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Chemical Science Jun 2024Transition metal multimetallic complexes have seen intense study due to their unique bonding and potential for cooperative reactivity, but actinide-transition metal...
Transition metal multimetallic complexes have seen intense study due to their unique bonding and potential for cooperative reactivity, but actinide-transition metal (An-TM) species are far less understood. We have synthesized uranium- and thorium-osmium heterometallic polyhydride complexes in order to study An-Os bonding and investigate the reactivity of An-Os interactions. Computational studies suggest the presence of a significant bonding interaction between the actinide center and the four coordinated osmium centers supported by bridging hydrides. Upon photolysis, these complexes undergo intramolecular C-H activation with the formation of an Os-Os bond, while the thorium complex may activate an additional C-H bond of the benzene solvent, resulting in a μ-η,η phenyl ligand across one Th-Os interaction.
PubMed: 38939147
DOI: 10.1039/d4sc02380c -
International Journal of Molecular... Jun 2024"Core/shell" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO, and the other is a semiconductor,...
"Core/shell" composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO, and the other is a semiconductor, TiO. These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the "core/shell" МFeO/SiO/TiO (М = Zn(II), Co(II)) type are synthesized with a core of MFeO produced by two different methods, namely the sol-gel method (SG) using propylene oxide as a gelling agent and the hydrothermal method (HT). SiO and TiO layer coating is performed by means of tetraethylorthosilicate, TEOS, Ti(IV) tetrabutoxide, and Ti(OBu), respectively. A combination of different experimental techniques is required to prove the structure and phase composition, such as XRD, UV-Vis, TEM with EDS, photoluminescence, and XPS. By Rietveld analysis of the XRD data unit cell parameters, the crystallite size and weight fraction of the polymorphs anatase and rutile of the shell TiO and of the ferrite core are determined. The magnetic properties of the samples, and their activity for the photodegradation of the synthetic industrial dyes Malachite Green and Rhodamine B are measured in model water solutions under UV light irradiation and simulated solar irradiation. The influence of the water matrix on the photocatalytic activity is determined using artificial seawater in addition to ultrapure water. The rate constants of the photocatalytic process are obtained along with the reaction mechanism, established using radical scavengers where the role of the radicals is elucidated.
Topics: Nanocomposites; Rosaniline Dyes; Catalysis; Water Pollutants, Chemical; Rhodamines; Titanium; Photolysis; Silicon Dioxide; Ferric Compounds; Photochemical Processes; X-Ray Diffraction
PubMed: 38928461
DOI: 10.3390/ijms25126755 -
Photodegradation of a Broad-Spectrum Antibiotic Azithromycin Using HO under Ultraviolet Irradiation.International Journal of Molecular... Jun 2024The photodegradation of azithromycin present was carried out in water using HO under UV irradiation. The reaction variables considered in this study were the amount of...
The photodegradation of azithromycin present was carried out in water using HO under UV irradiation. The reaction variables considered in this study were the amount of HO solution and the initial concentration of azithromycin to evaluate the performance of the photodegradation process. The azithromycin degradation was not observed in the dark during stirring for 20 min. The study showed an efficient photodegradation of azithromycin using HO as an oxidant in the presence of UV irradiation. The azithromycin degradation was altered significantly by the pH of the irradiated solution. The degradation was low at an acidic pH and showed an increasing trend as the pH changed to basic. The azithromycin degradation increased with a higher amount (higher concentration) of HO. The degradation of azithromycin decreased with a higher concentration of azithromycin in the reacting solution. The highest degradation of AZT was achieved in 1 h using a 1.0 ppm AZT solution containing 3 mL of HO. The experimental data obtained were well-fitted to zero-order reaction kinetics. The results of this study were found quite excellent. They showed 100% degradation in 1 h when compared with those reported in the literature, both with photocatalysis using nanomaterials and photolysis using light irradiation and/or HO. The UV/HO system was found to be quite efficient for the photodegradation of azithromycin, and this system can be applied to degrade other organic pollutants present in industrial wastewater.
Topics: Azithromycin; Hydrogen Peroxide; Ultraviolet Rays; Photolysis; Anti-Bacterial Agents; Hydrogen-Ion Concentration; Water Pollutants, Chemical; Kinetics
PubMed: 38928406
DOI: 10.3390/ijms25126702 -
International Journal of Molecular... Jun 2024Sulfonamides can be effectively removed from wastewater through a photocatalytic process. However, the mineralization achieved by this method is a long-term and...
Sulfonamides can be effectively removed from wastewater through a photocatalytic process. However, the mineralization achieved by this method is a long-term and expensive process. The effect of shortening the photocatalytic process is the partial degradation and formation of intermediates. The purpose of this study was to evaluate the sensitivity and transformation of photocatalytic reaction intermediates in aerobic biological processes. Sulfadiazine and sulfamethoxazole solutions were used in the study, which were irradiated in the presence of a TiO-P25 catalyst. The resulting solutions were then aerated after the addition of river water or activated sludge suspension from a commercial wastewater treatment plant. The reaction kinetics were determined and fifteen products of photocatalytic degradation of sulfonamides were identified. Most of these products were further transformed in the presence of activated sludge suspension or in water taken from the river. They may have been decomposed into other organic and inorganic compounds. The formation of biologically inactive acyl derivatives was observed in the biological process. However, compounds that are more toxic to aquatic organisms than the initial drugs can also be formed. After 28 days, the sulfamethoxazole concentration in the presence of activated sludge was reduced by 66 ± 7%. Sulfadiazine was practically non-biodegradable under the conditions used. The presented results confirm the advisability of using photocatalysis as a process preceding biodegradation.
Topics: Biodegradation, Environmental; Kinetics; Sulfonamides; Catalysis; Water Pollutants, Chemical; Titanium; Sulfamethoxazole; Photolysis; Wastewater; Sewage; Sulfadiazine; Water Purification
PubMed: 38928394
DOI: 10.3390/ijms25126688 -
International Journal of Molecular... Jun 2024Polyurethane/silk protein-bismuth halide oxide composite films were fabricated using a blending-wet phase transformationin situsynthesis method. The crystal structure,...
Polyurethane/silk protein-bismuth halide oxide composite films were fabricated using a blending-wet phase transformationin situsynthesis method. The crystal structure, micromorphology, and optical properties were conducted using XRD, SEM, and UV-Vis DRS characterize techniques. The results indicated that loaded silk protein enhanced the hydrophilicity and pore structure of the polyurethane composite films. The active species BiOX were observed to grow as nanosheets with high dispersion on the internal skeleton and silk protein surface of the polyurethane-silk protein film. The photocatalytic efficiency of BiOX/PU-SF composite films was assessed through the degradation of Rhodamine B under visible light irradiation. Among the tested films, the BiOBr/PU-SF composite exhibited the highest removal rate of RhB at 98.9%, surpassing the removal rates of 93.7% for the BiOCl/PU-SF composite and 85.6% for the BiOI/PU-SF composite. Furthermore, an active species capture test indicated that superoxide radical (•O) and hole (h) species played a predominant role in the photodegradation process.
Topics: Polyurethanes; Photolysis; Hydrophobic and Hydrophilic Interactions; Bismuth; Catalysis; Silk; Rhodamines; Coloring Agents; Oxides; Porosity; Light
PubMed: 38928359
DOI: 10.3390/ijms25126653 -
Photochemistry and Photobiology Jun 2024N-phenyl dibenzothiophene sulfoximine has been demonstrated to produce phenyl nitrene and dibenzothiophene S-oxide upon irradiation with UV-A light, and dibenzothiophene...
N-phenyl dibenzothiophene sulfoximine has been demonstrated to produce phenyl nitrene and dibenzothiophene S-oxide upon irradiation with UV-A light, and dibenzothiophene S-oxide upon further irradiation releases triplet atomic oxygen. Thus, N-phenyl dibenzothiophene sulfoximine exhibits a rare dual-release capability in its photochemistry. In this work, N-substituted dibenzothiophene sulfoximine derivatives are irradiated with UV-A light to compare their photochemistry and quantum yield of dibenzothiophene S-oxide production with that of N-phenyl dibenzothiophene sulfoximine. Both N-aryl and N-alkyl derivatives of dibenzothiophene sulfoximine are examined to observe their effects on the quantum yield of the photolysis reaction. Adding electron withdrawing N-aryl substituents is shown to increase the quantum yield of dibenzothiophene S-oxide production, while adding electron donating N-aryl substituents is shown to decrease the quantum yield. The quantum yield was slightly lowered or not increased by most N-alkyl substituents. Furthermore, the quantum yield was not augmented by branching and steric hindrance effects associated with the N-alkyl substituents. These results suggest that electronic modulation of the sulfoximine bonds affects the observed photolysis reaction.
PubMed: 38922878
DOI: 10.1111/php.13978 -
Chemosphere Jun 2024Dimethylsilanediol (DMSD) is the common degradation product of ubiquitous polydimethylsiloxane (PDMS) and volatile methylsiloxanes (VMS) in water and soil. Given the...
Dimethylsilanediol (DMSD) is the common degradation product of ubiquitous polydimethylsiloxane (PDMS) and volatile methylsiloxanes (VMS) in water and soil. Given the high solubility of DMSD in water, the further degradation of DMSD in this compartment is of particular importance. While DMSD appears relatively resistant to degradation in standard hydrolysis or biodegradation studies, it may degrade by indirect photolysis in surface waters through oxidation by hydroxyl radicals. The formation of hydroxyl radicals is governed by nitrate ions or other promoters in the presence of sunlight. In this study, we investigated the impact of nitrate ions on the oxidative decomposition of DMSD in water under simulated solar light. When exposed to solar light, DMSD can degrade all the way to the natural, mineralized substances, namely carbon dioxide (in the form of carbonic acid) and silicic acid, via the intermediate methylsilanetriol (MST).
PubMed: 38909861
DOI: 10.1016/j.chemosphere.2024.142670 -
The Science of the Total Environment Jun 2024Octylisothiazolinone (OIT) and Dichlorooctylisothiazolinone (DCOIT), widely used antibacterial agents in coatings, have seen a sharp increase in use in response to the...
Octylisothiazolinone (OIT) and Dichlorooctylisothiazolinone (DCOIT), widely used antibacterial agents in coatings, have seen a sharp increase in use in response to the Coronavirus disease 2019 (Covid-19) pandemic, ultimately leading to their increase in the aquatic environment. However, their photodegradation process in surface water is still unclear. The purpose of this study is to investigate the photodegradation kinetics and mechanisms of OIT and DCOIT in natural water environments. Under simulated solar irradiation, they undergo direct photolysis in both natural freshwater and seawater mainly via their excited singlet states, while no self-sensitization photolysis was observed. The direct photolysis rate constants of OIT and DCOIT were 1.19 ± 0.07 and 0.57 ± 0.03 h, respectively. In addition, dissolved organic matter (DOM), NO and Cl in natural waters did not contribute significantly to the photodegradation, and the light screening effect of DOM was identified as the main inhibiting factor. The photodegradation half-life of OIT was estimated to be 0.66 to 1.69 days, while the half-life of DCOIT was as high as 20.9 days during winter in surface water at 30°N latitude. Ring opening of the N-S bond and covalent bond breaking between CN are the main pathways for the photodegradation of OIT and DCOIT, which is verified by density-functional theory calculations. Ecological Structure Activity Relationships (ECOSAR) results indicate that OIT and DCOIT have "Very Toxic" biological toxicity, and the acute toxicity of their products is significantly reduced. It is noteworthy that the toxicity of the products of DCOIT is generally higher than that of OIT, and the chronic toxicity of most of the products is still above the "Toxic" level. Therefore, an in-depth understanding of the photodegradation mechanisms of OIT and DCOIT in aqueous environments is crucial for accurately assessing their ecological risks in natural water environments.
PubMed: 38909814
DOI: 10.1016/j.scitotenv.2024.174185 -
The Science of the Total Environment Jun 2024Inorganic nitrates were considered to be a potential source of atmospheric NO/HONO during the daytime. To better evaluate the contribution of nitrates photochemistry on...
Inorganic nitrates were considered to be a potential source of atmospheric NO/HONO during the daytime. To better evaluate the contribution of nitrates photochemistry on NO/HONO formation, the photolysis of nitrates in the real atmospheric environment needs to be further explored. Here, the NO generation by the photolysis of inorganic nitrates in the presence of total water-soluble organic carbon (WSOC) was quantified. The physicochemical properties of WSOC were measured to understand the underlying mechanism for the photolysis of inorganic nitrates with WSOC. WSOC enhanced or suppressed the photochemical conversion of nitrates to NO, with the quantum yield of NO (Φ) varying from (0.07 ± 0.02)% to (3.11 ± 0.04)% that depended on the light absorption properties of WSOC. Reactive oxygen species (ROS) generated from WSOC, including O/HO and OH, played a dual role in the NO formation. Light-absorbing substances in WSOC, such as N-containing and carbonyl aromatics, produced O/HO that enhanced the secondary conversion of NO to NO. On the other hand, OH derived from the WSOC photochemistry inhibited the nitrates photodegradation and the NO formation. HONO source strength by the aqueous photolysis of nitrates with WSOC was estimated to be lower than 100 ppt h, which may partly contribute to the atmospheric HONO source in some cases.
PubMed: 38909793
DOI: 10.1016/j.scitotenv.2024.174203 -
Water Research Jun 2024Krypton chloride (KrCl*) excimer lamps (222 nm) are used as a promising irradiation source to drive ultraviolet-based advanced oxidation processes (UV-AOPs) in water...
Krypton chloride (KrCl*) excimer lamps (222 nm) are used as a promising irradiation source to drive ultraviolet-based advanced oxidation processes (UV-AOPs) in water treatment. In this study, the UV/peracetic acid (PAA) process is implemented as a novel UV-AOPs for the degradation of emerging contaminants (ECs) in water. The results demonstrate that UV/PAA process exhibits excellent degradation performance for carbamazepine (CBZ), with a removal rate of 90.8 % within 45 min. Notably, the degradation of CBZ in the UV/PAA process (90.8 %) was significantly higher than that in the UV/PAA process (15.1 %) at the same UV dose. The UV/PAA process exhibits superior electrical energy per order (EE/O) performance while reducing resource consumption associated with the high-energy UV/PAA process. Quenching experiments and electron paramagnetic resonance (EPR) detection confirm that HO• play a dominant role in the reaction. The contributions of direct photolysis, HO•, and other active species (RO• and O) are estimated to be 5 %, 88 %, and 7 %, respectively. In addition, the effects of Cl, HCO, and humic acid (HA) on the degradation of CBZ are evaluated. The presence of relatively low concentrations of Cl, HCO, and HA can inhibit CBZ degradation. The UV/PAA oxidation process could also effectively degrade several other ECs (i.e., iohexol, sulfamethoxazole, acetochlor, ibuprofen), indicating the potential application of this process in pollutant removal. These findings will propel the development of the UV/PAA process and provide valuable insights for its application in water treatment.
PubMed: 38909423
DOI: 10.1016/j.watres.2024.121943