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Application of Photoactive Nanomaterials in Degradation of Pollutants

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Nanomaterials and Nanotechnology".

Deadline for manuscript submissions: closed (31 December 2018) | Viewed by 37330

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Special Issue Editor

Special Issue Information

Dear Colleagues,

Photoactive nanomaterials are receiving increasing attention due to their potential application in light-driven degradation of water and gas-phase pollutants.

The ability to exploit the strong potential of photoactive materials and access their properties relies on the ability to tune their size/shape dependent chemical-physical properties and on the ability to integrate them in photo-reactors or to deposit them on large surfaces. Therefore, the synthetic approach, as well as the post-synthesis manipulation could strongly affect the final photocatalytic properties of the nanomaterials. Thus far, a plethora of nanomaterials have been proposed for the degradation of pollutants driven by UV or Visible light: semiconductors, plasmonic nanoparticles, magnetic nanoparticles, hybrid nanocatalysts merging the properties of different crystalline domain and nanocomposite based on nanoparticles dispersed in suitable host matrix. One of the major concern in the large-scale application of nanomaterial assisted photocatalytic processes is to avoid the release of nanocatalysts in the environment during or after the photocatalytic treatment, therefore the immobilization of nanocatalyst onto suitable supports is a key point to promote their practical application.

The potential application of photoactive nanomaterials in environmental field includes abatement of organic pollutant in water, water disinfection and abatement of gas-phase pollutants in outdoor and indoor applications.

We invite contributors to submit original papers that account for recent advances in the field of photoactive nanomaterials for the degradation of pollutants assisted by UV, visible or solar light.

Dr. Roberto Comparelli
Guest Editor

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Keywords

  • photoactive nanomaterials synthesis
  • supported photocatalysts
  • advanced oxidation processes
  • water treatments
  • water disinfection
  • recalcitrant pollutants
  • gas-phase pollutants
  • NOx
  • VOCs

Published Papers (8 papers)

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Editorial

Jump to: Research, Review

4 pages, 185 KiB  
Editorial
Special Issue: Application of Photoactive Nanomaterials in Degradation of Pollutants
by Roberto Comparelli
Materials 2019, 12(15), 2459; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12152459 - 02 Aug 2019
Cited by 3 | Viewed by 1986
Abstract
Photoactive nanomaterials are receiving increasing attention due to their potential application to light-driven degradation of water and gas-phase pollutants. However, to exploit the strong potential of photoactive materials and access their properties require a fine tuning of their size/shape dependent chemical-physical properties and [...] Read more.
Photoactive nanomaterials are receiving increasing attention due to their potential application to light-driven degradation of water and gas-phase pollutants. However, to exploit the strong potential of photoactive materials and access their properties require a fine tuning of their size/shape dependent chemical-physical properties and on the ability to integrate them in photo-reactors or to deposit them on large surfaces. Therefore, the synthetic approach, as well as post-synthesis manipulation could strongly affect the final photocatalytic properties of nanomaterials. The potential application of photoactive nanomaterials in the environmental field includes the abatement of organic pollutant in water, water disinfection, and abatement of gas-phase pollutants in outdoor and indoor applications. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)

Research

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16 pages, 2899 KiB  
Article
Photocatalytic Performance of CuxO/TiO2 Deposited by HiPIMS on Polyester under Visible Light LEDs: Oxidants, Ions Effect, and Reactive Oxygen Species Investigation
by Hichem Zeghioud, Aymen Amine Assadi, Nabila Khellaf, Hayet Djelal, Abdeltif Amrane and Sami Rtimi
Materials 2019, 12(3), 412; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12030412 - 29 Jan 2019
Cited by 48 | Viewed by 3882
Abstract
In the present study, we propose a new photocatalytic interface prepared by high-power impulse magnetron sputtering (HiPIMS), and investigated for the degradation of Reactive Green 12 (RG12) as target contaminant under visible light light-emitting diodes (LEDs) illumination. The CuxO/TiO2 nanoparticulate [...] Read more.
In the present study, we propose a new photocatalytic interface prepared by high-power impulse magnetron sputtering (HiPIMS), and investigated for the degradation of Reactive Green 12 (RG12) as target contaminant under visible light light-emitting diodes (LEDs) illumination. The CuxO/TiO2 nanoparticulate photocatalyst was sequentially sputtered on polyester (PES). The photocatalyst formulation was optimized by investigating the effect of different parameters such as the sputtering time of CuxO, the applied current, and the deposition mode (direct current magnetron sputtering, DCMS or HiPIMS). The results showed that the fastest RG12 degradation was obtained on CuxO/TiO2 sample prepared at 40 A in HiPIMS mode. The better discoloration efficiency of 53.4% within 360 min was found in 4 mg/L of RG12 initial concentration and 0.05% Cuwt/PESwt as determined by X-ray fluorescence. All the prepared samples contained a TiO2 under-layer with 0.02% Tiwt/PESwt. By transmission electron microscopy (TEM), both layers were seen uniformly distributed on the PES fibers. The effect of the surface area to volume (dye volume) ratio (SA/V) on the photocatalytic efficiency was also investigated for the discoloration of 4 mg/L RG12. The effect of the presence of different chemicals (scavengers, oxidant or mineral pollution or salts) in the photocatalytic medium was studied. The optimization of the amount of added hydrogen peroxide (H2O2) and potassium persulfate (K2S2O8) was also investigated in detail. Both, H2O2 and K2S2O8 drastically affected the discoloration efficiency up to 7 and 6 times in reaction rate constants, respectively. Nevertheless, the presence of Cu (metallic nanoparticles) and NaCl salt inhibited the reaction rate of RG12 discoloration by about 4 and 2 times, respectively. Moreover, the systematic study of reactive oxygen species’ (ROS) contribution was also explored with the help of iso-propanol, methanol, and potassium dichromate as OH radicals, holes (h+), and superoxide ion-scavengers, respectively. Scavenging results showed that O2 played a primary role in RG12 removal; however, OH radicals’ and photo-generated holes’ (h+) contributions were minimal. The CuxO/TiO2 photocatalyst was found to have a good reusability and stability up to 21 cycles. Ions’ release was quantified by means of inductively coupled plasma mass spectrometry (ICP-MS) showing low Cu-ions’ release. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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21 pages, 5372 KiB  
Article
Enhanced Photocatalytic and Antimicrobial Performance of Cuprous Oxide/Titania: The Effect of Titania Matrix
by Marcin Janczarek, Maya Endo, Dong Zhang, Kunlei Wang and Ewa Kowalska
Materials 2018, 11(11), 2069; https://0-doi-org.brum.beds.ac.uk/10.3390/ma11112069 - 23 Oct 2018
Cited by 46 | Viewed by 4764
Abstract
A simple, low-cost method was applied to prepare hybrid photocatalysts of copper (I) oxide/titania. Five different TiO2 powders were used to perform the study of the effect of titania matrix on the photocatalytic and antimicrobial properties of prepared nanocomposites. The photocatalytic efficiency [...] Read more.
A simple, low-cost method was applied to prepare hybrid photocatalysts of copper (I) oxide/titania. Five different TiO2 powders were used to perform the study of the effect of titania matrix on the photocatalytic and antimicrobial properties of prepared nanocomposites. The photocatalytic efficiency of such a dual heterojunction system was tested in three reaction systems: ultraviolet-visible (UV-Vis)-induced methanol dehydrogenation and oxidation of acetic acid, and 2-propanol oxidation under visible light irradiation. In all the reaction systems considered, the crucial enhancement of photocatalytic activity in relation to corresponding bare titania was observed. The reaction mechanism for a specific reaction and the influence of titania matrix were discussed. Furthermore, antimicrobial (bactericidal and fungicidal) properties of Cu2O/TiO2 materials were analyzed. The antimicrobial activity was found under UV, visible and solar irradiation, and even for dark conditions. The origin of antimicrobial properties with emphasis on the role of titania matrix was also discussed. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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16 pages, 1974 KiB  
Article
Photocatalytic Degradation of Diclofenac by Hydroxyapatite–TiO2 Composite Material: Identification of Transformation Products and Assessment of Toxicity
by Sapia Murgolo, Irina S. Moreira, Clara Piccirillo, Paula M. L. Castro, Gianrocco Ventrella, Claudio Cocozza and Giuseppe Mascolo
Materials 2018, 11(9), 1779; https://0-doi-org.brum.beds.ac.uk/10.3390/ma11091779 - 19 Sep 2018
Cited by 48 | Viewed by 5055
Abstract
Diclofenac (DCF) is one of the most detected pharmaceuticals in environmental water matrices and is known to be recalcitrant to conventional wastewater treatment plants. In this study, degradation of DCF was performed in water by photolysis and photocatalysis using a new synthetized photocatalyst [...] Read more.
Diclofenac (DCF) is one of the most detected pharmaceuticals in environmental water matrices and is known to be recalcitrant to conventional wastewater treatment plants. In this study, degradation of DCF was performed in water by photolysis and photocatalysis using a new synthetized photocatalyst based on hydroxyapatite and TiO2 (HApTi). A degradation of 95% of the target compound was achieved in 24 h by a photocatalytic treatment employing the HApTi catalyst in comparison to only 60% removal by the photolytic process. The investigation of photo-transformation products was performed by means of UPLC-QTOF/MS/MS, and for 14 detected compounds in samples collected during treatment with HApTi, the chemical structure was proposed. The determination of transformation product (TP) toxicity was performed by using different assays: Daphnia magna acute toxicity test, Toxi-ChromoTest, and Lactuca sativa and Solanum lycopersicum germination inhibition test. Overall, the toxicity of the samples obtained from the photocatalytic experiment with HApTi decreased at the end of the treatment, showing the potential applicability of the catalyst for the removal of diclofenac and the detoxification of water matrices. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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18 pages, 8801 KiB  
Article
Photoelectrocatalytic Degradation of Paraquat by Pt Loaded TiO2 Nanotubes on Ti Anodes
by Levent Özcan, Turan Mutlu and Sedat Yurdakal
Materials 2018, 11(9), 1715; https://0-doi-org.brum.beds.ac.uk/10.3390/ma11091715 - 13 Sep 2018
Cited by 18 | Viewed by 3907
Abstract
Nanotube structured TiO2 on Ti surface were prepared in ethylene glycol (Ti/TiO2NTEG) medium by anodic oxidation method with different times and then the plates were calcinated at different temperatures. Non-nanotube structured Ti/TiO2, prepared by thermal oxidation method, and [...] Read more.
Nanotube structured TiO2 on Ti surface were prepared in ethylene glycol (Ti/TiO2NTEG) medium by anodic oxidation method with different times and then the plates were calcinated at different temperatures. Non-nanotube structured Ti/TiO2, prepared by thermal oxidation method, and nanotube structured TiO2 on Ti plate in hydrogen fluoride solution were also prepared for comparison. Pt loaded Ti/TiO2NTEG photoanodes were also prepared by cyclic voltammetry method with different cycles and the optimum loaded Pt amount was determined. Photoanodes were characterized by using X-ray Diffraction (XRD), Scanning Electron Microscopy-Energy-Dispersive X-ray Analysis (SEM-EDX), and photocurrent methods. XRD analyses proved that almost all TiO2 is in anatase phase. SEM analyses show that nanotubes and Pt nanoparticles on nanotube surface are dispersed quite homogeneously. The longest nanotubes were obtained in the ethylene glycol medium and the nanotube length increased by increasing applied anodic oxidation time. In addition, a linear correlation between nanotube length and XRD peak intensity was found. Moreover, SEM-EDX and XRD analyses evidence that Pt nanoparticles on nanotube surface are metallic and in cubic structure. Photoelectrocatalytic degradation of paraquat was performed using the prepared photoanodes. Moreover, electrocatalytic and photocatalytic degradations of paraquat were also investigated for comparison, however lower activities were observed. These results evidence that the photoanodes show a significant synergy for photoelectrocatalytic activity. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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17 pages, 21584 KiB  
Article
Influence of Titanium Dioxide Nanoparticles on the Sulfate Attack upon Ordinary Portland Cement and Slag-Blended Mortars
by Atta-ur-Rehman, Abdul Qudoos, Hong Gi Kim and Jae-Suk Ryou
Materials 2018, 11(3), 356; https://0-doi-org.brum.beds.ac.uk/10.3390/ma11030356 - 28 Feb 2018
Cited by 40 | Viewed by 6807
Abstract
In this study, the effects of titanium dioxide (TiO2) nanoparticles on the sulfate attack resistance of ordinary Portland cement (OPC) and slag-blended mortars were investigated. OPC and slag-blended mortars (OPC:Slag = 50:50) were made with water to binder ratio of 0.4 [...] Read more.
In this study, the effects of titanium dioxide (TiO2) nanoparticles on the sulfate attack resistance of ordinary Portland cement (OPC) and slag-blended mortars were investigated. OPC and slag-blended mortars (OPC:Slag = 50:50) were made with water to binder ratio of 0.4 and a binder to sand ratio of 1:3. TiO2 was added as an admixture as 0%, 3%, 6%, 9% and 12% of the binder weight. Mortar specimens were exposed to an accelerated sulfate attack environment. Expansion, changes in mass and surface microhardness were measured. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC) tests were conducted. The formation of ettringite and gypsum crystals after the sulfate attack were detected. Both these products had caused crystallization pressure in the microstructure of mortars and deteriorated the mortars. Our results show that the addition of nano-TiO2 accelerated expansion, variation in mass, loss of surface microhardness and widened cracks in OPC and slag-blended mortars. Nano-TiO2 containing slag-blended mortars were more resistant to sulfate attack than nano-TiO2 containing OPC mortars. Because nano-TiO2 reduced the size of coarse pores, so it increased crystallization pressure due to the formation of ettringite and gypsum thus led to more damage under sulfate attack. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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11 pages, 1686 KiB  
Article
Shell Layer Thickness-Dependent Photocatalytic Activity of Sputtering Synthesized Hexagonally Structured ZnO-ZnS Composite Nanorods
by Yuan-Chang Liang, Ya-Ru Lo, Chein-Chung Wang and Nian-Cih Xu
Materials 2018, 11(1), 87; https://0-doi-org.brum.beds.ac.uk/10.3390/ma11010087 - 07 Jan 2018
Cited by 15 | Viewed by 4224
Abstract
ZnO-ZnS core-shell nanorods are synthesized by combining the hydrothermal method and vacuum sputtering. The core-shell nanorods with variable ZnS shell thickness (7–46 nm) are synthesized by varying ZnS sputtering duration. Structural analyses demonstrated that the as-grown ZnS shell layers are well crystallized with [...] Read more.
ZnO-ZnS core-shell nanorods are synthesized by combining the hydrothermal method and vacuum sputtering. The core-shell nanorods with variable ZnS shell thickness (7–46 nm) are synthesized by varying ZnS sputtering duration. Structural analyses demonstrated that the as-grown ZnS shell layers are well crystallized with preferring growth direction of ZnS (002). The sputtering-assisted synthesized ZnO-ZnS core-shell nanorods are in a wurtzite structure. Moreover, photoluminance spectral analysis indicated that the introduction of a ZnS shell layer improved the photoexcited electron and hole separation efficiency of the ZnO nanorods. A strong correlation between effective charge separation and the shell thickness aids the photocatalytic behavior of the nanorods and improves their photoresponsive nature. The results of comparative degradation efficiency toward methylene blue showed that the ZnO-ZnS nanorods with the shell thickness of approximately 17 nm have the highest photocatalytic performance than the ZnO-ZnS nanorods with other shell layer thicknesses. The highly reusable catalytic efficiency and superior photocatalytic performance of the ZnO-ZnS nanorods with 17 nm-thick ZnS shell layer supports their potential for environmental applications. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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Review

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21 pages, 3961 KiB  
Review
Scalable Synthesis of Mesoporous TiO2 for Environmental Photocatalytic Applications
by Francesca Petronella, Alessandra Truppi, Massimo Dell’Edera, Angela Agostiano, M. Lucia Curri and Roberto Comparelli
Materials 2019, 12(11), 1853; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12111853 - 07 Jun 2019
Cited by 38 | Viewed by 5430
Abstract
Increasing environmental concern, related to pollution and clean energy demand, have urged the development of new smart solutions profiting from nanotechnology, including the renowned nanomaterial-assisted photocatalytic degradation of pollutants. In this framework, increasing efforts are devoted to the development of TiO2-based [...] Read more.
Increasing environmental concern, related to pollution and clean energy demand, have urged the development of new smart solutions profiting from nanotechnology, including the renowned nanomaterial-assisted photocatalytic degradation of pollutants. In this framework, increasing efforts are devoted to the development of TiO2-based nanomaterials with improved photocatalytic activity. A plethora of synthesis routes to obtain high quality TiO2-based nanomaterials is currently available. Nonetheless, large-scale production and the application of nanosized TiO2 is still hampered by technological issues and the high cost related to the capability to obtain TiO2 nanoparticles with high reaction yield and adequate morphological and structural control. The present review aims at providing a selection of synthetic approaches suitable for large-scale production of mesoporous TiO2-based photocatalysts due to its unique features including high specific surface area, improved ultraviolet (UV) radiation absorption, high density of surface hydroxyl groups, and significant ability for further surface functionalization The overviewed synthetic strategies have been selected and classified according to the following criteria (i) high reaction yield, (ii) reliable synthesis scale-up and (iii) adequate control over morphological, structural and textural features. Potential environmental applications of such nanostructures including water remediation and air purification are also discussed. Full article
(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)
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