Chemical Scavenging Research Articles

Research advancements in sulfide scavengers for oil and gas sectors

Abstract Sulfide species (inorganic and organic sulfides) are well known for their toxicity and corrosiveness. Several industries, including oil and gas, are prone to corrosive damage due to sulfides that necessitate their timely removal using appropriate methods. Employing chemical scavengers is the most suitable method where the scavenger combine with dissolved sulfides in aqueous/hydrocarbon phase and convert them to a nontoxic and less corrosive form that can be easily removed from the stream. Instead of direct chemical scavenger addition, different approaches, including absorption and adsorption methods, are employed in eliminating sulfide species from gas streams in different industrial applications. This review provides a detailed account of various sulfide scavengers used in oil and gas sweetening. Most recent research advancements in this area are highlighted. A brief account of the latest reported works on novel adsorbents for the desulfurization process for refinery fuels is also provided. The review ends with a short discussion on catalytic hydrodesulfurization.

The effect of Hydrogen sulfide oxidation with ultraviolet light and aeration on sour water treatment via membrane contactors

During natural gas extraction and production, hydrogen sulfide (H2S) is often brought to the surface. In some cases, H2S could be present in water streams, referred to as “sour water”, treatment of that sour water is required before disposal or reuse. Sour water can be treated in a variety of ways including conventional stripping and chemical scavenging. Hydrophobic membrane contactors are an alternative technology for the treatment of sour water. Due to the hydrophobic nature of the membrane, dissolved gases, including H2S, can pass through while water is retained on the feed side. The sodium hydroxide receiving solution acts as a trap that captures the H2S. Once the H2S is trapped, ultraviolet (UV) light and oxygen can be applied to oxidize the sulfide to non-hazardous forms of sulfur allowing more disposal options for the receiving solution. This research focused on evaluating the feasibility and performance of a hybrid process combining a membrane contactor and a sulfide oxidation step through UV light and aeration.Oxidation experiments showed that UV light alone can oxidize the sulfide to disulfide. On the other hand, UV combined with oxygen, via aeration, was capable of further oxidizing sulfide to sulfate and thiosulfate; the two main sulfur species present in the treated water based on mass balance calculations. Both oxidation methods (UV with and without aeration) were found to follow a first order reaction rate, that of UV alone was 0.015 min−1, and when combined with aeration the rate was more than two times higher (0.035 min−1). The proposed hybrid technology can be applied in both upstream and downstream operations as a standalone process for the treatment of sour produced and process water.

Photogeneration of reactive oxygen species over ultrafine TiO2 particles functionalized with rutin\u2013ligand induced sensitization and crystallization effects

Interaction of amorphous and crystalline TiO2 ultrafine particles (2–6 nm) with rutin results in the formation of colored nanomaterials of an excellent dispersity and enhanced colloidal stability in aqueous media. The FTIR and Raman spectra confirmed attachment of the rutin ligand via vicinal hydroxyl groups in a catechol-like fashion. The binding of rutin to amorphous TiO2 gives rise to spontaneous crystallization of the parent nanoparticles into hydrogen titanates (H2Ti3O7 and H2Ti12O25). Such structural transformations result in photosensitization toward visible light with enhanced efficiency of the charge separation and interfacial charge transfer processes, confirmed by detailed photoelectrochemical studies of the examined nanomaterials. The effectiveness of the photocatalytic ROS generation reactions was also strongly influenced by hydrogen peroxide, which plays a double role of a reactant prone to reduction and generation of hydroxyl radicals or a redox agent destroying the intra-band gap electronic states, suppressing thereby charge recombination. The photoinduced charge transfer processes lead to generation of various reactive oxygen species, which were detected by EPR using DMPO spin trap (HOO· detection) and in the reaction with terephthalic acid acting as a chemical scavenger (HO· detection). Complexation of TiO2 particles with rutin shifts the photogeneration of hydroperoxyl (HOO·) and hydroxyl (HO·) radicals toward visible light (λ > 400 nm). A triple effect of rutin attachment to titania was established. It consists in pronounced photosensitization, promotion of crystallization and enhancement of the colloidal stability of ultrafine titania particles. Environmental implications of these assets on the photoinduced redox reactions with hydrogen peroxide in aqueous solutions upon UV or visible light irradiation were also discussed.

Synthesis of bismuth oxyiodide (BiOI) by means of microwaves in glycerol with high photocatalytic activity for the elimination of NOx and SO2

A facile microwave route was successfully developed to synthesize BiOI in glycerol as a medium of reaction. The temperature and time of synthesis were selected as the critical experimental variables to rule the physicochemical properties of the samples prepared. The products were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy, adsorption–desorption N2 isotherms, diffuse reflectance spectroscopy, scanning electron microscopy, X-ray electron spectroscopy and thermogravimetric/differential scanning calorimetry (TGA/DSC). The photocatalytic activity of BiOI samples was tested in the oxidation reactions of nitric oxide (NO) and sulfur dioxide (SO2) in gaseous phase under visible light radiation. The photocatalysts with the highest activity were the samples prepared by microwave irradiation at 135 °C for 20–34 min and were able to remove 97.8% of NO2 and 85.2% of SO2. The analysis by XRD revealed aspects of the samples that improved its photocatalytic activity, such as the preferential crystalline orientation in (110) BiOI planes, as well as the presence of the secondary crystalline phases Bi, Bi2O2.5 and Bi4O5I2. The use of chemical scavengers revealed that the ion superoxide (O2−) and photogenerated electrons (e−) were the predominant active species in the mechanism of the NO oxidation reaction.

Impacts of sulfidation of silver nanowires on the degradation of bisphenol A in water

Silver nanowires (AgNWs) are widely produced in many electronic and optical products, and could be inevitably discharged into the aquatic environments. Sulfidation is one of the most important transformation processes of AgNWs, and could significantly affect their fate and interactions with other pollutants in aquatic environment. In the present study, the sulfidation products of AgNWs with different atomic ratio of Ag and S were prepared under environmentally relevant conditions. The crystal structure, elemental composition, morphology and size of the sulfidation products were comprehensively characterized by powder X-ray diffraction, UV–vis spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscope. The products were heterostructured nanowires and the Ag2S/Ag molar ratio increased with extension of the reaction time. The produced Ag2S–Ag nanowires displayed a good photocatalytic activity and facilitated the degradation of the copresent organic pollutant bisphenol A (BPA) under simulated sunlight irradiation. As sulfidation time increased, more Ag2S was generated and the Ag2S–Ag composites displayed high promotion effect on BPA degradation. This effect could be ascribed to the favorable synergistic effects between Ag2S and AgNWs, such as high electron-hole separation efficiency and low charge transfer resistance. The chemical scavenger experiments demonstrated that superoxide anion radicals and photogenerated holes in the sulfidation products of AgNWs could be the main reactive species for photocatalytic degradation.

Modeling Impact of Ce on Fuel-Cell Performance and Durability

Throughout the lifetime of a polymer-electrolyte fuel cell, the membrane undergoes chemical degradation that causes defects to form and grow, contributes to a loss of performance, and can lead to cell failure. A combination of accelerated stress tests (ASTs)1-2 and modeling studies3-4 have been performed on this topic to better understand membrane degradation mechanisms and how to mitigate them5-6. During fuel-cell operation, formed peroxide radicals due to reactant gas crossover attack the polymer backbone and end chains, leading to membrane thinning and formation and growth of defects such as cracks and pinholes. This study builds upon our previous modeling study on membrane degradation to analyze the addition of chemical scavengers into the fuel-cell membrane to mitigate the effects of chemical degradation via radical attack. The developed model is transient and 1D across the fuel-cell sandwich. The transport and concentration of cerium is modeled using an ion-transport model based on concentration solution theory, thereby allowing the evaluation of how water gradients also move cerium ions throughout the ionomer, resulting in nonintuitive distributions. The model results also show how drive-cycle testing impacts the performance of the cell and the location of cerium, where relaxation of the applied gradients help redistribute the cerium in the ionomer. The purpose of the study is to optimize the cerium amount in both the membrane and catalyst layers by balancing effects of mitigation of chemical degradation and performance due to the impact of cerium on the ionomer material properties. For the latter, a key feature is accounting for the nonlinearities induced by the impacts of cerium on membrane and catalyst-layer ionomer properties. Acknowledgements The authors would like to thank Hans Johansen for helpful discussions and Los Alamos National Laboratory for providing material property data. Funding support was supplied by the Fuel Cell Performance and Durability Consortium (FC-PAD), by the Fuel Cell Technologies Office (FCTO), Office of Energy Efficiency and Renewable Energy (EERE), of the U.S. Department of Energy under contract number DE-AC02-05CH11231. References R. Borup, et al., Chem. Rev., 107, 3904 (2007)F. A. de Bruijn, et al., Fuel Cells, 8, 3 (2008).R. Singh, et al., J. Electrochem. Soc., 165, F3328 (2018)K. H. Wong and E. Kjeang, J. Electrochem. Soc., 166, F128 (2019).M. Zatón, et al., Sustainable Energy & Fuels, 1, 409 (2017).F. D. Coms, et al., in The Chemistry of Membranes Used in Fuel Cells: Degradation and Stabilization, 1st ed., S. Schlick Editor, John Wiley & Sons, Inc. (2018).

Uncovering the mechanism of novel AgInS2 nanosheets/TiO2 nanobelts composites for photocatalytic remediation of combined pollution

In this work, a novel AgInS2 nanosheets/TiO2 nanobelts photocatalyst was prepared by a facile hydrothermal method. The AgInS2/TiO2 with the optimal ration showed excellent photocatalytic performance in simultaneous Escherichia coli (E. coli) disinfection and Cr(VI) reduction or E. coli disinfection and bisphenol A (BPA) degradation. The superior photocatalytic effect were possibly attributed to formation of heterojunction between AgInS2 nanosheets and TiO2 nanobelts, which could increase the absorption of visible light, facilitate the separation of photo-induced carrier and held the redox of photo-generated e– and h+. The production of reactive species during the disinfection process was also investigated by employing chemical scavengers, electron spin resonance, and spectroscopy technique, revealing the paramount role of h+ and O2•–. This study paves a new way to rationally design the novel TiO2 nanobelts or AgInS2 nanosheets based photocatalysts for combined pollution remediation in water environment.

Rapid degradation of organics by peroxymonosulfate activated with ferric ions embedded in graphitic carbon nitride

In this study, Fe3+ was embedded in graphitic carbon nitride (g-C3N4) and used as a catalyst for acid orange 7 (AO7) removal via peroxymonosulfate (PMS) activation. The w/w% Fe3+ dopant was varied (0–2.5) and the changes in the physical and chemical characteristics of g-C3N4 after Fe3+ doping were studied. The results indicated that, while there was no distinct change in the g-C3N4 morphology, Fe3+ doping increases the specific surface area and catalytic active sites for enhanced PMS activation. However, increasing the Fe3+ doping decreased the structural stability of the g-C3N4. It was found that the g-C3N4 with 2.5 w/w% Fe3+ dopant (denoted as gCN-Fe3) gave the highest AO7 removal rate (initial rate constant, ki = 0.096 min−1) with at least 5.6 higher than that of g-C3N4. The effects of PMS dosage, gCN-Fe3 loading and pH on AO7 removal were investigated. The results showed that increasing the gCN-Fe3 loading provided ~3.7 times better performance enhancement compared to increasing the PMS dosage while pH 5 (ki = 0.151 min−1) was the optimum pH. The chemical scavengers were employed to identify the dominant reactive species. Based on the results, it is proposed that higher valent Fe species generated from the interaction between PMS and Fe3+ is the dominant reactive species. The results also indicated that gCN-Fe3 can still retain its catalytic activity after three cycles and AO7 mineralization was achieved. Besides AO7, the gCN-Fe3/PMS system can be employed to degrade various other organics including antibiotics and endocrine disruptors. This indicates that the catalyst has promising application as PMS activator for organics removal.

Data-Driven Identification of Hydrogen Sulfide Scavengers.

Hydrogen sulfide (H2 S) is an important signaling molecule whose up- and down-regulation have specific biological consequences. Although significant advances in H2 S up-regulation, by the development of H2 S donors, have been achieved in recent years, precise H2 S down-regulation is still challenging. The lack of potent/specific inhibitors for H2 S-producing enzymes contributes to this problem. We expect the development of H2 S scavengers is an alternative approach to address this problem. Since chemical sensors and scavengers of H2 S share the same criteria, we constructed a H2 S sensor database, which summarizes key parameters of reported sensors. Data-driven analysis led to the selection of 30 potential compounds. Further evaluation of these compounds identified a group of promising scavengers, based on the sulfonyl azide template. The efficiency of these scavengers in in vitro and in vivo experiments was demonstrated.

Data‐Driven Identification of Hydrogen Sulfide Scavengers

AbstractHydrogen sulfide (H2S) is an important signaling molecule whose up‐ and down‐regulation have specific biological consequences. Although significant advances in H2S up‐regulation, by the development of H2S donors, have been achieved in recent years, precise H2S down‐regulation is still challenging. The lack of potent/specific inhibitors for H2S‐producing enzymes contributes to this problem. We expect the development of H2S scavengers is an alternative approach to address this problem. Since chemical sensors and scavengers of H2S share the same criteria, we constructed a H2S sensor database, which summarizes key parameters of reported sensors. Data‐driven analysis led to the selection of 30 potential compounds. Further evaluation of these compounds identified a group of promising scavengers, based on the sulfonyl azide template. The efficiency of these scavengers in in vitro and in vivo experiments was demonstrated.

Chemical Fingerprinting, Anticancer, Anti-inflammatory and Free Radical Scavenging Properties of Calamintha fenzlii Vis. Volatile Oil from Palestine

Many phytochemicals have medicinal properties including anti-inflammatory, antioxidant and cytotoxic activities. The current study aims to estimate and identify the chemical composition of Calamintha fenzlii Vis. leaves volatile oil and to evaluate its cytotoxic, anti-inflammatory and antioxidant properties. The volatile oil (VO) of C. fenzlii leaves was separated using microwave ultrasonic method and the chemical composition was characterized using Gas Chromatography–Mass Spectroscopy method. The anti-inflammatory, antioxidant and cytotoxic activities were determined using a COX inhibitor screening, the DPPH-free radical scavenging and MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-cyrboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) cell viability colorimetric assays, respectively. The chemical constituents of C. fenzlii VO were dominated by oxygenated monoterpenoid (96.91%). The major chemical components of C. fenzlii VO were represented by menthone 68.93% and pulegone 23.1%. The cytotoxicity test results revealed that the 23.22, 11.6, 5.8 and 2.9 mg/ml of C. fenzlii VO treatments induced cell death significantly (p ≤ 0.0001) by 70%, while 1.4 and 0.7 mg/ml induced cell cytotoxicity significantly (p ≤ 0.0001) by approximately 50% and 40%, respectively. The VO showed moderate antioxidant activity with an IC50 value of 15.38 ± 0.81 µg/ml. The COX-1 IC50 value was 0.215 µg/ml, while COX-2 IC50 was 0.241 µg/ml. Our data demonstrate for the first time that the VO of the Palestinian C. fenzlii plant possesses cytotoxic, anti-inflammatory and antioxidants effects. It is a good source of therapeutic active compounds that could have potential applications in the nutraceutical and pharmaceutical industries.

Catalytically active nitrogen-doped porous carbon derived from biowastes for organics removal via peroxymonosulfate activation

In this study, N-doped porous carbons (N–doped PCs) were prepared from various biowastes by thermal annealing method under inert atmosphere and compared. Due to the differences in the textural characteristics and %w/w inorganic content, the choice of biowaste influenced the intrinsic (extent of N doping, % graphitic N) and extrinsic (specific surface area) properties of the resultant N-doped PC. The N–doped PCs were employed to activate peroxymonosulfate (PMS) for bisphenol A (BPA) removal. It was found that the N–doped PCs prepared from spent coffee ground (PC–SC) and saw dust, with higher at.% graphitic N (44–46 at.%) and specific surface area (>400 m2 g−1), performed significantly better (apparent rate constant, kapp = 0.072–0.087 min−1) than those prepared from banana peel, orange peel and dried leaves (kapp < 0.046 min−1). The PC–SC was selected to investigate the effects of catalyst loading and PMS dosage on BPA degradation, and the results indicated that increasing the catalyst loading is 1.5 times more beneficial than increasing the PMS dosage. The reactive oxygen species (ROS) was studied using chemical scavengers and electron paramagnetic resonance spectrometer which indicated that the 1O2 (induced from the interaction between the PC–SC and PMS) was the dominant ROS in the PC–SC/PMS system. The BPA degradation intermediates were also identified using the LC/MS/MS system and the possible BPA degradation pathways are proposed. This study conspicuously shows that biowastes can be used as a sustainable resource to produce PC for application in environmental redox catalysis. However, the right selection of biowaste is crucial to produce high-performance PC for PMS activation.

A new approach for improving microalgal biohydrogen photoproduction based on safe & fast oxygen consumption

Microalgal H2 photoproduction has the potential of being an affordable method for producing this alternative fuel; however extreme sensitivity of hydrogenase enzyme to photosynthetic O2 naturally prevents large-scale H2 production upon illumination. Although a two-phase sulfur deficiency method has been established to deal with this incompatibility, its time and cost demanding, so that this model is not commercially scalable. Despite much research has been conducted, no proper economic alternative for the sulfur deprivation model, with higher or even same productivity and sustainability, has been presented till now. Herein we propose a simple and viable alternative, through introducing a chemical O2 scavenger system, called oxysorb, to algal cultures.Oxysorb, in non-cytotoxic concentrations (including 50 or 100 mM sodium ascorbate and 5 ppm cupric sulfate) for CC124 as well as pgr5 cultures (containing 30 μg/ml chlorophyll) showed a fast, safe and persisted O2 removal capacity, initiating H2 production in the sulfur-containing cultures, either in photoheterotrophic or in autotrophic conditions. Total H2 production obtained with CC124 and pgr5 cultures, containing 100 mM oxysorb, was 2–5.5 times higher than sulfur-deprived ones (measured in a small closed system). This higher H2 productivity in the oxysorb approach was achieved due to anoxia establishment with no ROS production and without impacting PSII activity.

CoMn2O4 Catalyst Prepared Using the Sol-Gel Method for the Activation of Peroxymonosulfate and Degradation of UV Filter 2-Phenylbenzimidazole-5-sulfonic Acid (PBSA).

In this study, a bimetallic oxide catalyst of cobalt-manganese (CoMn2O4) was synthesized using the sol-gel method, and it was then characterized using a variety of techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption isotherms. The obtained novel catalyst, i.e., CoMn2O4, was then used as an activator of peroxymonosulfate (PMS) for the catalytic degradation of a commonly-used UV filter, 2-phenylbenzimidazole-5-sulfonic acid (PBSA) in water. The effects of various factors (e.g., catalyst dosage, PMS concentration, reaction temperature, and pH) in the process were also evaluated. Chemical scavengers and electron paramagnetic resonance (EPR) tests showed that the •OH and SO4•− were the main reactive oxygen species. Furthermore, this study showed that CoMn2O4 is a promising catalyst for activating PMS to degrade the UV filters.

Potential use of real-time dissolved oxygen sensors for oxygen scavenging feedback control

The North Sea oil and gas sector has been operational since the 1970’s and the natural pressure in the reservoirs has been gradually decreasing, which has led to an increased use of water injection to facilitate the required pressure for oil and gas extraction. This involves high pressure and flow of sea water, which is transported through the offshore facilities and due to the corrosive environment, it introduces corrosion. One of the main culprits is dissolved oxygen, which the offshore operators actively remove with vacuum and chemical oxygen scavengers. The vacuum deaerators have a removal limit, after which the dissolved oxygen concentration is decreased using chemical oxygen scavengers most often sodium sulfite, but this adds a cost. The main expense is not the chemical itself, but the side product of the chemical reaction, which leaves sulfates, that feed sulfate reducing bacteria, leading to a production of Hydrogen sulfide which leads to sour corrosion. One solution to reduction in dissolved oxygen and oxygen scavenger is proper control of the facilities. This work investigates the potential for feedback control of the facilities using an online dissolved oxygen instrument, where an experimental study of three commercial dissolved oxygen instruments has been performed, with good results.

New Chemical Insights into the Beneficial Role of Al2O3 Cathode Coatings in Lithium-ion Cells.

Inorganic surface coatings such as Al2O3 are commonly applied on positive electrode materials to improve the cycling stability and lifetime of lithium-ion cells. The beneficial effects are typically attributed to the chemical scavenging of corrosive HF and the physical blockage of electrolyte components from reaching the electrode surface. The present work combines published thermochemistry data with new density functional theory calculations to propose a new mechanism of action: the spontaneous reaction of the LiPF6 electrolyte salt with Al2O3-based surface coatings. Using 19F and 31P solution nuclear magnetic resonance spectroscopy, it is demonstrated that the storage of LiPF6-containing electrolyte solution with Al2O3 produces LiPO2F2, a well-known electrolyte additive. The production of LiPO2F2 is also observed for electrolyte solutions that were stored for 14 days at 40 °C with Al2O3-coated LiNi0.6Mn0.2Co0.2O2 (NMC622) and LiNi0.8Co0.15Al0.05O2 (NCA) materials. Given the beneficial nature of this species for the lifetime and stability of lithium-ion cells, this reaction is here proposed to similarly benefit the performance of cells that use Al2O3-coated cathode materials.

Novel soil remediation technology for simultaneous organic pollutant catalytic degradation and nitrogen supplementation

This study developed a novel remediation technology based on urea-hydrogen peroxide (UHP) activated by a synthesized Fe-impregnated biochar (FB). The technology can simultaneously degrade sulfamethoxazole (SMZ) and supply nitrogen nutrition in cropland soil. Experimental results showed that 97.56% of SMZ was removed in the FB-UHP system within 24 h, whereas 7.12% and 14.65% were removed in the individual application of FB and UHP. Chemical probe and scavenger test results demonstrated that SMZ degradation mainly occurred through oxidation of hydroxyl radicals generated from the activation of UHP by FB. The effects of FB pyrolysis temperature, initial pH, and reaction temperature were investigated. The combination of UHP and FB led to efficient SMZ degradation at a wide pH range of 2–10. Catalytic durability test results showed that FB exhibited good stability even after four uses. A soil column leaching experiment showed that the addition of FB-UHP reduced the SMZ leaching from the soil by 95.06%, increased the nitrogen content on surface soil by approximately 2.5 times, and decreased the nitrogen leaching by 97.57%. Early-stage seedling growth bioassay confirmed that FB-UHP significantly enhanced the SMZ degradation, increased the soil nitrogen content, and improved the lettuce plant growth. Therefore, application of FB-activated UHP is a promising technology for agricultural soil remediation.

Mesoporous SiO2/BiVO4/CuOx nanospheres for Z-scheme, visible light aerobic C–N coupling and dehydrogenation

In light of the growing demand to use renewable energy, we have synthesized a mesoporous bismuth vanadate-copper oxide-silica photocatalyst (SiO2/BiVO4/CuOx) to act as a chromophore in a Z-scheme system. These photocatalysts are intended for effective light harvesting and charge separation in the synthesis of solar chemicals, using air as an environmentally benign oxidant. Full characterization of the SiO2/BiVO4/CuOx was conducted, including X-ray photoelectron spectroscopy (XPS), UV photoelectron spectroscopy (UPS), and scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), which confirm the presence of CuOx at the heterojunction of the nanostructures. The other characterization methods that were employed included powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), elemental mapping, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), N2 sorption experiments, photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS), and photocurrent measurements. Notably, the SiO2/BiVO4/CuOx nanospheres perform seven times faster than bulk BiVO4 and provide higher yields for the oxidative coupling of amines to imines, which are valuable precursors for agrochemicals and active pharmaceutical ingredients. The superior photocatalysis of SiO2/BiVO4/CuOx is attributed to the surface CuOx nanoparticles that increase the average PL lifetime from 2.3 to 4.5ns, which improved the charge separation and decreased the unproductive recombinations of electron–hole pairs. In addition, the photocurrent density of the SiO2/BiVO4/CuOx electrode was about 3.5 times higher than that of SiO2/BiVO4, while lower charge transfer resistance was observed by EIS. Meanwhile, chemical scavenging experiments revealed that holes and superoxide radicals were the main reactive oxygen species in the photocatalytic reaction. The nanospheres also show broad functional group tolerance, good recyclability with high conversions, and high to moderate yields for the oxidatively coupled imine products after eight runs. Thus, we demonstrate that an effective and green approach in artificial photosynthesis is applicable for organic synthesis as well.

Operando Monitoring of F– Formation in Lithium Ion Batteries

Online electrochemical mass spectrometry (OEMS) was applied to study the influence of tris(trimethylsilyl)phosphate (TMSPa) as an additive in 1 M LiPF6 (fluoroethylene carbonate/diethylene carbonate (DEC)) electrolyte on the gas evolution in Li-rich/NCM full cells during cycling. The results indicate that TMSPa neither influences the solid electrolyte interphase (SEI) formation on the anode nor the surface reconstruction on the cathode but acts as a chemical scavenger for HF and LiF. TMSPa thus lowers the electrolyte acidity and suppresses further LiPF6 decomposition, resulting in lower impedance and higher lithium ion battery (LIB) performance. Furthermore, the selective reactivity of TMSPa toward fluorides leads to the formation of Me3SiF enabling the additive to act as a chemical probe and to study HF/LiF formation operando by OEMS. By this methodology, we were able to identify contributions from SEI formation, proton and reactive oxygen formation >4.2 V, cross-talk between the anode and cathode, and t...

Evaluation of Chemical Content and Radical Scavenging Activity of Allium vineale L. Extract and Its Elemental Analysis

Evaluation of Chemical Content and Radical Scavenging Activity of Allium vineale L. Extract and Its Elemental Analysis