Thiocyanate Solutions Research Articles

Competitive Ligand Binding and Photosensitivity Studies of Iron(III)-thiocyanate in presence of Glutamate ion

Addition of a chelating ligand (glutamate ion) to [Fe(SCN)]2+ solution leads to change in the colour. On increasing the glutamate ion concentration in iron thiocyanate complex solution, the colour of [Fe(SCN)]2+ disappears with the emergence of a new peak at lower wavelength due to the formation of [Fe(Glu)]2+complex. The conductance of [Fe(SCN)]2+ complex ion in solution is high while on addition of different concentrations of glutamate ion to iron thiocyanate complex, their conductance value decreases due to formation of [Fe(Glu)]2+. Photosensitivity studies of a series of solutions prepared by the addition of glutamate ion of varying concentrations to ferric chloride-ammonium thiocyanate/potassium thiocyanate solution in the short UV region demonstrate the better stability of [Fe(Glu)]2+compared to [Fe(SCN)]2+ and the rate kinetics of decomposition has been reported.

Damage tolerance and failure analysis of tie-down cables after long service life in a cable-stayed bridge

The paper examines the damage tolerance of prestressing steel wire-strands failed after being exposed without protection to environmental action for 30 years as tie-down cables of a cable-stayed bridge. The influence of corrosion pitting, cross-section losses and possible assisted cracking on the tensile behavior of the Zn-coated prestressing steel strand-wires was experimentally determined, as well as their susceptibility to aggressive environments. A damage tolerance assessment was completed by performing fracture tests of as-received wire-samples exposed to an aqueous solution of ammonium thiocyanate while tensile loaded by applying a constant load followed by an increasing load at low strain rate. The fractographic analysis of the wires broken in-service and in-laboratory proved the induced damage to be very similar and provided evidence of environmental damage in some of the service ruptures. The damage tolerance assessment is in agreement with the two types of wire ruptures found in the failed wire-strands. These sequentially occurred over the 30 years of service, with the brittle ruptures of the mostly exposed peripheral wires being due to environmentally assisted cracking and preceding the ductile ones of the remaining wires by mechanical overloading.

Electrochemical dissolution behavior of gold and its main coexistent sulfide minerals in acid thiocyanate solutions

Electrochemical tests were developed to investigate the electrochemical dissolution behavior of gold and its main coexistent sulfide minerals in acid thiocyanate solutions. The optimal leaching conditions for gold in acidic thiocyanate system were pH 2, 0.15 mol·L−1 thiocyanate and 0.2 g·L−1 Fe3+. Fe3+ addition to the acidic thiocyanate system promoted gold dissolution significantly, arsenopyrite dissolution was inhibited, chalcopyrite dissolution was increased, and the dissolution behavior of other associated minerals remained mostly unchanged. Thiocyanate made gold and associated mineral leaching easier. The galvanic corrosion effect of gold and its main coexistent sulfide minerals in an acidic thiocyanate-free system was that the chalcocite, arsenopyrite and pyrite acted as a cathode to reduce anodic gold dissolution; galena as an anode undergoes oxidation to inhibit anodic gold dissolution. There was almost no galvanic corrosion behavior between stibnite, yellow sphalerite and black sphalerite and gold. Thiocyanate addition changed the galvanic corrosion behavior of stibnite and yellow sphalerite in the thiocyanate system, which inhibited anodic gold dissolution. In the acidic thiocyanate system in the presence of ferric iron, the arsenopyrite promoted anodic gold dissolution, the chalcocite and gold were mostly free of galvanic corrosion, and the remaining minerals inhibited anodic gold dissolution.

Titrimetric Analysis of Chloride Concentration in Beers using Synthetic Mercury(II) Compound

The monothiocyanato-mercuric(II) nitrate [Hg(SCN)NO3] reagent has been prepared synthetically in an aqueous medium and subjected for studies of titrimetric analysis of chloride concentration in beers. In this studies, a measured volume of beer sample was added into known and an excess amount of Hg(SCN)NO3 reagent and the surplus Hg(SCN)NO3 was determined by back titration against standard potassium thiocyanate (KSCN) solution using ferric nitrate [Fe(NO3)3] indicator. The chloride ion and Hg(SCN)NO3 were found to be reacting in the 1:1 stoichiometric ratio. The amount of chloride in beer was determined with the amount of Hg(SCN)NO3 utilized in the titration reaction. The presence of organic and inorganic materials had no effect on the titrimetric assay of chloride concentration in beers as proved by the chloride recovery experiment. The statistical analysis of results showed average standard deviation of 0.01034 and average relative error 1.12%, which indicates the accuracy of the procedure.

Germanium Extraction from Sulfuric Acid Solutions in the Presence of Thiocyanate Ion

The extraction of Ge (IV) from sulfuric acid solutions in the presence of thiocyanate ion with various extractants (caprylic, poly(2-ethylhexyl)phosphonitrile, bis(2,4,4-trimethylpentyl) dithiophosphinic acids, trialkylmethylammonium thiocyanate, etc.) has been studied. In all cases, the thiocyanate ion increases germanium extraction as compared to the extraction from sulfuric acid solutions. During the germanium extraction with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301, HR), a significant increase in the germanium extraction is due to the formation of a cationic intracomplex compound of the composition [Ge(OH)3-nRn]+[HSO4], where n = 1-3. Due to the large synergistic effect for the extraction of Ge, it is possible to use an extractant with a concentration of 0.1-0.15 mol/l. Trialkylmethylammonium thiocyanate (TAMAR), also shows a high efficiency of germanium extraction from sulfate thiocyanate solutions. For 5-6 stages of extraction with a 0.5 M solution of ТАМАР, the extraction of Ge was 99.5 %. The composition of the extracted complex supposedly corresponds to (R4N)2[Ge(CNS)6]. The use of extraction systems based on Cyanex 301 and ТАМАR in the presence of thiocyanate ion significantly reduces the concentration of extractants and is of undoubted practical interest for hydrometallurgical processes for the germanium extraction

An imaging approach for in-situ measurement of refractive index of a porous medium

Refractive index matching (RIM) is often used for flow measurement in porous media studies that use optical techniques. However, the refractive index of transparent porous media, often constructed of beads, is not always readily available or measurable with commonly used measuring devices such as refractometers. Therefore, an alternative technique is needed for determining the refractive index of the beads forming the porous media. The available methods in the literature involve a rigorous procedure and use a laser to illuminate the medium. Their setups are often complex and are sensitive to small changes in the temperature or wavelength and sometimes needs continuous stirring of the medium to have a homogeneous porous media. A new approach for measuring and matching the refractive index of beads that minimizes the limits of the available techniques is presented here. Unlike common RIM measurement approaches, the proposed technique involves no laser light and therefore is relatively simpler than similar approaches found in the literature. This approach uses shadow imaging to capture images of the beads forming the porous medium while the RIM fluid flows through it. A comparison approach using a reference image and a structural similarity metric to quantify the level of the refraction index matching is used to identify the refractive index of the dispersed phase. The approach is verified experimentally using borosilicate glass beads as the dispersed phase. Two different RIM fluids, Potassium thiocyanate (KSCN) solutions and a mixture of Drakeol 7, as silicone oil and soybean oil are used as the test fluids to compare the independency performance of the approach. The approach not only identifies the general refractive index of the dispersed phase but can also be used to identify local spatial variations in the porous media. In addition, using the imaging approach minimizes the effort for determining the refractive index of the solid for flow experiments and reduces the need for equipment or changes to the setup.

Thiocyanate-Treated Perovskite-Nanocrystal-Based Light-Emitting Diodes with Insight in Efficiency Roll-Off.

Light emitting diodes (LED) based on halide perovskite nanocrystals (NC) have received widespread attention in recent years. In particular, LEDs based on CsPbBr3 NCs were the object of special interest. Here, we report for the first time green LED based on CsPbBr3 NCs treated with ammonium thiocyanate solution before purification with polar solvent. The champion device fabricated based on the treated CsPbBr3 NCs showed high efficiency and high stability during operation as well as during storage. A study on morphology and current distribution of NC films under applied voltages was carried out by conductive atomic force microscopy, giving a hint on efficiency roll-off. The current work provides a facile way to treat sensitive perovskite NCs and to fabricate perovskite NC-based LED with high stability. Moreover, the results shed new light on the relation between film morphology and device performance and on the possible mechanism of efficiency roll-off in NC LED.

Steric hindrance and exchange in the coadsorption of octanethiol and decyl thiocyanate on Au(111)

Organic thiocyanates (R–SCN) form thiolate self-assembled monolayers (SAMs) on metal surfaces through the cleavage of the S–CN bond. Comparison of thiocyanate and thiol monolayers prepared using the same deposition conditions demonstrate substantial differences in the formation of the respective monolayers. These studies directly compare the self-assembly of thiocyanates and thiols. Mixed SAMs were formed through the simultaneous exposure of an Au(111) surface to octanethiol and decyl thiocyanate at different concentrations and ratios and were characterized under ambient conditions using scanning tunneling microscopy. The resulting SAMs consist primarily of octanethiolates, including when the concentration of decyl thiocyanate in solution is in excess by two orders of magnitude. Reducing the solution concentration of both octanethiol and decyl thiocyanate while maintaining the same relative ratio enhances the persistence and surface coverage of decyl thiocyanate on the surface. Thiocyanate displacement is likely facilitated by thiols, which is lessened when the octanethiol concentration is reduced. Furthermore, thiocyanate adsorption is limited by the bulkier head group. Here, we demonstrate how the deposition conditions of two compounds can be used to guide the formation of the mixed self-assembled monolayers from components with differing adsorption kinetics. This can provide greater control of the surface composition which would be useful in the patterning of surfaces.

Synthesis of Iron Nanoparticles by Thermal Decomposition of Diironnonacarbonyl in Ionic Liquid and Their Potential Use as Nanotracers for Mixer Studies in Liquids Feeds

Iron nanoparticles with dynamic light scattering median diameter around 10 nm have been prepared by thermal decomposition under a nitrogen atmosphere from diironnonacarbonyl (DINC) dissolved in n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF). The effect of temperature changes in the range of 170&#176C - 200&#176C and changes in concentration of DINC in BMIMBF in the range of 0.1% - 0.9% on the properties of obtained iron nanoparticles has been investigated. The stable dispersion of iron nanoparticle in ethanol has been prepared after separation of nanoparticles from ionic liquid by centrifugation following by their re-dispersion in ethanol. The possibility of quantitative analysis of iron content in ethanol dispersion by deposition of ferromagnetic nanoparticles on the surface of plastic-protected neodymium magnet, dissolution of iron in hydrochloric acid and addition of ammonium thiocyanate solution following by spectrophotometric determination of iron cations at wavelength of 490 nm has been investigated. The feasibility of using the same approach in case of addition of ethanol dispersion of iron nanoparticles to the liquid animal feeds for evaluation of efficiency of their mixing has been discussed.

Synthesis of Butadiynyl-Strapped Corona[6]arenes and Their Selective Anion Binding Properties.

A number of butadiynylene-strapped O6-corona[6]arenes were synthesized straightforwardly through intramolecular oxidative homocoupling of O6-corona[6]arenes, which contained at least two N-propargyl-phthalimide segments. The mono-macrocyclic reactants were prepared from the reaction between 3,6-dichlorotetrazine and N-propargyl-3,6-dihydroxyphthalimide and another 1,4-dihydroxybenzene derivative with roughly a 3:2:1.3-1.5 ratio in a one-pot reaction manner. The synthesized butadiynylene-strapped corona[3]arene[3]tetrazines acted as highly selective electron-deficient macrocyclic hosts to form 1:1 complexes with thiocyanate in solution, and the association constant (Ka) was up to 1390 M-1. The anion-π noncovalent interactions provided the driving force for host-guest complexation.

The Role of Specific Ion Effects in Ion Transport: The Case of Nitrate and Thiocyanate

The selective transport of trivalent rare earth metals from aqueous to organic environments with the help of amphiphilic "extractants" is an industrially important process. When the amphiphilic extractant is positively charged or neutral, the coextracted background anions are not only necessary for charge balance but also have a large impact on extraction efficiency and selectivity. In particular, the opposite selectivity trends observed throughout the lanthanide series in the presence of nitrate and thiocyanate ions have not been explained. To understand the role of background anions in the phase transfer of lanthanide cations, we use a positively charged long-chain aliphatic molecule, modeling a common extractant, and gain molecular level insight into interfacial headgroup-anion interactions. By combining surface sensitive sum frequency generation spectroscopy with X-ray reflectivity and grazing incidence X-ray diffraction, we observed qualitative differences in the orientational and overall interfacial structure of nitrate and thiocyanate solutions at a positively charged Langmuir monolayer. Though nitrate adsorbs without dramatic changes to the solvation structure at the interface or the monolayer ordering, thiocyanate significantly alters the water structure and reduces monolayer ordering. We suggest that these qualitatively different adsorption trends help explain a reversal in system selectivity toward lighter or heavier lanthanides in solvent extraction systems in the presence of nitrate or thiocyanate anions.

Granulated Sorption Material Based on Cellulose for Extracting Silver from Thiocyanate Solutions

The ability to apply granulated materials with cellulose as sorbents for silver extraction from thiocyanate solutions in industrial technological schemes is studied. Samples extracted from sulfite unbleached pulp from coniferous wood via preactivation, dilution, chemical modification, and extraction with successive curing of granules formed are studied. The granule surface is shown to possess a developed pore system with diameter of 2–5 μm. The optimum time of silver sorption from a potassium thiocyanate solution by a cellulose-containing sorbent with a weight of 500 ± 2 mg is found to be 120 min. The silver anion complexes can be completely extracted from thiocyanate solutions with a silver content of not higher than 1 g/L. The experimentally evaluated sorption capacity of a cellulose-containing material in relation to silver is 20 mg/g.

Thermodynamic analysis of a novel combined double ejector-absorption refrigeration system using ammonia/salt working pairs without mechanical pumps

This paper proposed an absorption refrigeration system which employed two ejectors as cycle power source instead of mechanical pumps. Ammonia/lithium nitrate and ammonia/sodium thiocyanate solutions are applied as working pairs as well as an air-cooled type absorber are put up in this system. The liquid-vapor ejector is located at the inlet of the absorber, the steam-driven jet pump is set at the up-stream of the back flow of solution heat exchanger. Thermodynamic performance of this absorption refrigeration system has been comprehensively studied by numerical method; thus, comparison has been made with the conventional absorption refrigeration system. The result indicates that, compared with conventional air-cooled absorption refrigeration cycles, this novel combined double-ejector refrigeration cycle (DEARC) sacrifices part of refrigerant which leads to a decline of system COP value. But still, COP of DEARC can reach 0.6354, which is sufficient for practical use under exhaust heat conditions. Pressure ratio of liquid-vapor and the absorber outlet solution temperature are both two factors which make it possible to improve the system performance furthermore. Vapor consumption ratio is another key factor which has great influence to system performance. The wider range of generating temperature and the air-cooled type absorber of DEARC make it easy for the whole system to achieve miniaturization and simplification.

Polymeric Inclusion Membrane (PIM) for Thiocyanate Extraction from Acid-Neutral Solution

Thiocyanate can be found in the gold mine tailing that use cyanide method for gold extraction. Reaction of cyanide ion and sulphuric ion producing thiocyanate in the tailing which enhancing the environmental problem. A new polymeric inclusion membrane (PIM) has been developed to extract thiocyanate from acid to neutral solution. PIM was produced by diluting PVC as base polymer, trioctylamine (TOA) and tetraoctyl methyl ammonium chloride (TOMAC) as carriers, and 1-decanol as plasticizer in tetrahydrofurane (THF) as solvent. Thiocyanate concentration was measured based on the formation of Fe(III)-thiocyanate complex at 457 nm. As a result, thiocyanate could be extracted up to 42% using PIM technique with composition (w/w) 70% PVC, 15% TOMAC as carrier, and 15% 1-decanol as plasticizer. Feed phase was contained of 80 mg/L thiocyanate solution at pH 4. Stripping phase was contained of sodium chloride solution of 1.0 M

Plasma Level of MicroRNAs, MiR-107, MiR-194 and MiR-210 as Potential Biomarkers for Diagnosis Intestinal-Type Gastric Cancer in Human

Background:Timely and sensitive diagnosis of gastric cancer is crucial for efficient treatment and survival of the patients. microRNAs have been considered as diagnostic biomarkers in different type of cancers including gastric cancer. In the present study, the expression profile of four microRNAs, miR-103, miR-107, miR-194 and miR-210 were evaluated in patients with intestinal-type of gastric cancer (IGC) in order to assess their diagnosis utility as noninvasive biomarkers.Methods:A total number of 100 plasma samples from patients with gastric cancer and healthy controls were obtained and total RNA was extracted using a commercial monophasic solution of phenol and guanidium thiocyanate. Reverse transcription (RT) reactions were performed by specific stem-loop RT primers and M-MuLV RT-enzyme. The expression patterns of microRNAs were assessed using reverse transcription quantitative real-time PCR (RT-qPCR) method and the expression of SNORD47 RNA was used as the reference for normalization.Results:The results indicate that the plasma levels of miR-107, miR-194, and miR-210 were significantly lower in patients. Receiver operating characteristic (ROC) curve analysis showed that the patients could be distinguished from healthy individuals at the cutoff levels of 0.504, 0.266, and 0.394 of miR-107, miR-194, and miR-210, respectively. On the other hand, the expression levels of these miRNAs were not significantly different in different clinicopathological stages of the disease.Conclusion:These findings suggest that the plasma levels of miR-107, miR-194 and miR-210 were downregulated in patients with ICG and propose these molecules as potential non-invasive biomarkers for detection of IGC.

Heat Capacity and Volume Properties of Ammonium Thiocyanate in N-Methylpyrrolidone Solution at 298.15 K

The heat capacity and volumetric properties of ammonium thiocyanate solutions in N-methylpyrrolidone are measured at 298.15 K by calorimetric and densimetric means. Concentration dependences of the partial and apparent molar heat capacities and volumes of the investigated systems are discussed. The standard partial molar heat capacity and volume of NH4CNS, and the standard heat capacity and volume of ammonium and thiocyanate ions in N-methylpyrrolidone at 298.15 K are calculated.

Structure of Polyacrylonitrile Fibers Produced from N-Methylmorpholine-N-Oxide Solutions

Structural and morphological evolution of polyacrylonitrile (PAN) samples from starting powder of a ternary copolymer to fibers produced from concentrated solutions of PAN in N-methylmorpholine-N-oxide (NMMO) was studied using x-ray diffraction for the first time. X-ray exposures in transmission and reflection geometries allowed the structures of outer and inner parts of the PAN fibers to be differentiated. It was shown that a shell—core structure formed in the precipitation bath during fiber spinning. A comparison of x-ray diffraction patterns of fibers spun using the NMMO process and industrial samples spun from DMSO and aqueous sodium thiocyanate solutions did not reveal fundamental structural differences.

Guanidine thiocyanate solution facilitates sample collection for plant rhizosphere microbiome analysis.

The interactions between rhizosphere microorganisms and plants are important for the health and development of crops. Analysis of plant rhizosphere bacterial compositions, particularly of those with resistance to biotic/abiotic stresses, may improve their applications in sustainable agriculture. Large-scale rhizosphere samplings in the field are usually required; however, such samples, cannot be immediately frozen. We found that the storage of samples at room temperature for 2 days leads to a considerable reduction in the operational taxonomic unit (OTU) number and the indices of bacterial alpha-diversity of rhizosphere communities. In this study, in order to overcome these problems, we established a method using guanidine thiocyanate (GTC) solution for the preservation of rhizosphere samples after their collection. This method allowed the maintenance of the samples for at least 1 day at room temperature prior to their cryopreservation and was shown to be compatible with conventional DNA isolation protocols. Illumina sequencing of V3 and V4 hypervariable regions of the 16S rRNA gene was used to assess the feasibility and reliability of this method, and no significant differences were observed in the number of OTUs and in the Chao and Shannon indices between samples stored at −70 °C and those stored in GTC solution. Moreover, the representation of Pseudomonas spp. in samples stored in GTC solution was not significantly different from that in samples stored at −70 °C, as determined by real-time quantitative polymerase chain reaction (p > 0.05). Both types of samples were shown to cluster together according to principal coordinate analysis. Furthermore, GTC solution did not affect the bacterial taxon profiles at different storage periods compared with those observed when storing the samples below −70 °C. Even incubation of thawed samples (frozen at −70 °C) for 15 min at room temperature induced minor changes in the bacterial composition. Taken together, our results demonstrated that GTC solution may provide a reliable alternative for the preservation of rhizosphere samples in the field.

Layer-by-layer MoS2:GO composite thin films for optoelectronics device applications

With reference of our previous report (Appl. Surf. Sci. 474(2019)227), the molybdenum disulphide (MoS2) thin film were prepared by the dip-coating technique at different temperatures (400 °C–450 °C) using methanolic solution of ammonium molybdate and ammonium thiocyanate that are used as bare-substrate for the deposition of graphene oxide (GO) thin films. For the deposition of graphene oxide (GO), commercially purchased GO (0.5 mg in 10 mL aqueous solution) was deposited by dip-coating technique on dip-deposited MoS2 thin film to make layer-by-layer MoS2:GO composite thin films and hence studied their electronic and electrical behaviours. The micro-structural and surface morphology were studied using Raman spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy, whereas optical band estimated from the optical absorption spectra. The electronic structure and their bonding properties were studied using X-ray photoelectron spectroscopy and the electrical behaviours were observed from the current-voltage (I-V) characteristic curve. The formation of different phases of MoS:GO thin films show an enhanced electronic and electrical performance due to their unique-structure and the synergetic effect of MoS2:GO nanosheets when compared to those of bare MoS2.

The electrochemical dissolution of single silver nanoparticles enlightened by hyperspectral dark-field microscopy

Nowadays, silver nanoparticles are extensively employed in several branches of industry and medicine. Hence, those particles are amongst the most studied class of nanomaterials, yet their reactivity and in particular their reactivity in biological systems is still poorly understood. This discrepancy leads to a huge demand for further insights into the reaction dynamics of electrochemical reactions. For this purpose, coupled opto- and spectro-electrochemical dark-field microscopy is used herein to study the electrochemical oxidation and dissolution process of individual silver nanoparticles in thiocyanate solutions. It is observed, that upon electrochemical oxidation of silver, a silver thiocyanate complex is formed. This is indicated by a change of both the measured plasmon resonance frequency and scattering intensity, simultaneous to the detection of an oxidative current. Subsequently, this silver pseudo-halide is chemically converted to a silver thiocyanate complex with higher solubility in the presence of high thiocyanate concentrations. This follow-up reaction is only detectable thanks to in situ spectroscopy as no current is associated with this chemical conversion but a distinct change in the spectroscopy response of the individual particles is seen. We were thus able to reveal that the total conversion of silver nanoparticles in the presence of thiocyanate is a multi-step process which lasts much longer than the electrochemical response suggests.