Special Issue "Photocatalytic Degradation of Organic Wastes in Water"

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: 30 November 2020.

Special Issue Editors

Prof. Dr. María V. López-Ramón
Website
Guest Editor
Faculty of Experimental Science, Dept. of Inorganic & Organic Chemistry, University of Jaen, Jaen 23071, Spain
Interests: preparation and characterization of carbon materials and magnetic nanomaterials; heterogeneous catalysis and photocatalysis; adsorption and advanced oxidation processes for water treatment; environment
Prof. Dr. José Rivera-Utrilla
Website
Guest Editor
Univ Granada, Fac Sci, Dept Inorgan Chem, E-18071 Granada, Spain
Interests: preparation of new nanostructured carbon materials as catalysts and photocatalysts to develop advanced water treatments; removal of pollutants from aqueous and gaseous phases by adsorption/bioadsorption/biodegradation processes and catalysis using advanced carbon materials; new treatments of water contaminated by organic pollutants by integrated technologies based on advanced oxidation/reduction processes (ozonation, photooxidation, radiolysis) and carbon materials
Prof. Dr. Manuel Sánchez-Polo
Website
Guest Editor
Univ Granada, Fac Sci, Dept Inorgan Chem, E-18071 Granada, Spain
Interests: carbon materials; water treatment; advanced oxidation processes; photocatalysis; UV/solar radiation

Special Issue Information

Dear Colleagues,

In recent years, public concerns have arisen about environmental pollution by so-called emerging organic pollutants (EOPS) in water sources and factory effluents, because of their potentially adverse effects on human health and aquatic ecosystems. A large number of physical and biological processes have been proposed to remove pollutants from water, but they do not completely remove the majority of EOPs. Advanced oxidation processes (AOPs) based on catalytic, electrochemical, and photochemical reactions are currently available and are able to degrade a large number of pollutants. An important group of AOPs is represented by photocatalytic processes, in which luminous radiation produces the electronic activation of the semiconductor material that constitutes the catalyst. TiO2 is one of the most widely applied materials as photocatalysts in water decontamination, both alone and in combination with other materials acting as doping agents and/or material supports. However, the use of this semiconductor material presents known disadvantages; therefore, it is very important to continue working on the search for new, more efficient photocatalysts with better performance.
This Special Issue on “Photocatalytic Degradation of Organic Wastes in Water” is intended to cover the progresses and new trends in the preparation and characterization of photocatalytic materials, with particular emphasis on their applications in environmental remediation for the removal of emerging organic pollutans from different types of water.

Prof. Dr. José Rivera-Utrilla
Prof. María V. López-Ramón
Prof. Dr. Manuel Sánchez-Polo
Guest Editor

Manuscript Submission Information

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Keywords

  • Photocatalysts design and synthesis
  • photoactivity
  • UV/visible light
  • solar light
  • organic pollutants
  • reaction kinetics and mechanism
  • stability and reusability
  • degradation by-products
  • environmental applications
  • water treatments

Published Papers (10 papers)

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Research

Open AccessArticle
Au-TiO2 Synthesized by a Microwave- and Sonochemistry-Assisted Sol-Gel Method: Characterization and Application as Photocatalyst
Catalysts 2020, 10(9), 1052; https://doi.org/10.3390/catal10091052 - 13 Sep 2020
Abstract
Titanium dioxide (TiO2) is a widely used and well studied photocatalyst synthesized using different methodologies, including sol-gel, which allows one to modify the material in a one-pot step. By using a microwave- and sonochemistry-assisted sol-gel method, x wt.% Au-TiO2 photocatalysts [...] Read more.
Titanium dioxide (TiO2) is a widely used and well studied photocatalyst synthesized using different methodologies, including sol-gel, which allows one to modify the material in a one-pot step. By using a microwave- and sonochemistry-assisted sol-gel method, x wt.% Au-TiO2 photocatalysts were successfully synthesized. Physicochemical characterization of the photocatalysts shows an average crystallite size of 10.5 nm and an even morphological distribution of spherical particles with the sonochemistry synthesis method. For the microwave method an average value of crystallite size of 8.3 nm was found and it presents an increase with the amount of Au load. The cyclic voltammetric response and Mott-Schottky analysis are consistent with a semiconductor material containing metallic particles and for a heterophase junction of anatase and brookite with oxygen vacancies, respectively. The photocatalytic activity was assessed by paracetamol degradation in an aqueous solution as model. The sonochemistry-synthesized photocatalysts display the most promising results as they have a better paracetamol removal and the amount of gold in the catalyst (0.7 wt.%) was found to be optimal for this process. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
Synthesis and Characterization of Zinc Peroxide Nanoparticles for the Photodegradation of Nitrobenzene Assisted by UV-Light
Catalysts 2020, 10(9), 1041; https://doi.org/10.3390/catal10091041 - 10 Sep 2020
Abstract
The contamination of both soil and water by nitrobenzene (NB) is a problem that has been studied, where several reactive agents have been developed for the degradation of this compound as well as different methods. Nanoparticles with semiconductive properties have been studied for [...] Read more.
The contamination of both soil and water by nitrobenzene (NB) is a problem that has been studied, where several reactive agents have been developed for the degradation of this compound as well as different methods. Nanoparticles with semiconductive properties have been studied for organic compounds photodegradation due to their assistance in optimizing the degradation processes. Two of the most promising photocatalysts are ZnO and TiO2 because of their optimal results. In the present work the performance of the zinc peroxide (ZnO2) nanoparticles was evaluated. ZnO2 nanoparticles were synthesized from zinc acetate and hydrogen peroxide using the Sol-Gel method under ultrasound assistance. The characterization was carried out by UV–Vis spectroscopy, infrared Fourier transform total reflectance (ATR-FT-IR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), Zeta potential, dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and Energy Dispersive X-ray spectroscopy (EDX). The experiments for the degradation of NB were carried out in a photoreactor with UV lamps of 254 nm at 25 °C, using a solution of nitrobenzene with the nanoparticles. The best conditions for NB photodegradation were 30 ppm (ZnO2) and 15 ppm (NB) at pH 2, reaching up to 90% degradation in 2 h. The intermediates formed during the photodegradation of NB were identified by gas chromatography mass spectrometry. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
The Effect of Electrolytes on the Photodegradation Kinetics of Caffeine
Catalysts 2020, 10(6), 644; https://doi.org/10.3390/catal10060644 - 08 Jun 2020
Abstract
Unsuccessfully treated by the existing wastewater-treatment processes, caffeine concentrations in wastewater effluents and natural reservoirs are constantly rising. Photodegradation treatment processes are drawing much attention due to their potential to oxidize and remove such, and similar contaminating compounds from treated waters. In continuation [...] Read more.
Unsuccessfully treated by the existing wastewater-treatment processes, caffeine concentrations in wastewater effluents and natural reservoirs are constantly rising. Photodegradation treatment processes are drawing much attention due to their potential to oxidize and remove such, and similar contaminating compounds from treated waters. In continuation to our previous work on the photodegradation kinetics of caffeine in water by UV/H2O2 and UV/TiO2, this work evaluates the influence of various electrolytes, including NaCl, KCl, MgCl2, NaBr, and KBr, on the kinetics of the UV/H2O2 photodegradation of caffeine, aiming at estimating the efficiency of the method in more complex water systems. Results show that the efficiency of the UV/H2O2 photodegradation reactions is strongly affected by ionic strength and the presence of electrolytes in the solution. While chloride electrolytes were shown to optimize or reduce the process efficiency pending on their concentration. The sole presence of NaBr and KBr shows an immediate reduction in the efficiency of the photodegradation. Empirical apparent-rate-coefficients and curves describing the effect of the different electrolytes on the photodegradation kinetics of caffeine are presented. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
Adsorption and Photocatalytic Study of Phenol Using Composites of Activated Carbon Prepared from Onion Leaves (Allium fistulosum) and Metallic Oxides (ZnO and TiO2)
Catalysts 2020, 10(5), 574; https://doi.org/10.3390/catal10050574 - 20 May 2020
Abstract
The aim of this study was to evaluate and compare the adsorption and photocatalytic activity of activated carbon-based photocatalysts. Titanium dioxide (TiO2) and zinc oxide (ZnO) were chosen as semiconductors to prepare composites with activated carbon by the wet impregnation method. [...] Read more.
The aim of this study was to evaluate and compare the adsorption and photocatalytic activity of activated carbon-based photocatalysts. Titanium dioxide (TiO2) and zinc oxide (ZnO) were chosen as semiconductors to prepare composites with activated carbon by the wet impregnation method. Activated carbon was prepared using as starting material onion leaves (Allium fistulosum) and as activating agent phosphoric acid (H3PO4). Photooxidation and batch adsorption of phenol was studied to compare the efficiency of the materials prepared. The results showed that the composite AC–TiO2 has a greater photocatalytic activity and a better adsorption capacity compared to AC–ZnO composite. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessFeature PaperArticle
Solar Degradation of Sulfamethazine Using rGO/Bi Composite Photocatalysts
Catalysts 2020, 10(5), 573; https://doi.org/10.3390/catal10050573 - 20 May 2020
Cited by 1
Abstract
Heterogeneous photocatalysts for water decontamination were obtained by the optimized synthesis of bismuth-functionalized reduced graphene oxide (rGO/Bi) using the Hummer method and microwave treatment. Sulfamethazine (SMZ) was used as model pollutant to evaluate the photocatalytic efficacy. Photocatalysts were characterized by VP-SEM, HRTEM, XDR, [...] Read more.
Heterogeneous photocatalysts for water decontamination were obtained by the optimized synthesis of bismuth-functionalized reduced graphene oxide (rGO/Bi) using the Hummer method and microwave treatment. Sulfamethazine (SMZ) was used as model pollutant to evaluate the photocatalytic efficacy. Photocatalysts were characterized by VP-SEM, HRTEM, XDR, XPS, RAMAN, and FTIR analyses, which confirmed the effective reduction of GO to rGO and the presence of bismuth as a crystalline phase of Bi2O3 polydispersed on the surface. Their performance was influenced by the rGO/Bi ratio, microwave temperature, and treatment time. The as-obtained 5%rGO/Bi composite had the highest photocatalytic activity for SMZ degradation under visible light irradiation (λ > 400 nm), achieving 100% degradation after only 2 h of treatment. The degradation yield decreased with higher percentages of rGO. Accordingly, the rGO/Bi catalysts efficiently removed SMZ, showing a high photocatalytic activity, and remained unchanged after three treatment cycles; furthermore, cytotoxicity tests demonstrated the nontoxicity of the aqueous medium after SMZ degradation. These findings support the potential value of these novel composites as photocatalysts to selectively remove pollutants in water treatment plants. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
Hydrothermal Synthesis of rGO-TiO2 Composites as High-Performance UV Photocatalysts for Ethylparaben Degradation
Catalysts 2020, 10(5), 520; https://doi.org/10.3390/catal10050520 - 08 May 2020
Cited by 2
Abstract
A series of reduced graphene oxide-TiO2 composites (rGO-TiO2) were prepared by hydrothermal treatment using graphite and titanium isopropoxide as raw materials. The structural, surface, electronic, and optical properties of the prepared composites were extensively characterized by N2 adsorption, FTIR, [...] Read more.
A series of reduced graphene oxide-TiO2 composites (rGO-TiO2) were prepared by hydrothermal treatment using graphite and titanium isopropoxide as raw materials. The structural, surface, electronic, and optical properties of the prepared composites were extensively characterized by N2 adsorption, FTIR, XRD, XPS, Raman spectroscopy, and DRS. GO was found to be effectively reduced and TiO2 to be in pure anatase phase in all composites obtained. Finally, experiments were performed to evaluate the effectiveness of these new materials as photocatalysts in the degradation of ethylparaben (EtP) by UV radiation. According to the band-gap energies obtained (ranging between 3.09 eV for 4% rGO-TiO2 to 2.55 eV for 30% rGO-TiO2), the rGO-TiO2 composites behave as semiconductor materials. The photocatalytic activity is highest with a rGO content of 7 wt% (7% rGO-TiO2), being higher than observed for pure TiO2 (Eg = 3.20 eV) and achieving 98.6% EtP degradation after only 40 min of treatment. However, the degradation yield decreases with higher percentages of rGO. Comparison with rGO-P25 composites showed that a better photocatalytic performance in EtP degradation is obtained with synthesized TiO2 (rGO-TiO2), probably due to the presence of the rutile phase (14.1 wt %) in commercial P25. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
Synthesis of Magnetic Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 Nanoparticles: The Photocatalytic Effects on Organic Pollutants upon Irradiation with UV-Vis Light
Catalysts 2020, 10(5), 494; https://doi.org/10.3390/catal10050494 - 01 May 2020
Cited by 1
Abstract
Magnetic Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 nanoparticles with different molar ratios of CeVO4 to other inorganic components were synthesized through co-precipitation with a sonochemical-assisted method. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier [...] Read more.
Magnetic Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 nanoparticles with different molar ratios of CeVO4 to other inorganic components were synthesized through co-precipitation with a sonochemical-assisted method. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, vibrating sample magnetometry, and scanning electron microscopy (SEM) methods were used for the physico–chemical characterization of the obtained nanoparticles. As shown in the SEM images, the average sizes of the Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 nanoparticles that formed aggregates were approximately 50–70 nm and 80–100 nm, respectively. The photocatalytic performance of these nanoparticles was examined by measuring methylene blue degradation under visible light (assisted by H2O2). The sample with a mass ratio of 1:2:1 (Fe3O4/ZnWO4/CeVO4, S4) exhibited optimal photocatalytic performance, and thus this sample was subsequently used for the photodegradation of different organic pollutants upon irradiation with ultraviolet (UV) and visible light. Approximately 90% and 70% degradation of methyl violet and methylene blue, respectively, was observed after visible light irradiation. Additionally, the mechanism of the photocatalytic reaction was investigated by measuring ˙OH release under UV light in a system with terephthalic acid and by measuring the release of ˙O2, ˙OH, and hole scavengers. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
Degradation of Meropenem by Heterogeneous Photocatalysis Using TiO2/Fiberglass Substrates
Catalysts 2020, 10(3), 344; https://doi.org/10.3390/catal10030344 - 20 Mar 2020
Abstract
Meropenem (MER), a carbapenem, is considered a last-resort antibiotic. Its presence in water bodies, together with other antibiotics, has brought about environmental problems related to the destruction of natural microorganisms and the development of antibiotic-resistant bacteria. Herein, the degradation of MER by heterogeneous [...] Read more.
Meropenem (MER), a carbapenem, is considered a last-resort antibiotic. Its presence in water bodies, together with other antibiotics, has brought about environmental problems related to the destruction of natural microorganisms and the development of antibiotic-resistant bacteria. Herein, the degradation of MER by heterogeneous photocatalysis using TiO2 immobilized on fiberglass substrates is reported. Morphological characterization of the substrates was performed by Scanning Electron Microscopy (SEM). Three pH values (4.0, 5.7, and 7.9) were tested for the treatment of MER solutions (100 mg/L). The best rate constants and MER removals were obtained at pH 4.0 (0.032 min−1; 83.79%) and 5.7 (0.032 min−1; 83.48%). Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removals of 25.80% and 29.60% were achieved for the treatment at a pH value of 5.7. The reuse and regeneration of the plates were also tested. The activity of the substrates was maintained until the fourth cycle of reuse, nonetheless, a decrease in MER removal was observed for the 5th cycle. After the fourth cycle of reuse, the activity of the substrates was recovered by a regeneration procedure involving a wash stage of the substrates with a 1% H2O2 solution in an ultrasonic bath. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
Ultrasonication-Assisted Synthesis of ZnxCd1−xS for Enhanced Visible-Light Photocatalytic Activity
Catalysts 2020, 10(3), 276; https://doi.org/10.3390/catal10030276 - 01 Mar 2020
Abstract
ZnxCd1−xS as a solid solution photocatalyst has attracted widespread attention for its unique adjustable band gap structure and good and stable performance. A novel synthesis approach for ZnxCd1−xS is still required to further improve its [...] Read more.
ZnxCd1−xS as a solid solution photocatalyst has attracted widespread attention for its unique adjustable band gap structure and good and stable performance. A novel synthesis approach for ZnxCd1−xS is still required to further improve its performance. In this study, we synthesized a series of ZnxCd1−xS (x = 0−1) solid solutions via an ultrasonication-assisted hydrothermal route. In comparison with conventional methods of preparation, the sample prepared by our innovative method showed enhanced photocatalytic activity for the degradation of a methyl orange (MO) solution under visible light due to its high crystallinity and small crystallite size. Furthermore, the composition and bandgap of ZnxCd1−xS can be tuned by adjusting the mole ratio of Zn2+/Cd2+. Zn0.3Cd0.7S shows the highest level of activity and stability for the degradation of MO with k = 0.85 h−1, which is 2.2 times higher than that of CdS. The balance between band gap structure-directed redox capacity and light absorption of Zn0.3Cd0.7S accounts for its high photocatalytic performance, both of which are determined by the composition of the solid solution. Also, a degradation mechanism of MO over the sample is tentatively proposed. This study demonstrates a new strategy to synthesize highly efficient sulfide photocatalysts. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Open AccessArticle
NOM (HA and FA) Reduction in Water Using Nano Titanium Dioxide Photocatalysts (P25 and P90) and Membranes
Catalysts 2020, 10(2), 249; https://doi.org/10.3390/catal10020249 - 19 Feb 2020
Abstract
This study examined the removal of natural organic substances (humic acids-HA, and fulvic acids-FA) from model solutions using photocatalysis and ultrafiltration. The effect of two nano titanium dioxide types (P25 and P90) with different active surface areas and two UV lamps (low-pressure and [...] Read more.
This study examined the removal of natural organic substances (humic acids-HA, and fulvic acids-FA) from model solutions using photocatalysis and ultrafiltration. The effect of two nano titanium dioxide types (P25 and P90) with different active surface areas and two UV lamps (low-pressure and medium-pressure) on the effectiveness of FA and HA removal during photocatalysis was tested. An integrated photocatalytic + ultrafiltration system was also analyzed to determine the effectiveness of FA and HA removal and the changes in the relative permeate flux (Ultrafiltration Membrane Fouling-UF). We observed that photocatalysis using the P90 nano titanium dioxide was more efficient than the P25 due to the larger surface area (2×). The decomposition of organic substances proceeded efficiently up to 30 min of solution exposure, and the use of a medium-pressure lamp accelerated compound decomposition relative to the low-pressure lamp. The applied photocatalysis + ultrafiltration system was characterized by a high degree of FA removal while improved hydraulic efficiency was observed during ultrafiltration. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes in Water)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Hydrothermal synthesis of GO/TiO2 composites with high performance as UV photocatalysts for degradation of parabens

Authors: M. Ruidíaz-Martínez, M. A. Álvarez-Merino, M.V. López-Ramón, G. Cruz-Quesada, J. Rivera-Utrilla, M. Sánchez-Polo.

Title: The Effect of Electrolytes on the Degradation Kinetics of Caffeine in water by UV/H2O2

Authors: Pedro M. Rendel1,* and Giora Rytwo1

 

Title: On the synthesis of BiOBr and ZnS/BiOBr nanomaterials for the visible-light driven photocatalytic degradation of ibuprofen in tap water.
Authors: Juan C. Durán-Álvarez; Iván Carranza; Carolina Martínez-Avelar; Mario Rodríguez-Varela; Rodolfo Zanella
Affiliation: Universidad Nacional Autónoma de México
Abstract: This work aimed to synthesize BiOBr in the form of nanopowder to remove the pseudo-persistent contaminant ibuprofen. Precipitation and solvothermal methods were tested, using Bi(NO3)3 and KBr as precursors. Nanoplatelets were obtained using the former method, while microspheres were produced using the hydrothermal path. The photocatalytic potential of the synthesized materials was measured through batch tests, using 250 mL of a 30 ppm ibuprofen solution under visible light irradiation. The highest degradation and mineralization yields were obtained using the BiOBr microspheres. This material was then decorated with ZnS microspheres via the hydrothermal route. In pure water, the ZnS/BiOBr heterostructure was able to completely degrade ibuprofen upon 90 min of irradiation, while mineralization was near 70%. Then, when environmentally relevant conditions (tap water and 50 ppb of ibuprofen) were used, similar degradation and mineralization rates were obtained. The outstanding photocatalytic performance was related to the transfer of the charge carriers from the BiOBr to the ZnS microspheres. Degradation by-products were identified by LC-MS/MS, and a degradation path was proposed.

Title: Photodegradation of pyridine by means of a rotary photodisk reactor (RFDR) using zinc oxide (znO) doped with nano aluminum particles using natural light
Authors: Carlos montalvo
Affiliation: University of city carmen

Title: Biosynthesis of ZnO/SnO2 on Methylene Blue degradation: Effect of various loadings
Authors: LM Mahlaule-Glory; NC Hintsho-Mbita*
Affiliation: University of Limpopo

Title: The Effect of Electrolytes on the Degradation Kinetics of Caffeine in water by UV/H2O2
Authors: Pedro M. Rendel1,* and Giora Rytwo1,2
Affiliation: 1 Environmental Physical Chemistry Laboratory, MIGAL, Galilee Research Institute, Kiryat Shmona, Israel. 2 Department of Environmental Sciences, Tel Hai College, Upper Galilee, Israel
Abstract: Considered the world's most widely consumed psychoactive drug, caffeine became a widespread environmental pollutant, contaminating both the hydrosphere as well as the pedosphere, by thus leading to an unclear effect on the surrounding biosphere. Unsuccessfully treated by regular wastewater-treatment plants, caffeine concentrations in discharged effluents and natural reservoirs are constantly rising. Photodegradation is recently drawing much attention due to its potential to oxidize such contaminating compounds. In continuation to our previous work on the photodegradation kinetics of caffeine in water by UV/H2O2 and UV/TiO2, this work, evaluates the degredation kinetics in the presence of different electrolytes, including NaCl, KCl, MgCl, NaBr, and KBr, thus is order to evaluate the method efficiency in waters in more complex water systems. Results show that the degradation kinetics follows a pseudo-first-order, and affected differently by the presence of the different ions, mostly resulting in slower degradation rates. Empirical rate laws describing the degradation kinetics of caffeine in the presence of the different electrolytes are presented.

Title: Synthesis of Magnetic Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 Nanoparticles: The Photocatalytic Effects on Organic Pollutants under UV-Vis Light Irradiation
Authors: Marta E. Plonska-Brzezinska
Affiliation: Medical University of Bialystok, Faculty of Pharmacy with the Division of Laboratory Medicine
Abstract: The magnetic Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 nanoparticles with different molar ratios of CeVO4 were synthesized via co-precipitation with sonochemical-assisted method. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transformation infrared spectroscopy, ultraviolet-visible diffuse reflection spectroscopy, vibrating sample magnetometer and scanning electron microscopy (SEM) methods were used for the physico-chemical characterization of the obtained nanoparticles. The SEM images showed that the average size of Fe3O4/ZnWO4 and Fe3O4/ZnWO4/CeVO4 aggregates are about 50–70 nm and 80-100 nm, respectively. The photocatalytic performance of these nanoparticles was examined by methylene blue degradation under visible light (assisted by H2O2). The sample with the mass ratio 1:2:1 (Fe3O4/ZnWO4/CeVO4) showed the optimal photocatalytic performances, thus subsequently, this sample was used for photodegradation of different organic pollutants under UV and visible light irradiation. Almost 100% degradation by visible light irradiation and by exposure to UV light is observed for methyl violet and methyl orange, respectively. Additionally, the mechanism of photocatalytic reaction was investigated by releasing ˙OH under UV light in a system including terephthalic acid, as well as by ˙O2−, ˙OH, and holes scavengers.

Title: Solar Degradation of the Sulfamethazine Drug Assisted by rGO/Bi Composite Photocatalysts
Authors: María Victoria López Ramón
Affiliation: Faculty of Experimental Science, Dept. of Inorganic & Organic Chemistry, University of Jaen, Jaen 23071, Spain

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