ОЧИСТКА ГАЗОВЫХ ВЫБРОСОВ ОТ СО2 В СРЕДЕ ТРИФТОРУКСУСНОЙ КИСЛОТЫ ПРИ ДОБЫЧЕ НЕФТИ И ГАЗА

The optimal parameters of catalytic purification of flue gases from SO2 and CO2 in trifluoroacetic acid solutions are determined. It is shown that flue gas cleaning from carbon dioxide and sulfur dioxide using trifluoroacetic acid solutions as a catalyst is carried out at room temperature and atmospheric pressure with an efficiency of 100%. The process of gas purification from sulfur dioxide and carbon dioxide is carried out in a non-aggressive medium of trifluoroacetic acid (TFA) solutions. The possibility of increasing the absorption capacity of the reaction medium by pumping the exhaust gases through trifluoroacetic acid solutions has been established. At the same time, polluting waste gases — toxic sulfur and carbon oxides — are converted into higher oligomers (oxides), and then, as a result of their interaction with water, present directly in the reaction medium — TFA aqueous solution, into the corresponding acids. The formation of trifluoroacetic acid esters to a lesser extent leads to an increase in the absorptivity of the reaction medium, a reduction in the number of regeneration stages, a simplified separation of by-products, and, consequently, a simplification of their utilization process due to the absence of the need to purify the latter from these esters.

The dissolution of manganese oxides in sulfuric acid solutions of various concentrations has been studied by kinetic methods. We have investigated the dissolution of manganese oxides of various compositions in sulfuric acid solutions of various concentrations. The composition of the manganese oxides and the sulfuric acid concentration have been shown to influence the dissolution rate. We have calculated kinetic parameters of the dissolution of manganese oxides in sulfuric acid solutions (dissolution rate, activation energy for dissolution, and reaction orders) and proposed a model for the dissolution of manganese oxides in sulfuric acid solutions.

An N–S acyl shift reaction of thiol-containing peptides in a trifluoroacetic acid (TFA) solution was confirmed by a combination of 13C NMR spectroscopy, reversed-phase (RP) HPLC, and MS analyses. A model peptide containing a cysteine residue was transformed into an S-peptide in a TFA solution. The S-peptide was quickly transformed to the original peptide during RP-HPLC analysis even when an eluent that contained 0.1% TFA was used. A peptide that had an N-2-mercapto-4,5-dimethoxybenzyl (Dmmb) group was also transformed into an S-peptide, forming a thioester bond with the thiol of the Dmmb group by TFA treatment. The generated S-peptide was isolated by directly injecting the reaction mixture into a RP-HPLC and was readily converted to the corresponding 2-sulfoethyl thioester via an intermolecular thiol exchange reaction with sodium 2-mercaptoethanesulfonate. The 2-sulfoethyl peptide thioester is widely used as a building block in polypeptide synthesis. The N–S acyl shift reaction observed in peptides with or without an auxiliary group provides a new route for the preparation of peptide thioesters.

Silk sericin (SS)/silk fibroin (SF) blend nanofibers have been produced by electrospinning in a binary SS/SF trifluoroacetic acid (TFA) solution system, which was prepared by mixing 20 wt.% SS TFA solution and 10 wt.% SF TFA solution to give different compositions. The diameters of the SS/SF nanofibers ranged from 33 to 837 nm, and they showed a round cross section. The surface of the SS/SF nanofibers was smooth, and the fibers possessed a bead-free structure. The average diameters of the SS/SF (75/25, 50/50, and 25/75) blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50) blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100) blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure.

Chemical structures of cellulose and chitosan dissolved in trifluoroacetic acid (TFA) and those of cellulose and chitosan films cast from their TFA solutions were studied by 13C‐NMR and infrared (IR) spectroscopy. Cellulose is trifluoroacetylated selectively at the C6–hydroxyl groups in the TFA solution, and chitosan is dissolved in TFA by forming amine salts with TFA at the C2–amine groups. IR analyses of cellulose films cast from its TFA–acetic acid solutions showed that partly trifluoroacetylated cellulose in the solution state turns to partly acetylated cellulose in the solid state during evaporation of the solvents in air by the ester interchange. Chitosan films cast from its TFA–acetic acid solutions still have the amine salts with TFA. These acetyl groups in cellulose films and TFA in chitosan films are removable by soaking the films in 1N NaOH at room temperature for 1 day.

Украина занимает одно из первых мест в Европе по показателям цереброваскулярной заболеваемости и смертности от инсульта. Поэтому создание новых лекарственных средств для лечения этих патологий – актуальная задача современной фармации, а создание нового комбинированного препарата на основе глицина (нейротрасмиттерной аминокислоты) и тиотриазолина (антиоксиданта) целесообразно и актуально. Для нового комбинированного лекарственного средства предложена рациональная лекарственная форма – таблетки. Для созданных комбинированных таблеток необходимо разработать методы стандартизации. Чаще всего для стандартизации готовых лекарственных форм и аптечного, и заводского изготовления используют физико-химические методы исследования. Наше внимание привлек метод высокоэффективной жидкостной хроматографии, который позволяет одновременно провести стандартизацию действующих веществ в одной навеске. Для разработки методики ВЭЖХ прежде всего необходимо подобрать оптимальные условия проведения анализа действующих веществ. Цель работы – подбор оптимальных условий одновременного определения глицина с тиотриазолином в модельной смеси методом ВЭЖХ. Материалы и методы . В ходе исследований использовали глицин, тиотриазолин. Исследования проводили с использованием модульной системы ВЭЖХ BISCHOFF со спектрофотометрическим детектором Lambda 1010. Использовали колонки Prontosil 120-5-CN, Hypersil ODS-C18-5u. В качестве элюента использовали воду, 0,05 % водный раствор трифторуксусной кислоты Bu 4 NHSO 4 3,4 г/л в воде, Bu 4 NHSO 4 3,4 г/л, 0,02 М Na 2 HPO 4 в воде, Bu 4 NHSO 4 3,4 г/л, 0,05 % раствор трифторуксусной кислоты в воде. Результаты. Согласно полученным результатам, среди различных использованных элюентов и фаз в дальнейшем для совместного определения глицина с тиотриазолином и в модельной смеси, и в комбинированных лекарственных формах целесообразно использовать в качестве элюента тетрабутиламмоний в условиях ион парного хроматографирования на обратной фазе с одновременным использованием кислого буфера – 0,05 % раствора трифторуксусной кислоты. Выводы. В ходе исследований подобраны оптимальные условия одновременного определения глицина с тиотриазолином в одной навеске. Установили, что определение действующих веществ необходимо проводить в условиях ион парного хроматографирования на обратной фазе при использовании элюента тетрабутиламмония с одновременным использованием кислого буфера – 0,05 % раствора трифторуксусной кислоты.

The anodic dissolution of nickel was studied galvanostatically in hydrochloric acid solutions of various concentrations. The reaction orders of chloride ion and hydrogen ion concentrations were found to be 0.5 and 1.0, respectively. An anodic Tafel slope equal to 120 ± 10 mV · decade−1 was obtained. The dissolution rate of nickel at constant acid concentration was increased with stirring of the solution and increasing temperature. The activation energy, ΔH, for the anodic dissolution process was found to be 12 kcal · mol−1. The presence of oxygen in solutions assisted the passivation process. The effect of addition of aniline and some of its derivatives (o-, m-, and p-anisidine) as inhibitors on the dissolution kinetics of Ni in 1 M HCl was also investigated. These compounds inhibited the anodic dissolution of nickel without affecting the Tafel slope, indicating that the adsorption of such inhibitors could not interfere with the mechanism of metal dissolution.

Oxidation by the ultra-short lived radical cation of water, H2O˙+, can potentially take place at the interface of water and numerous heterogeneous systems involved in radiation therapy, energy and environmental industries. The oxidation processes induced by H2O˙+ can be mimicked in highly concentrated solutions where the nearest neighbors of H2O˙+ may be molecules other than water. The reactivity of H2O˙+ and D2O˙+ is probed in hydrogenated and deuterated sulfuric acid solutions of various concentrations. The oxidized solute, sulfate radical, is observed at 7 ps and remarkably higher yields are found in deuterated solutions. The isotopic effects reveal the competition between two ultrafast reactions: proton transfer toward H2O (D2O) and electron transfer from HSO4- to H2O˙+ (D2O˙+). Density functional theory simulations decipher the electron transfer mechanism: it proceeds via sub-femtosecond charge migration and is not affected by isotopic substitution. This work definitively demonstrates why direct oxidation triggered by H2O˙+ can be competitive with proton transfer.

The present paper deals with the electrochemical behavior of three types of sensors based on modified screen-printed electrodes (SPEs): a sensor based on carbon nanofibers (CNF/SPE), a sensor based on nanofibers of carbon modified with gold nanoparticles (CNF-GNP/SPE) and a biosensor based on nanofibers of carbon modified with gold nanoparticles and tyrosinase (CNF-GNP-Ty/SPE). To prepare the biosensor, the tyrosinase (Ty) was immobilized on the surface of the electrode already modified with carbon nanofibers and gold nanoparticles, by the drop-and-dry technique. The electrochemical properties of the three electrodes were studied by cyclic voltammetry in electroactive solutions, and the position and shape of the active redox peaks are according to the nature of the materials modifying the electrodes. In the case of ferulic acid, a series of characteristic peaks were observed, the processes being more intense for the biosensor, with the higher sensitivity and selectivity being due to the immobilization of tyrosinase, a specific enzyme for phenolic compounds. The calibration curve was subsequently created using CNF-GNP-Ty/SPE in ferulic acid solutions of various concentrations in the range 0.1–129.6 μM. This new biosensor allowed low values of the detection threshold and quantification limit, 2.89 × 10−9 mol·L−1 and 9.64 × 10−9 mol·L−1, respectively, which shows that the electroanalytical method is feasible for quantifying ferulic acid in real samples. The ferulic acid was quantitatively determined in three cosmetic products by means of the CNF-GNP-Ty/SPE biosensor. The results obtained were validated by means of the spectrometric method in the infrared range, the differences between the values of the ferulic acid concentrations obtained by the two methods being under 5%.

Since the beginning of this century, trichloroacetic acid solutions of various concentrations have been used for chemical exfoliation. These solutions have been prepared by using four different formulas. To prepare a 50% solution, for instance, water may be added to 50 g of trichloroacetic acid crystals until 100 ml of solution is obtained (weight-to-volume solution). Alternatively, 50 g of water may be added to 50 g of trichloroacetic acid crystals (weight-to-weight solution), or 50 g of trichloroacetic acid crystals may be solved in 100 ml of water (weight-plus-volume solution). Finally, a saturated trichloroacetic acid solution (or "100% solution") may be diluted by an equal volume of water (dilution). Depending on the method used, these so-called 50% solutions contain 40 to 71 weight-to-volume percentages of trichloroacetic acid. From a review of 120 publications on trichloroacetic acid peeling that have appeared since 1926, it was concluded that the authors of 87 of these publications (73 percent) did not report their formula for the trichloroacetic acid solution. Any one of the four methods was reported to have been used by the 33 authors who did report their formula. Eight of 10 internationally reputed pharmacopeias were found not to include the formula of a trichloroacetic acid solution. Proper evaluation of results and prevention of complications of trichloroacetic acid chemexfoliation is only feasible if both the concentration and the formula of trichloroacetic acid solution are reported by the author. Practitioners who use a trichloroacetic acid solution need to establish that the concentration of the solution they apply corresponds with that of the solution reported in the literature.

Fundamental investigations on preparation of Am(VI) in nitric acid solutions of various concentrations were carried out in order to develop a partitioning method for americium from high level liquid waste generated from the reprocessing of spent fuel. A mixture of ammonium peroxodisulfate and silver nitrate was used as oxidizing reagent. The yields of Am(VI) were determined as a function of the concentrations of nitric acid (0.01—2 M) and oxidizing reagent (0.1—2M) and temperature (55–85°C). The yield of Am(VI) decreased with increasing concentration of nitric acid. In 1 M nitric acid solution, increasing the concentration of ammonium peroxodisulfate resulted in increased of Am(VI) yield. When 1.5 M ammonium peroxodisulfate and 0.01 M silver nitrate were used, 90% of the americium in 1M nitric acid solution was oxidized to the hexavalent state at 85°C.

We present a new integrated optical sensor for absorption spectroscopy in a hostile environment, based on a nanochannel waveguide structure in glass. The nanochannel waveguide is made by bonding two ion-exchanged borosilicate glass wafers, one of them being etched by reactive ion etching to create a 100 nm deep fluidic channel. Typical fluid/light interaction factors of 2.3 % can be achieved inside a 7.4 pL volume of fluid, over a 550 nm bandwidth, surmounting evanescent wave sensors in terms of confinement efficiency and allowing spectrometric measurements. Absorption measurements have been performed on hexahydrate neodymium nitrate in nitric acid solutions of various concentrations leading to a minimum detectable absorption coefficient of 0.57 cm^-1, which can be further decreased by implementing low bending-loss spiral-like nanochannel waveguides.

Corrosion resistance of titanium-molybdenum-tantalum alloys in sulfuric acid solutions of various concentrations at 20°

Relationships between the infusion speed and lethal dose of several amino acid solutions of various concentrations were studied in male Sprague Dawley rats. When the amino acid solutions were continuously infused at various speeds, a functional relationship between the dose producing a cardiac arrest (DCA) and infusion speed was established. The DCA/infusion speed was characterized by two ranges with an increasing DCA as increase or decrease of infusion speed and by its intermediate range of a flat minimum with a practically constant DCA regardless of varying the infusion speed. A practically constant LD50 was obtained in the infusion of each amino acid solution within the infusion speed in the intermediate range. The LD50 of each amino acid solution was dependent on the crystalloid osmotic pressure.

This study concentrates on the removal of the heavy metals from dredged sediments from a polluted marine area. The metals examined were Cr, Cu, Fe, Ni, Pb and Zn. It was found that the sediments were substantially contaminated by several metals including Cr, Fe, Zn and Cu whereas others such as Ni and Pb seem to be present at normal levels. The metal form distribution in the dredged dried sediments found by the application of a sequential extraction partitioning procedure indicated that an important part of the metal content was carried by the reducible and the organic phase. Batch extraction experiments with acid solutions of various concentrations were carried out in order to investigate the heavy metal removal from the contaminated sediments. Extraction results showed that for most metals studied the percentage extracted was satisfactory. Following, the forms of the remaining in the sediments metals were determined using selective sequential extraction analysis and the results indicated that the residual fraction is hardly removed as opposed to the other fractions which are easily removed by the hydrochloric acid extraction and compose 50 percent of the initial amount of metals present.