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1.
Appl Radiat Isot ; 166: 109371, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33080553

ABSTRACT

This studystudy focuses on the effect of radiation treatment and hydrogen peroxide (H2O2) on the toxicity of anticancer methotrexate. For cytotoxicity, different bioassays such as Allium cepa, hemolytic, brine shrimp were employed. The Ames test was used for mutagenicity analysis. The solutions having concentrations 5, 10 and 15 ppm were irradiated with UV radiation exposure time 15, 30, 45, 60, 75 and 90 min and gamma radiation absorbed doses 0.3, 0.6, 0.9, 1.2, 2, 3 and 4 kGy in combination with with H2O2. There was a clear difference observed for aqueous solution before and after treatment with reference to cytotoxicity and mutagenicity. In Allium cepa test, a 47.07, 44.36 and 38.23% increase in root length (RL), root count (RC) and mitotic index (MI) was observed, respectively, for UV/H2O2 treatment and in the case of gamma/H2O2 treatment, the RL, RC and MI were increased up to 49.39, 52.63 and 52.38%, respectively. Brine shrimp test has shown 85.95 and 91.30% decrease in toxicity using UV/H2O2 and gamma/H2O2 respectively, while hemolytic test has shown 19.21 and 26.32% hemolysis using UV/H2O2 and gamma/H2O2, respectively. The mutagenicity reduced up to 82.3, 86.46 and 89.59% (TA98) and 85.42, 87.5 and 90.63% (TA100) for UV/H2O2 while 89.59, 90.63 and 93.75% (TA98) and 84.38, 89.59 and 92.71% (TA100) for gamma/H2O2. The UV and gamma radiation along with H2O2 based AOPs are promising approaches to detoxify the wastewater which can be extended to real hospital liquid effluent effectively.


Subject(s)
Antineoplastic Agents/radiation effects , Methotrexate/radiation effects , Wastewater/toxicity , Animals , Antineoplastic Agents/toxicity , Artemia/drug effects , Biological Assay , Gamma Rays , Humans , Hydrogen Peroxide , Medical Waste , Methotrexate/toxicity , Mutagenicity Tests , Onions/drug effects , Onions/growth & development , Ultraviolet Rays , Wastewater/chemistry , Water Pollutants, Chemical/radiation effects , Water Pollutants, Chemical/toxicity , Water Purification/methods
2.
Article in English | MEDLINE | ID: mdl-31924135

ABSTRACT

The influence of the pH and the contaminant desorption/emulsification on ozone (O3), ozone-hydrogen peroxide (O3/H2O2) and ozone-photolysis (O3/UV) oxidation reactions were performed to treat crude petroleum (CP) contaminated soil and water samples. Oxidation efficiency is also related to both free radicals formation in reaction medium (which is dependent of the pH), and contaminant availability (which is dependent of the compounds solubilization or desorption processes). Thus, batch basic processes of O3/H2O2 or O3/UV were improved with sonication system and surfactant addition. In the case of O3/H2O2 process, the reactions were performed at adjusted (pH = 11) and natural pH (free pH= 4-5). The effectiveness of the improved advanced oxidation processes were evaluated through the time-course analysis of the chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and total organic carbon (TOC) values. For both improved treatment processes, CP-contaminated water samples displayed higher values for TOC removal and BOD5/COD ratios than CP-contaminated soil samples. The O3/H2O2 process provided better results than the O3/UV process regarding degradation efficiency, but the former is associated with higher treatment costs due to H2O2 consumption. Overall, oxidation treatment processes increase their efficiencies when reactions are carried out associated with solubilization and desorption systems promoted by sonication/surfactant action.


Subject(s)
Hydrogen Peroxide/chemistry , Ozone/chemistry , Petroleum/analysis , Soil Pollutants/analysis , Ultraviolet Rays , Water Pollutants, Chemical/analysis , Biological Oxygen Demand Analysis , Hydrogen-Ion Concentration , Models, Theoretical , Oxidation-Reduction , Petroleum/radiation effects , Photolysis , Soil/chemistry , Soil Pollutants/radiation effects , Water Pollutants, Chemical/radiation effects , Water Purification/methods
3.
Environ Toxicol Chem ; 38(8): 1811-1819, 2019 08.
Article in English | MEDLINE | ID: mdl-31070808

ABSTRACT

The Deepwater Horizon oil spill resulted in the release of large amounts of crude oil into waters of the Gulf of Mexico (USA). A significant portion of the oil reached coastal waters and shorelines where aquatic organisms reside. Four years after the spill, oil remains in small quantities along the coast. Given the high volume of oil coupled with the high ultraviolet light intensities of the Gulf of Mexico, continued polycyclic aromatic hydrocarbon phototoxicity may be occurring in the Gulf region. The objective of the present study was to determine the potential for phototoxicity at 5 field sites (oiled, remediated, and unoiled) in Barataria Bay (LA, USA) to caged mysid shrimp and sheepshead minnows and to evaluate the phototoxic potential of field-collected oil water accommodated fractions (WAFs). Water chemistries were similar between field-collected oil WAFs and ambient waters, excluding the most oiled field site. Field bioassays indicated no phototoxic risk of heavily weathered crude oil under the highly turbid conditions present during the study. Laboratory WAFs of field-collected oil resulted in phototoxicity to mysid shrimp, suggesting a potential for phototoxicity of heavily weathered crude oil remaining in the Gulf of Mexico. Environ Toxicol Chem 2019;38:1811-1819. © 2019 SETAC.


Subject(s)
Aquatic Organisms/drug effects , Bays/chemistry , Petroleum Pollution/analysis , Petroleum/toxicity , Polycyclic Aromatic Hydrocarbons/toxicity , Ultraviolet Rays , Water Pollutants, Chemical/toxicity , Animals , Biological Assay , Crustacea/drug effects , Gulf of Mexico , Killifishes , Louisiana , Oil and Gas Fields , Petroleum/radiation effects , Polycyclic Aromatic Hydrocarbons/radiation effects , Water Pollutants, Chemical/radiation effects , Weather
4.
Environ Pollut ; 245: 950-956, 2019 Feb.
Article in English | MEDLINE | ID: mdl-30682751

ABSTRACT

Black phosphorus (BP), a superior two-dimensional (2D) semiconductor, has attracted much attention due to its unique properties. The graphene (GR)-BP hybrid was synthesized through one pot chemical vapor transport (CVT) approach. The characterization results indicated that P atom was successfully incorporated into GR by the formation of P-C bond. Remarkably, the newly-synthesized GR-BP represented high photocatalytic activity towards 2-chlorophenol (2-CP) degradation, due to the high efficiency of charge separation and transformation caused by the direct band gap of BP and carrier mobility of GR. The removal efficiency for 2-CP reached up to 87.08% within visible light irradiation for 180 min (λ > 420 nm). The degradation rate of GR-BP hybrid for 2-CP was approximately 7.29-fold than that of BP within 30 min. In addition, the little increasing of the peak for P-O bond in GR-BP hybrid was observed after being exposed in air for 15 days, meant that the stability of BP was significantly enhanced. It was caused by the decreasing of the oxidation sites in BP due to the formation of P-C bond in hybrid. In brief, our synthetic method for GR-BP not only provides a novel route for the improvement of the stability of BP, but also constitutes an insight into the promising practical application of BP in the photocatalysis field.


Subject(s)
Chlorophenols/chemistry , Graphite/chemistry , Light , Phosphorus/chemistry , Photolysis , Water Pollutants, Chemical/chemistry , Adsorption , Catalysis , Chlorophenols/radiation effects , Graphite/chemical synthesis , Oxidation-Reduction , Water Pollutants, Chemical/radiation effects
5.
Environ Sci Pollut Res Int ; 26(5): 4180-4191, 2019 Feb.
Article in English | MEDLINE | ID: mdl-29797201

ABSTRACT

Mesoporous phosphorous-doped TiO2 (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol-gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV-Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH 8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO2 stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O-H bond were observed by FTIR analysis compared with bare TiO2. The P was substitutionally incorporated in the TiO2 lattice network as P5+ replacing Ti4+ to form Ti-O-P bonds and additionally present as PO43- on the TiO2 surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO2 1.0 wt% calcined at 450 °C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.


Subject(s)
Light , Nanoparticles/chemistry , Phosphorus/chemistry , Sulfamethazine/analysis , Titanium/chemistry , Water Pollutants, Chemical/analysis , Catalysis , Particle Size , Photochemical Processes , Photolysis , Sulfamethazine/radiation effects , Surface Properties , Water Pollutants, Chemical/radiation effects
6.
Mar Pollut Bull ; 133: 828-834, 2018 Aug.
Article in English | MEDLINE | ID: mdl-30041383

ABSTRACT

During the Deepwater Horizon oil spill rapid natural weathering of Macondo crude oil occurred during the transport of oil to coastal areas. In response to the DWH incident, dispersant was applied to Macondo crude oil to reduce the movement of oil to coastal regions. This study aimed to assess the narcotic and phototoxicity of water-accommodated fractions (WAFs) of weathered Macondo crude oil, and chemically-enhanced WAFs of Corexit 9500 to Pacific (Crassostrea gigas) and eastern (Crassostrea virginica) oyster larvae. Phototoxic effects were observed for larval Pacific oysters exposed to combinations of oil and dispersant, but not for oil alone. Phototoxic effects were observed for larval eastern oysters exposed to oil alone and combinations of oil and dispersant. Corexit 9500 did not exhibit phototoxicity but resulted in significant narcotic toxicity for Pacific oysters. Oyster larvae may have experienced reduced survival and/or abnormal development if reproduction coincided with exposures to oil or dispersant.


Subject(s)
Crassostrea/drug effects , Petroleum/toxicity , Water Pollutants, Chemical/toxicity , Animals , Crassostrea/chemistry , Crassostrea/growth & development , Larva/chemistry , Larva/drug effects , Larva/growth & development , Light , Petroleum/analysis , Petroleum/radiation effects , Petroleum Pollution/adverse effects , Petroleum Pollution/analysis , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/radiation effects
7.
Water Res ; 141: 297-306, 2018 Sep 15.
Article in English | MEDLINE | ID: mdl-29803095

ABSTRACT

The persistence of toxicity associated with the soluble naphthenic organic compounds (NOCs) of oil sands process-affected water (OSPW) implies that a treatment solution may be necessary to enable safe return of this water to the environment. Due to recent advances in high-resolution mass spectrometry (HRMS), the majority of the toxicity of OSPW is currently understood to derive from a subset of toxic classes, comprising only a minority of the total NOCs. Herein, oxidative treatment of OSPW with buoyant photocatalysts was evaluated under a petroleomics paradigm: chemical changes across acid-, base- and neutral-extractable organic fractions were tracked throughout the treatment with both positive and negative ion mode electrospray ionization (ESI) Orbitrap MS. Elimination of detected OS+ and NO+ classes of concern in the earliest stages of the treatment, along with preferential degradation of high carbon-numbered O2- acids, suggest that photocatalysis may detoxify OSPW with higher efficiency than previously thought. Application of petroleomic level analysis offers unprecedented insights into the treatment of petroleum impacted water, allowing reaction trends to be followed across multiple fractions and thousands of compounds simultaneously.


Subject(s)
Oil and Gas Fields , Organic Chemicals/chemistry , Organic Chemicals/radiation effects , Petroleum , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects , Industrial Waste , Mass Spectrometry , Oxidation-Reduction , Photolysis , Wastewater
8.
Chemosphere ; 201: 59-65, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29518735

ABSTRACT

A high-efficient photo-induced wastewater fuel cell (WFC) for neutral wastewater treatment was proposed in this paper based on radicals catalytic reaction of Fe3+/Fe2+- EDTA complexes in the system which has a lower redox potential than Fe3+/Fe2+ and can accelerate easily the conversion of slow catalytic step from Fe (III) to Fe (II). The results indicated that the WFC shows an excellent performance in a wide pH range of 5-9 and achieves optimal efficiency for organic degradation and electricity generation at pH 7.0. The removal ratio of organic pollutants (Rhodamine b, Phenol, and Methylene Blue) increased to 69.42%, 53.99% and 82.7% from 29.87%, 16.25% and 39% respectively after 3 h operation at an initial pH of 7.0. Meanwhile, the short-circuit current is up to 1.24-2.16 times that of the WFC without EDTA-ferrous complex. Furthermore, the system almost does not produce any sludge. The proposed WFC system can keep stable of Fe3+/Fe2+ in neutral solution and generate more intermediate active free radicals to treat neutral wastewater and recover the abundant chemical energy in organics.


Subject(s)
Edetic Acid/chemistry , Electricity , Ferric Compounds/chemistry , Ferrous Compounds/chemistry , Wastewater/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Bismuth/chemistry , Catalysis , Electrodes , Energy Transfer , Platinum/chemistry , Reactive Oxygen Species/chemistry , Sunlight , Vanadates/chemistry , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects
9.
Article in English | MEDLINE | ID: mdl-29206081

ABSTRACT

Direct (UV) and hydrogen peroxide-assisted (UV/H2O2) photolysis were investigated in bench-scale for removing the organic compounds present in the electrodialysis reversal (EDR) brine from a refinery wastewater reclamation plant. In the UV/H2O2 experiments, a COD:H2O2 molar ratios of 1:1, 1:2 and 1:3 were tested by recirculating the brine in the UV reactor for 120 min. Results showed a significant reduction in UVA254, whereas no reduction was observed for chemical oxygen demand (COD), in the UV process, suggesting great cleavage but limited mineralization of the organic matter. UV/H2O2 with C:H2O2 ratio of 1:3 exhibited high efficiency in removing the organic matter (COD removal of 92% with an electrical energy per removal order (EEO) value of 22 kW h m-3). Although the EDR brine has high salinity, no strong scavenging effect of •OH was found in the water matrix due to the high concentration of anions, especially chloride and bicarbonate. Finally, UV/H2O2 with C:H2O2 ratio of 1:3 and residence time of 120 min is an efficient alternative for organic matter removal of EDR brine from refinery wastewater reclamation plant showing total capital cost (CapEx) estimated at US$ 369,653.00 and total operational cost (OpEx), at US$ 1.772 per cubic meter of effluent.


Subject(s)
Hydrogen Peroxide/chemistry , Organic Chemicals/isolation & purification , Petroleum , Salts/isolation & purification , Ultraviolet Rays , Water Pollutants, Chemical/isolation & purification , Water Purification/methods , Biological Oxygen Demand Analysis , Conservation of Water Resources/methods , Filtration/methods , Humans , Hydrogen Peroxide/pharmacology , Oil and Gas Industry/methods , Oxidation-Reduction , Petroleum/analysis , Photolysis , Salinity , Waste Disposal Facilities , Waste Disposal, Fluid/methods , Wastewater/chemistry , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects
10.
Environ Sci Pollut Res Int ; 25(1): 693-703, 2018 Jan.
Article in English | MEDLINE | ID: mdl-29063391

ABSTRACT

Efficient oxidative degradation of pharmaceutical pollutants in aquatic environments is of great importance. This study used magnetic BiOCl@Fe3O4 catalyst to activate persulfate (PS) under simulated solar light irradiation. This degradation system was evaluated using atenolol (ATL) as target pollutant. Four reactive species were identified in the sunlight/BiOCl@Fe3O4/PS system. The decreasing order of the contribution of each reactive species on ATL degradation was as follows: h+ ≈ HO· > O2·- > SO4·-. pH significantly influenced ATL degradation, and an acidic condition favored the reaction. High degradation efficiencies were obtained at pH 2.3-5.5. ATL degradation rate increased with increased catalyst and PS contents. Moreover, ATL mineralization was higher in the sunlight/BiOCl@Fe3O4/PS system than in the sunlight/BiOCl@Fe3O4 or sunlight/PS system. Nine possible intermediate products were identified through LC-MS analysis, and a degradation pathway for ATL was proposed. The BiOCl@Fe3O4 nanomagnetic composite catalyst was synthesized in this work. This catalyst was easily separated and recovered from a treated solution by using a magnet, and it demonstrated a high catalytic activity. Increased amount of the BiOCl@Fe3O4 catalyst obviously accelerated the efficiency of ATL degradation, and the reusability of the catalyst allowed the addition of a large dosage of BiOCl@Fe3O4 to improve the degradation efficiency.


Subject(s)
Atenolol/analysis , Bismuth/chemistry , Magnetite Nanoparticles/chemistry , Sodium Compounds/chemistry , Sulfates/chemistry , Sunlight , Water Pollutants, Chemical/analysis , Water Purification/methods , Atenolol/radiation effects , Catalysis , Oxidation-Reduction , Water Pollutants, Chemical/radiation effects
11.
Environ Pollut ; 220(Pt A): 644-649, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27769773

ABSTRACT

Oxytetracycline (OTC) is one of the most used antibiotics in aquaculture. The main concern related to its use is the bacterial resistance, when ineffective treatments are applied for its removal or inactivation. OTC photo-degradation has been suggested as an efficient complementary process to conventional methods used in intensive fish production (e.g.: ozonation). Despite this, and knowing that the complete mineralization of OTC is difficult, few studies have examined the antibacterial activity of OTC photoproducts. Thus, the main aim of this work is to assess whether the OTC photoproducts retain the antibacterial activity of its parent compound (OTC) after its irradiation, using simulated sunlight. For that, three Gram-negative bacteria (Escherichia coli, Vibrio sp. and Aeromonas sp.) and different synthetic and natural aqueous matrices (phosphate buffered solutions at different salinities, 0 and 21‰, and three different samples from marine aquaculture industries) were tested. The microbiological assays were made using the well-diffusion method before and after OTC has been exposed to sunlight. The results revealed a clear effect of simulated sunlight, resulting on the decrease or elimination of the antibacterial activity for all strains and in all aqueous matrices due to OTC photo-degradation. For E. coli, it was also observed that the antibacterial activity of OTC is lower in the presence of sea-salts, as demonstrated by comparison of halos in aqueous matrices containing or not sea-salts.


Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Aquaculture , Oxytetracycline/chemistry , Oxytetracycline/pharmacology , Photolysis/radiation effects , Sunlight , Water/chemistry , Anti-Bacterial Agents/analysis , Anti-Bacterial Agents/radiation effects , Aquaculture/methods , Hydrogen-Ion Concentration , Microbial Sensitivity Tests , Oxytetracycline/analysis , Oxytetracycline/radiation effects , Portugal , Salinity , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/pharmacology , Water Pollutants, Chemical/radiation effects
12.
Mar Pollut Bull ; 114(2): 751-758, 2017 Jan 30.
Article in English | MEDLINE | ID: mdl-27823828

ABSTRACT

This study investigated the effects of 3 model oil dispersants (Corexit EC9500A, Corexit EC9527A and SPC 1000) on photodegradation of pyrene under simulated sunlight. Both Corexit dispersants enhanced photodegradation of pyrene, while SPC1000 slightly inhibited the reaction. Span 80 and Tween 85 were the key ingredients causing the effects, though the underlying mechanisms differed. Span 80 enriches pyrene in the upper layer of water column, whereas Tween 85 induces a photosensitization process. Two reactive oxygen species, 1O2 and O2-, were found responsible for pyrene photodegradation, though the presence of EC9500A suppressed the 1O2 pathway. In terms of photodegradation products, EC9500A enhanced generation of polyaromatic intermediates, i.e., phenaleno[1,9-cd][1,2]dioxine, 1-hydroxypyrene, and 1,8-pyrenequinone, but did not alter the classical photodegradation pathway. The Corexit dispersants were more prone to photochemical decomposition, with multiple by-products detected. The information aids in our understanding of the effects of dispersants on photochemical weathering of oil compositions.


Subject(s)
Models, Theoretical , Petroleum/analysis , Photolysis , Pyrenes/analysis , Seawater/chemistry , Sunlight , Water Pollutants, Chemical/analysis , Petroleum/radiation effects , Petroleum Pollution/analysis , Pyrenes/chemistry , Pyrenes/radiation effects , Reactive Oxygen Species/analysis , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects
13.
Mar Pollut Bull ; 113(1-2): 316-323, 2016 Dec 15.
Article in English | MEDLINE | ID: mdl-27726932

ABSTRACT

Polycyclic aromatic hydrocarbons (PAHs) have been reported to absorb ultraviolet (UV) light, resulting in enhanced toxicity. Early developmental stages of bivalves may be particularly susceptible to photo-enhanced toxicity during oil spills. In the current study, toxicity tests were conducted with sperm and three larval ages of the eastern oyster (Crassostrea virginica) to evaluate the photo-enhanced toxicity of low-energy water-accommodated fractions (WAFs) of two weathered Macondo crude oils collected from the Deepwater Horizon incident. Larvae exposed to oil WAFs under UV-filtered light demonstrated consistently higher survival and normal development than larvae exposed to WAFs under UV light. The phototoxicity of weathered Macondo oil increased as a function of increasing UV light intensity and dose. Early developing oyster larvae were the most sensitive to photo-enhanced toxicity, whereas later shelled prodissoconch larvae were insensitive. Comparisons between two weathered crude oils demonstrated that toxicity was dependent on phototoxic PAH concentration and UV light intensity.


Subject(s)
Crassostrea/drug effects , Petroleum Pollution/adverse effects , Petroleum/toxicity , Polycyclic Aromatic Hydrocarbons/toxicity , Ultraviolet Rays , Water Pollutants, Chemical/toxicity , Animals , Crassostrea/growth & development , Gulf of Mexico , Larva/drug effects , Larva/growth & development , Lethal Dose 50 , Petroleum/analysis , Petroleum/radiation effects , Polycyclic Aromatic Hydrocarbons/analysis , Polycyclic Aromatic Hydrocarbons/radiation effects , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/radiation effects , Weather
14.
Water Sci Technol ; 74(6): 1283-1295, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27685959

ABSTRACT

This study aimed to investigate the use of red mud (RM) - a byproduct of aluminum production, as a photocatalyst, which was characterized physical-chemically and used in the photodegradation of the target compound bisphenol A (BPA). Chemical processing was performed in the RM (acid treatment, chemical reduction and calcination) to verify the most active catalyst. From the results obtained, a complete degradation kinetics of BPA was carried out using a synthetic matrix (BPA in deionized water) and a real matrix (BPA in wastewater) using natural RM/calcined and TiO2 for comparison. The results indicated the potential use of the RM/calcined, which was able to degrade between 88 and 100% of the pollutant in a synthetic sample. Tests on a real effluent sample resulted in degradation rates that ranged from 59 to 100% with chemical oxygen demand reductions of up to 23% using natural RM/calcined in comparison to TiO2. The blank system (irradiation of the solution without the use of a photocatalyst) and the natural RM/calcined one, resulted in reductions of the toxicity in the effluent sample (measured by EC20 using the marine bacteria Vibrio fischeri) of about 12 times, whereas the same treatment using TiO2 resulted in a toxicity reduction of only seven times. Within these results, the RM/calcined showed potential to be used in wastewater treatment in polishing processes.


Subject(s)
Benzhydryl Compounds/chemistry , Phenols/chemistry , Photolysis , Wastewater/chemistry , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects , Aliivibrio fischeri/drug effects , Biological Oxygen Demand Analysis , Catalysis , Oxidation-Reduction , Titanium , Wastewater/toxicity
15.
Chemosphere ; 152: 446-58, 2016 Jun.
Article in English | MEDLINE | ID: mdl-27003367

ABSTRACT

Toxic effects of petroleum to marine zooplankton have been generally investigated using dissolved petroleum hydrocarbons and in the absence of sunlight. In this study, we determined the influence of natural ultraviolet B (UVB) radiation on the lethal and sublethal toxicity of dispersed crude oil to naupliar stages of the planktonic copepods Acartia tonsa, Temora turbinata and Pseudodiaptomus pelagicus. Low concentrations of dispersed crude oil (1 µL L(-1)) caused a significant reduction in survival, growth and swimming activity of copepod nauplii after 48 h of exposure. UVB radiation increased toxicity of dispersed crude oil by 1.3-3.8 times, depending on the experiment and measured variables. Ingestion of crude oil droplets may increase photoenhanced toxicity of crude oil to copepod nauplii by enhancing photosensitization. Photoenhanced sublethal toxicity was significantly higher when T. turbinata nauplii were exposed to dispersant-treated oil than crude oil alone, suggesting that chemical dispersion of crude oil may promote photoenhanced toxicity to marine zooplankton. Our results demonstrate that acute exposure to concentrations of dispersed crude oil and dispersant (Corexit 9500) commonly found in the sea after oil spills are highly toxic to copepod nauplii and that natural levels of UVB radiation substantially increase the toxicity of crude oil to these planktonic organisms. Overall, this study emphasizes the importance of considering sunlight in petroleum toxicological studies and models to better estimate the impact of crude oil spills on marine zooplankton.


Subject(s)
Copepoda/drug effects , Lipids/chemistry , Petroleum , Ultraviolet Rays , Water Pollutants, Chemical , Zooplankton/drug effects , Animals , Petroleum/radiation effects , Petroleum/toxicity , Petroleum Pollution , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects , Water Pollutants, Chemical/toxicity
16.
Chemosphere ; 144: 1655-64, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26519796

ABSTRACT

In this paper, undoped and several differently doped (with Fe(3+), N(-), and γ-Al2O3) TiO2-nanoparticle-based photocatalysts and those covered with ultrasmall gold nanoparticles (AuNPs) were engineered. Their photocatalytic performance was studied by utilizing them for the liquid-phase decomposition of the model dye methylene blue (MB) under visible-light irradiation. The structural, morphological, physico-chemical, and optical properties of the photocatalysts were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, diffuse-reflectance UV-Vis absorption spectroscopy, Raman spectroscopy and transmission electron microscopy. Photodegradation kinetics of MB was followed by measuring the absorbance of MB at 664 nm at different irradiation times, whereas the mineralization of MB was examined by determining the total organic carbon (TOC) content. The photocatalytic activity of TiO2 nanoparticles was shown to be significantly increased by introducing dopants into the crystal lattice and depositing AuNPs on the surface. Among those, γ-Al2O3 doped TiO2 nanoparticles covered with deposited AuNPs show the best photocatalytic performance. Altogether, the here engineered photocatalysts as consisting of doped TiO2 nanoparticles decorated with AuNPs establish novel three-component nanocomposite systems, where synergetic interactions between surface AuNPs, dopants and TiO2 were shown to significantly enhance the photocatalytic activity.


Subject(s)
Catalysis , Gold/chemistry , Metal Nanoparticles/chemistry , Methylene Blue/radiation effects , Photolysis , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/radiation effects , Aluminum Oxide/analysis , Ferric Compounds/analysis , Nitrates/analysis , Sunlight , Titanium/analysis
17.
Chemosphere ; 145: 351-9, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26692512

ABSTRACT

This work reports the treatment of crystallized-fruit effluents, characterized by a very low biodegradability (BOD5/COD <0.19), through the application of a UV-A LED photo-Fenton process. Firstly, a Box-Behnken design of Response Surface Methodology was applied to achieve the optimal conditions for the UV-A LED photo-Fenton process, trying to maximize the efficiency by saving chemicals and time. Under the optimal conditions ([H2O2] = 5459 mg/L; [Fe(3+)] = 286 mg/L; time >180 min), a COD removal of 45, 64 and 74% was achieved after 360 min, using an irradiance of 23, 70 and 85 W/m(2) respectively. Then a combination of UV-A LED photo-Fenton with coagulation-flocculation-decantation attained a higher COD removal (80%), as well as almost total removal of turbidity (99%) and total suspended solids (95%). Subsequent biodegradability of treated effluents increased, allowing the application of a biological treatment step after the photochemical/CFD with 85 W/m(2).


Subject(s)
Fruit , Hydrogen Peroxide/chemistry , Iron/chemistry , Light , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects , Bacteria/metabolism , Crystallization , Flocculation , Oxidation-Reduction , Waste Disposal, Fluid/methods , Wastewater/chemistry
18.
J Hazard Mater ; 282: 241-8, 2015 Jan 23.
Article in English | MEDLINE | ID: mdl-25262384

ABSTRACT

Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis - HP, eletrochemical oxidation - EO and photo-assisted electrochemical oxidation - PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NPnEO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NPnEO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NPnEO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250W lamp and a current density of 10mA/cm(2) showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NPnEO, avoiding the contamination of water resources.


Subject(s)
Endocrine Disruptors , Ethylene Glycols , Surface-Active Agents , Ultraviolet Rays , Waste Disposal, Fluid/methods , Water Pollutants, Chemical , Carbon/analysis , Cell Survival/drug effects , Electrochemistry , Endocrine Disruptors/chemistry , Endocrine Disruptors/radiation effects , Endocrine Disruptors/toxicity , Ethylene Glycols/chemistry , Ethylene Glycols/radiation effects , Ethylene Glycols/toxicity , Lactuca/drug effects , Lactuca/genetics , Lactuca/growth & development , Mutagenicity Tests , Onions/drug effects , Onions/genetics , Onions/growth & development , Oxidation-Reduction , Photolysis , Plant Roots/drug effects , Plant Roots/genetics , Plant Roots/growth & development , Surface-Active Agents/chemistry , Surface-Active Agents/radiation effects , Surface-Active Agents/toxicity , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/radiation effects , Water Pollutants, Chemical/toxicity
19.
Water Res ; 68: 304-15, 2015 Jan 01.
Article in English | MEDLINE | ID: mdl-25462738

ABSTRACT

After an oil spill, crude oil in the marine environment is affected by a variety of processes collectively called weathering. Photooxidation induced by ultraviolet (UV) light from the sun is one of the most significant processes of long-term weathering that changes the chemical nature of oil. Experimental studies on photooxidation in the natural environment are generally not practicable due to the variability of factors that are more readily controlled in a laboratory. The emission spectra and irradiance of artificial lamps are critical factors for simulating sunlight, and the process of acceleration should be differentiated from simulation. We present a comprehensive review of the exposure conditions affecting in vitro photooxidation studies, including the types of lamps, their spectra and irradiance levels and maintenance conditions. The importance of xenon arc, metal halide along with mercury­xenon, high-pressure mercury lamps and other lamps with respect to their spectral characteristics is discussed and the selection guide is provided. A brief discussion on other factors affecting photooxidation rates and outcomes, such as photosensitisers, photodegraders, solvents and the synergistic effects of compounds is also given.


Subject(s)
Lighting/instrumentation , Petroleum/radiation effects , Ultraviolet Rays , Oxidation-Reduction , Petroleum Pollution , Photochemical Processes/radiation effects , Sunlight , Water Pollutants, Chemical/radiation effects
20.
Environ Sci Pollut Res Int ; 22(1): 516-26, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25087498

ABSTRACT

The purpose of this work was detailed physicochemical, radiological, and toxicological characterization of the composite sample of water intended for human consumption in the Cameron/Tuba City abandoned uranium mining area before and after a combined electrochemical/advanced oxidation treatment. Toxicological characterization was conducted on human lymphocytes using a battery of bioassays. On the bases of the tested parameters, it could be concluded that water used for drinking from the tested water sources must be strictly forbidden for human and/or animal consumption since it is extremely cytogenotoxic, with high oxidative stress potential. A combined electrochemical treatment and posttreatment with ozone and UV light decreased the level of all physicochemical and radiological parameters below the regulated values. Consequently, the purified sample was neither cytotoxic nor genotoxic, indicating that the presented method could be used for the improvement of water quality from the sites highly contaminated with the mixture of heavy metals and radionuclides.


Subject(s)
Electrochemical Techniques , Uranium/toxicity , Water Pollutants, Chemical/toxicity , Water Pollutants, Radioactive/toxicity , Water Purification/methods , Animals , Comet Assay , Humans , Lipid Peroxidation , Metals, Heavy/analysis , Mining , Ozone , Radioisotopes/analysis , Risk Assessment , Toxicity Tests , Ultraviolet Rays , Uranium/analysis , Uranium/radiation effects , Water , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/radiation effects , Water Pollutants, Radioactive/analysis , Water Pollutants, Radioactive/radiation effects , Water Quality
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