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21 pages, 4921 KiB

Open AccessFeature PaperArticle

Photodegradation of Pharmaceutical Pollutants: New Photocatalytic Systems Based on 3D Printed Scaffold-Supported Ag/TiO₂ Nanocomposite

by Laura Bergamonti, Claudia Graiff, Carlo Bergonzi, Marianna Potenza, Cinzia Reverberi, Maria Cristina Ossiprandi, Pier Paolo Lottici, Ruggero Bettini and Lisa Elviri

Catalysts 2022, 12(6), 580; https://doi.org/10.3390/catal12060580 - 25 May 2022

Cited by 7 | Viewed by 2225

Abstract

Due to the release of active pharmaceutical compounds in wastewater and their persistence in the environment, dangerous consequences can develop in the aquatic and terrestrial organisms. Chitosan/Ag/TiO₂ 3D printed scaffolds, at different Ag nanoparticle concentrations (10, 100, 1000 ppm) are investigated here [...] Read more.

Due to the release of active pharmaceutical compounds in wastewater and their persistence in the environment, dangerous consequences can develop in the aquatic and terrestrial organisms. Chitosan/Ag/TiO₂ 3D printed scaffolds, at different Ag nanoparticle concentrations (10, 100, 1000 ppm) are investigated here as promising materials for photocatalytic degradation under the UV–Vis irradiation of pharmaceutical compounds in wastewater. As target drugs, amoxicillin, paracetamol and their 1:1 mix were selected. Ag nanoparticles increase the photocatalytic efficiency of the system based on titanium dioxide embedded in the chitosan scaffold: in the presence of Chitosan/Ag₁₀₀/TiO₂, the selected pharmaceuticals (PhCs), monitored by UV–Vis spectroscopy, are completely removed in about 2 h. The photodegradation products of the PhCs were identified by Liquid Chromatography–Mass Spectroscopy and assessed for their toxicological impact on six different bacterial strains: no antibacterial activity was found towards the tested strains. This new system based on Ag/TiO₂ supported on 3D chitosan scaffolds may represent an effective strategy to reduce wastewater pollution by emerging contaminants. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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29 pages, 8659 KiB

Open AccessArticle

Preparation and Characterization of Supported Molybdenum Doped TiO₂ on α-Al₂O₃ Ceramic Substrate for the Photocatalytic Degradation of Ibuprofen (IBU) under UV Irradiation

by Chukwuka Bethel Anucha, Emin Bacaksiz, Vassilis N. Stathopoulos, Pavlos K. Pandis, Christos Argirusis, Constantina-Dia Andreouli, Zoi Tatoudi and Ilknur Altin

Catalysts 2022, 12(5), 562; https://doi.org/10.3390/catal12050562 - 19 May 2022

Cited by 5 | Viewed by 2175

Abstract

TiO₂-based photocatalyst materials have been widely studied for the abatement of contaminants of emerging concerns (CECs) in water sources. In this study, 1.5 wt% Mo-doped HRTiO₂ was obtained by the sonochemical method. The material was analyzed and characterized for thermal, [...] Read more.

TiO₂-based photocatalyst materials have been widely studied for the abatement of contaminants of emerging concerns (CECs) in water sources. In this study, 1.5 wt% Mo-doped HRTiO₂ was obtained by the sonochemical method. The material was analyzed and characterized for thermal, structural/textural, morphological, and optical properties using TGA-DSC, XRD, TEM, FTIR, XPS, SEM-EDS, BET (N₂ adsorption-desorption measurement and BJH application method), and UV-Vis/DRS measurement. By the dip-coating technique, ~5 mg of Mo/HRTiO₂ as an active topcoat was deposited on ceramic. In suspension and for photocatalyst activity performance evaluation, 1 g/L of 1.5 wt% (Mo)/HRTiO₂ degraded ~98% of initial 50 mg/L IBU concentration after 80 min of 365 nm UV light irradiation and under natural (unmodified) pH conditions. Effects of initial pH condition, catalyst dosage, and initial pollutant concentration were also investigated in the photocatalyst activity performance in suspension. The photocatalyst test on the supported catalyst removed ~60% of initial 5mg/L IBU concentration, while showing an improved performance with ~90% IBU removal employing double and triple numbers of coated disk tablets. After three successive cycle test runs, XRD phase reflections of base TiO₂ component of the active photocatalyst supported layer remained unchanged: An indication of surface coat stability after 360 min of exposure under 365 nm UV irradiation. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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13 pages, 2239 KiB

Open AccessArticle

Acesulfame K Photodegradation over Nitrogen-Doped TiO₂

by Katarzyna Pstrowska, Hanna Czapor-Irzabek, Daniel Borowiak and Ewa Burchacka

Catalysts 2021, 11(10), 1193; https://doi.org/10.3390/catal11101193 - 30 Sep 2021

Viewed by 1915

Abstract

Acesulfame K is a zero-calorie alternative to sugar used worldwide. There is contradictory information on the toxicity of the compound, but its accumulation in the aquatic environment is undeniable. In this study, one-pot sol-gel synthesis was used to obtain nitrogen-doped TiO₂ photocatalysts. [...] Read more.

Acesulfame K is a zero-calorie alternative to sugar used worldwide. There is contradictory information on the toxicity of the compound, but its accumulation in the aquatic environment is undeniable. In this study, one-pot sol-gel synthesis was used to obtain nitrogen-doped TiO₂ photocatalysts. Doping up to 6.29 wt % of nitrogen caused an increase in the surface area of the catalysts (48.55–58.23 m²∙g⁻¹) and a reduction of the pH_PZC value (5.72–5.05). Acesulfame K photodegradation was tested at the initial concentration of 20–100 ppm and the catalyst concentration at the level of 1 g∙L⁻¹. Compared to the pure anatase, 4.83–6.29 wt % nitrogen-doped TiO₂ showed an effective photodegradation of Acesulfame K. Ninety percent molecule removal was obtained after ~100 min, ~90 min, and ~80 min for initial concentrations of 20 ppm, 50 ppm, and 100 ppm, respectively. The increased activity of the catalysts is due to the modification of the TiO₂ lattice structure and probably the limitation of the photogenerated electron/hole charge carrier recombination. It was shown that the electrostatic interactions between Acesulfame K and the catalyst surface play an important role in the photodegradation efficiency. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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11 pages, 3642 KiB

Open AccessArticle

Highly Porous SnO₂/TiO₂ Heterojunction Thin-Film Photocatalyst Using Gas-Flow Thermal Evaporation and Atomic Layer Deposition

by Sungjin Kim, Hyeon-Kyung Chang, Kwang Bok Kim, Hyun-Jong Kim, Ho-Nyun Lee, Tae Joo Park and Young Min Park

Catalysts 2021, 11(10), 1144; https://doi.org/10.3390/catal11101144 - 23 Sep 2021

Cited by 10 | Viewed by 2593

Abstract

Highly porous heterojunction films of SnO₂/TiO₂ were prepared using gas-flow thermal evaporation followed by atomic layer deposition (ALD). Highly porous SnO₂ was fabricated by introducing an inert gas, Ar, during thermal evaporation. To build heterogeneous structures, the TiO₂ [...] Read more.

Highly porous heterojunction films of SnO₂/TiO₂ were prepared using gas-flow thermal evaporation followed by atomic layer deposition (ALD). Highly porous SnO₂ was fabricated by introducing an inert gas, Ar, during thermal evaporation. To build heterogeneous structures, the TiO₂ layers were conformally deposited on porous SnO₂ with a range of 10 to 100 cycles by means of ALD. The photocatalytic properties for different TiO₂ thicknesses on the porous SnO₂ were compared using the degradation of methylene blue (MB) under UV irradiation. The comparisons showed that the SnO₂/TiO₂-50 heterostructures had the highest photocatalytic efficiency. It removed 99% of the MB concentration, and the decomposition rate constant (K) was 0.013 min⁻¹, which was approximately ten times that of the porous SnO₂. On the other hand, SnO₂/TiO₂-100 exhibited a lower photocatalytic efficiency despite having a TiO₂ layer thicker than SnO₂/TiO₂-50. After 100 cycles of TiO₂ ALD deposition, the structure was transferred from the heterojunction to the core–sell structure covered with TiO₂ on the porous SnO₂, which was confirmed by TEM analysis. Since the electrons photogenerated by light irradiation were separated into SnO₂ and produced reactive oxygen, O₂⁻, the heterojunction structure, in which SnO₂ was exposed to the surface, contributed to the high performance of the photocatalyst. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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19 pages, 5548 KiB

Open AccessFeature PaperArticle

Rapid Microwave-Assisted Synthesis of Fe₃O₄/SiO₂/TiO₂ Core-2-Layer-Shell Nanocomposite for Photocatalytic Degradation of Ciprofloxacin

by Ivana Gabelica, Lidija Ćurković, Vilko Mandić, Ivana Panžić, Davor Ljubas and Krešo Zadro

Catalysts 2021, 11(10), 1136; https://doi.org/10.3390/catal11101136 - 22 Sep 2021

Cited by 16 | Viewed by 3166

Abstract

In this work, magnetic nanoparticles based on magnetite were successfully prepared via rapid microwave-assisted synthesis. In order to obtain the ternary core–shell Fe₃O₄/SiO₂/TiO₂ nanocomposite, first magnetite (Fe₃O₄) nanoparticles were coated with a [...] Read more.

In this work, magnetic nanoparticles based on magnetite were successfully prepared via rapid microwave-assisted synthesis. In order to obtain the ternary core–shell Fe₃O₄/SiO₂/TiO₂ nanocomposite, first magnetite (Fe₃O₄) nanoparticles were coated with a protective layer of silica (SiO₂) and finally with titania (TiO₂). The composite configuration comprising porous and photoactive shells should facilitate the removal of organic micropollutants (OMPs) from water. Furthermore, the magnetic core is critical for processing the management of the photocatalytic powder suspension. The magnetization of the prepared magnetic nanoparticles was confirmed by vibrating-sample magnetometry (VSM), while the structure and morphology of the core–shell nanocomposite were investigated by means of XRD, FTIR, and SEM. Adsorption and photocatalysis were evaluated by investigating the removal efficiency of ciprofloxacin (CIP) as a model OMP using the prepared magnetic core–shell nanocomposite under UV-A light irradiation. It was found that the Fe₃O₄/SiO₂/TiO₂ nanocomposite showed good synergistic adsorption and photocatalytic properties. The measurement of iron in eluate confirmed that no leaching occurred during the photocatalytic examination. The recovery of magnetic nanocomposite by an external magnetic field confirmed that the magnetically separated catalyst is highly suitable for recycling and reuse. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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19 pages, 4786 KiB

Open AccessArticle

Synthesis of New Antibiotics Derivatives by the Photocatalytic Method: A Screening Research

by Wojciech Baran, Ewa Masternak, Dominika Sapińska, Andrzej Sobczak and Ewa Adamek

Catalysts 2021, 11(9), 1102; https://doi.org/10.3390/catal11091102 - 13 Sep 2021

Cited by 3 | Viewed by 1841

Abstract

The aim of our study was to assess the possibility of using the photocatalytic process conducted in the presence of TiO₂ to obtain new stable derivatives of antibacterial drugs. The possibility of introducing hydroxyl, chlorine, or bromide groups into antibiotics molecules was [...] Read more.

The aim of our study was to assess the possibility of using the photocatalytic process conducted in the presence of TiO₂ to obtain new stable derivatives of antibacterial drugs. The possibility of introducing hydroxyl, chlorine, or bromide groups into antibiotics molecules was investigated. The experiments were conducted in aqueous solutions in the presence of TiO₂-P25 as a photocatalyst, Cl⁻ and Br⁻ ions, and antibiotics belonging to eight different chemical classes. All experiments were initiated by UVa radiation. The kinetics of photocatalytic reactions and their quantum yield were determined, and the stable products were identified. All of the antibiotics used in the experiments underwent a photocatalytic transformation, and the quantum yields were in the range from 0.63 to 22.3%. The presence of Br⁻ or FeCl₃ significantly increased the efficiency of the photocatalytic process performed in the presence of TiO₂, although Br⁻ ion also acted as an inhibitor. Potentially biologically active chlorine derivatives from Trimethoprim, Metronidazole, Chloramphenicol, and bromine derivatives from Trimethoprim, Amoxicillin were obtained under experimental conditions. The potentially inactive halogen derivatives of Sulfamethoxazole and hydroxyl derivatives described in the literature were also identified. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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12 pages, 969 KiB

Open AccessArticle

Photocatalytic Oxidation of Chlorantraniliprole, Imidacloprid, Pirimicarb, Thiamethoxam and Their Main Photoreaction InterMediates as Impacted by Water Matrix Composition under UVA-LED Exposure

by Marina Aliste, Isabel Garrido, Gabriel Pérez-Lucas, Simón Navarro and José Fenoll

Catalysts 2021, 11(5), 609; https://doi.org/10.3390/catal11050609 - 10 May 2021

Cited by 3 | Viewed by 2066

Abstract

Processes on wastewater treatment plants (WWTP) are not always efficient for pollutant removal. A new, low-cost, and effective technology is needed. In this work, the photocatalytic degradation of four insecticides, chlorantraniliprole, imidacloprid, pirimicarb, and thiamethoxam, has been examined in different water matrices (irrigation [...] Read more.

Processes on wastewater treatment plants (WWTP) are not always efficient for pollutant removal. A new, low-cost, and effective technology is needed. In this work, the photocatalytic degradation of four insecticides, chlorantraniliprole, imidacloprid, pirimicarb, and thiamethoxam, has been examined in different water matrices (irrigation water, leaching waters, and WWTP effluent). Lab experiments were conducted with TiO₂ and ZnO, as photocatalysts, with and without Na₂S₂O₈ as an oxidant, exposed to UVA irradiation with LED lamps. Previously, different loadings of TiO₂ and ZnO were assessed on the disappearance kinetics of the different insecticides to know the optimal efficiency. The effect of water matrices, susceptible to being contaminated with the target insecticides, was discussed when the photocatalytic system TiO₂/Na₂S₂O₈ was applied. The abatement of their main transformation products (TPs) was also monitored during the studied photoperiods. A total of 13 TPs were detected in the different water matrices studied. All of them were formed and eliminated during the photoperiod, except thiamethoxam urea which was present from the beginning of the experiments due to its hydrolysis in water. In conclusion, UVA-LED lamps are a good source to carry out heterogeneous photocatalysis in WWTP, since its high efficiency, low-cost, long lifetime, and effectiveness on pollutant removal. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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13 pages, 3867 KiB

Open AccessArticle

rGO Functionalized ZnO–TiO₂ Core-Shell Flower-Like Architectures for Visible Light Photocatalysis

by Evangelia Vasilaki, Nikos Katsarakis, Spyros Dokianakis and Maria Vamvakaki

Catalysts 2021, 11(3), 332; https://doi.org/10.3390/catal11030332 - 5 Mar 2021

Cited by 11 | Viewed by 2800

Abstract

Core-shell heterostructures with a complex, flower-like morphology, comprising a ZnO core and a TiO₂ shell decorated with reduced graphene oxide (rGO) sheets by hydrothermal wrapping, are reported to extend the absorption properties of the semiconductors toward the visible light range. The ternary [...] Read more.

Core-shell heterostructures with a complex, flower-like morphology, comprising a ZnO core and a TiO₂ shell decorated with reduced graphene oxide (rGO) sheets by hydrothermal wrapping, are reported to extend the absorption properties of the semiconductors toward the visible light range. The ternary photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, diffuse reflectance UV–Vis, and attenuated total reflectance-Fourier transform infrared spectroscopy. Its photocatalytic performance was evaluated under visible light irradiation using methylene blue dye as a model pollutant. The rGO-modified ZnO–TiO₂ photocatalyst exhibited superior photoactivity compared to that of the parent ZnO–TiO₂ core-shell structures, which was dependent on its graphene content. The enhanced photocatalytic response was attributed to the higher absorption in the visible light range, as well as the pronounced electron and hole separation in the ternary system. Full article

(This article belongs to the Special Issue Photocatalytic Activity of TiO₂ and Its Applications)

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