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Search results for: FREE RADICALS
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Role of biochar-based free radicals in immobilization and speciation of metals in the contaminated soil-plant environment
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Blood free Radicals Concentration Determined by Electron Paramagnetic Resonance Spectroscopy and Delayed Cerebral Ischemia Occurrence in Patients with Aneurysmal Subarachnoid Hemorrhage
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A critical review on biochar-assisted free radicals mediated redox reactions influencing transformation of potentially toxic metals: Occurrence, formation, and environmental applications
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Hunting for the Magnesium(I) Species: Formation, Structure, andReactivity of some Donor-Free Grignard Compounds
PublicationMagnesium bromide radicals have to be prepared as high-temperature molecules and trapped as a metastable solution because a seemingly simple reduction of donor-free Grignard compounds failed. However, the essential role of magnesium(I) species during the formation of Grignard compounds could be demonstrated experimentally.
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Formation of CN (B2∑+) radicals in the vacuum-ultraviolet photodissociation of pyridine and pyrimidine molecules
PublicationFormation of the excited CN(B2∑+) free radicals in the photodissociation of pyridine (C5H5N) and pyrimidine (C4H4N2) molecules was investigated over the energy ranges 16–27 and 14.7–25 eV, respectively. Photon-induced fluorescence spectroscopy was applied to detect the vibrationally and rotationally excited CN radicals by recording the B2∑+→X2∑+ emission bands (violet system). The measured dissociation yield curves demonstrate...
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Reactive extrusion of biodegradable aliphatic polyesters in the presence of free-radical-initiators: A review
PublicationNowadays, growing attention is being paid to the environment and sustainability, what fully justified research works focused on modification of biodegradable polymers and their composites. In this field of research reactive extrusion seems to be the most promising approach, which fits well to sustainable development strategy. In In the present work, the in-situ modification of biodegradable aliphatic polyesters and the compatibilization...
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Hydrogen migration in formation of NH(A3Π) radicals via superexcited states in photodissociation of isoxazole molecules
PublicationFormation of the excited NH(A 3Π) free radicals in the photodissociation of isoxazole (C3H3NO) molecules has been studied over the 14-22 eV energy range using photon-induced fluorescence spectroscopy. The NH(A 3Π) is produced through excitation of the isoxazole molecules into higher-lying superexcited states. Observation of the NH radical, which is not a structural unit of the isoxazole molecule, corroborates the hydrogen atom...
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Decolorisation of Methylene Blue with Sodium Persulfate Activated with Visible Light in the Presence of Glucose and Sucrose
PublicationThe paper presents the results of research on the methylene blue (MB) degradation with sodium persulfate (PDS) activated with visible light (Vis) in the presence of glucose and sucrose. The following test were examined: absence and presence of sugars in concentrations of 50–300 mM, presence and absence of Vis radiation, pH of the model solution (6.0–12.0), identification of free radicals, kinetics of the pseudo-first-order reaction....
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Synthesis, characterization, and application of 2D/2D TiO2-GO-ZnFe2O4 obtained by the fluorine-free lyophilization method for solar light-driven photocatalytic degradation of ibuprofen
PublicationIn this study, we report the potential of 2D/2D TiO2- GO-ZnFe2O4 photocatalyst obtained using the fluorine-free lyophilization technique for the degradation of ibuprofen belonging to the group of active pharmaceutical ingredients (API). The improved ibuprofen degradation under simulated solar light was achieved in the presence of a composite of 2D TiO2 combined with GO and embedded ZnFe2O4, which additionally provides superparamagnetic...
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Visible light activity of pulsed layer deposited BiVO4/MnO2 films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation
PublicationThin films containing BiVO4 and MnO2 deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27–115 nm) were...
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A novel hierarchically-porous diamondized polyacrylonitrile sponge-like electrodes for acetaminophen electrochemical detection
PublicationA novel composite electrode material consisting of tangled fibrous polyacrylonitrile-based hierarchically-struc- tured nanocomposites has been produced by wet-spinning, carbonized and decorated with a carbon nano- architecture by microwave plasma-enhanced chemical vapor deposition and investigated as a metal-free electrode for the enhanced electrochemical detection of acetaminophen. Surprisingly, the hierarchical fiber ar- chitecture...
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Elimination and migration of hydrogen in the vacuum-ultraviolet photodissociation of pyridine molecules
PublicationElimination of the excited hydrogen atoms H(n), n = 4–7, and hydrogen migration in formation of the excited NH(A 3Π) free radicals in the photodissociation of pyridine, C5H5N, molecules have been studied over the 17.5–70 eV photon energy range. In the measurements the photon-induced fluorescence spectroscopy technique has been applied. Both fragments are produced through excitation of pyridine molecules into higher-lying superexcited...
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Graphitic carbon nitride/bismuth-based Z-scheme heterojunctions for the photocatalytic removal of pharmaceuticals and personal care products — a review
PublicationZ-scheme heterojunction in recent years is one of the most promising approaches in photocatalytic materials in solar light region for various environmental applications, including the removal of pharmaceuticals and personal care products (PPCPs). Integrating g-C3N4 and Bi-based semiconductors via Z-scheme is highly effective in providing efficient flow of charge carriers along with suitable redox sites. The g-C3N4/Bi-based photocatalysts...
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Relationship between heart rate variability, blood pressure and arterial wall properties during air and oxygen breathing in healthy subjects
PublicationPrevious studies reported that normobaric hyperoxia influences heart rate, arterial pressure, cardiac output and systemic vascular resistance, but the mechanisms underlying these changes are still not fully understood. Several factors are considered including degeneration of endothelium-derived nitric oxide by reactive oxygen species, the impact of oxygen-free radicals on tissues and alterations of autonomic nervous system function....
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The influence of ILs on TiO2 microspheres activity towards 5-FU removal under artificial sunlight irradiation
PublicationIn this work, the effect of various ionic liquids (ILs), namely, choline chloride [Chol][Cl], hexadecylpyridynium chloride [HDPy][Cl], and tributylmethylammonium chloride [TBMA][Cl], on the morphology, surface compo-sition in relation to photocatalytic oxidation of 5-fluorouracil (5-FU) and phenol in the presence of TiO2 pho-tocatalysts under artificial sunlight conditions was investigated. The highest photoactivity towards cytostatic...
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Structure, Physicochemical and Biological Properties of an Aqua (2,2′,2′′-Nitrilotriacetato)-oxidovanadium(IV) Salt with 4-Methylpyridinium Cation
PublicationThe crystal structure of a nitrilotriacetate (nta) oxidovanadi-um(IV) salt with 4-methylpyridinium cation, [4-Me(Py)H]+, of [4-Me(Py)H][VO(nta)(H2O)] stoichiometry was determined. The com-plex comprises a discrete mononuclear [VO(nta)(H2O)]–coordinationentity that can be rarely found among other known compounds con-taining nitrilotriacetate oxidovanadium(IV) moieties. The complex wascharacterized by spectroscopic (IR and EPR) methods,...
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Influence of Diosmin Treatment on the Level of Oxidative Stress Markers in Patients with Chronic Venous Insufficiency
PublicationOxidative stress plays an important role in the pathophysiology of many human disorders, while antioxidants prevent the development of various adverse symptoms. Diosmin is a natural flavonoid applied in vascular system disorders, especially in chronic venous insufficiency (CVI), and it plays a significant part in the alleviation of CVI symptoms. Due to antioxidant activity, it also has the ability to scavenge the oxygen free radicals...
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Determination of isoprostanes in exhaled breath condensate samples by liquid chromatography coupled with tandem mass spectrometry
PublicationOxidative stress (OS) is a state of imbalance between continuously generating reactive oxygen species (ROS) during normal cell metabolism and mechanism of detoxifying oxygen radicals through a network of antioxidative enzymes. Isoprostanes are prostaglandin -like substances that are produced in vivo primarily by free radical-induced peroxidation of arachidonic acid. The measurement of isoprostanes in biological fluids and/or tissue...
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Interactions between bioactive components determine antioxidant, cytotoxic and nutrigenomic activity of cocoa powder extract
PublicationNumerous studies have shown, rather disappointingly, that isolated bioactive phytochemicals are not as biologically effective as natural plant products. Such a discrepancy may be explained by the concept of food synergy, which was verified in this research for cocoa extract versus its major components with regard to cancer chemoprevention. The evaluation embraced the relationship between redox properties evaluated in cell-free systems...
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Data on hydrogen migration in cation-induced dissociation of furan molecules
Open Research DataThe data include furan luminescence spectra obtained in collisions with H3+ and C+ cations and theoretical spectra of OH and CH radicals published in [1].
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Influence of the Addition of Selected Spices on Sensory Quality and Biological Activity of Honey
PublicationBee honey is nutritious and has numerous health benefits, but its taste is for many people too bland. Honey with addition of spices could be important to the food industry as a functional product with positive health image and interesting taste. Such product would definitely meet health-driven consumers’ expectations. Therefore, the aim of this study was to evaluate the effect of addition of selected spices on sensory, antimicrobial,...
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Structural, mechanical and thermal behavior assessments of PCL/PHB blends reactively compatibilized with organic peroxides
PublicationThe efficiency of two commercially available organic peroxides, dicumyl peroxide (DCP) and di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB), during reactive processing of poly (ε-caprolactone)/poly (3-hydroxybutyrate) (PCL/PHB) blends was investigated. The changes in chemical structure of PCL/PHB blends, as a function of organic peroxide type (DCP/BIB) and content (in range: 0–1.0 parts by weight - pbw), were characterized by Fourier...
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Biological Activity of Tea-Chokeberry and Chokeberry Fermented Beverages
PublicationFermented beverages, such as kombucha are gaining more and more popularity due to their beneficial effects on human health. These products are obtained by the fermentation of tea infusion using so called tea fungus. This microbial consortium can also be used to prepare fermented fruit beverages. Therefore, the aim of this study was to determine the changes in the antioxidant profile of tea-chokeberry and chokeberry beverages...
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Receptor for advanced glycation end‐products: Biological significance and imaging applications
PublicationThe receptor for advanced glycation end-products (RAGE or AGER) is a transmembrane, immunoglobulin-like receptor that, due to its multiple isoform structures, binds to a diverse range of endo- and exogenous ligands. RAGE activation caused by the ligand binding initiates a cascade of complex pathways associated with producing free radicals, such as reactive nitric oxide and oxygen species, cell proliferation, and immunoinflammatory...
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Combination of air-dispersion cathode with sacrificial iron anode generating Fe2+Fe3+2O4 nanostructures to degrade paracetamol under ultrasonic irradiation
PublicationIn the present study, ultrasound (US) was coupled with an electrochemical process (ECP) consisting of a novel cathode of carbon cloth (CC)-carbon black (CB) as the nano-composite air-dispersion cathode (NADC) for the degradation of paracetamol (APAP) in an aquatic medium. The NADC favored in situ production of H2O2 by the cathodic reduction. The implementation of iron sacrificial anode instead of dimensionally stable anodes resulted...
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The Unfolded Protein Response: A Double-Edged Sword for Brain Health
PublicationEfficient brain function requires as much as 20% of the total oxygen intake to support normal neuronal cell function. This level of oxygen usage, however, leads to the generation of free radicals, and thus can lead to oxidative stress and potentially to age-related cognitive decay and even neurodegenerative diseases. The regulation of this system requires a complex monitoring network to maintain proper oxygen homeostasis. Furthermore,...
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Endothelial dysfunction due to eNOS uncoupling: molecular mechanisms as potential therapeutic targets
PublicationNitric oxide (NO) is one of the most important molecules released by endothelial cells, and its antiatherogenic properties support cardiovascular homeostasis. Diminished NO bioavailability is a common hallmark of endothelial dysfunction underlying the patho‑ genesis of the cardiovascular disease. Vascular NO is synthesized by endothelial nitric oxide synthase (eNOS) from the substrate L‑arginine (L‑Arg), with tetrahydrobiopterin...
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Degradation of tetracycline antibiotic utilizing light driven-activated oxone in the presence of g-C3N4/ZnFe LDH binary heterojunction nanocomposite
PublicationIn the present study, a binary heterojunction nanocomposite composed of graphitic carbon nitride (g-C3N4) and Zn/Fe-contained layered double hydroxide (ZnFe LDH) was employed as heterogeneous catalyst for the decomposition of tetracycline (TC) antibiotic utilizing Oxone and UV light irradiation. The sole use of g-C3N4/ZnFe LDH as adsorbent led to the negligible elimination of TC. In addition, the sole use of Oxone or UV (photolysis)...
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First highly effective non-catalytic nitrobenzene reduction in UV/dithionite system with aniline production – Advanced reduction process (ARP) approach
PublicationAdvanced reduction processes (ARPs) are currently intensively investigated as an alternative to Advanced Oxidation Processes (AOPs). The study presents efficient reduction of nitrobenzene under non-catalytic conditions through reaction with free radicals having reductive potential. Effective conversion of nitrobenzene in a model wastewater solution, was obtained for sodium dithionite (SDT)/ dithionite (DTN). The developed process...
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Multidirectional Characterization of Phytochemical Profile and Health-Promoting Effects of Ziziphora bungeana Juz. Extracts
PublicationZiziphora species (Lamiaceae) have been used in traditional medicine as sedatives, anti-septics, carminatives, or expectorants. Despite their common applications in phytotherapy, there is still lack of evidence about the composition of their extracts and its impact on biological properties of the plants. The aim of this study was to evaluate the content of Ziziphora bungeana, a less studied species growing in Kazakhstan, using...
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Photocatalytic degradation of acetaldehyde in high temperature reaction chamber
Open Research DataThis dataset contains chromatograms recorded during the decomposition of acetaldehyde in a high-temperature reaction chamber under UV irradiation using TiO2 (titanium dioxide) as photocatalysts. It includes data on the influence of flow rate, TiO2 (titanium dioxide) filling the entire reactor, a thin layer of TiO2 (titanium dioxide) supported on KBr...
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Polyurethane/Silane-Functionalized ZrO2 Nanocomposite Powder Coatings: Thermal Degradation Kinetics
PublicationA polyurethane (PU)-based powder coating reinforced with vinyltrimethoxysilane (VTMS)-functionalized ZrO2 nanoparticles (V-ZrO2) for thermal stability was developed. Chemical structure, microstructure and thermal degradation kinetics of the prepared coatings were investigated. The peak of aliphatic C–H vibrating bond in the Fourier transform infrared (FTIR) spectrum of V-ZrO2 was a signature of VTMS attachment. Scanning electron...
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Reactions of methyl radicals with silica supported silver nanoparticles in aqueous solutions
PublicationSilica supported silver nanoparticles (Ag°–SiO2 –NCs, NCs=nanocomposites) suspended in aqueous solutions are efficient catalysts for the dimerization of methyl radicals to produce ethane, while bare silica is quite inert towards the interaction with methyl radicals. In the presence of small amounts of ethanol adsorbed on the SiO2 surface, the reaction path with methyl radicals is changed and methane is formed as the major product.
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Degradation of bisphenol S – a contaminant of emerging concern - by synergistic ozone and percarbonate based AOP
PublicationDegradation of bisphenol S was studied using ozone activated by sodium percarbonate and the effectiveness of optimized process was compared with the peroxone process. The influence of several factors including sodium percarbonate concentration, ozone dose, pH, and water matrix were investigated. A synergetic coefficient of 3.84 was achieved for the combination of sodium percarbonate and ozone, confirming the effectiveness of this...
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Degradation kinetics and mechanism of pentoxifylline by ultraviolet activated peroxydisulfate
PublicationDegradation of pentoxifylline (PTX) by sodium peroxydisulfate (SPDS) assisted by UV irradiation has been investigated in deionized water. The treatment was more favorable over direct photolysis or peroxydisulfate oxidation alone. The effects of various parameters, including different dosage of oxidant agent, PTX concentration, initial solution pH levels, and the presence of inorganic ions like chloride, nitrate and carbonate have...
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Ultrasound-assisted heterogeneous activation of persulfate and peroxymonosulfate by asphaltenes for the degradation of BTEX in water
PublicationThis study investigated – for the first time - the simultaneous degradation of benzene, toluene, ethylbenzene and o-xylene (BTEX) by persulfate (PS) and peroxymonosulfate (PMS) activated by asphaltenes (Asph) under ultrasound (US) irradiation. Advantageous properties such as high thermal stability, low production cost and extensive availability make asphaltenes as an appealing carbonaceous material for heterogeneous catalysis....
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Activation of peroxymonosulfate using carbon black nano-spheres/calcium alginate hydrogel matrix for degradation of acetaminophen: Fe3O4 co-immobilization and microbial community response
PublicationHerein, we focused on the degradation of acetaminophen (ACT) drug in liquid phase by peroxymonosulfate (PMS) activated by carbon black nano-spheres (CBNS). The nanostructured activator was immobilized into calcium alginate hydrogel matrix (CAHM) to avoid the washout of the fine nanostructures. The Langmuir modeling showed an insignificant contribution to the adsorption process in the removal of ACT. The basic pH conditions favored...
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Tetracycline degradation for wastewater treatment based on ozone nanobubbles advanced oxidation processes (AOPs) – Focus on nanobubbles formation, degradation kinetics, mechanism and effects of water composition
PublicationPresence of pharmaceuticals, especially antibiotics, in industrial and domestic effluents causes serious damage to the environment. Classic wastewater treatment processes, in particular conventional biological treatment methods, are not sufficient to rapidly eliminate antibiotics. Typically, Advanced Oxidation Processes (AOPs) based on activation of hydrogen peroxide, ozone or persulfate for formation of particular type of radical...
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Observation of the Hydrogen Migration in the Cation-Induced Fragmentation of the Pyridine Molecules
PublicationThe ability to selectively control chemical reactions related to biology, combustion, and catalysis has recently attracted much attention. In particular, the hydrogen atom relocation may be used to manipulate bond-breaking and new bond-forming processes and may hold promise for far-reaching applications. Thus, the hydrogen atom migration preceding fragmentation of the gas-phase pyridine molecules by the H+, H2+, He+, He2+, and...
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Chemical and biological evaluation of antioxidant activity of endogenous redox-active compounds compared to plant-derived exogenous antioxidants
PublicationThe research conducted so far has shown that endogenous antioxidants, despite being regarded as the first line of antioxidant defense, may not be sufficient to maintain redox homeostasis in cells exposed to oxidative stress. The results obtained in the doctoral dissertation show that endogenous redox-active compounds were moderate or weak scavengers of ABTS and DPPH radicals, while in cellular setting, their impact on the reducing...
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Ab initio chemical kinetics of Isopropyl acetate oxidation with OH radicals
PublicationGlobal reactivity descriptors of isopropyl acetate (IPA) and thermo-kinetic aspects of its oxidation via OH radicals have been studied. Transition state theory (TST) was utilized to estimate the bimolecular rate constants. Ten oxidation pathways have been investigated, and all of them are exothermic. The potential energy diagram has been sketched using different pre- and post-reactive complexes for all reaction pathways. Rate coefficient...
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Hydrogen migration observed in fragmentation of the pyridine molecules in collisions with the H+, H2+, He+and He++cations
PublicationThe hydrogen atom migration preceding fragmentation of the pyridine molecules by the H+, H2+, He+ and He++ collisions has been investigated in the 5-2000 eV energy range. The pyridine molecule structure is lacking of the NH group, thus formation of the NH radicals is an evidence of the H atom relocation prior to the cation-induced fragmentation. The NH(A3Π) fragmentation yields measured by detecting its A3Π→X3Σ− fluorescence show...
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Design and synthesis of TiO2/Ti3C2 composites for highly efficient photocatalytic removal of acetaminophen: The relationships between synthesis parameters, physicochemical properties, and photocatalytic activity
PublicationIn this study, we report the potential of TiO2/Ti3C2 composite fabricated by oxidation of MXene for degradation of persistent organic pollutants. The effect of the synthesis conditions (time, temperature, and reaction environment) on the morphology, physicochemical properties, and photocatalytic activity was investigated. It was found that acetaminophen degradation was positively correlated with TiO2 content in the composite structure. Furthermore,...
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Advanced Oxidation Processes for Degradation of Water Pollutants—Ambivalent Impact of Carbonate Species: A Review
PublicationAdvanced oxidation processes (AOPs) hold great promise in the removal of organic contaminants. Reactive oxygen species (ROS) produced in AOPs react with target pollutants to initially form several intermediate compounds that finally undergo complete mineralization. Such observations are reported, especially for laboratory-scale experiments performed in pure water. On the other hand, while considering real contaminated wastewater...
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High-performance activation of ozone by sonocavitation for BTEX degradation in water
PublicationThis work presents a novel advanced oxidation process (AOP) for degradation of emerging organic pollutants – benzene, toluene, ethylbenzene and xylenes (BTEXs) in water. A comparative study was performed for sonocavitation assisted ozonation under 40–120 kHz and 80–200 kHz dual frequency ultrasounds (DFUS). Based on the obtained results, the combination of 40–120 kHz i.e., low-frequency US (LFDUS) with O3 exhibited excellent oxidation...
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A Computational Analysis of the Proton Affinity and the Hydration of TEMPO and Its Piperidine Analogs
PublicationThe study investigated the impact of protonation and hydration on the geometry of nitroxide radicals using B3LYP and M06-2X methods. Results indicated that TEMPO exhibited the highest proton affinity in comparison to TEMPOL and TEMPONE. Two pathways contribute to hydrated protonated molecules. TEMPO shows lower first enthalpies of hydration (ΔH1-M), indicating stronger H-bonding interactions, while TEMPONE shows higher values,...
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Facile preparation of extremely photoactive boron-doped TiO2 nanotubes arrays
PublicationDoping of TiO2 nanotube arrays with boron was realized via electrochemical treatment of as-anodized titania immersed in electrolyte containing boric acid. The photoactivity of doped and pure titania was examined by means of photoelectrochemical and photocatalytic response under UV-vis irradiation. The results showed that photocurrent density of B-TNTs is remarkably higher (7.5 times) than density of pure TiO2 nanotube arrays. Furthermore,...
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Studies on Treatment of Bitumen Effluents by Means of Advanced Oxidation Processes (AOPs) in Basic pH Conditions
PublicationThe paper presents the results of studies on chemical treatment of effluents from production of bitumen of petroleum origin. Due to the presence of sulfide ions, the pH of these effluents is strongly alkaline. Several Advanced Oxidation Processes (AOPs) were studied, including the use of hydroxyl and sulfate radicals oxidants, the hydrodynamic cavitation as well as sonocavitation. The best processes allow to obtain 45% reduction...
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Studies on treatment of bitumen effluents by means of Advanced Oxidation Processes (AOPs) in basic pH conditions
PublicationThe paper presents the results of studies on chemical treatment of effluents from production of bitumen of petroleum origin. Due to the presence of sulfide ions, the pH of these effluents is strongly alkaline. Several Advanced Oxidation Processes (AOPs) were studied, including the use of hydroxyl and sulfate radicals oxidants, the hydrodynamic cavitation as well as sonocavitation. The best processes allow to obtain 45% reduction...
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Photoactivity of decahedral TiO2 loaded with bimetallic nanoparticles: Degradation pathway of phenol-1- 13 C and hydroxyl radical formation
PublicationDecahedral TiO2decorated with bimetallic nanoparticles were synthesized via radiolysis and photode-position method. The effect of bimetallic surface composition (Ag Pt, Ag Au, Au Pd, Au Pt) as well asdeposition technique (simultaneous or sequential) on the photocatalytic activity in phenol degradationand efficiency of hydroxyl radicals generation under UV–vis light irradiation were investigated. Modifiedand pristine decahedral...