Presence Of Carboxylic Acids Research Articles

FTIR and GC-MS analyses of raw materials produced from food wastes used in synthesis of biofilms

The present study carried out the GC-MS and FTIR analyses of raw materials (ripe plantain peel powder, cassava starch, glycerol, acetic acid (vinegar) and eggshell powder) produced from food wastes that are used in production of biofilm. The GC-MS results revealed the presence of pentadecane, bis (2-methylpropyl) ester and benzoic acid, 3-(2-Hydroxy-6-methylphenyl)-4(3H)-quinazolinone). The FTIR analysis revealed 17 peaks for glycerol, 16 peaks for vinegar, 15 peaks for cassava starch, 16 peaks for eggshell; representing the functional groups of ether, ethene, amine, carboxylic acid, nitriles, methylene cyclic ester, primary, secondary and tertiary alcohols common to hydrocarbons. The presence of carboxylic acid was important for enhancing the mechanical and chemical properties of biofilms thereby making them viable alternatives to petroleum-based plastics. Amines contributed to the flexibility, strength, and thermal degradation resistance of biofilms, thus aiding in their biodegradability. In conclusion, the study showed that the raw materials possessed biological activities and their functional groups indicated that the raw materials are safe to humans and the environment.

Low‐Temperature Hydrogenation of Carboxylic Acids to Alcohols over Heterogeneous FeOx‐Modified Ru Catalyst

AbstractSelective hydrogenation of carboxylic acids to alcohols is generally difficult due to the low reactivity of the carboxy group, and the development of effective catalysts enabling high yields of the target alcohols at low reaction temperatures (<473 K) is challenging. Herein, we found that SiO2‐supported FeOx‐modified Ru (Ru−FeOx/SiO2) with the Fe/Ru molar ratio of 0.4 was an effective and reusable heterogeneous catalyst for the hydrogenation of carboxylic acids at a low reaction temperature of 413 K, providing the alcohols in high yields (up to 97 %). The addition of Fe species drastically suppressed the hydrogenolysis of the C−C bond of the alkyl chain to methane, leading to high selectivity to the alcohols. Based on the activity tests and catalyst characterizations, Ru metals were covered by the reduced Fe species, such as Fe metal or Fe2+, and the active site is the interface between the Fe species and Ru metals. From the reactivity comparison of the related compounds, the alcohol is synthesized via the formation of the aldehyde, and the reactivity of the alcohol is very low in the presence of carboxylic acids. As a result, the hydrogenolysis of the produced alcohol is suppressed, leading to the high selectivity of the alcohol.

Fluoride removal using tartaric acid-modified rice husk biochar: Comprehensive batch and column studies

Tartaric Acid-modified Rice Husk biochar (TARH) was evaluated as an efficient and cost-effective adsorbent to eliminate Fluoride (F¯) ions from aqueous solutions. F¯ is a major contaminant in groundwater, and current conventional treatment methods have certain drawbacks in treating higher concentrations of fluoride. The adsorption efficiency of TARH was improved by pre-treating rice husk biochar using tartaric acid (organic acid), which was confirmed by FT-IR measurement, indicating the presence of carboxylic acids, hydroxyl groups, and amine surface functional groups. The study optimized fluoride batch adsorption experiments by considering the parameters affecting adsorption, including pH, contact time, initial concentration, and adsorbent dosage using the Central Composite Design (CCD) from Response Surface Methodology (RSM). Maximum fluoride adsorption of 74.73% was attained by TARH under ideal circumstances (an initial fluoride concentration of 32 mg/L, a pH of 7, 0.25 g/100 mL of adsorbent dosage, and 180 minutes contact duration). The CCD models showed an exceptional R2 value of 0.988 for fluoride adsorption, illustrating their efficacy. Three-dimensional response surface plots were visualized to analyse the effects of control parameters on %adsorption, and statistical analysis supported the validity of the CCD model. Isotherm models and adsorption kinetics were investigated. The adsorption exhibited monolayer adsorption according to the Langmuir isotherm model and a pseudo-second-order rate-limiting phase due to chemisorption. The column adsorption studies were performed for various experimental factors such as influent fluoride concentration (4–16 ppm), influent flow rate (4–8 mL/min), and fixed-bed depth (4–8 cm). The experimental data were examined using the Yoon-Nelson, Thomas, and BDST models, which revealed a substantial correlation between the experimental findings and model predictions. The effectiveness of TARH was examined by regeneration study and case study was performed to evaluate the fluoride removal from actual water samples.

Multifunctional Iron–Porphyrin Additive for Hole‐Transporting Layer Toward Efficient and Stable Perovskite Solar Cells

Spiro‐OMeTAD, as a crucial component of hole‐transporting layer (HTL), exhibits limited mobility and conductivity, and the lithium bis‐trifluoromethanesulfonimide dopant is sensitive to water vapor, which imposes restrictions on the photovoltaic properties of perovskite solar cells (PSCs). Herein, the iron–porphyrin (FePP) is introduced into Spiro‐OMeTAD solution as additive, which facilitates the oxidation process of Spiro‐OMeTAD, leading to the enhancement of hole mobility and hole extraction and transport. Besides, the surface Pb2+ defects of perovskite film are cured by the presence of carboxylic acids (COOH) in FePP. As a result, the photovoltaic properties of PSCs with FePP additive have been improved with a power conversion efficiency (PCE) of 21.58%. Moreover, FePP can further anchor Li+ ions in HTL to prevent it from being invaded by water vapor. Dramatically, the degradation of unencapsulated devices with FePP is suppressed significantly, which retains 82.0% of its original PCE under 10–20% relative humidity (RH) after 7100 h and maintains about 79.6% of its original PCE under 50–60% RH after 1000 h. Thus, this study shows that the design and development of multifunctional HTL additives holds great potential for achieving highly efficient and durable PSCs.

Use of graphitic carbon nitrides as solar-light-driven photocatalysts for the reduction of p-nitrobenzoic acid

The use of graphitic carbon nitrides (g-C3N4) as photocatalysts for the reduction of p-nitrobenzoic acid (PNBA) under simulated sunlight has been investigated. The photocatalysts were synthesized through the thermal polymerization of melamine and urea. The effects of the g-C3N4 precursor employed in the synthesis, the thermal exfoliation treatment, the addition of sacrificial agents, and the pH conditions were evaluated. It was found that the presence of carboxylic acids as sacrificial electron donors was required to attain the photocatalytic reduction of PNBA, while amines or alcohols did not lead to any activity for this purpose. Furthermore, it was observed that the precursor used in the synthesis of graphitic carbon nitride had a slight influence on the photocatalytic activity, whereas the thermal treatment of the bulk g-C3N4 materials exhibited a favourable effect. The best results were obtained upon addition of oxalic acid at pH = 3 using the carbon nitride exfoliated materials, achieving in these conditions the complete removal of PNBA after ca. 60 min of irradiation. Time resolved profiles of p-aminobenzoic acid (PABA) agree with an initial reduction of PNBA to form this compound, followed by oxidation of PABA by reactive oxygen species formed in the reaction medium.

Palladium Catalysis: Dependence of the Efficiency of C-N Bond Formation on Carboxylate Ligand and Metal Carboxylate or Carboxylic Acid Additive.

The Pd-catalyzed inter- and intramolecular reactions of nitrogen compounds are often carried out with palladium carboxylates, sometimes in the presence of carboxylic acids or alkali metal carboxylates. This Mini-Review highlights the dependence of the reaction efficiency on the nature of the ligand and the carboxylate additives. The proposed reaction mechanisms are presented with, as far as possible, personal comments.

Per- and polyfluoroalkyl substances inhibit human and rat 17β-hydroxysteroid dehydrogenase 1: Quantitative structure-activity relationship and molecular docking analysis

Per- and polyfluoroalkyl (PFAS) substances are enduring industrial materials. 17β-Hydroxysteroid dehydrogenase isoform 1 (17β-HSD1) is an estrogen metabolizing enzyme, which transforms estrone into estradiol in human placenta and rat ovary. Whether PFAS inhibit 17β-HSD1 and what the structure-activity relationship (SAR) remains unexplored. We screened 18 PFAS for inhibiting human and rat 17β-HSD1 in microsomes and studied their SAR and mode of action(MOA). Of the 11 perfluorocarboxylic acids (PFCAs), C8-C14 PFCAs at a concentration of 100 μM substantially inhibited human 17β-HSD1, with order of C11 (half-maximal inhibition concentration, IC50, 8.94 μM) > C10 (10.52 μM) > C12 (14.90 μM) > C13 (30.97 μM) > C9 (43.20 μM) > C14 (44.83 μM) > C8 (73.38 μM) > others. Of the 7 per- and poly-fluorosulfonic acids (PFSAs), the potency was C8S (IC50, 14.93 μM) > C7S (80.70 μM) > C6S (177.80 μM) > others. Of the PFCAs, C8-C14 PFCAs at 100 μM markedly reduced rat 17β-HSD1 activity, with order of C11 (IC50, 9.11 μM) > C12 (14.30 μM) > C10 (18.24 μM) > C13 (25.61 μM) > C9 (67.96 μM) > C8 (204.39 μM) > others. Of the PFSAs, the potency was C8S (IC50, 37.19 μM) > C7S (49.38 μM) > others. In contrast to PFOS (C6S), the partially fluorinated compound 6:2 FTS with an equivalent number of carbon atoms demonstrated no inhibition of human and rat 17β-HSD1 activity at a concentration of 100 μM. The inhibition of human and rat enzymes by PFAS followed a V-shaped trend from C4 to C14, with a nadir at C11. Moreover, human 17β-HSD1 was more sensitive than rat enzyme. PFAS inhibited human and rat 17β-HSD1 in a mixed mode. Docking analysis revealed that they bind to the NADPH and steroid binding site of both 17β-HSD1 enzymes. The 3D quantitative SAR (3D-QSAR) showed that hydrophobic region, hydrogen bond acceptor and donor are key factors in binding to 17β-HSD1 active sites. In conclusion, PFAS exhibit inhibitory effects on human and rat 17β-HSD1 depending on factors such as carbon chain length, degree of fluorination, and the presence of carboxylic acid or sulfonic acid groups, with a notable V-shaped shift observed at C11.

COMPARATIVE CHARACTERISTICS OF THE LOW MOLECULAR WEIGHT METABOLOME OF MACROPHYTES IN DIFFERENT WATER BODIES IN THE WATER AREA OF THE KANDALAKSHA BAY OF THE WHITE SEA

The Kandalaksha Bay of the White Sea underwent a first-of-its-kind comparative examination of the composition of essential oils of structure-forming macrophytes growing in freshwater and saltwater habitats. The essential oils of the aquatic macrophytes Nuphar lutea (L.) Sm., Ruppia maritima L., Zostera marina L., Fucus vesiculosus L., and Ascophyllum nodosum (L.) Le Jolis were obtained by steam hydrodistillation using the Clevenger apparatus from dried plants. Gas chromatography-mass spectrometry (GC/MS complex SHIMADZU GCMS-QP2010 Ultra) was used to analyze the qualitative and quantitative composition of LMWOCs (low molecular weight organic compounds). The component composition of the low molecular weight metabolome (LM) of macrophytes was shown to depend on both plant species specificity and plant habitat conditions (hydrological features, trophic state). More LMWOCs are found in plants from freshwater habitats than from marine ones. The investigated plants had only a few major compounds, ranging in number from 4 to 14. They accounted for between 70 and 83% of the overall concentration of all compounds in freshwater N. lutea and between 82 and 95% of the total concentration of LMWOCs in marine macrophytes. The most significant (% of the total essential oil) main components in macrophytes were carboxylic acids, specifically hexadecanoic, tetradecanoic, linoleic, and linolenic. The outcomes gained proved that the presence of carboxylic acids is a sign of a healthy macrophyte environment. The composition of LM of plants from northern habitats (marine and freshwater) contains high total concentrations of LMWOCs (including valuable ones from the perspective of economic use), making it possible to consider them as a valuable natural renewable resource for obtaining raw materials for various economic uses.

Хімічні властивості та характеристики поверхневої активності гумінової кислоти з бурого вугілля

The article is devoted to the study of some specific physicochemical properties of humic acids, which are attracting increasing attention due to their potential applications. The unique structural composition, which includes both hydrophilic and hydrophobic sites, makes these materials a versatile agent in various technological processes. It has been shown that humic acid solutions have the properties of surfactants and can serve as a natural alternative to surfactants. The paper presents the results of studies of a sample of humic acid obtained from lignite. Infrared spectroscopy has revealed signs of the aromatic structure of humic acid, the presence of phenolic and other functional groups, such as hydroxyl and nitrile. The presence of carboxylic acids, esters, and complex esters was established. The complex and heterogeneous nature of humic acids has been confirmed, which makes them promising for use as surfactants. No clear evidence of the presence of -NH₂ groups was found in the IR spectrum. This suggests that lignite humic acids generally correspond to the structural formula reported in the literature. The potentiometric titration of the lignite humic acid sample made it possible to determine the dissociation constants of functional groups. The obtained values are close to the calculated dissociation constants of carboxyl groups for the model molecule of lignite humic acid. The analysis of the calculated properties of humic acid based on various structural models showed that lignite is a promising raw material for the production of humic acids with certain surface-active properties. Compared to other structures, humic acid from lignite is more hydrophobic and less soluble in water, which indicates the prospects of its use as a surfactant with better interaction with the oil phase. Keywords: humic acids, lignite, surfactant, infrared spectroscopy, composition, functional groupsб structural model. Corresponding author: Bannikov L.P., e-mail: ukhinbannikov@gmail.com

Geochemical characteristics of bitumen seeps from the pila spi and bekhme formations: insights from fourier transform infrared spectroscopy and trace metals

A collection of 9 bitumen samples from Pila Spi Formation (Middle–Late Eocene) and Bekhme Formation (Late Campanian – Early Maastrichtian) were subjected for geochemical analysis of Fourier Transform Infrared Spectroscopy (FTIR) and trace metals. The results of FTIR analysis reveal the different intensity for the samples of both formations. The broad band centered around 1500–2000 cm−1 which is indicative of the presence of C=O Stretch band and C=C Stretch might be assigned to a carbonyl stretching. The Frequency of the bitumen - derived asphaltene samples of the Gulley Keer indicate the presence of Carboxylic acids, while no band appeared for Bekhme samples which indicates the absence of Carboxylic acid. The peak absorption bands of the analyzed samples at 1452, 2802, 2905, and 3050cm−1 can be due to C-H bending, Alkyl C-H stretch, and Alkenyl C-H stretching respectively. Based on the Aromatic, Aliphatic and long chain indices as well as the ratio of Nickle to Vanadium, two different sources of the organic matter are suggested for analyzed samples. Moreover, all samples from both sections are believed to be from a marine euxinic carbonate environment with the exception of one sample that seems to be marine anoxic- shale- carbonate.

Extraction and characterisation of Cerbera odollam seed oil as a potential plant-based corrosion inhibitor

Certain types of commercial corrosion inhibitors consist of a specific, tannic acid-derived compounds. Tannin compounds are antioxidants and widely found in many species of plants. In this works, oil from the seeds of the poisonous fruit, sea mango (Cerbera odollam), was seen as a potential candidate for a natural corrosion inhibitor. The oil was extracted via solvent extraction using a Soxhlet extractor for 6 hours at varying temperatures between 100 to 200 °C. The solvents used were hexane and methanol. Structural characterisation of active corrosion inhibition compounds in the oil samples was analysed using Fourier Transform infrared spectroscopy (FTIR) and Gas Chromatography Mass Spectroscopy (GC-MS). Thermogravimetric analysis (TGA) was done to determine the seed oil’s thermal stability and decomposition temperature. The highest extraction yield was found using hexane as the solvent at 150 °C. TGA results indicated that the oil was stable at temperatures below 200 °C. The presence of carboxylic acids, as evidenced by the FTIR and GC-MS analysis, indicated possible corrosioninhibitive properties of the extracts. Phytochemical screening tests revealed that tannin, saponin, phenol, and steroid were present in the sea mango seed oil while flavonoid was undetected

Palladium Catalysis: Dependence of the Efficiency of C−C Bond Formation on Carboxylate Ligand and Alkali Metal Carboxylate or Carboxylic Acid Additive. Part A: the C(sp2)−C(sp2), C(sp2)−C(sp3) and C(sp3)−C(sp3) Bonds

AbstractA variety of Pd‐catalyzed reactions are carried out with palladium carboxylates in the presence of carboxylic acids and/or alkali metal carboxylates. This review is Part A of three reviews highlighting the dependence of the efficiency of the formation of the different C−C bonds on the nature of the carboxylate unit. Part A concerns inter‐ and intramolecular reactions leading to the formation of a C(sp2)−C(sp2), C(sp2)−C(sp3) or C(sp3)−C(sp3) bond. The variety of procedures and additives is presented as well as the reaction mechanisms with, as far as possible, personal comments.

Development of a Small Molecule Hydrogen Evolution Catalyst

Based on prior work done by Diane K. Smith et al on redox responsive 3 hydrogen bond array dimers, a fundamental investigation on the nature of proton coupled electron transfer (PCET) was done by surveying a series of new electroactive “host” H-bond dimers. In these dimers, electron transfer should induce proton transfer across a H-bond, increasing the overall strength of hydrogen bond binding the “guest” and “host”. In particular, the goal was to investigate how electrochemical behavior and binding strength changes as the relative acidity of the electro-inactive “guest” changes in a 2-hydrogen bond array. For this task, amido pyridinium derivatives will be used as the redox active "hosts" and a series of different carboxylic acid, 2-hydroxypyridine, and amide derivatives as the electro-inactive "guests". Unexpectedly, in the presence of carboxylic acids, the amido pyridinium acts as a hydrogen evolution catalyst. During guest host cyclic voltammogram (CV) titrations, there was a large anodic shift of 500 mV and a catalytic increase in current, which is characteristic of an EC mechanism (figure 2). A series of investigations into this mechanism were done following the initial discovery, including scan rate and concentration dependence CV’s, spectro-electrochemical studies, bulk electrolysis, DEMS, and DFT calculations. These studies allowed us to propose the mechanism below (figure 1) for hydrogen evolution. This presentation will detail our efforts to characterize this hydrogen evolution catalyst, the relevance of small molecule hydrogen evolution catalyst, and how we intend to modify it for synthetic purposes.Figure 1 (left image): Reduction of pyridinium amide with and without guests and proposed mechanism of hydrogen evolutionFigure 2 (right image): CV of pyridinium amide in the presence of dodecanoic acid Figure 1

Use of Some Metalferrites as Catalyst in Benzil-Benzilicacid Rearrangement Reaction

Magnesium ferrite was used to catalyse the Benzil-Benzilic acid rearrangement reaction of 1,2-rearrangement of 1,2-diketones to α-hydroxy carboxylic acids in presence of a base. Magnesium ferrite was prepared by hydrothermal process. It was characterized by Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction Spectroscopy (XRD), and Energy Dispersive X-Ray Spectroscopy (EDX). The crystalline size of magnesium ferrite was found to have 82.47nm and these are irregular in shape. It was found that the yield of the product (benzilic acid) in the presence of Mg ferrite was 81.6%, which is almost 2.3 times the yield obtained in the absence of catalyst. A comparative study was made with different metal ferrites as catalyst and it was found that the activity of metal ferrites followed the order: MgFe2O4 > Cu Fe2O4 > Ni Fe2O4 > Co Fe2O4 > Zn Fe2O4

Carboxylic acids and light interact to affect nanoceria stability and dissolution in acidic aqueous environments.

Cerium atoms on the surfaces of nanoceria (i.e., cerium oxide in the form of nanoparticles) can store or release oxygen, cycling between Ce3+ and Ce4+; therefore, they can cause or relieve oxidative stress within living systems. Nanoceria dissolution occurs in acidic environments. Nanoceria stabilization is a known problem even during its synthesis; in fact, a carboxylic acid, namely citric acid, is used in many synthesis protocols. Citric acid adsorbs onto nanoceria surfaces, limiting particle formation and creating stable dispersions with extended shelf life. To better understand factors influencing the fate of nanoceria, its dissolution and stabilization have been previously studied in vitro using acidic aqueous environments. Nanoceria agglomerated in the presence of some carboxylic acids over 30 weeks, and degraded in others, at pH 4.5 (i.e., the pH value in phagolysosomes). Plants release carboxylic acids, and cerium carboxylates are found in underground and aerial plant parts. To further test nanoceria stability, suspensions were exposed to light and dark conditions, simulating plant environments and biological systems. Light induced nanoceria agglomeration in the presence of some carboxylic acids. Nanoceria agglomeration did not occur in the dark in the presence of most carboxylic acids. Light initiates free radicals generated by ceria nanoparticles. Nanoceria completely dissolved in the presence of citric, malic, and isocitric acid when exposed to light, attributed to nanoceria dissolution, release of Ce3+ ions, and formation of cerium coordination complexes on the ceria nanoparticle surface that inhibit agglomeration. Key functional groups of carboxylic acids that prevented nanoceria agglomeration were identified. A long carbon chain backbone containing a carboxylic acid group geminal to a hydroxy group in addition to a second carboxylic acid group may optimally complex with nanoceria. The results provide mechanistic insight into the role of carboxylic acids in nanoceria dissolution and its fate in soils, plants, and biological systems.

Reactive Polymer as Artificial Solid Electrolyte Interface for Stable Lithium Metal Batteries

AbstractLithium (Li) metal anodes have the highest theoretical capacity and lowest electrochemical potential making them ideal for Li metal batteries (LMBs). However, Li dendrite formation on the anode impedes the proper discharge capacity and practical cycle life of LMBs, particularly in carbonate electrolytes. Herein, we developed a reactive alternative polymer named P(St‐MaI) containing carboxylic acid and cyclic ether moieties which would in situ form artificial polymeric solid electrolyte interface (SEI) with Li. This SEI can accommodate volume changes and maintain good interfacial contact. The presence of carboxylic acid and cyclic ether pendant groups greatly contribute to the induction of uniform Li ion deposition. In addition, the presence of benzyl rings makes the polymer have a certain mechanical strength and plays a key role in inhibiting the growth of Li dendrites. As a result, the symmetric Li||Li cell with P(St‐MaI)@Li layer can stably cycle for over 900 h under 1 mA cm−2 without polarization voltage increasing, while their Li||LiFePO4 full batteries maintain high capacity retention of 96 % after 930 cycles at 1C in carbonate electrolytes. The innovative strategy of artificial SEI is broadly applicable in designing new materials to inhibit Li dendrite growth on Li metal anodes.

Reactive Polymer as Artificial Solid Electrolyte Interface for Stable Lithium Metal Batteries.

Lithium (Li)metal anodes have the highest theoretical capacity and lowest electrochemical potential making them ideal for Li metal batteries (LMBs). However, Li dendrite formation on the anode impedes the proper discharge capacity and practical cycle life of LMBs, particularly in carbonate electrolytes.Herein, we developed a reactive alternative polymer namedP(St-MaI) containing carboxylic acid and cyclic ether moieties which would in-situform artificial polymeric solid electrolyte interface (SEI) with Li. This SEI can accommodate volume changes and maintain good interfacial contact. The presence of carboxylic acid and cyclic ether pendant groups greatly contribute to the induction of uniform Li ion deposition. In addition, the presence of benzyl rings makes the polymer have a certain mechanical strength and plays a key role in inhibiting the growth of Lidendrites. As a result, the symmetric Li||Li cell with P(St-MaI)@Li layer can stably cycle for over 900 h under 1 mA cm-2without polarization voltage increasing, while their Li||LiFePO4full batteries maintain high capacity retention of 96% after 930 cycles at 1C in carbonate electrolytes.The innovative strategy of artificialSEI is broadly applicable in designing new materials to inhibit Li dendrite growth on Li metal anodes.

Ligand-Mediated Control of the Surface Oxidation States of Copper Nanoparticles Produced by Laser Ablation

We report on studies that demonstrate how the chemical composition of the surface of copper nanoparticles (CuNPs) - in terms of percentage copper(I/II) oxides - can be varied by the presence of N-donor ligands during their formation via laser ablation. Changing the chemical composition thus allows systematic tuning of the surface plasmon resonance (SPR) transition. The trialed ligands include pyridines, tetrazoles, and alkylated tetrazoles. CuNPs formed in the presence of pyridines, and alkylated tetrazoles exhibit a SPR transition only slightly blue shifted with respect to CuNPs formed in the absence of any ligand. On the other hand, the presence of tetrazoles results in CuNPs characterized by a significant blue shift of the order of 50-70 nm. By comparing these data also with the SPR of CuNPs formed in the presence of carboxylic acids and hydrazine, this work demonstrates that the blue shift in the SPR is due to tetrazolate anions providing a reducing environment to the nascent CuNPs, thus preventing the formation of copper(II) oxides. This conclusion is further supported by the fact that both AFM and TEM data indicate only small variations in the size of the nanoparticles, which is not enough to justify a 50-70 nm blue-shift of the SPR transition. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) studies further confirm the absence of Cu(II)-containing CuNPs when prepared in the presence of tetrazolate anions.

Interphase formation with carboxylic acids as slurry additives for Si electrodes in Li-ion batteries. Part 1: performance and gas evolution

Rendering the solid electrolyte interphase and the inter-particle connections more resilient to volume changes of the active material is a key challenge for silicon electrodes. The slurry preparation in a buffered aqueous solution offers a strategy to increase the cycle life and capacity retention of silicon electrodes considerably. So far, studies have mostly been focused on a citrate buffer at pH = 3, and therefore, in this study a series of carboxylic acids is examined as potential buffers for slurry preparation in order to assess which chemical and physical properties of carboxylic acids are decisive for maximizing the capacity retention for Si as active material. In addition, the cycling stability of buffer-containing electrodes was tested in dependence of the buffer content. The results were complemented by analysis of the gas evolution using online electrochemical mass spectrometry in order to understand the SEI layer formation in presence of carboxylic acids and effect of high proton concentration.

Fenton-like photocatalyzed degradation of dibutyl phthalate with goethite and carboxylic acids

Detailed investigation of photocatalyzed degradation of dibutyl phthalate (DBP), an endocrine disrupter, in the presence of α-FeOOH (goethite) and different carboxylic acids is the focus of this study. To get a better insight into the efficiency of the degradation, the influence of different parameters, such as concentration of total Fe and Fe(II), dissolved oxygen, DBP concentration, pH and salinity is investigated. The reaction mechanism consists of several interrelationship steps. The first step is the chemical reaction of carboxylic acid groups of the organic acids with hydroxyl groups of the α-FeOOH and a charge transfer upon illumination generating Fe(II). The second step is the release of Fe(II) into the solution followed by H2O2 oxidation to form highly photoactive hydroxyl complex of iron(III) and ˙OH. Simultaneously, the superoxide radical O2˙− and hydroperoxyl radical is formed in acidic solutions in presence of carboxylic acids as well. This mechanism explains the genesis of different reactive species oxidizing DBP. From the variety of the studied carboxylic acids (oxalic, citric, salicylic, pyruvic, maleic, and fumaric), oxalic acid is the best Fe-ligand for the photoreductive dissolution of goethite. Concentrations of the total amount of Fe and its dissociated forms Fe(II) as well as oxygen and hydroxyl radicals play a fundamental role in efficiency of DBP degradation. The photodegradation of DBP with goethite and the use of suitable carboxylic acids under optimized reaction conditions could be an efficient process for decontamination of polluted waters.