Potassium Cyanide Solution Research Articles

Silver(I) recovery on thiomorpholine - modified functional polymer

The functional polymer containing heterocyclic ligands was synthesized by microwave modification of a crosslinked poly(vinylbenzyl chloride–divinylbenzene) matrix with thiomorpholine. The modification yield was 89.3%. The sorbent was used to recover Ag(I) from the synthetic and real chloride solutions. The maximum sorption capacity of Ag(I) was approximately 180 mg Ag/g. The sorption kinetic data were well-fitted to the pseudo-first-order kinetic model. The degree of silver desorption was approximately 50.0% using a 1.0% potassium cyanide solution in a 0.50% hydrogen peroxide solution. The resin retained its capacity toward Ag(I) in five consecutive sorption/desorption cycles. The thiomorpholine modified resin was highly selective toward Ag(I) in relation to Cu(II), Pb(II), Co(II), Ni(II), and Zn(II) from the real chloride leaching solution.

Low-temperature crystallization of LaFeO3 perovskite with inherent catalytically surface for the enhanced oxygen evolution reaction

This study reports a facile and economic method for LaFeO3 perovskite crystallization process at low temperature range from 300 °C to 500 °C and an outstanding oxygen evolution reaction (OER) catalyst based on inherent catalytically surface. As a key material for low temperature synthesis, cyanogel-peroxo-complex as a metastable molecular precursor was synthesized via ligand exchange using potassium cyanide solution to provide superoxo (O2–) ligand to Fe-CN-La gel structure, leading to a high degree of crystallinity with ideal ABO3 stoichiometry at low temperatures (400 ∼ 500 °C). Electrocatalysts based on LaFeO3 nanoparticles were fabricated, showing an outstanding OER performance with low overpotential of ∼ 438 mV at 100 mA/cm2 and small Tafel slope of 61 mV·dec–1 under alkaline conditions, better than commercialized available IrOx/C catalysts. Its OER performance is attributed to the inherent oxygen-deficient layer at the surface created at low temperature (300 °C). Long-term stability test shows no significant change (< 1%) in the potential during 50 h, indicating a high stability of such catalysts.

Preparation of Zinc Cyanide and Elimination of Free Alkali in Cyanide

Zinc cyanide can be prepared by double decomposition reaction of sodium cyanide or potassium cyanide with zinc chloride. Before the preparation of zinc cyanide, it is necessary to remove the free alkali in the raw material sodium cyanide or potassium cyanide. Magnesium chloride is used to remove the free alkali in sodium cyanide or potassium cyanide. The concentration of cyanide ion in potassium cyanide solution under different conditions is measured. The results show that magnesium chloride can not only remove the original free alkali in potassium cyanide, but also promote the hydrolysis of potassium cyanide to produce new free alkali and react with it to form new precipitate. By analyzing the components of the precipitate, it is determined that the main components in the precipitation are Mg(OH)2 and MgCO3. The final conclusion: after the free alkali in cyanide is removed by magnesium chloride, the solution must be quickly put into the double decomposition reaction to reduce the further loss of cyanide ion; In the preparation of zinc cyanide, the adding order needs to be noted: the cyanide aqueous solution must be added into the zinc chloride solution to ensure the excess of zinc chloride.

Functionalized Cellulose‐Co(II)‐Bis‐Terpyridine Hybrid Material as Colorimetric Sensor for Micromolar Aqueous Cyanide

AbstractA novel surface modification approach is taken to cyanide‐sensing by using functionalized cellulose surface that is chemically modified by immobilizing cobalt(II)‐bis‐terpyridine complex on it. The cobalt(II)‐bis‐tpy complex can exhibit selective “naked eye” colorimetric detection of micromolar level cyanide in aqueous solution, where the visible red‐orange color of cobalt(II)‐bis‐tpy complex solution (aqueous) disappears in the presence of cyanide ions. In order to make the sensor more proficient and easy to use, these cobalt(II)‐bis‐tpy molecules are chemically grafted on the surface of microcrystalline cellulose and cellulose paper, which turns the color of functionalized cellulose orange‐red. Both of these colored cellulose powder and paper exhibit color loss in 10−6m aqueous solution of potassium cyanide. This functionalized hybrid inorganic–organic paper offers an easy “dip and detect” cyanide sensing.

Electroless copper plating of tungsten powders and preparation of WCu20 composites by microwave sintering

In the present work, tungsten powders coated with copper by electroless plating method, and preparation of WCu20 composites by microwave sintering with copper-coated tungsten powder as raw material. The result shows that at the situation of a temperature of 60 °C, pH value of 12–13, with formaldehyde solution (53 ml/L) as reducing agent, iron potassium cyanide solution (0.3 g/L) as stabilizer, tartaric acid potassium sodium (15 g/L) and EDTA-2Na (19 g/L) mixture solution as compound complexing agent, the thickness of surface coating was relatively uniform, which is around 0.6–1.1 μm. The WCu20 composites were fabricated by microwave sintering with copper-coated tungsten powder as raw material shows uniform microstructure distribution, relatively high density. The hardness of the WCu20 composites increased with the temperature. While the temperature of sintering at 1100 °C for 1 h, the density could be up to 15.22 g/cm3, relative density was 97.13%, which shows better properties.

Can excreted thiocyanate be used to detect cyanide exposure in live reef fish?

Cyanide fishing, where a solution of sodium or potassium cyanide is used to stun reef fish for easy capture for the marine aquarium and live fish food trades, continues to be pervasive despite being illegal in many countries and destructive to coral reef ecosystems. Currently, there is no easy, reliable and universally accepted method to detect if a fish has been exposed to cyanide during the capture process. A promising non-invasive technique for detecting thiocyanate ions, the metabolic byproduct excreted by exposed fish, has been reported in the literature. In an effort to validate this method, four cyanide exposure studies on Amphiprion ocellaris (common clownfish) were carried out over three years. Fish were either exposed to the same (25 ppm) or twice the concentration (50 ppm) as the previsouly published method. Over 100 water samples of fish exposed to cyanide were analyzed by reverse phase HPLC with a C30 column treated with polyethylene glycol and UV detector operating at 220 nm. No thiocyanate was detected beyond the analytical standards and positive controls prepared in seawater. As an alternate means of detecting thiocyanate, water samples and thiocyanate standards from these exposures were derivatized with monobromobimane (MBB) for LC-MS/MS analysis. Thiocyanate was detected in standards with concentrations as low as 0.6 μg/L and quantified to 1 μg/L, but thiocyanate could not be detected in any of the water samples from fish exposed to cyanide with this method either, confirming the HPLC results. Further, we calculated both the mass balance of thiocyanate and the resultant plausible dosage of cyanide from the data reported in the previously published method. These calculations, along with the known lethal dosage of cyanide, further suggests that the detection of thiocyanate in aquarium water is not a viable method for assessing fish exposure to cyanide.

Determination of cobalt species in nutritional supplements using ICP-OES after microwave-assisted extraction and solid-phase extraction

Cobalt content (as vitamin B12 and inorganic cobalt) in two nutritional supplements, namely Spirulina platensis and Saccharomyces cerevisiae known as a “superfood”, has been determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Several sample pre-treatment protocols have been applied and compared. Microwave-assisted acid digestion efficiently decomposed all cobalt-containing compounds, thus allowed obtaining total cobalt content in supplements examined. Vitamin B12 was extracted from the samples with acetate buffer and potassium cyanide solution exposed to mild microwave radiation for 30 min, and cyanocobalamin was separated from the extract by on-column solid phase extraction using C-18 modified silica bed. About 100% of cobalt species was extracted using the triple microwave-assisted extraction procedure. Total cobalt content was 20-fold greater in Spirulina tablets than the declared cobalamin content (as Co). The ICP-OES method precision was about 3% and detection limit was 1.9 and 2.7 ng Co mL−1 for inorganic cobalt or cyanocobalamin, respectively.

A novel extraction method for the preparation of heparinized chicken (Gallus gallus domesticus) and horse (Equus caballus) whole blood for 1H-NMR metabolomics using Drabkin’s reagent

Despite the ease of collection, heparinized whole blood (HWB) is underutilized in 1 H-NMR-based metabolomics particularly because of the lack of sample homogeneity. Drabkin’s reagent (DR), an aqueous solution of potassium ferricyanide, potassium cyanide, and sodium bicarbonate, causes hemolysis and has been used for quantification of hemoglobin. The objectives of this study were to determine if the use of DR with HWB for metabolomics samples would result in consistent hemolysis, while being invisible to 1 H-NMR and quenching metabolic activity. HWB from a chicken ( Gallus gallus domesticus ) and a horse ( Equus caballus ) was used. All HWB samples were mixed 1:10 volume:volume HWB:DR. Spectrophotometric evaluation of incubated DR treated samples revealed little change in absorbance after approximately 10-15 min incubation at room temperature (20-21 °C); all following samples were incubated for 10 min, except where noted. Samples subjected to five repeated extractions with DR showed a decrease in absorbance of >95% after the first extraction; all subsequent samples were extracted with a single aliquot of DR. Lyophilized DR rehydrated with a 100% deuterium oxide solution was invisible to 1 H-NMR. Standard (10 min incubation, 20 min centrifugal filtration) and delayed (120 min incubation, 20 min centrifugal filtration) samples were prepared for both species and did not appear considerably different upon visual inspection with the exception of minor differences in the major peaks of the metabolites 3-methylhistidine and betaine in the chicken samples. Comparison of standard and delayed samples via two-sample Kolmogorov-Smirnov tests found no significant differences with either species (chicken p = 1, horse p = 0.9887). Use of DR resulted in consistent, complete hemolysis, while being invisible to 1 H-NMR and quenching metabolic activity for at least 140 min at room temperature. This protocol should be considered when HWB is the only sample type available and/or if the investigator is interested in questions specific to erythrocyte metabolism.

Potassium Cyanide and the Effect on the Rate of Decomposition of Mice in Grave-Soil

As a body decomposes, a multitude of physiochemical changes occur that are interdependent on physical factors including temperature, humidity and pH, and victim characteristics such as weight, clothing and ante-mortem pathology. One aspect that has not been investigated is to what extent poisons such as cyanides have on a decomposing cadaver. Cyanides are used extensively throughout industry from mining to electroplating, and found in some fruits. They have also been used to commit murders and suicides. Therefore, it is necessary to determine whether cyanide has any effect on the rate of decomposition of a body buried in a soil environment as well as to assess whether overall mass loss is a viable post-mortem interval estimation method. One hundred dead house mice (Mus. musculus) were weighed and then intragastrically injected with doses of 0, 5000, 10000, 20000 and 30000 parts per million (ppm) potassium cyanide solution. The mice were then buried in separate containers of 300g top soil. Five M. musculus samples were randomly assigned to one of four Day Removal Categories (DRCs). The removal categories were 7,14,21 and 30 days after initial burial. In each DRC, the mice were removed, cleaned, photographed, characterised using a scoring system developed by Megyesi et al. [1] and then weighed again. A percentage change was calculated between the initial and removal masses. Statistical analysis was conducted using Levene Test, oneway ANOVA and Welch F-Test. Results suggested that potassium cyanide concentration was not statistically significant to the overall rate of decomposition observed, however photographs and decompositional scoring suggested there was a localised effect observed by an increased concavity of the stomach and abdominal areas. Critical analysis deemed mass loss an unviable post-mortem interval estimation tool due to a dependence on numerous factors, many of which are lost at the time of death.

Reduction of secondary phases in Cu2SnSe3 absorbers for solar cell application

The creation of secondary phases, such as Cu2−xSe and SnSe, and their influence on electrical properties of Cu2SnSe3 (CTSe) thin films fabricated by selenization of Cu–Sn metal precursors are investigated. The Cu2−xSe content in CTSe films is estimated via deconvolution of grazing incidence X-ray diffraction (GIXRD) patterns, and the results suggest that the Cu2−xSe content increases with the increasing Cu/Sn ratio in metal precursors. We also found that using Se and SnSe mixture powders as Se source is an effective approach to suppress the creation of Cu2−xSe secondary phase. Meanwhile, selective etching of Cu2−xSe is realized by potassium cyanide (KCN) solution. Hall measurement results reveal that the secondary phase of Cu2−xSe rather than SnSe makes major contribution to the high carrier concentration (larger than 1018cm−3) of CTSe films. The approach to further decrease the carrier concentration in CTSe films is discussed.

Electronic effects of Cd on the formation of the CdS/CuInS2 heterojunction

The possibility of doping and Fermi level pinning of CuInS2 thin layer solar cell absorbers caused by the diffusion of Cd into the absorber during junction formation via chemical bath deposition was investigated. The analysis of thin CdS layers deposited on CuInS2 showed the amount of deposition-induced band bending on the CuInS2 surface (position of the Fermi level in the respective bandgaps) was not experimentally reproducible. However, the value of the valence band offset between the two materials was reproducible between different depositions within the error of the measurement. Thus, the deposition of the CdS does not lead to a consistent pinning position of the Fermi level in the CuInS2/CdS heterojunction. The removal of the CdS layers with HCl left a thin Cd-containing layer on the CuInS2 surface and it was shown that this surface was not doped by the remaining Cd. Furthermore, the influence of the HCl of the CuInS2 was explored and found to form a reproducible surface richer in Cu than CuInS2 etched in potassium cyanide solution.

Influence of the surface roughness of silver halide fibers on their transmission in the near infrared

Silver halide crystals are highly transparent from the visible to the mid-infrared, but fibers extruded from these crystals have low transmission in the near infrared in the spectral range 1–3μm. We found that this low transmission is partly due to surface roughness and that it can be highly improved by treatment with potassium cyanide solution. Using the Rayleigh criteria for a simple planar waveguide model, we showed that the attenuation due to surface roughness is theoretically dependant on the square of the roughness and on the inverse square of wavelength. Experimentally, the measured surface attenuation indeed follows this behavior. The reduced attenuation in the near infrared is crucial, especially for applications such as the development of silver halide fiber lasers.

On-line chemical vapour generation of cadmium in the presence of hexacyanochromate(iii) for determination by inductively coupled plasma mass spectrometry (ICP-MS)

A vapour generation (VG) procedure has been described for determination of Cd by ICP-MS. Volatile species of Cd were generated on-line by interacting acidic sample solution containing potassium hexacyanochromate(III), K3Cr(CN)6, with sodium borohydride (NaBH4). The hexacyanochromate(III) complex was generated on-line by reacting 0.04 mol L-1 chromium(III) nitrate and 0.16 mol L-1 potassium cyanide (KCN) solutions in water. The resulting suspension of chromium(III) hydroxide, Cr(OH)3, was fed continuously to acidic stream of sample solution in the presence of excess KCN. The experimental conditions were optimized for effective generation of volatile species of Cd. Optimum signals were obtained from reaction of sample solutions in 4% v/v HCl with 2% m/v NaBH4 solution. Presence of K3Cr(CN)6 improved the efficiency of Cd vapour generation substantially affording 15-fold higher sensitivity. This phenomenon was thought to occur through formation of reactive intermediates evolved from interaction of [Cr(CN)6]3- with NaBH4 that react with Cd(II) to increase the yield volatile Cd species. Under the optimum conditions, no significant interferences were observed from the transition metals, including Cu and Ni, up to 1.0 μg mL-1 levels. Among the hydride forming elements, Bi, Pb, Sb and Sn depressed the signals above 0.1 μg mL-1. The detection limits (3s) were 6.2 and 5.2 ng L-1 for 110Cd and 111Cd isotopes, respectively. The method was successfully applied to determination of Cd by ICP-MS in several certified reference materials, including Nearshore seawater (CASS-4), Bone ash (SRM 1400), Dogfish liver (DOLT-4) and Mussel tissue (SRM 2976).

The Uptake of Gold(I) from Ammonia Leaching Solution by Imidazole Containing Polymeric Resins

The polymeric resins containing guanylthiourea, 1-methylimidazole, 2-mercapto-1-methylimidazole ligands have been synthesized from vinylbenzyl chloride-divinylbenzene copolymers and used in the removal of Au(I) from ammonium buffer and ammoniacal thiosulphate solutions. The best gold sorption from ammonium buffer that contains 100 g/dm3 NH3 · H2O and 5 g/dm3 (NH4)2SO4, is reached in the case of 1-methylimidazole resin (2) (27.9 mg/g) and all three resins do not have a measurable sorption of copper(II) ammine complexes. The resins display a higher affinity towards gold(I) from ammoniacal thiosulphate solutions than from the ammonium buffer solution. The XPS analysis of gold loaded resins suggests the presence of gold at Au(I) oxidation state, most likely in the form of ionic pair Au(NH3)2 +OH− or neutral complex AuNH3OH and as highly-dispersed metallic gold. The degree of gold desorption is about 50% using 1% potassium cyanide solution in 0.3% hydrogen peroxide solution. Resins retain their capacity towards gold in five consecutive sorption/desorption cycles.

Sensitive determination of total aliphatic amines in water samples by spectrofluorimetry using the new fluorogenic probe 3-(4-fluorobenzoyl)-2-quinolinecarboxaldehyde

A rapid and highly sensitive fluorogenic method has been developed for the determination of total primary aliphatic amines with a novel fluorogenic derivatizing reagent, 3-(4-fluorobenzoyl)-2-quinolinecarboxaldehyde (FBQCA). FBQCA selectively reacts with amines to form a highly fluorescent isoindole in buffer of pH 9.7 and in the presence of potassium cyanide solution. The fluorescence intensity of derivatized products are detected at λex/λem = 480/546 nm. The results of the experiments showed a linear dynamic range of 1 × 10−8 to 6 × 10−6 mol L−1 with a detection limit (S/N = 3) of 6 nmol L−1. The method was successfully used for the direct spectrofluorimetric determination of aliphatic amines in water samples with recoveries of 95–104%.

Optimization of a new resin, Amberlyst 36, as a solid‐phase extractor and determination of copper(II) in drinking water and tea samples by flame atomic absorption spectrometry

A new simple and reliable method has been developed to separate and preconcentrate trace copper ion in drinking water and tea samples for subsequent measurement by flame atomic absorption spectrometry (FAAS). The copper ions are adsorbed quantitatively during passage of aqueous solutions through Amberlyst 36 cation exchange resin. After the separation and preconcentration stage, the analyte was eluted with a potassium cyanide solution and determined by FAAS. Different factors including pH of sample solution, sample volume, amount of resin, flow rate of aqueous solution, volume and concentration of eluent, and matrix effects for preconcentration were examined. The analytical figures of merit for the determination of copper are as follows: analytical detection limit (3 sigma), 0.26 microg/L; precision (RSD), 3.1% for 100 microg/L; enrichment factor, 200 (using 1000 mL of sample solution and 5 mL of eluent); time of analysis, 3.5 h (for obtaining enrichment factor of 200); capacity of resin, 125 mg/g. The method was applied for copper determination by FAAS in tap water, commercial natural spring water, commercial treated drinking water, and commercial tea bag sample. The accuracy of the method is confirmed by analyzing tea leaves (GBW 07605). The results demonstrated good agreement with the certified values.

Removal of copper and nickel contaminants from Si surface by use of cyanide solutions

The cleaning method using cyanide solutions has been developed to remove heavy metals such as copper (Cu) and nickel (Ni) from Si surfaces. Immersion of Si wafers with both Cu and Ni contaminants in potassium cyanide (KCN) solutions of methanol at room temperature decreases these surface concentrations below the detection limit of total reflection X-ray fluorescence spectroscopy of ∼3×10 9 atoms/cm 2. UV spectra of the KCN solutions after cleaning of the Cu-contaminated Si surface show that stable copper-cyanide complexes are formed in the solution, leading to the prevention of the re-adsorption of copper in the solutions. From the complex stability constants, it is concluded that the Cu(CN) 4 3− is the most dominant species in the KCN solutions.

Access to a novel niobium octahedral cluster core via soft chemistry: synthesis and structure of K 2.6Cs 3.4[Nb 6Cl 4O 4(OH) 4(CN) 6]·3H 2O containing isolated Nb 6Cl i4O i4(OH) i4(CN) a6 cluster unit

The synthesis and the structure of K 2.6Cs 3.4[Nb 6Cl 4O 4(OH) 4(CN) 6]·3H 2O are described in the present work. It has been obtained by the interaction of Cs 2Ti 3Nb 12Cl 27O 8 oxychloride with an aqueous solution of potassium cyanide. The crystal structure—determined by single crystal X-ray diffraction at room temperature (monoclinic, C2/ c, a=13.4336(3) Å, b=15.9281(3) Å, c=15.9619(3) Å, β=90.2177(9)°, V=3415.3(1) Å 3, Z=4)—is built from a novel (Nb 6O i 4(OH) i 4Cl i 4) cluster core which exhibits for the first time four hydroxyl groups in addition to four chlorine and four oxygen atoms in inner position; six apical CN ligands complete the coordination of the Nb 6 cluster. Structural and electronic properties of this unit are discussed by comparison with other niobium oxychlorides and oxides based on (Nb 6Cl 12− x O x ) n+ cluster core.

Exploring the structure of a hydrogen cyanide polymer by electron spin resonance and scanning force microscopy.

Aqueous solutions of potassium cyanide and ammonium hydroxide are known to yield a heterogeneous cyanide polymer, containing paramagnetic sites and biologically significant substructures including polypeptides. Here, such solutions were used to prepare various samples of polymer for study by X-band and W-band electron spin resonance (ESR), scanning electron microscopy (SEM), and scanning force microscopy (SFM). Elemental composition of a typical sample of the polymer was C-35.2%, N-38.47%, 0-14.51%, and H-4.13%, exposing the polymer to 6M HCl hydrolyzed portions of the polymer and released glycine and traces of other amino acids. The X-band ESR spectra consist of a single slightly asymmetric line centered at g = 2.003; spin concentration measurements made at X-band using a nitroxide radical standard yield approximate radical concentrations of 10(18) spins/gm. W-band ESR indicates the presence of a single rhombic paramagnetic site with g(x) = 2.0025, g(y) = 2.0030, and g(z) = 2.0048 and the possibility of small 14N hyperfine splittings. The ESR spin echo studies yield a longitudinal relaxation time, Tl of 75 microS and a short-phase memory relaxation time, Tm, of about 300 nS. Scanning electron microscopy studies of the polymer show that it is made of ellipsoidal particles about one micron in size. The particles tend to clump together when suspended in aqueous solution. The particles disperse and dissolve in dimethyl sulfoxide (DMSO); when these solutions dry on microscope slides, optical microscopy shows a branched island morphology for the polymer. This morphology is reminiscent of snowflakes and is identified as dendritic. Phase contrast SFM of the dendritic arms show a striking segregation and ordering of various components of the polymer. Paramagnetic sites are conserved in the series of steps leading to dendritic structures.

Kinetics of Anodic Dissolution of Gold in Cyanide Solutions Containing Bismuth Hydroxy Compounds

Effective values of order of the reaction of the gold dissolution process by cyanide ions p, transfer coefficient α, and exchange current i0 are measured at constant values of the coverage of the gold surface by bismuth adatoms θ. The constancy of θ is ensured by maintaining a constant value of the time t during which the electrode is in contact with solution after the renewal of its surface until the instant of taking measurements. The solutions under study contain 2.5 × 10–6 to 7 × 10–6 M bismuth hydroxy compounds, 0.1 M KCN, 0.01 M KAu(CN)2, and 0.1 M KOH. With increasing t, quantities p, α, and i0 increase from 0.17, 0.1, and 10–5 A cm–2, respectively, which are the values typical for the gold dissolution process in plain potassium cyanide solutions, to p ≅ 1.1, α ≅ 0.45, and i0 ≅ 2 × 10–4 A cm–2. The increase in the quantity p by approximately a unity is interpreted as an evidence in favor of the assumption that the presence of bismuth adatoms alters the nature of the limiting stage: the latter starts involving cyanide ions localized outside an adsorption layer, rather than the adsorbed cyanide ions only, as is the case in plain solutions. A comparison of obtained results with the data of similar investigations performed earlier in thallium- and lead-containing solutions shows that possible mechanism of acceleration of anodic process suggested in the previous works may be used for explaining regularities of the gold dissolution process observed in the presence of bismuth adatoms as well.