electrospinning all solid layers of the DSSC. We report on electrospinning the counter electrode with a graphite catalyst followed by a thin nonconductive barrier layer and preparing the front electrode by electrospinning semiconducting TiO2 from a polymer solution dyed with natural dyes. Both electrodes were coated with a conductive polymer before the system was finally filled with a fluid electrolyte. While the efficiency is lower than for glass-based cells, possible problems such as short-circuits—which often occur in fiber-based DSSCs—did not occur in this proof-of-concept. Since graphite particles did not fully cover the counter electrode in this first study, and the typical bathochromic shift indicating adsorption of dye molecules on the TiO2 layer was not observed, several ways are open to increase the efficiency in forthcoming studies. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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16 pages, 14781 KiB  
Review
Active Site Engineering on Two-Dimensional-Layered Transition Metal Dichalcogenides for Electrochemical Energy Applications: A Mini-Review
by Chueh-An Chen, Chiao-Lin Lee, Po-Kang Yang, Dung-Sheng Tsai and Chuan-Pei Lee
Catalysts 2021, 11(2), 151; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11020151 - 21 Jan 2021
Cited by 10 | Viewed by 2758
Abstract
Two-dimensional-layered transition metal dichalcogenides (2D-layered TMDs) are a chemically diverse class of compounds having variable band gaps and remarkable electrochemical properties, which make them potential materials for applications in the field of electrochemical energy. To date, 2D-layered TMDs have been wildly used in [...] Read more.
Two-dimensional-layered transition metal dichalcogenides (2D-layered TMDs) are a chemically diverse class of compounds having variable band gaps and remarkable electrochemical properties, which make them potential materials for applications in the field of electrochemical energy. To date, 2D-layered TMDs have been wildly used in water-splitting systems, dye-sensitized solar cells, supercapacitors, and some catalysis systems, etc., and the pertinent devices exhibit good performances. However, several reports have also indicated that the active sites for catalytic reaction are mainly located on the edge sites of 2D-layered TMDs, and their basal plane shows poor activity toward catalysis reaction. Accordingly, many studies have reported various approaches, namely active-site engineering, to address this issue, including plasma treatment, edge site formation, heteroatom-doping, nano-sized TMD pieces, highly curved structures, and surface modification via nano-sized catalyst decoration, etc. In this article, we provide a short review for the active-site engineering on 2D-layered TMDs and their applications in electrochemical energy. Finally, the future perspectives for 2D-layered TMD catalysts will also be briefly discussed. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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8 pages, 1101 KiB  
Perspective
Heterogeneous Photocatalysis Scalability for Environmental Remediation: Opportunities and Challenges
by Sherif A. Younis and Ki-Hyun Kim
Catalysts 2020, 10(10), 1109; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10101109 - 25 Sep 2020
Cited by 44 | Viewed by 3740
Abstract
Heterogeneous photocatalysis is an ecofriendly technique for purifying organic pollutants in environmental systems. While pilot-scale photoreactors have explored photocatalytic system upscalibility, their practical implementation is restricted for various reasons. These include feed composition alteration, complicated photoreactor designs, high operation and synthesis costs, photocatalyst [...] Read more.
Heterogeneous photocatalysis is an ecofriendly technique for purifying organic pollutants in environmental systems. While pilot-scale photoreactors have explored photocatalytic system upscalibility, their practical implementation is restricted for various reasons. These include feed composition alteration, complicated photoreactor designs, high operation and synthesis costs, photocatalyst poisoning, low quantum yield under solar irradiation, fast exciton recombination, and low reuse or regeneration capabilities. In this paper, we highlight the photocatalyst scalability challenges for real-world applications. We also provide an in-depth discussion on photocatalyst opportunities for effective air and water pollution control. Lastly, we offer a contemporary perspective on photocatalysis scale-up for the real environmental treatment. Full article
(This article belongs to the Special Issue Innovative Catalytic and Photocatalytic Systems for Environmental Remediation)
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