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A simple and green visual method for determination of Total Acid Number (TAN) is proposed for analysis of different engine fuels, especially biodiesel, its raw materials and blends with petroleum fuels. Two 4-hydroxystyryl N-octylpyridinium bromides dyes: 4-[-2-(4-hydroxy-3-methoxyphenyl) ethenyl]-1-octylpyridinium bromide and 4-[-2-(4-hydroxy-3,5-dymethylphenyl) ethenyl]-1-octylpyridinium bromide were used as indicators. Determination of TAN in butanol medium in the presence of 10−5–10−4 mol/L of the indicator have shown a high color contrast. Well-marked transition from pale yellow to blue/violet merocyanine form provides for determination of more than 0.01 mg/g of free fatty acids and more strong acids with RSD 1–5%. For the vast majority of samples, the value of the acid numbers found by the proposed method is in good agreement with the data obtained according to the standard ASTM D664-11 method. The optimal conditions for analysis of TAN in diesel samples were found. Particular attention is paid to the FTIR-spectrometric determination of biodiesel content in commercial diesel fuel samples. The content of biodiesel with a characteristic peak in the region that is responsible for the carbonyl group (1730–1750 cm−1) can be seen on the IR spectra.

The synthesis of a new hexabromotellurate of triazole ring-containing amino acid is described. XRD, NMR and DFT analysis of the structure of protonated [(5-amino-4-phenyl-4H-1,2,4-triazol-3-yl)sulfanyl]acetic acid testifies the protonation of the first nitrogen atom of the triazole ring. Hirshfeld surface analysis identifies numerous intermolecular interactions in the newly synthesized organic-inorganic hybrid hexabromotellurate. The DFT based comprehensive analysis of the structures of possible conformers also testifies the higher thermodynamic stability of the 1-protonated triazole cation, whereas the starting [(5-amino-4-phenyl-4H-1,2,4-triazol-3-yl)sulfanyl]acetic acid exists in solution in neutral form with the intermolecular hydrogen bond between the carboxylic acid OH group and the second nitrogen of the triazole ring. The experimentally observed NMR upfield shift of the signal of the exocyclic amino group was studied via GIAO computations and was explained through the analysis of the HOMOs of the neutral and protonated forms of the triazole compound.

A new cetylpyridinium picrate ionic liquid has been synthesized and characterized by differential thermal analysis, XRD, FT-IR, and NMR (1H and 13C) spectroscopy. Differential thermal analysis indicates the congruent melting of cetylpyridinium picrate and a temperature range of liquid state is 47–267 °C. A solid form of the sample characterized with a polymorphic transformation at 37 °C, which was confirmed via the XRD analysis. The interionic charge-transfer interactions, namely the charge transfer from the picrate anion to the cetylpyridinium cation, were detected by comparison of NMR spectra of DMSO solutions of the ionic liquid and cetylpyridinium chloride. The H–NMR chemical shifts’ differences of about 0.2 ppm and 0.1 ppm were observed in the case of the o-protons and the α-methylene group protons, respectively. Additionally, the charge-transfering between the attracted ions was confirmed by DFT calculations. Based on the solid state NMR technique, the higher ions mobility was suggested for the solid sample of the ionic liquid in comparison to the solid cetylpyridinium chloride monohydrate. Moreover, the association constants KA at 22, 30, 40, and 50 °C, obtained from the electrical conductivity measurements, clearly testifies much lower dissociation in the case of picrate. The KA values of cetylpyridinium picrate and chloride in DMSO medium at 22 °C equal 748.7 L/mol and 525.0 L/mol, respectively. The performed DFT computations of the reduced density gradient function in four proposed structures of the new ionic liquid cation-anion pair identifies the presence of weak non-covalent C H•••O N interactions between cetyl chain hydrogen atoms and nitro groups of picrate was explored through DFT calculations and analysis of the RDG function.

The present study is dedicated to development of improved method for determination of trace amounts of fluorides in natural waters which is based on the interaction of fluorides with ion associate (IA) of Al(III), salicylic aldehyde acylhydrazones (benzhydrazone (SABH) and 4-picolinhydrazone (SAPH)) and polymethine dye Astra Phloxine FF (AP). Comparison of analytical forms [Al(SABH)2]⋅AP and [Al(SAPH)2]⋅AP showed that the analytical system Al(III)-SAPH-AP is more effective, namely, a higher level of preconcentration of the analytical form is ensured by and extraction equilibrium is achieved faster. Based on the study, we propose a new, fast, simple, reliable, sensitive, and accurate method of the indirect UV–Vis-spectrophotometric determination of fluorides grounded on the interaction of fluorides with IA of Al(III), SAPH and AP with the utilization of vortex-assisted liquid-liquid microextraction (VALLME). The method is based on the discoloration of the microextract of IA of Al(III), SAPH and AP (Al-SAPH-AP) in presence of fluoride ions due to the formation of fluoride complexes of aluminum with higher stability. The effect of various factors has been studied. The optimal conditions of the UV–Vis-spectrophotometric determination of fluorides were defined as: pH 7.0–10.0, 1.0⋅10−6 mol⋅L−1 Al(III); 4.0⋅10−5 mol⋅L−1 SAPH; 1.0⋅10−6 mol⋅L−1 AP; λ = 560 nm. VALLME have been carried out in 250 μL of CCl4 at 20:1 vol ratios of aqueous and organic phases, with vortexing at 3000 rpm for 15 s followed by centrifugation at 2000 rpm for 2 min. The determination of fluorides is feasible in the presence of various interferences. The calibration curve shows the linear dependence in the range of 0.3–114 μg⋅L−1 of the fluorides concentration (R2 = 0.993) with the limit of detection of 0.086 μg⋅L−1 and the limit of determination of 0.284 μg⋅L−1. The accuracy of the proposed protocol of fluorides determination was verified towards a reference method on the samples of natural rivers waters (RSD 2.6–3.1%, recovery 98.3–101.4%).

We propose a facile route for the surface functionalization of activated carbons (ACs), which are used as a solid matrix with good mechanical properties, but have the deficiency of the active surface sites to form the AC-based solid acids (ACSA) by the direct chemical method. The route includes three stages that provide active and stable strong acidic surface layer. The surface chemistry changes at the functionalization stages were controlled with thermogravimetric (TG) and thermoprogrammed desorption (TPD) methods. N2 adsorption-desorption studies demonstrate the conservation of the AC meso- and macroporosity. According to XPS, DRIFT, TG-TPD-IR, and potential titrimetry data, the ACSA obtained by sulfonation of the styrene functionalized AC are contained up to 1.1 mmol g−1 of the strong acidic SO3H groups. The surface functionalization, as reported route, gives no prominent structural changes, from XRD data, the large macropores and transport channels maintain, from SEM data, and MicroRaman spectra show no defecting of the initial carbon matrix. The obtained ACSA are effective catalysts for the dehydration of 2-propanol and combine the high efficiency of work with the increased thermal stability of the surface layer. The thermoresistance of the ACSA significantly exceeds that of the Amberlyst-15 WET catalyst.

A few different theoretical methods for assigning the partial atomic charges were benchmarked for calculation of the hydrophilic/lipophilic index (HLI). The coefficients were selected to produce the best correlation of the HLI values with the experimental octanol-water partition. Different parameters were checked in calculations of partial charges to get the best performance of the HLI values obtained. Thus, four partitioning schemes (Coulson, Mulliken, Merz-Kollman, Ford-Wang) were benchmarked for calculations of atomic charges with six semiempirical methods (AM1, PM3, RM1, PM6, PM6-D3H4, PM7). Moreover, five distinct types of partial atomic charges (Mulliken, Hirshfeld, Löwdin, CHELPG, NPA), obtained at the Hartree-Fock and DFT levels of theory with three basis sets, were tested for their ability to produce the HLI values with the best correlation to experimental logP coefficients of 50 mono-charged organic anions. In the case of the semiempirical methods, the best correlation between the HLI and logP values (the correlation coefficient r = 0.9216) was obtained with the AM1 Ford-Wang parametric electrostatic potential charges. The Mulliken and Coulson charges calculated with the PM7 method can be used as an alternative to AM1, with the r values of 0.9107 and 0.8984, respectively. In the case of the DFT, the PBE/def2-TZVP natural population analysis charges produce the best correlation (r = 0.9220). Nevertheless, in spite of a marginally lower performance (r = 0.9159), the NPA charges computed at the PBE/def2-SVP level are more robust and can be regarded as the optimum choice for calculating the HLI values. Graphical abstract The hydrophilic/lipophilic index (HLI).

In this study, natural microporous activated carbon (AC) was barothermal treated with hydrogen peroxide vapors at 553 and 623 K. Nitrogen adsorption proves the formation of micro-mesoporous ACs with S ext of 350 m2 g−1 at S BET = 1250 m2 g−1. The texture of ACs drastically depends on the oxidant concentration and temperature at the treatment. Thermal behavior of the initial and obtained ACs was examined in an argon dynamic atmosphere with thermogravimetric (TG) analysis. Thermoprogrammed desorption coupled with infrared spectroscopy (TPD-IR) and MS spectroscopy monitoring of evolved gases were used to disclose the regularities of the surface groups thermodestruction. TG-TPD-IR shows that the barothermal oxidation suppresses the rich surface chemistry of the initial AC, of 1 mmol g−1 of oxygen-containing functional groups. The oxidation causes selective functionalization of the AC surface with 2.6–4.3 mmol g−1 of non-acidic quinolic (Qu) groups. The CO/CO2 release from the barothermal treated ACs has reached the Boudouard equilibrium at temperatures above 930 K. Thermal stability of two different surface centers, single spaced and vicinal Qu groups, is assigned as a factor responsible for issues related to the thermodesorption of CO/CO2 and the passage of the reversed reaction of Boudouard–Bell.

BACKGROUND Anthocyanins, compounds that represent the major group of flavonoids in berries, are one of the most powerful natural antioxidants. The aim of this study was to evaluate biological activities and comparison of anthocyanin-rich extracts prepared from chokeberry (Aronia melanocarpa), elderberry (Sambucus nigra), bilberry (Vaccinium myrtillus) and blueberry (V. corymbosum) on the porcine intestinal epithelial IPEC-1 cell line. RESULTS The IC50 values calculated in the antioxidant cell-based dichlorofluorescein assay (DCF assay) were 1.129 mg L−1 for chokeberry, 1.081 mg L−1 for elderberry, 2.561 mg L−1 for bilberry and 2.965 mg L−1 for blueberry, respectively. We found a significant negative correlation (P < 0.001) between cyanidin glycosides content and IC50 values. Moreover, extracts rich in cyanidin glycosides stimulated proliferation of IPEC-1 cells and did not have cytotoxic effect on cells at an equivalent in vivo concentration. CONCLUSIONS We found that the chokeberry and elderberry extracts rich in cyanidin glycosides possess better antioxidant and anticytotoxic activities in comparison to blueberry or bilberry extracts with complex anthocyanin profiles. © 2015 Society of Chemical Industry

One of the major goals when creating new energy systems is to provide clean and affordable energy. Currently, there is an excessive increase in the cost of fossil fuels and natural gas because of increased energy consumption and the inability to meet demand. That is why it is necessary to find reliable renewable energy sources and processes that will produce energy materials without toxic by-products in order to preserve the environment and to ensuring sustainable development and a strong economy. From environmental safety reasons, this need has led to the development of the catalytic synthesis of energetic materials from greenhouse gases; in particular, this paper proposes an efficient approach to producing methane by hydrogenation of carbon dioxide over Co–Ni catalysts.

Large transition-metal contents add desirable physical properties, such as redox reactivity, magnetism, and electric or ionic conductivity to micas and make them interesting for a variety of materials-science applications. A Mn- and F-rich tainiolite mica, ${\rm{Cs}}\left( {{\rm{Mn}}_2^{2 + }{\rm{Li}}} \right){\rm{S}}{{\rm{i}}_4}{{\rm{O}}_{10}}{{\rm{F}}_2}$ , was synthesized by a high-temperature melt-synthesis technique. Subsequent annealing for 10 days led to a single-phase and coarsegrained material. Single-crystal X-ray diffraction studies were performed and characteristic geometric parameters were compared to the analogous ferrous compound, synthetic Fe-rich tainiolite, ${\rm{Cs}}\left( {{\rm{Fe}}_2^{2 + }{\rm{Li}}} \right){\rm{S}}{{\rm{i}}_4}{{\rm{O}}_{10}}{{\rm{F}}_2}$ . Both tainiolite structures are outside the compositional stability limits for the 2:1 layer structure, and incorporating the relatively large cation Mn2+ requires significant structural adjustments in both the octahedral and tetrahedral sheets. As expected, increasing the ionic radius of the octahedral cation from 0.78 A (VIFe2+) to 0.83 A (VIMn2+) reduces the octahedral flattening angle from = 57.05° to = 56.4°, the smallest value ever observed for a tetrasilicic mica. However, even this small value is insufficient to match the lateral sizes of the tetrahedral and octahedral sheets and, in addition, unusual structural adjustments in the tetrahedral sheet are required. The average tetrahedral bond length is much greater (1.643 A) than the average value observed for tetrasilicic micas (1.607 A,) and a significant difference between the apical (1.605 A) and the basal bond lengths (1.656 A) and an enlarged basal flattening angle (τbasal = 106.29°) are noted. These parameters indicate: (1) that the 2:1 layer might be more flexible than previously thought, to allow matching of the lateral dimensions of the tetrahedral and octahedral sheets; and (2) that many other compositions that appear interesting from a materials-science point of view might be accessible.

Ferrous tainiolite, Cs[Fe2Li]o[Si4]tO10F2, has been synthesized from the melt in gastight molybdenum crucibles. The electric conductivity has been measured by impedance spectroscopy. As compared to natural micas, which are insulators, good conductivity is observed. The layered silicate can be further modified by ion exchange, which makes it a promising host structure for sensor materials. The estimated activation energy is as low as 0.79 eV. Upon Ba2+ exchange for Cs+, structural Fe2+ is partially oxidized (33%), and the layer charge is reduced significantly, resulting in a coarse-grained but swollen (monolayer hydrate) smectite-type layered silicate. Therefore, further functionalization by pillaring will be feasible resulting in a conducting microporous material. The new material has been characterized by the analysis of chemical composition (wavelength dispersive X-ray spectroscopy and laser ablation-inductively coupled plasma−mass spectrometry), differential thermal analysis, electron microscopy, Mossb...

Solid solutions in CuGaSe2–ZnSe and CuInSe2–ZnSe systems have been obtained by radio frequency heating. In order to prepare n-type phases based on CuGaSe2, p-type (CuGa)1−xZn2xSe4 and (CuIn)1−xZn2xSe4 (0.05⩽x⩽0.1) single crystals were doped by Ag, Hg, Cd, Zn implantation. The crystal structure of the solid solutions was studied by X-ray diffraction; the substitutors as well as the implantant valence states were analyzed using X-ray photoelectron spectroscopy. Hall effect, electrical conductivity, and the charge carrier mobility of an n-type zinc-implantated solid solution (CuGa)1−xZn2xSe4 and (CuIn)1−xZn2xSe4 (0.05⩽x⩽0.1) were studied.

Anthocyanins, compounds that represent the major group of flavonoids in berries, are one of the most powerful natural antioxidants. The aim of this study was to evaluate biological activities and comparison of anthocyanin-rich extracts prepared from chokeberry (Aronia melanocarpa), elderberry (Sambucus nigra), bilberry (Vaccinium myrtillus) and blueberry (V. corymbosum) on the porcine intestinal epithelial IPEC-1 cell line.The IC50 values calculated in the antioxidant cell-based dichlorofluorescein assay (DCF assay) were 1.129 mg L(-1) for chokeberry, 1.081 mg L(-1) for elderberry, 2.561 mg L(-1) for bilberry and 2.965 mg L(-1) for blueberry, respectively. We found a significant negative correlation (P0.001) between cyanidin glycosides content and IC50 values. Moreover, extracts rich in cyanidin glycosides stimulated proliferation of IPEC-1 cells and did not have cytotoxic effect on cells at an equivalent in vivo concentration.We found that the chokeberry and elderberry extracts rich in cyanidin glycosides possess better antioxidant and anticytotoxic activities in comparison to blueberry or bilberry extracts with complex anthocyanin profiles.

Ferrous tainiolite, Cs[Fe2Li]o[Si4]tO10F2, has been synthesized from the melt in gastight molybdenum crucibles. The electric conductivity has been measured by impedance spectroscopy. As compared to natural micas, which are insulators, good conductivity is observed. The layered silicate can be further modified by ion exchange, which makes it a promising host structure for sensor materials. The estimated activation energy is as low as 0.79 eV. Upon Ba2+ exchange for Cs+, structural Fe2+ is partially oxidized (33%), and the layer charge is reduced significantly, resulting in a coarse-grained but swollen (monolayer hydrate) smectite-type layered silicate. Therefore, further functionalization by pillaring will be feasible resulting in a conducting microporous material. The new material has been characterized by the analysis of chemical composition (wavelength dispersive X-ray spectroscopy and laser ablation-inductively coupled plasma−mass spectrometry), differential thermal analysis, electron microscopy, Mossb...