Reagent Solution Research Articles

Experimental studies on the durability and leaching properties of alkali-activated tailings subjected to different environmental conditions

This paper presents an investigation on the durability and leaching behavior of gold MTs-based geopolymer by conducting a series of experiments that included uniaxial compressive tests (UCT) and static monolithic leaching tests, considering submersion into three different reagent solutions: deionized (DI) water, salty water, and acidic water to mimic its resistance to different environmental impacts. The strength degradation of the geopolymer prior to and after immersion in different reagent solutions were measured by performing UCT tests. The interpretations of strength degradation were examined by conducting a series of experiments to investigate the ties between the material strength and microscopic insights. The leaching element concentrations were obtained by performing the Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses of the leachates. Results indicate that the strength degradation after immersion into three different reagent solutions were approximately equal to 50%. The strength degradation of the gold MTs-based geopolymer resulted from the hydrated minerals after immersion may have influenced the chemical process during solution immersion. The leaching analyses showed that the geopolymer was ineffective in immobilizing the As, Si, and S elements. The evolution of conductivity was consistent with the element concentrations with time. Leaching mechanism indicated that the leaching elements were mainly dominated by diffusion and surface wash-off. Finally, with the finding that only considers surface wash-off and diffusion, the first-order reaction/diffusion model (FRDM) can reasonably describe the leaching kinetics of the elements with immersion duration.

Comparison of the Biological Properties of Plasma-Treated Solution and Solution of Chemical Reagents

Presently, plasma-treated solutions (PTS) are widely introduced into medicine. Plasma-activated solutions contain various reactive forms of oxygen and nitrogen which provide the desired biological effects. Yet it remains unclear exactly which components of the treated solution are the most important and what the difference is between the plasma-treated solution and a chemically prepared solution composed of the same components. In this work, we show that the chemically prepared mixture of nitrites, nitrates, and hydrogen peroxide with concentrations similar to the plasma-treated solution exerts a fundamentally different effect on a cell culture. The chemically prepared solution has higher cyto- and genotoxicity and causes necrosis, while under the action of the plasma-treated solution, apoptotic processes develop in the cells slowly.

Thermodynamics of chalcocite dissolving in solutions of flotation reagents

This work describes the formation of the ionic composition of the sorption layer during the concentration of copper-lead and pyrite-copper-zinc ore. The thermodynamics of the sorption layer of a sulfhydryl collector (sodium diisobutyl thiophosphate and potassium butyl xanthate) on the surface of chalcocite under various conditions of its oxidation has been studied using pH- and redoxometry. The nature of the change in the chalcocite electrode potential depending on the type of modifier and storage device, as well as on pH, has been experimentally clarified. The differences in the collective action of a one-component accumulator and a mixture of flotation reagents were revealed based on the thermodynamics analysis of the flotation process reactions. In addition, the optimal conditions for the flotation were determined. It was found that the quality of the concentrate is mainly influenced by two factors, such as the pulp redox potential and the pH of the medium. Mathematical equations of the optimal reagent and hydrodynamic enrichment regimes with the maximum dissolution of ore minerals in solutions of flotation reagents were modeled.

Physical-chemical properties of FM-1 reagent as a potential collector for ion flotation of lanthanoids

The physical-chemical properties of the industrial reagent “FM-1” have been investigated. These properties are necessary for evaluating its use as a collector in the processes of concentration of rare earth metal ions by ion flotation. “FM-1”, which is based on sodium salts of aminomethylenephosphonic acids, is used as a flocculant for oil production and purification of process waters from suspended particles and petroleum products. Protolytic equilibriums in aqueous solutions of the reagents were studied. The values of dissociation constants equaling pKa1 = 2.31±0.26 and pKa2 = 8.82±0.34 were determined spectrophotometrically. Surface tension of the reagent solutions at the solution-air interface was studied. The “FM-1” reagent was classified as a strong surface-active substance with the following parameters: Minimal surface tension σmin = 29 mN∙m-1, surface activity G = 0.031 N∙m2∙mol-1, critical concentration of micelle formation 1∙10–3 mol∙L-1. The regularities of the reagent’s interaction with lanthanum (III) ions were studied. A high degree of lanthanum ions’ precipitation (over 99.7 %) was observed over a rather wide interval of pH values (4.00–12.00); at this point, at pH ≥ 7.5, lanthanum hydroxide can co-precipitate. The formation of compounds in a solution with molar ratios [La]:[FM-1] = 1:1 and 1:2 was established by conductometric titration method. The findings of chemical analysis, FTIR spectroscopy and elemental analysis of the isolated precipitates suggested their structural formula. A possibility for the “FM-1” reagent to be used as a collector for the ion flotation of lanthanum (III)ions was shown

Triangular-wave controlled amplitude-modulated flow analysis for extending dynamic range to saturated signals.

We have applied our amplitude-modulated flow analysis concept to extend the dynamic range to saturated analytical signals. Sample solution, the flow rate FS of which is periodically varied with a triangular control signal Vc, is merged with a reagent solution delivered at a constant flow rate FR. While the total flow rate FT is kept constant, a diluent with FT-(FS + FR) flow rate is aspirated from the third channel. The analytical signal Vd obtained downstream is processed by fast Fourier transform to obtain the amplitudes of the wave components in Vd. When the sample concentration CS is low, Vd shows a triangular profile like Vc; the sum of the amplitudes ΣA is proportional to CS. When CS is high, Vd shows a trapezoidal profile because of the Vd saturation. A linear calibration curve can also be obtained for such saturated signals by plotting CSΣA against CS. The proof of the concept is validated by applying it to spectrophotometric determinations of a dye (Methylene Blue) and colored complexes of Fe2+ - phenanthroline and Fe3+ - Tiron.

Potentials of N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol as novel charge transfer acceptors in pharmaceutical analysis of some quinolones and cephalosporins

BackgroundQuinolones and cephalosporins are antibiotic agents with activity against Gram-positive and Gram-negative bacteria. They contain chromophores and amine groups which are electron-rich centres capable of donating electrons to electron-deficient compounds. A survey of the literature revealed that 2, 4-dinitro-1-naphthol, a nitroaromatic useful in chemical synthesis, can accept electrons in charge transfer reactions. This work investigates N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol in the formation of charge transfer complexes by accepting electrons from selected quinolones and cephalosporins. Five other nitroaromatics (i.e. 4-nitro-1-naphthylamine, 2-nitro-1-naphthol, 2,4-dinitro-1-naphthylamine, 1-nitronaphthalene and 1,4-dinitronaphthalene) were screened in addition to the aforementioned and compared for charge transfer complexes formation. Spot test was used to establish charge transfer complex formation at room and elevated temperatures with determination done by visual inspection and thin layer chromatographic analysis of the reaction mixture. Ultraviolet visible absorption spectroscopy was used to estimate the extent of complexes.ResultsOnly solutions of adducts of N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol gave instant and distinct colour with each drug used at room and elevated temperature. While the former gave deep golden yellow, the latter gave golden yellow against their blank reagent solutions which were, lemon and greenish yellow respectively. Visual inspections of 2-nitro-1-naphthol adduct solutions showed no colour change from the yellow colour of the blank reagent solution, even though the Ultraviolet visible absorption spectra revealed the formation of charge transfer complexes. The adducts solutions of 4-nitro-1-naphthylamine, 2,4-dinitro-1-naphthylamine, 1-nitronaphthalene and 1,4-dinitronaphthalene showed no colour change from their blank reagent solutions and their Ultraviolet visible absorption spectra revealed no formation of charge transfer complexes.ConclusionUltraviolet visible absorption spectral analysis shows superiority of N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol in charge-transfer complex formation over other nitroaromatics screened. N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol are good acceptors of electrons from these drugs, hence could be useful as charge transfer reagents in ultraviolet visible spectrophotometric analysis of these drugs.

Synthesis optimization of phase-singularized UZM-5 zeolite under hydrothermal conditions: The critical control points of its crystalline phase and crystallinity

Pure UZM-5 zeolite with either nanosheet or rosette-shaped morphology have been successfully synthesized by a charge density mismatch (CDM) method under a corresponding tumbling or static conditions. The synthesis parameters were fully investigated to abstain from commonly accompanying by-products, including SOD or amorphous phase which greatly interfered with the use of UZM-5. The crystalline phases and relative crystallinity of resultant products were carefully substantiated by using scanning electron microscope and X-ray diffraction. As a result, the molar ratios of water and structure directing agents thereof were deemed to be two vital parameters which had significant effects on the well-defined pure-phase UZM-5 zeolite production. Trace ethanol added in the reagent solution was found to play a role in zeolite purification. There is an urgent need in electrocatalytic reduction of nitrate to ammonia. In this work, pure UZM-5 zeolite with Lewis acid sites served as catalyst matrix for the application to produce this valuable chemical. Excellent ammonia production rate with high faradaic efficiency was achieved by using the obtained novel UZM-5-based catalyst for the reduction reaction, strongly proving the great potential of this young zeolite in catalysis applications.

New Chemoresistive Gas Sensors with Active Elements Prepared by Layer-by-Layer Chemical Assembly with the Participation of Reagent Solutions and Their Analytical Capabilities

New Chemoresistive Gas Sensors with Active Elements Prepared by Layer-by-Layer Chemical Assembly with the Participation of Reagent Solutions and Their Analytical Capabilities

Hybridoma Screening by Antibody Capture: Detection of Intracellular Binding by Immunofluorescence.

Hybridoma screening by immunofluorescence stainings of whole cells can be adapted to screen for antibodies to internal proteins by permeabilizing the cells before applying the hybridoma supernatants. In this protocol, cells are attached to a solid support (glass slides), which makes them easy to manipulate and transfer between different reagent solutions.

Applications of poly(α-olefin)s as solvents in organometallic chemistry

Poly(α-olefin)s (PAOs) that can be used as alternative solvents and solvent systems for catalysis and synthesis can substitute for conventional alkane solvents like pentane, hexane, and heptane for storage and in reactions of reactive organometallics. In this work, we show that organolithium reagents including polymer-supported diphenyllithium and triaryllithium reagents have extended stability as suspensions or as solutions in PAOs just as is the case for alkyllithium reagents. These highly colored species are stable in PAO solvents for months. PAOs can also be used as safer solvents for dialkylmagnesium reagents. In PAO solvents, these dialkylmagnesium reagents behave in reactions with electrophiles like benzaldehyde, benzophenone, and carbon dioxide the same as they do in heptane. PAOs can also be used as recyclable solvents in hydroboration/oxidation of alkenes when products are separated from the PAO by distillation or extraction. In contrast to PAO solutions of alkyllithium or dialkylmagnesium reagents, the PAO in a solution of trihexylborane in PAO did not itself inflame on exposure to a propane torch flame. While the alkylborane did burn briefly with a green flame, that flame due to the borane self-extinguishes after the borane is consumed. The PAO does not itself catch fire. Finally, we examined the recyclability and reactivity of PAO solvents containing a polyisobutylene (PIB) bound analog of LDA in enolate chemistry. Our results show that lithium PIB-tert-butylamide in PAO behaves like LDA or PIB-tert-butylamide in THF or heptane in formation of trimethylsilyl enol ethers from ketones with the difference being that PIB-tert-butylamide in a PAO solution is a fully recyclable reagent/solvent system.

One-step immunoassay for food allergens based on screened mimotopes from autodisplayed FV-antibody library

One-step immunoassay detects a target analyte simply by mixing a sample with a reagent solution without any washing steps. Herein, we present a one-step immunoassay that uses a peptide mimicking a target analyte (mimotope). The key idea of this strategy is that the mimotopes are screened from an autodisplayed FV-antibody library using monoclonal antibodies against target analytes. The monoclonal antibodies are bound to fluorescence-labeled mimotopes, which are quantitatively released into the solution when the target analytes are bound to the monoclonal antibodies. Thus, the target analyte is detected without any washing steps. For the mimotope screening, an FV-antibody library was exhibited on the outer membrane of E. coli with a diversity of >106 clones/library using autodisplay technology. The targeted clones were screened from the autodisplayed FV-antibody library using magnetic beads with immobilized monoclonal antibodies against food allergens. The analysis of binding properties of a control strain with mutant FV -antibodies composed of only CDR1 and CDR2 demonstrated that the CDR3 regions of the screened FV-antibodies showed binding affinity to food allergens. The CDR3 regions were synthesized into peptides as mimotopes for the corresponding food allergens (mackerel, peanuts, and pig fat). One-step immunoassays for food allergens were demonstrated using mimotopes against mackerel, peanut, and pig fat without any washing steps in solution without immobilization of antibodies to a solid support.

Физико-химические свойства N-(бензоил)-N'-(фенилсульфонил)гидразина

The work is devoted to the study of the physicochemical and surface-active properties of N-(benzoyl)-N'-(phenylsulfonyl)hydrazine (BPSH) to assess the possibility of using the reagent in the processes of concentration of non-ferrous metal ions. The solubility of the reagent in ethanol, 0.1 mol/l KOH solution, toluene, chloroform, and hexane was studied by spectrophotometry, refractometry, and gravimetry. Acid-base equilibria in reagent solutions and hydrolytic stability were studied by spectrophotometric method. The surface activity of BFSH was studied by the stalagmometric method.

Efficiency of using peroxide-carbonate compounds in reagent complexes for leaching gold hard to recover from placer

The article deals with the data of theoretical and experimental studies of the processes of activation gold leaching using reactive peroxide carbonate compounds, obtained by electrophotochemical treatment of solutions of initial reagents of the corresponding composition, in the composition of reagent complexes. The obtained results of the experiments on the interaction of various carbonate and peroxide-carbonate compounds with sodium cyanide in the process of mixing activated and non-activated solutions with aqueous cyanide solutions in different order definitely prove that supramolecular percarbonate-cyanide compounds are being formed in them. It has been established that these activated solutions, prepared on the basis of the initial hydrocarbonate ones, contain metastable compounds that provide a higher rate of gold extraction from crude minerals than standard aqueous cyanic solutions of the same initial concentration.

Preconcentration of sulphonamides in bovine milk by the cloud point extraction method using smartphone-based digital images.

Sulphonamides are a group of synthetic antibiotics used specially in veterinary medicine. Among the procedures employed in the sample preparation for sulphonamide determination are liquid-liquid extraction (LLE) and solid-phase extraction (SPE) that use large volumes of organic solvents. Hence, a clean procedure was developed based on preconcentration and cloud point extraction (CPE) without using organic solvents to quantify total sulphonamides in bovine milk. The procedure was optimized as follows: 2 mL of pre-cleaned milk sample, 2 mL of reagent solution and 1 mL of Triton X-114 7% (m/v) were added to a tube, heated in a water bath at 40 °C for 10 minutes and centrifuged at 2950 rcf for 20 minutes. Digital image acquisition was employed directly at the tube without removing the supernatant/aqueous phase. The linear response was observed between 10 and 400 μg L-1 of total sulphonamides and described by the following equation: S = 2.50 + 0.0514C (μg L-1) and R = 0.999. The LOD and the CV (n = 11) were estimated to be 10 μg L-1 and 1.3%, respectively. The main interferents present at their usual concentrations in the sample did not interfere with the results. Spike and recovery tests of total sulphonamides were carried out in UHT and pasteurized milk with recovery values between 73 and 106% and the results obtained for this kind of sample were in agreement with those achieved by a high performance liquid chromatography (HPLC) procedure at the 95% confidence level. The analytical procedure presents an adequate sensitivity to determine total sulphonamides in bovine milk and does not require organic solvents, being aligned to the principles of green chemistry.

ТЕСТ-РОССЫПИ НА ОСНОВЕ МОДИФИЦИРОВАННОЙ КОСТРЫ КОНОПЛИ ДЛЯ ЭКСПРЕССНОГО ОПРЕДЕЛЕНИЯ ПОДВИЖНЫХ ФОРМ ФОСФОРА И СУЛЬФИТОВ В ПОЧВАХ И ВОДНЫХ ПРОБАХ

The methods of manufacturing test placers and compositions for visual-blister colorimetric determination of concentrations of phosphate ions and sulfi te ions for their quantitative determination in soils and water bodies have been optimized. The test placer contains all the reagents for the analytical reaction. Placers allow the quantitative determination of phosphates and sulfi des in aqueous samples without prior preparation of reagent solutions. In a blister cell with a diameter of 6 mm, a much more intense color was achieved with a solution layer of no more than 2 mm. The application of reagents to the surface of homogenized and discolored hemp awns avoids their contact until the chemical analytical reaction takes place. The composition of placers and the conditions for applying reagents are optimized. Suffi ciently high acidity can be provided by hydrosulfate ions with the addition of a few drops of solution. The reaction proceeds in the volume of the added test solution, which is 2-3 drops.

Identification of benzydamine and its metabolit in the presence of certain anti-inflammatory non-steroidal drugs

The aim of the work. Currently, a large number of cases of non-medical use of benzydamine hydrochloride have been described. The identification of benzydamine and its metabolite, benzydamine N-oxide, in the presence of some non-steroidal anti-inflammatory drugs, has been insufficiently studied. Therefore, the development of a method for its identification in biological material is an urgent task.
 Materials and methods. The subjects of the study were benzydamine hydrochloride and its metabolite, as well as some non-steroidal anti-inflammatory drugs, which are its analogues in terms of pharmacological action. The studies were carried out by methods of thin layer chromatography and high-performance liquid chromatography.
 Results. At the first stage a screening method for benzydamine identification was studied using the extraction in acidic and basic conditions. It was shown that benzydamine can be isolated in both medias with subsequent development with a solution of iodoplatinate and Dragendorff's reagent according to Munier or with Mandelin reagent respectively. The mobile phase was selected and respective hRf for the target molecule were defined.
 After a preliminary identification of benzydamine a reference method for the final confirmation of the drug that had led to poisoning was proposed. A robust, specific and accurate reversed phase HPLC method was chosen. It was shown that benzydamine exists in biological material mainly in a form of metabolite – benzydamine N-oxide. The selected method was able to separate and determine key analytes in biological samples after a preparative isolation by TLC method. The comparison with UV spectra of the reference standard of benzydamine hydrochloride was proposed to avoid false positive conclusion of drug identification.
 Conclusions. Proposed methodology can be applied for routine identification of benzydamine poisoning in toxicological laboratories

Quantification of superhydrophobic functionalization for laser textured metal surfaces

Laser texturing is a facile method to promote modified surface wetting properties. While most laser textured metal surfaces are natively superhydrophilic, here we establish a quantitative relationship between post-texturing chemical modification and water contact angles from ca. 80° < θw < 180°. A nanosecond laser-based high-throughput surface nanostructuring (nHSN) method is used to texture aluminum alloy surfaces. The textured surfaces are immersed in ethanol solutions of chlorosilane reagent [CF3(CF2)5(CH2)2SiCl3] (FOTS) at different concentrations and different times to achieve superhydrophobicity. The role played by the two chemical treatment parameters, concentration and treatment time, is investigated and quantified. Water contact angle, reflection-based infrared spectroscopy and energy-dispersive X-ray spectroscopy are used to characterize the functionalized surface. The goal of this research is to quantify the effects of surface chemical modification on the resulting material functionality using surface sensitive spectroscopic techniques. Our results show that both the solution concentration and the immersion treatment time play significant roles in the attachment of functional groups (-CF2-, -CF3) on surface. Further, concentrations of FOTS as low as 0.1% with six hours of chemical immersion treatment, or short treatment times as low as three hours with 0.5% FOTS solution are adequate to achieve superhydrophobicity.

Influence of phosphorus fertilizers of various composition on the yield of tomato crops and control of their consumption by plants

Phosphate fertilizers are widely used for growing crops. To obtain phosphoric fertilizers, phosphoric acid purified using organic solvents, one of which is 100% tributyl phosphate, is used. The authors of the paper have chosen this solvent to obtain purified phosphoric acid. Purification from impurities included the stages of extraction and reextraction. On the basis of the re-extract and chemically pure phosphoric acid, a phosphoric fertilizer magnesium-ammonium phosphate (MgNH4PO4) was synthesized and used in the greenhouse experiment. The greenhouse experiment consisted in growing a tomato crop included three options for fertilization. A comparative analysis of the stimulating effect of magnesium-ammonium phosphate, synthesized with the use of phosphoric acid of varying degrees of purification, on the yield of tomato culture has been carried out.The paper proposes a blister-colorimetric version of the determination of phosphate ions in a blister cell containing a mixture of dry reagents in the form of a bulk. The optimal conditions for carrying out colorimetry have been selected. The proposed method makes it possible to semi-quantitatively determine phosphorus in various objects without preparing reagent solutions, using a bulk packed in an ampoule or blister, and can be used to control phosphorus consumption by plants, which, in turn, allows regulating the introduction of nutrients in the form of dressings.

USE OF MODIFIED REAGENTS SOLUTIONS WHEN PREPARING DRINKING WATER

Currently, attention is paid to the intensification of the process of natural and wastewater treatment, improvement of technology, development of new effective methods of intensification of water treatment. This will simplify the existing technology of water treatment, reduce labor-intensive processes of preparation and dosing of reagents, reduce the cost of operating treatment plants, increase their productivity, improve quality and reduce the cost of treated water. Treatment of water with a modified coagulant solution allows to increase the hydraulic size of the coagulated suspension. The strongest effect of the modified coagulant solution has on the hydraulic suspension size of 0.2 mm/s and less, i.e. the smallest and the suspension, which is difficult to remove, which creates conditions for more intensive sedimentation in settling tanks and improve the quality of water clarification and fed to fast filters. It has been experimentally determined that the treatment of water with a modified solution of aluminum sulfate coagulant should be performed when the content of suspended solids in the clarified water is up to 100–150 mg / dm3. The color of the clarified water during treatment with a modified solution of aluminum sulfate coagulant does not depend on the content of suspended solids and is 1.5-1.6 times lower than the color than when using a conventional coagulant solution. It is established that the use of a modified solution of aluminum sulfate coagulant in water purification can reduce the residual aluminum content in clarified water by an average of 50-60%. The results of researches of the modified solutions of reagents which are used at preparation of drinking water are presented. It is established that water treatment with a modified solution of aluminum sulfate coagulant allows to improve the quality of drinking water preparation by suspended solids, color, reduce the content of aluminum salts in the clarified water, thereby increasing the environmental safety of drinking water.

Sonochemical activation of amine hydrochloric acid solution used as a collector in sylvinite ore flotation

This paper covers the problems of improving the efficiency of a specific flotation reagent (amine hydrochloric acid solution) through the dispersion of floccules using preliminary sonochemical activation. The influence of various combinations of acoustic power (from 168 to 420 W in increments of 84 W) and ultrasound exposure time (30, 60 and 150 s) on the physical and chemical characteristics of the mineral/flotation reagent system has been studied. The results demonstrate that preliminary ultrasonic exposure of the reagent reduces the size of amine hydrochloric acid floccules. This, in turn, increases the specific surface area of collector micelles, improving the reagent distribution on the mineral surface. The contact angles for KCl particles were measured after the sonochemical activation and after the amine adsorption, which confirmed better hydrophobization of the sylvite mineral surface. It has been found that higher power values and ultrasonic exposure times produce a more electropositive zeta potential of the reagent solution. It has also been established that the use of a pre-activated solution of hydrochloric acid amine improves KCl recovery as compared with the use of a non-activated flotation reagent. The efficiency of ultrasonic activation of the amine emulsion used at potash flotation plants has been assessed. A positive effect of preliminary ultrasonic exposure of the emulsion on the KCl flotation process was established.The study was carried out with the financial support of the Ministry of Education and Science of the Russian Federation as part of the implementation of the program of activities of the world-class scientific and educational center "Rational Subsoil Use".