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Keywords = immobilised photocatalyst

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21 pages, 4597 KiB  
Article
Preparation of Non-Covalent BPTCD/g-C3N4 Heterojunction Photocatalysts and Photodegradation of Organic Dyes Under Solar Irradiation
by Xing Wei, Gaopeng Jia, Ru Chen and Yalong Zhang
Nanomaterials 2025, 15(14), 1131; https://doi.org/10.3390/nano15141131 - 21 Jul 2025
Viewed by 304
Abstract
In this study, the BPTCD/g-C3N4 heterojunction photocatalyst was successfully prepared by the hydrothermal method. BPTCD (3,3′,4,4′-benzophenone tetracarboxylic dianhydride) is immobilised on the surface of g-C3N4 by non-covalent π-π stacking. The BPTCD/g-C3N4 heterojunction photocatalyst is [...] Read more.
In this study, the BPTCD/g-C3N4 heterojunction photocatalyst was successfully prepared by the hydrothermal method. BPTCD (3,3′,4,4′-benzophenone tetracarboxylic dianhydride) is immobilised on the surface of g-C3N4 by non-covalent π-π stacking. The BPTCD/g-C3N4 heterojunction photocatalyst is an all-organic photocatalyst with significantly improved photocatalytic performance compared with g-C3N4. BPTCD/g-C3N4-60% was able to effectively degrade MO solution (10 mg/L) to 99.9% and 82.8% in 60 min under full spectrum and visible light. The TOC measurement results indicate that MO can ultimately be decomposed into H2O and CO2 through photocatalytic action. The photodegradation of methyl orange by BPTCD/g-C3N4 composite materials under sunlight is mainly attributed to the successful construction of the heterojunction structure and its excellent π-π stacking effect. Superoxide radicals (O2) were found to be the main active species, while OH and h+ played a secondary role. The synthesised BPTCD/g-C3N4 also showed excellent stability in the activity of photodegradation of MO in wastewater, with the performance remaining above 90% after three cycles. The mechanism of the photocatalytic removal of MO dyes was also investigated by the trap agent experiments. Additionally, BPTCD/g-C3N4-60% demonstrated exceptional photodegradation performance in the degradation of methylene blue (MB). BPTCD/g-C3N4 heterojunctions have great potential to degrade organic pollutants in wastewater under solar irradiation conditions. Full article
(This article belongs to the Section Environmental Nanoscience and Nanotechnology)
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17 pages, 6919 KiB  
Article
Life Cycle Assessment of Immobilised and Slurry Photocatalytic Systems for Removal of Natural Organic Matter in Water
by Dan C. A. Gowland, Neil Robertson and Efthalia Chatzisymeon
Environments 2024, 11(6), 114; https://doi.org/10.3390/environments11060114 - 28 May 2024
Cited by 2 | Viewed by 1870
Abstract
This study investigates the environmental impacts caused by the scaling up of the photocatalytic purification of drinking water using ultraviolet light-emitting diode technology. The life cycle assessment methodology was utilised to estimate the environmental impacts of two different reactor setups commonly used in [...] Read more.
This study investigates the environmental impacts caused by the scaling up of the photocatalytic purification of drinking water using ultraviolet light-emitting diode technology. The life cycle assessment methodology was utilised to estimate the environmental impacts of two different reactor setups commonly used in lab-scale studies: an immobilised and a suspended TiO2 catalytic system. The functional unit adopted was the treatment of 1 L of water with an initial 7.8 mg/L concentration of natural organic matter, achieving a final 1 mg/L concentration. The use of a suspended photocatalyst was found to have an environmental footprint that was 87% lower than that of the immobilised one. From the sensitivity analysis, the environmental hotspots of the treatment process were the electricity usage and immobilised catalyst production. Therefore, alternative scenarios investigating the use of a renewable electricity mix and recyclable materials were explored to enhance the environmental performance of the photocatalytic treatment process. Using a renewable electricity mix, a decrease of 55% and 15% for the suspended and immobilised catalyst, respectively, was observed. Additionally, the process of recycling the glass used to support the immobilised catalyst achieved a maximum reduction of 22% in the environmental impact from the original scenario, with 100 glass reuses appearing to provide diminishing returns on the environmental impact savings. Full article
(This article belongs to the Special Issue Photocatalytic Applications in Wastewater Treatment)
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15 pages, 3956 KiB  
Article
Photocatalytic Degradation of Neonicotinoid Insecticides over Perlite-Supported TiO2
by Vanja Kosar, Ana-Marija Križanac, Ivana Elizabeta Zelić, Stanislav Kurajica and Vesna Tomašić
Processes 2023, 11(9), 2588; https://doi.org/10.3390/pr11092588 - 29 Aug 2023
Cited by 5 | Viewed by 1680
Abstract
The aim of this study was to investigate the photocatalytic degradation of the neonicotinoid insecticide acetamiprid in aqueous solution. Experiments were carried out in a 250 mL batch reactor with recirculation of the reaction mixture and using a UVA-LED radiation source with a [...] Read more.
The aim of this study was to investigate the photocatalytic degradation of the neonicotinoid insecticide acetamiprid in aqueous solution. Experiments were carried out in a 250 mL batch reactor with recirculation of the reaction mixture and using a UVA-LED radiation source with a heterogeneous UVC-modified perlite-based TiO2 photocatalyst. The photocatalytic degradation of acetamiprid was optimized using a Box–Behnken design (BBD) of the response surface methodology (RSM). The variables in the process optimization were catalyst type, volume of the reaction mixture, and light radiation intensity. From the experimental data obtained, the conversions of the photocatalytic reactions, the reaction rate constants, and the mean square deviations were calculated. The experimental results have shown that the conversion of the reaction is significantly affected by the type of catalyst, i.e., the method used to immobilise the photocatalytic layer on the perlite granules. The highest conversions of 48.49% were reached with catalysts obtained by impregnation methods, while the conversions were quite low (8.68%) for catalysts obtained by sol-gel methods. It was also found that the highest conversions were achieved with the highest radiation intensity and the smallest volume of reaction mixture. Full article
(This article belongs to the Section Catalysis Enhanced Processes)
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13 pages, 2499 KiB  
Article
Performance of TiO2-Based Tubular Membranes in the Photocatalytic Degradation of Organic Compounds
by Carmen Barquín, Aranza Vital-Grappin, Izumi Kumakiri, Nazely Diban, Maria J. Rivero, Ane Urtiaga and Inmaculada Ortiz
Membranes 2023, 13(4), 448; https://doi.org/10.3390/membranes13040448 - 20 Apr 2023
Cited by 4 | Viewed by 3230
Abstract
This work presents the photocatalytic degradation of organic pollutants in water with TiO2 and TiO2/Ag membranes prepared by immobilising photocatalysts on ceramic porous tubular supports. The permeation capacity of TiO2 and TiO2/Ag membranes was checked before the [...] Read more.
This work presents the photocatalytic degradation of organic pollutants in water with TiO2 and TiO2/Ag membranes prepared by immobilising photocatalysts on ceramic porous tubular supports. The permeation capacity of TiO2 and TiO2/Ag membranes was checked before the photocatalytic application, showing high water fluxes (≈758 and 690 L m−2 h−1 bar−1, respectively) and <2% rejection against the model pollutants sodium dodecylbenzene sulfonate (DBS) and dichloroacetic acid (DCA). When the membranes were submerged in the aqueous solutions and irradiated with UV-A LEDs, the photocatalytic performance factors for the degradation of DCA were similar to those obtained with suspended TiO2 particles (1.1-fold and 1.2-fold increase, respectively). However, when the aqueous solution permeated through the pores of the photocatalytic membrane, the performance factors and kinetics were two-fold higher than for the submerged membranes, mostly due to the enhanced contact between the pollutants and the membranes photocatalytic sites where reactive species were generated. These results confirm the advantages of working in a flow-through mode with submerged photocatalytic membranes for the treatment of water polluted with persistent organic molecules, thanks to the reduction in the mass transfer limitations. Full article
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13 pages, 4131 KiB  
Article
Photocatalytic Properties of Immobilised Graphitic Carbon Nitride on the Alumina Substrate
by Milan Vukšić, Martina Kocijan, Lidija Ćurković, Tina Radošević, Damjan Vengust and Matejka Podlogar
Appl. Sci. 2022, 12(19), 9704; https://doi.org/10.3390/app12199704 - 27 Sep 2022
Cited by 10 | Viewed by 2072
Abstract
Textile industries significantly impact the contamination of wastewater. Conventional wastewater treatment methods consider the most common pollutants; however, they are very expensive and commonly produce toxic by-products. In the scientific community, advanced oxidation processes appear to be the most appealing, and a majority [...] Read more.
Textile industries significantly impact the contamination of wastewater. Conventional wastewater treatment methods consider the most common pollutants; however, they are very expensive and commonly produce toxic by-products. In the scientific community, advanced oxidation processes appear to be the most appealing, and a majority of the published work considers heterogeneous photocatalysis for the degradation of various toxic chemicals. For convenience, the reaction is performed directly in the water environment. In this work, a metal-free graphitic carbon nitride (g-C3N4) was prepared through a simple thermal method using urea as a precursor. Prepared g-C3N4 was deposited on the surface of the alumina ceramic ring by the dip-coating method using ethylene glycol as binder. The alumina ceramic ring, as substrate, was prepared by the slip casting method. Photocatalytic properties of immobilised graphitic carbon nitride were used for degradation of methylene blue as a model pollutant under simulated solar light irradiation. The photocatalyst was characterised by XRD, FTIR, UV-Vis DRS, TGA, BET and SEM/EDX analyses. The photocatalytic degradation of MB from an aqueous solution was found to increase with increasing irradiation time. It was found that the graphitic carbon nitride immobilised on alumina ceramic is convenient for largescale environmental applications because the whole setup is cheap, nontoxic, easy to operate and offers reusability with a high removal rate of MB after three consecutive cycles. Full article
(This article belongs to the Section Surface Sciences and Technology)
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13 pages, 2262 KiB  
Article
Visible-Light-Driven Photocatalytic Inactivation of Bacteria, Bacteriophages, and Their Mixtures Using ZnO-Coated HDPE Beads as Floating Photocatalyst
by Marius Urbonavicius, Sarunas Varnagiris, Simona Tuckute, Sandra Sakalauskaite, Emilija Demikyte and Martynas Lelis
Materials 2022, 15(4), 1318; https://doi.org/10.3390/ma15041318 - 10 Feb 2022
Cited by 5 | Viewed by 2305
Abstract
Semiconductor materials used as photocatalysts are considered among the most effective ways to treat biologically polluted water. Certainly, efficiency depends on the selection of photocatalyst and its substrate, as well as the possibility of its application in a broader spectrum of light. In [...] Read more.
Semiconductor materials used as photocatalysts are considered among the most effective ways to treat biologically polluted water. Certainly, efficiency depends on the selection of photocatalyst and its substrate, as well as the possibility of its application in a broader spectrum of light. In this study, a reactive magnetron sputtering technique was applied for the immobilisation of ZnO photocatalyst on the surface of HDPE beads, which were selected as the buoyant substrates for enhanced photocatalytic performance and easier recovery from the treated water. Moreover, the study compared the effect on the inactivation of the microorganism between ZnO-coated HDPE beads without Ni and with Ni underlayer. Crystal structure, surface morphology, and chemical bonds of as-deposited ZnO films were investigated by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Visible-light-induced photocatalytic treatment was performed on the Gram-negative and Gram-positive bacteria and bacteriophages PRD1, T4, and their mixture. Higher bacteria inactivation efficiency was obtained using the ZnO photocatalyst with Ni underlayer for the treatment of S. Typhimurium and M. Luteus mixtures. As for infectivity of bacteriophages, T4 alone and in the mixture with PRD1 were more affected by the produced photocatalyst, compared with PRD1. Full article
(This article belongs to the Special Issue Advanced Oxide-Based Materials for Photocatalytic Applications)
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14 pages, 7324 KiB  
Article
Immobilised rGO/TiO2 Nanocomposite for Multi-Cycle Removal of Methylene Blue Dye from an Aqueous Medium
by Martina Kocijan, Lidija Ćurković, Igor Bdikin, Gonzalo Otero-Irurueta, María J. Hortigüela, Gil Gonçalves, Tina Radošević, Damjan Vengust and Matejka Podlogar
Appl. Sci. 2022, 12(1), 385; https://doi.org/10.3390/app12010385 - 31 Dec 2021
Cited by 24 | Viewed by 3580
Abstract
This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO [...] Read more.
This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO2 NPs and rGO-TiO2 nanocomposite were synthesised through a simple hydrothermal method of titanium isopropoxide precursor followed by calcination treatment. Deposition of prepared photocatalysts was performed by spin-coating method. Additionally, ethylene glycol was mixed with the prepared TiO2 NPs and rGO-TiO2 nanocomposite to enhance film adhesion on the glass surface. The photocatalytic activity under ultraviolet and simulated solar irradiation was examined. Further, the influence of different water matrices (milli-Q, river, lake, and seawater) and reactive species (h+, OH, and e) on the photocatalytic efficiency of the immobilised rGO/TiO2 nanocomposite was careful assessed. MB dye photocatalytic degradation was found to increase with increasing irradiation time for both irradiation sources. The immobilisation of prepared photocatalysts is very convenient for environment applications, due to easy separation and reusability, and the investigated rGO/TiO2-coated glass sheets demonstrated high efficiency in removing MB dye from an aqueous medium during five consecutive cycles. Full article
(This article belongs to the Special Issue Advances of Graphene-Based Nanoplatforms)
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36 pages, 9397 KiB  
Review
A Review of Photoelectrocatalytic Reactors for Water and Wastewater Treatment
by Stuart McMichael, Pilar Fernández-Ibáñez and John Anthony Byrne
Water 2021, 13(9), 1198; https://doi.org/10.3390/w13091198 - 26 Apr 2021
Cited by 54 | Viewed by 10829
Abstract
The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination [...] Read more.
The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). This review will explain the fundamental mechanism of PECs, photoelectrodes, the different types of PEC reactors reported in the literature, the (photo)electrodes used, the contaminants degraded, the key findings and prospects in the research area. Full article
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17 pages, 5519 KiB  
Article
Floating ZnO QDs-Modified TiO2/LLDPE Hybrid Polymer Film for the Effective Photodegradation of Tetracycline under Fluorescent Light Irradiation: Synthesis and Characterisation
by Anwar Iqbal, Usman Saidu, Farook Adam, Srimala Sreekantan, Noorfatimah Yahaya, Mohammad Norazmi Ahmad, Rajabathar Jothi Ramalingam and Lee D. Wilson
Molecules 2021, 26(9), 2509; https://doi.org/10.3390/molecules26092509 - 25 Apr 2021
Cited by 28 | Viewed by 3826 | Correction
Abstract
In this work, mesoporous TiO2-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used [...] Read more.
In this work, mesoporous TiO2-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used to investigate the physicochemical properties of the floating hybrid polymer film catalyst (8%-ZT@LLDPE). The highest removal (89.5%) of TC (40 mg/L) was achieved within 90 min at pH 9 due to enhanced water uptake by the LDDPE film and the surface roughness of the hybrid film. The formation of heterojunctions increased the separation of photogenerated electron-hole pairs. The QDs size-dependent quantum confinement effect leads to the displacement of the conduction band potential of ZnO QDs to more negative energy values than TiO2. The displacement generates more reactive species with higher oxidation ability. The highly stable film photocatalyst can be separated easily and can be repeatedly used up to 8 cycles without significant loss in the photocatalytic ability. The scavenging test indicates that the main species responsible for the photodegradation was O2. The proposed photodegradation mechanism of TC was demonstrated in further detail based on the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS). Full article
(This article belongs to the Special Issue Environmental Applications of Polymers)
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17 pages, 2979 KiB  
Article
Immobilised Cerium-Doped Zinc Oxide as a Photocatalyst for the Degradation of Antibiotics and the Inactivation of Antibiotic-Resistant Bacteria
by Ian Zammit, Vincenzo Vaiano, Ana R. Ribeiro, Adrián M. T. Silva, Célia M. Manaia and Luigi Rizzo
Catalysts 2019, 9(3), 222; https://doi.org/10.3390/catal9030222 - 1 Mar 2019
Cited by 36 | Viewed by 5671
Abstract
The threat of antibiotic resistance to the wellbeing of societies is well established. Urban wastewater treatment plants (UWTPs) are recognised sources for antibiotic resistance dissemination in the environment. Herein a novel cerium-doped zinc oxide (Ce-ZnO) photocatalyst is compared to ZnO and the benchmark [...] Read more.
The threat of antibiotic resistance to the wellbeing of societies is well established. Urban wastewater treatment plants (UWTPs) are recognised sources for antibiotic resistance dissemination in the environment. Herein a novel cerium-doped zinc oxide (Ce-ZnO) photocatalyst is compared to ZnO and the benchmark TiO2-P25 in the immobilised form on a metallic support, to evaluate a photocatalytic process as a possible tertiary treatment in UWTPs. The catalysts were compared for the removal of two antibiotics, trimethoprim (TMP) and sulfamethoxazole (SMX), and for the inactivation of Escherichia coli (E. coli) strain DH5-Alpha in isotonic sodium chloride solution and of autochthonous bacteria in real secondary wastewater. In real wastewater, E. coli and other coliforms were monitored, as well as the respective fractions resistant to ofloxacin and azithromycin. In parallel, Pseudomonas aeruginosa and the respective sub-population resistant to ofloxacin or ciprofloxacin were also monitored. Photocatalysis with both ZnO and Ce-ZnO was faster than using TiO2-P25 at degrading the antibiotics, with Ce-ZnO the fastest against SMX but slower than undoped ZnO in the removal of TMP. Ce-ZnO catalyst reuse in the immobilised form produced somewhat slower kinetics maintained >50% of the initial activity, even after five cycles of use. Approximately 3 log10 inactivation of E. coli in isotonic sodium chloride water was recorded with reproducible results. In the removal of autochthonous bacteria in real wastewater, Ce-ZnO performed better (more than 2 log values higher) than TiO2-P25. In all cases, E. coli and other coliforms, including their resistant subpopulations, were inactivated at a higher rate than P. aeruginosa. With short reaction times no evidence for enrichment of resistance was observed, yet with extended reaction times low levels of bacterial loads were not further inactivated. Overall, Ce-ZnO is an easy and cheap photocatalyst to produce and immobilise and the one that showed higher activity than the industry standard TiO2-P25 against the tested antibiotics and bacteria, including antibiotic-resistant bacteria. Full article
(This article belongs to the Special Issue Environmental Applications of Photocatalytic Processes)
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