New Trends in the Photocatalytic Removal of Organic Dyes

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

Deadline for manuscript submissions: closed (30 June 2019) | Viewed by 70055

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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
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Special Issue Information

Dear Colleagues,

Currently, different types of dyes consisting of varied chemical compounds are used in the production of consumer products, including paints, textiles, printing inks, paper, and plastics, depending on the type of textile or product being dyed. The effluent generated by these activities are one of the main causes of environmental pollution, because the effluent coming from the dyeing industry is highly colored, causing damage to aquatic life. For this reason, water pollution due to the dyeing industry is a matter of great concern, as large quantities of effluent are discharged into water bodies. However, due to the low biodegradability of dyes, the typical biological treatment processes are not very effective in the treatment of wastewater containing dyes. In this context, heterogeneous photocatalysis can be effectively exploited for the removal of various dye pollutants present in liquid media. Heterogeneous photocatalysis may represent one of the main challenges in the field of the treatment and decontamination of water, because it is able to work at ambient temperature and atmospheric pressure. Its operating principle is based on the simultaneous action of the light source and a catalyst (semi-conductor), which allows the degradation of organic pollutants.

This Special Issue is focused on “New trends in the Photocatalytic Removal of Organic Dyes”, featuring the state-of-the-art in this field. Research papers related to the synthesis and characterization of novel photocatalysts (active under UV or visible light, as well as under solar light) and their uses in the removal of organic dyes from aqueous solutions are welcome in this Special Issue.

Prof. Vincenzo Vaiano
Guest Editor

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Keywords

  • Heterogeneous photocatalysis
  • Organic dyes in water
  • Novel photocatalysts
  • Doped semiconductors
  • Hybrid systems
  • UV light, visible light, solar light

Published Papers (14 papers)

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Research

11 pages, 1939 KiB  
Communication
High Photocatalytic Activity under Visible Light for a New Morphology of Bi2WO6 Microcrystals
by Willison Eduardo Oliveira Campos, Francisco Xavier Nobre, Geraldo Narciso da Rocha Filho, Marcos Augusto Ribeiro da Silva, Carlos Emmerson Ferreira da Costa, Luís Adriano Santos do Nascimento and José Roberto Zamian
Catalysts 2019, 9(8), 667; https://doi.org/10.3390/catal9080667 - 05 Aug 2019
Cited by 20 | Viewed by 3281
Abstract
In this work, a new morphology was obtained for bismuth tungstate (Bi2WO6-glyc) using a hydrothermal method with the addition of glycerol as a surfactant. In order to compare, the bismuth tungstate without glycerol as the surfactant, i.e., Bi2 [...] Read more.
In this work, a new morphology was obtained for bismuth tungstate (Bi2WO6-glyc) using a hydrothermal method with the addition of glycerol as a surfactant. In order to compare, the bismuth tungstate without glycerol as the surfactant, i.e., Bi2WO6, was synthesized. Structural characterization by XRD and Rietveld refinement confirmed the orthorhombic structure as a single phase for all samples with high crystallinity. All active modes in Raman spectroscopy for the orthorhombic phase of bismuth tungstate were confirmed in agreement with XRD analysis. N2 adsorption/desorption and size pore distribution confirmed the high surface area (85.7 m2/g) for Bi2WO6-glyc when compared with Bi2WO6 (8.5 m2/g). The optical band gap by diffuse reflectance was 2.78 eV and 2.88 eV for Bi2WO6-glyc and Bi2WO6, respectively. SEM images confirmed the different morphology for these materials, and microstructures with cheese crisp were observed for Bi2WO6-glyc (cheese crisp). On the other hand, flower-like microcrystals were confirmed for Bi2WO6 sample. The photocatalytic performance of Bi2WO6-glyc (94.2%) in the photodegradation of rhodamine B (RhB) dye solutions at 60 min was more expressive than Bi2WO6 (81.3%) and photolysis (8.2%) at 90 min. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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17 pages, 12515 KiB  
Article
Photocatalytic Degradation of Azo Dye Reactive Violet 5 on Fe-Doped Titania Catalysts under Visible Light Irradiation
by Antonio Zuorro, Roberto Lavecchia, Marika Michela Monaco, Giuseppina Iervolino and Vincenzo Vaiano
Catalysts 2019, 9(8), 645; https://doi.org/10.3390/catal9080645 - 29 Jul 2019
Cited by 72 | Viewed by 6346
Abstract
The presence of azo dyes in textile effluents is an issue of major concern due to their potential impact on the environment and human health. In this study we investigate the photocatalytic degradation under visible light of Reactive Violet 5 (RV5), an azo [...] Read more.
The presence of azo dyes in textile effluents is an issue of major concern due to their potential impact on the environment and human health. In this study we investigate the photocatalytic degradation under visible light of Reactive Violet 5 (RV5), an azo dye widely used in the textile industry. A preliminary screening of different titania-based catalysts was carried out to identify the best candidate for RV5 removal. The selected catalyst was then tested in a stirred and aerated lab-scale reactor illuminated with a blue light-emitting diode (LED) source emitting in the wavelength range of 460–470 nm. The effects of pH, catalyst load, and hydrogen peroxide additions on the efficiency of dye removal were evaluated. Under the best conditions (pH 10, 3 g/L of catalyst, and 60 mM hydrogen peroxide), the dye solution was completely decolorized in about 2 h. Overall, the results obtained suggest that the proposed process may represent a suitable method for the removal of RV5 from textile effluents. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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16 pages, 4393 KiB  
Article
Enhanced Photocatalytic and Antibacterial Performance of ZnO Nanoparticles Prepared by an Efficient Thermolysis Method
by Md. Abu Hanif, Insup Lee, Jeasmin Akter, Md. Akherul Islam, Ali A. S. M. Zahid, Kamal Prasad Sapkota and Jae Ryang Hahn
Catalysts 2019, 9(7), 608; https://doi.org/10.3390/catal9070608 - 18 Jul 2019
Cited by 46 | Viewed by 6458
Abstract
ZnO nanoparticles (ZnO-NPs) were synthesized by a straightforward modified thermal method using only one chemical: zinc acetate dihydrate. The process is environmentally safer than other methods because it does not involve other chemicals or a catalyst, acid, or base source. X-ray diffraction analysis [...] Read more.
ZnO nanoparticles (ZnO-NPs) were synthesized by a straightforward modified thermal method using only one chemical: zinc acetate dihydrate. The process is environmentally safer than other methods because it does not involve other chemicals or a catalyst, acid, or base source. X-ray diffraction analysis indicated that the ZnO-NPs crystallize in the hexagonal wurtzite structure. The UV–vis absorption spectra revealed a marked redshift, which is critical for enhanced photocatalytic activity. We used methylene blue for photocatalytic activity tests and found an excellent degradation percentage (99.7%) within a short time (80 min). The antibacterial activity of the synthesized ZnO-NPs was tested against Escherichia coli at different concentrations of ZnO-NPs. The analysis revealed that the minimum inhibitory concentration (MIC) of the ZnO-NPs against E. coli was 30–50 μg/mL. Our ZnO-NPs were found to be more effective than previously reported ZnO-NPs synthesized via other methods. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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12 pages, 10347 KiB  
Article
Rate-Limiting Steps of Dye Degradation over Titania-Silica Core-Shell Photocatalysts
by Ariane Giesriegl, Jakob Blaschke, Shaghayegh Naghdi and Dominik Eder
Catalysts 2019, 9(7), 583; https://doi.org/10.3390/catal9070583 - 30 Jun 2019
Cited by 7 | Viewed by 3344
Abstract
In this work, we employed a step-by-step sol-gel process to controllably deposit ultra-thin layers of SiO2 on anatase nanoparticles in the range between 0 and 1 nm. The deposition was confirmed by TEM, EDX, and ATR-FTIR (e.g., Ti-O-Si band at 960 cm [...] Read more.
In this work, we employed a step-by-step sol-gel process to controllably deposit ultra-thin layers of SiO2 on anatase nanoparticles in the range between 0 and 1 nm. The deposition was confirmed by TEM, EDX, and ATR-FTIR (e.g., Ti-O-Si band at 960 cm-1). Zeta potential measurements unravelled a continuous change in surface charge density with increasing silica shell thickness. The photocatalysts were evaluated towards adsorption and degradation of positively-charged and negatively-charged dyes (methylene blue, methyl orange) under UV illumination. The growth mechanism follows the Stranski–Krastanov model with three thickness regimes: (a) Flat islands (first step), (b) mono/bilayers (second/third step), and (c) regular thick films (fourth/fifth step). The results suggest different rate limiting processes for these regimes: (a) For the thinnest scenario, acidic triple-phase boundaries (TPBs) increase the activity for both dyes with their accessibility being the rate limiting step; (b) for continuous mono/bilayers, dye adsorption on the negatively-charged SiO2 shells becomes the rate liming step, which leads to a stark increase in activity for the positively-charged MB and a decrease for MO; (c) for thicker shells, the activity decreases for both dyes and is limited by the charge transport through the isolating shells. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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18 pages, 4292 KiB  
Article
Electrospun Nanofibers Embedding ZnO/Ag2CO3/Ag2O Heterojunction Photocatalyst with Enhanced Photocatalytic Activity
by Nurafiqah Rosman, Wan Norharyati Wan Salleh, Farhana Aziz, Ahmad Fauzi Ismail, Zawati Harun, Syamsutajri Syamsol Bahri and Kazukiyo Nagai
Catalysts 2019, 9(7), 565; https://doi.org/10.3390/catal9070565 - 26 Jun 2019
Cited by 40 | Viewed by 4303
Abstract
The immobilization of photocatalyst onto substrate has a great potential for energy-intensive separation to avoid the costly separation process and unwanted release of photocatalyst into the treated water. In this study, electrospun nanofiber composed of polyvinylidene fluoride (PVDF) with the immobilized ZnO, ZnO/Ag [...] Read more.
The immobilization of photocatalyst onto substrate has a great potential for energy-intensive separation to avoid the costly separation process and unwanted release of photocatalyst into the treated water. In this study, electrospun nanofiber composed of polyvinylidene fluoride (PVDF) with the immobilized ZnO, ZnO/Ag2CO3, ZnO/Ag2CO3/Ag2O, and ZnO/Ag2O photocatalysts were prepared via the electrospinning process. The immobilized ZnO and heterojunctioned ZnO in the PVDF electrospun nanofiber were proven via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The electrospinning allowed high chemical binding of the nanofiber composite with good physical interaction between the photocatalyst and the electrospun nanofiber. AFM images obtained for the nanofibers were found to be rougher than that of the pristine PVDF electrospun nanofiber. Among the photocatalyst embedded, the immobilized ZnO/Ag2CO3/Ag2O had endowed the nanofiber with an excellent photocatalytic activity and recyclability for the degradation of the RR120 under UV light irradiation. Based on the results, effective immobilization of ZnO/Ag2CO3/Ag2O in PVDF nanofiber with 99.62% photodegradation in 300 min compared to PVDF-ZnO, PVDF-ZnO/Ag2CO3, and PVDF-ZnO/Ag2O of 28.14%, 90.49%, and 96.34%, respectively. The effective ZnO/Ag2CO3/Ag2O immobilization into polymers with affinity toward organic dye pollutants could both increase the efficiency and reduce the energy requirements for water treatment via the photocatalytic application. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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15 pages, 4395 KiB  
Article
Preparation of Palladium Nanoparticles Decorated Polyethyleneimine/Polycaprolactone Composite Fibers Constructed by Electrospinning with Highly Efficient and Recyclable Catalytic Performances
by Cuiru Wang, Juanjuan Yin, Shiqi Han, Tifeng Jiao, Zhenhua Bai, Jingxin Zhou, Lexin Zhang and Qiuming Peng
Catalysts 2019, 9(6), 559; https://doi.org/10.3390/catal9060559 - 22 Jun 2019
Cited by 85 | Viewed by 5769
Abstract
Nano-sized palladium nanoparticles showed high catalytic activity with severe limitations in catalytic field due to the tendency to aggregate. A solid substrate with large specific surface area is an ideal carrier for palladium nanoparticles. In present work, polyethyleneimine/polycaprolactone/Pd nanoparticles (PEI/PCL@PdNPs) composite catalysts were [...] Read more.
Nano-sized palladium nanoparticles showed high catalytic activity with severe limitations in catalytic field due to the tendency to aggregate. A solid substrate with large specific surface area is an ideal carrier for palladium nanoparticles. In present work, polyethyleneimine/polycaprolactone/Pd nanoparticles (PEI/PCL@PdNPs) composite catalysts were successfully designed and prepared by electrospinning and reduction methods using PEI/PCL elexctrospun fiber as carrier. The added PEI component effectively regulated the microscopic morphology of the PEI/PCL fibers, following a large number of pit structures which increased the specific surface area of the electrospun fibers and provided active sites for loading of the palladium particles. The obtained PEI/PCL@PdNPs catalysts for reductions of 4-nitrophenol (4-NP) and 2-nitroaniline (2-NA) exhibited extremely efficient, stable, and reusable catalytic performance. It was worth mentioning that the reaction rate constant of catalytic reduction of 4-NP was as high as 0.16597 s−1. Therefore, we have developed a highly efficient catalyst with potential applications in the field of catalysis and water treatment. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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14 pages, 4891 KiB  
Article
Solar-Light-Driven Efficient ZnO–Single-Walled Carbon Nanotube Photocatalyst for the Degradation of a Persistent Water Pollutant Organic Dye
by Kamal Prasad Sapkota, Insup Lee, Md. Abu Hanif, Md. Akherul Islam and Jae Ryang Hahn
Catalysts 2019, 9(6), 498; https://doi.org/10.3390/catal9060498 - 29 May 2019
Cited by 44 | Viewed by 5318
Abstract
An efficient photocatalyst, ZnO–single-walled carbon nanotube (ZnO–SWCNT) nanocomposite was successfully fabricated through a straightforward one-pot–two-chemical recrystallization technique followed by thermal decomposition. The photocatalytic efficiency of the prepared ZnO–SWCNT composite was investigated by assessing the degradation of a persistent water-pollutant dye (methylene blue, MB) [...] Read more.
An efficient photocatalyst, ZnO–single-walled carbon nanotube (ZnO–SWCNT) nanocomposite was successfully fabricated through a straightforward one-pot–two-chemical recrystallization technique followed by thermal decomposition. The photocatalytic efficiency of the prepared ZnO–SWCNT composite was investigated by assessing the degradation of a persistent water-pollutant dye (methylene blue, MB) under visible-light irradiation. We found that the synthesized photocatalyst is an effective and recyclable agent for the decomposition of an MB solution. Its photocatalytic performance was substantially better than that of pristine ZnO nanorods or pristine SWCNTs. The reusability of the photocatalyst was also examined, affirming that it could be used repeatedly for five cycles without conspicuous loss of morphology or catalytic performance. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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17 pages, 7111 KiB  
Article
A Mild in-Situ Method to Construct Fe-Doped Cauliflower-Like Rutile TiO2 Photocatalysts for Degradation of Organic Dye in Wastewater
by Xiangcheng Shi, Yanbin Zhang, Xiaoyu Liu, Huihui Jin, Haiyang Lv, Shujiao He, Haigang Hao and Changyan Li
Catalysts 2019, 9(5), 426; https://doi.org/10.3390/catal9050426 - 08 May 2019
Cited by 20 | Viewed by 3933
Abstract
A mild in situ method was developed to construct an iron doped rutile TiO2 photocatalyst like cauliflower for degradation synthetic textile dye-methyl orange. The synthesized photocatalysts presented distinguished photocatalytic activity. At the optimal Fe concentration (0.5%), the decomposition rate of methyl orange [...] Read more.
A mild in situ method was developed to construct an iron doped rutile TiO2 photocatalyst like cauliflower for degradation synthetic textile dye-methyl orange. The synthesized photocatalysts presented distinguished photocatalytic activity. At the optimal Fe concentration (0.5%), the decomposition rate of methyl orange (MO) was about 90% under 40 min of ultraviolet (UV) light irradiation. Whereas, to our knowledge, only 70% of the decomposition rate of MO was achieved by commercial photocatalyst P25 under the similar reaction condition. Additionally, the rutile preparation temperature did not exceed 100 °C, which was much lower than the traditional preparation calcination temperature (e.g., 600 °C). The specific surface area of Fe doped catalysts was bigger than that of the control sample and the catalyst characterization indicated that the doped iron was incorporated into the rutile TiO2 lattice and resulted in the lattice disorder. The lattice disorder would have generated surface defects in the crystal structure, which was in favor of the photocatalytic reaction. The UV-Vis diffuse refection characterization and Density Functional Theory (DFT) calculation suggested that doping a small amount of Fe into the lattice of rutile would lead to a narrower band gap and the formation of a doping energy level between conduction and valence bands of TiO2. This further increased the degradation efficiency of synthetic textile dyes in wastewaters. Our study has provided a relatively easy operation for synthesis Fe doped rutile TiO2, which is a benefit to decrease the cost in wastewater treatment process. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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15 pages, 3326 KiB  
Article
Zinc Oxide Nanoparticles Obtained by Supercritical Antisolvent Precipitation for the Photocatalytic Degradation of Crystal Violet Dye
by Paola Franco, Olga Sacco, Iolanda De Marco and Vincenzo Vaiano
Catalysts 2019, 9(4), 346; https://doi.org/10.3390/catal9040346 - 09 Apr 2019
Cited by 67 | Viewed by 5677
Abstract
In this work, the synthesis of zinc oxide (ZnO) photocatalyst from thermal decomposition of zinc acetate (ZnAc) nanoparticles obtained by supercritical antisolvent (SAS) precipitation was investigated. The optimization of calcination conditions of the SAS ZnAc was carried out, studying the effect of temperature [...] Read more.
In this work, the synthesis of zinc oxide (ZnO) photocatalyst from thermal decomposition of zinc acetate (ZnAc) nanoparticles obtained by supercritical antisolvent (SAS) precipitation was investigated. The optimization of calcination conditions of the SAS ZnAc was carried out, studying the effect of temperature (in the range 300–600 °C) on the production of ZnO nanoparticles. In particular, it was demonstrated that the organic residues in ZnO and its particle size, thus the specific surface area, strongly affect the photocatalytic performances. SAS micronization of ZnAc produces regular nanoparticles with a mean diameter of about 54.5 ± 11.5 nm, whereas unprocessed ZnAc is characterized by very large crystals. The experimental results evidenced that ZnAc prepared by SAS process calcined at 500 °C showed a regular nanometric structure (mean diameter: 65.0 ± 14.5 nm) and was revealed to be the best choice for the photocatalytic removal of crystal violet dye (CV). In fact, the photocatalytic activity performances of ZnO nanoparticles prepared by this route were higher with respect to that of ZnO from unprocessed ZnAc calcined at 500 °C (which is characterized by irregular tetrapods with mean size 181.1 ± 65.5 nm). The optimized photocatalyst was able to assure the complete CV decolorization in 60 min of UV irradiation time and a mineralization degree higher than 90% after 120 min of treatment time. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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16 pages, 33668 KiB  
Article
Dye-sensitized Photocatalyst of Sepiolite for Organic Dye Degradation
by Chitiphon Chuaicham, Radheshyam Pawar and Keiko Sasaki
Catalysts 2019, 9(3), 235; https://doi.org/10.3390/catal9030235 - 04 Mar 2019
Cited by 37 | Viewed by 6781
Abstract
The photocatalytic activity of sepiolite was examined for degradation of several dye compounds under visible light irradiation. Higher adsorption capacities and greater photocatalytic performance of cationic dyes (rhodamine B and methylene blue) were observed on sepiolite, in comparison with anionic dyes (orange II [...] Read more.
The photocatalytic activity of sepiolite was examined for degradation of several dye compounds under visible light irradiation. Higher adsorption capacities and greater photocatalytic performance of cationic dyes (rhodamine B and methylene blue) were observed on sepiolite, in comparison with anionic dyes (orange II and trypan blue). Superiority in the photocatalytic activity of cationic dyes is attributed to the strong electrostatic attraction and photosensitization properties of cationic dye molecules. Sepiolite has degraded 45.3% rhodamine B within 120 min, which is the greatest photocatalytic degradation efficiency when compared with other dyes. Subsequently, the reusability of spent sepiolite after adsorption of rhodamine B was evaluated by the degradation of trypan blue under the visible light irradiation. The photocatalytic degradation performance of trypan blue by spent sepiolite after adsorption of rhodamine B increased about twice as much as with pristine sepiolite, indicating that the dye-sensitized photocatalytic process could enhance the photocatalytic degradation ability of sepiolite. Through radical scavenger tests, it was found that a superoxide radical is mainly responsible for rhodamine B degradation. The possible mechanism of rhodamine B degradation under visible light irradiation was proposed. The sepiolite could be a potential catalyst for the degradation of organic pollutants in wastewater under solar light. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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20 pages, 4301 KiB  
Article
Fluorinated and Platinized Titania as Effective Materials in the Photocatalytic Treatment of Dyestuffs and Stained Wastewater Coming from Handicrafts Factories
by Julie Joseane Murcia, Ángela Carolina Cely, Hugo Alfonso Rojas, María Carmen Hidalgo and José Antonio Navío
Catalysts 2019, 9(2), 179; https://doi.org/10.3390/catal9020179 - 14 Feb 2019
Cited by 14 | Viewed by 2923
Abstract
In this study, commercial and lab-prepared TiO2 were modified by fluorination and platinum photodeposition; and the effect of these modifications over the physicochemical and photocatalytic properties of TiO2 was evaluated. It was found that F and Pt addition leads to the [...] Read more.
In this study, commercial and lab-prepared TiO2 were modified by fluorination and platinum photodeposition; and the effect of these modifications over the physicochemical and photocatalytic properties of TiO2 was evaluated. It was found that F and Pt addition leads to the modification of the optical and textural properties of TiO2. The materials prepared were tested in the photocatalytic degradation of different organic dyestuffs such as methylene blue (MB) and methyl orange (MO); the degradation of commercial anilines employed in the staining of natural fibers was also evaluated. Photocatalysis was also studied in this work as an eco-friendly treatment of wastewater coming from handicrafts factories. In general it was observed that the effectiveness of the photocatalytic treatment strongly depends on the substrate to be degraded, thus, fluorinated and platinized commercial Titania (Pt-F-P25) showed the best photocatalytic performance in the MB and MO photodegradation and in contrast, in the case of the anilines the highest degradation was obtained over commercial TiO2 fluorinated (F-P25). These results can be explained by differences observed in the structure and in the adsorption of these dyestuffs over the photocatalysts surfaces. F-P25 photocatalyst also demonstrated to be the best material for the treatment of real wastewater coming from handicrafts factories. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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15 pages, 4220 KiB  
Article
De-Ethylation and Cleavage of Rhodamine B by a Zirconium Phosphate/Silver Bromide Composite Photocatalyst
by Monica Pica, Silvia Calzuola, Anna Donnadio, Pier Luigi Gentili, Morena Nocchetti and Mario Casciola
Catalysts 2019, 9(1), 3; https://doi.org/10.3390/catal9010003 - 21 Dec 2018
Cited by 26 | Viewed by 3672
Abstract
A composite heterogeneous photocatalyst based on silver bromide was prepared by a reaction of silver exchanged zirconium phosphate (ZrP) and HBr. The ZrP/AgBr composite containing 53 wt% AgBr was tested in the photocatalytic degradation of Rhodamine B (RhB) and exhibited higher catalytic activity [...] Read more.
A composite heterogeneous photocatalyst based on silver bromide was prepared by a reaction of silver exchanged zirconium phosphate (ZrP) and HBr. The ZrP/AgBr composite containing 53 wt% AgBr was tested in the photocatalytic degradation of Rhodamine B (RhB) and exhibited higher catalytic activity with respect to pure AgBr. As a matter of fact, the time needed to achieve a percentage of chromophore cleavage of about 90% was 3 min for the composite versus the 30 min needed for pure AgBr. The ZrP/AgBr composite turned out to be stable for at least three consecutive cycles. The UV-Vis spectra of the RhB solution, recorded at different irradiation times, were also decomposed and the concentration of the species formed by de-ethylation and cleavage processes during photocatalysis were calculated; the data obtained for the AgBr-based catalysis were also compared with those for the AgCl-based catalysis, and the degradation mechanism was suggested for both catalytic systems. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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13 pages, 4008 KiB  
Article
Photocatalytic Degradation of Methylene Blue over TiO2 Pretreated with Varying Concentrations of NaOH
by Chentao Hou, Bo Hu and Jiaming Zhu
Catalysts 2018, 8(12), 575; https://doi.org/10.3390/catal8120575 - 22 Nov 2018
Cited by 138 | Viewed by 7601
Abstract
In this paper, different NaOH concentrations (2, 5, 10, and 15 M) were used to treat {001}TiO2. The effect of NaOH on the crystal structure, morphology, optical properties, light raw electronic-hole recombination, and degradation performance of {001}TiO2 on methylene blue [...] Read more.
In this paper, different NaOH concentrations (2, 5, 10, and 15 M) were used to treat {001}TiO2. The effect of NaOH on the crystal structure, morphology, optical properties, light raw electronic-hole recombination, and degradation performance of {001}TiO2 on methylene blue were studied. The results demonstrate that rutile TiO2 appeared when the NaOH concentration was as high as 10 M, showing much better photolytic performance than others. As the concentration of sodium hydroxide increases, the morphology changes accordingly. The specific surface area increases and the optical electronic-hole recombination rate decreases. Radical scavenging tests showed that hydroxyl radical and hole are very important in photocatalysis. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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10 pages, 1806 KiB  
Article
Photoelectrocatalytic vs. Photocatalytic Degradation of Organic Water Born Pollutants
by Ioannis Papagiannis, Georgia Koutsikou, Zacharias Frontistis, Ioannis Konstantinou, George Avgouropoulos, Dionissios Mantzavinos and Panagiotis Lianos
Catalysts 2018, 8(10), 455; https://doi.org/10.3390/catal8100455 - 15 Oct 2018
Cited by 19 | Viewed by 3697
Abstract
The azo dye Basic Blue 41 was subjected to photocatalytic and photoelectrocatalytic degradation using nanopararticulate titania films deposited on either glass slides or Fluorine doped Tin Oxide (FTO) transparent electrodes. The degradation was carried out by irradiating titania films with weak ultraviolet (UVA) [...] Read more.
The azo dye Basic Blue 41 was subjected to photocatalytic and photoelectrocatalytic degradation using nanopararticulate titania films deposited on either glass slides or Fluorine doped Tin Oxide (FTO) transparent electrodes. The degradation was carried out by irradiating titania films with weak ultraviolet (UVA) radiation. The degradation was faster when using FTO as a titania support even without bias and was further accelerated under forward electric bias. This result was explained by enhanced electron-hole separation even in the case of the unbiased titania/FTO combination. This system for organic material photocatalytic degradation was also successfully applied to the degradation of the anti-inflammatory drug piroxicam, which demonstrated a well distinguished degradation behavior in going from a plain glass support to unbiased and biased FTO. The degradation pathway of piroxicam has been additionally studied using liquid chromatography-accurate mass spectrometry analysis. Full article
(This article belongs to the Special Issue New Trends in the Photocatalytic Removal of Organic Dyes)
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