Cyanide Ion In Aqueous Solution Research Articles

Simple colorimetric chemodosimeters for selective sensing of cyanide ion in aqueous solution via termination of ICT transition by Michael addition

Three simple ferrocene based chemodosimeters for cyanide ion in aqueous solution have been prepared by one step condensation of commercially available starting materials and characterized spectroscopically. The receptors were designed in such a way that the intra molecular charge transfer (ICT) transition existing between the donor (ferrocene) and acceptor (cyano olefine) moieties imparts an intense pink color to the receptors (logɛ=2.92–3.06). The results of UV–vis, fluorescence and 1H and 13C NMR spectral studies indicated that the sensing mechanism involves Michael addition of CN− to the electropositively polarized C-atom of the CC bond. Such an addition reaction leads to “turn-off” of ICT transition and thus leading to a striking color change from pink to colorless. The observed variation in the electrochemical reduction potential (Epc) for the reduction of ferrocene moiety and the formation constants of the 1:1 receptor–CN− ion complexes could be explained using the Taft's polar substituent constants (σ*) of the substituents attached to the acceptor moiety. Moreover, the test strips fabricated using these receptors could instantaneously sense cyanide ion present in aqueous NaCN solution.

Monolayer molecular probes for detection of trace amounts of cyanide anions

A monolayer sensor M-P1 is developed for detection of cyanide ions in aqueous solution. The monolayer sensor has high sensitivity and selectivity, and is very efficient for detecting trace amounts of analytes in dilute solution.

Adsorption of cyanide ions in aqueous solution using raw and oxidized coke

The objective of this study was the use of raw and modified coke material for the adsorption of cyanide ions (CN−) in water. The surface functions of this material (carboxyl, lactones, phenol, and carbonyl) were modified by oxidation with sulfuric acid, nitric acid, and KMnO4 solution at varying concentrations. This chemical surface treatment improved the adsorption capacity. The experimental results of adsorbent/adsorbate equilibrium show that the adsorption isotherms follow the Freundlich model and the kinetic adsorption follows the pseudo-second-order model. Overall, coke material oxidized by KMnO4 has shown the best adsorption of CN− ions with an adsorption capacity qe = 1.28 mg g−1 at T = 20°C and pH 11.

Highly selective colorimetric/fluorometric chemodosimeters for cyanide ions in aqueous solution based on Michael addition to C-atom possessing different polar substituents

Two simple chemosensors, 3-(4-aminophenyl)-2-cyanoacrylic acid (1) and 3-(3-aminophenyl)-2-cyanoacrylic acid (2), exhibited visual colour and fluorescence changes selectively with cyanide ions in aqueous solution. Their anion sensing properties were investigated using UV–vis, fluorescence and 1H &13C NMR spectral studies and theoretical studies. The mechanism of sensing involves Michael addition of CN− to CC bond. The addition reaction was found to occur relatively easier with p-NH2C6H4 group (Taft’s σ∗ 0.16) substituted CC bond than that with m-NH2C6H4 group (σ∗ 0.58) substituted compound. The detection limits were calculated to be 33pM and 0.2nM for the receptors 1 and 2, respectively, which are lower than the maximum permissible concentration of cyanide ion in drinking water (1.9μM) set by the World Health Organization (WHO).

Pure zinc sulfide quantum dot as highly selective luminescent probe for determination of hazardous cyanide ion

A rapid and simple fluorescence method is presented for selective and sensitive determination of hazardous cyanide ion in aqueous solution based on functionalized zinc sulfide (ZnS) quantum dot (QD) as luminescent prob. The ultra-small ZnS QDs were synthesized using a chemical co-precipitation method in the presence of 2-mercaptoethanol (ME) as an efficient capping agent. The prepared pure ZnS QDs was applied as an optical sensor for determination of cyanide ions in aqueous solutions. ZnS nanoparticles have exhibited a strong fluorescent emission at about 424nm. The fluorescence intensity of QDs is linearly proportional to the cyanide ion concentration in the range 2.44×10−6 to 2.59×10−5M with a detection limit of 1.70×10−7M at pH11. The designed fluorescent sensor possesses remarkable selectivity for cyanide ion over other anions such as Cl−, Br−, F−, I−, IO3−, ClO4−, BrO3−, CO32−, NO2−, NO3−, SO42−, S2O42−, C2O42−, SCN−, N3−, citrate and tartarate with negligible influences on the cyanide detection by fluorescence spectroscopy.

A naphtholic Schiff base for highly selective sensing of cyanide via different channels in aqueous solution

A simple CN− sensor bearing a naphthol and an imine group was designed and synthesized, which showed both a colorimetric and a fluorescence turn-on response for cyanide ions in aqueous solution. The probe shows an immediate visible change in color from yellow to orange which then becomes colorless followed by a final change to pink, when cyanide is added; these color changes can be readily observed visually. The mechanism of the reaction of the probe with the cyanide ion was established by using 1H NMR and FT-IR spectroscopy and mass spectrometry. Moreover, test strips based on the sensor were fabricated, which could act as a convenient and efficient CN− test kit.

Highly sensitive and selective cyanide ion sensor based on modified ZnS nanoparticles

In this paper, we demonstrate the fabrication of a highly sensitive, selective, reproducible and reliable amperometric sensor for cyanide ion in aqueous solutions based on PEG modified ZnS nanoparticles (NPs). The fabricated cyanide ion sensor exhibits a very high and reproducible sensitivity of ∼79.7μAcm−2nM−1 with a response time less than 2s and a detection limit of 0.177×10−6molL−1, which is ∼16 times lower than maximum value of cyanide (2.7×10−6molL−1) permitted by the World Health Organization (WHO) in drinking water. Moreover, various amperometric responses of some common interfering ions (Cl−, Br−, NO3−, SO42− and CO32−) have also been recorded which confirm that the fabricated sensor is highly selective. This work demonstrates a simple, easy and promising technique for the detection of highly toxic and deadly cyanide ion in aqueous medium.

A specific sensing ensemble for cyanide ion in aqueous solution

A specific two-component ensemble probe has been designed and developed to detect cyanide ion in aqueous solution. It is comprised water-soluble fluorescence dye HPTS and boronic acid functionalized quencher/receptor TB3PB. The nucleophilic addition of cyanide ion to boronic acid groups of TB3PB yields an intramolecular complex which will weaken the electrostatic interaction of TB3PB and HPTS, and as a result, the fluorescence of HPTS recovers largely.

Highly selective chemodosimeter for cyanide based on a doubly activated Michael acceptor type of coumarin thiazole fluorophore

A doubly activated Michael acceptor type of coumarin thiazole fluorophore ( 1) was prepared and applied for the detection of cyanide ions in aqueous solution. The chemodosimeter exhibited a highly selective and sensitive response to cyanide over other various anions through the Michael addition of cyanide to 1. Upon the addition of cyanide ions, the apparent color and fluorescence changes of 1 were observable with a detection limit of 2.3 μM of the cyanide anions in aqueous solution.

Highly sensitive carbon paste electrode with silver-filled carbon nanotubes as a sensing element for determination of free cyanide ion in aqueous solutions

We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing element in ion-selective carbon paste electrodes for the determination of free cyanide in aqueous solution. The electrode was obtained by entrapping the silver-filled nanotubes into a carbon paste and displays a Nernstian response with a slope of 59.8 ± 0.3 mV decade−1, a very wide linear range (from 21.0 nM to 0.1 M of cyanide), a lower detection limit of 13.0 nM, and a response time of <2 min. The operational lifetime is up to 3 months without significant deviation in normal function.

A gold nanoparticle-based colorimetric sensing ensemble for the colorimetric detection of cyanide ions in aqueous solution

A colorimetric sensing ensemble was prepared by mixing readily prepared adenosine triphosphate (ATP)-stabilized AuNPs with Cu 2+–phenanthroline complexes. The sensing mechanism of the ensemble was examined by UV–vis spectrometry and transmission electron microscopy. The studies showed that the Cu 2+–phenanthroline complex was converted to free phenanthroline when exposed to cyanide anions and the free phenanthroline caused the ATP-stabilized AuNPs to aggregate, which in turn, resulted in a visible color change in the AuNP solution. The ensemble could detect cyanide ions in aqueous solution at physiological pH, either spectrophotometrically or visually, with high selectivity toward cyanide anions over a range of mono- and di-anions commonly found in biological and environmental systems. This sensing ensemble also allows a quantitative assay of the analyte in a neutral aqueous solution, down to a concentration of 10 −5 M.

Simple photometric determination of free cyanide ion in aqueous solution with 2,6-dichlorophenolindophenol

Abstract In this work, a simple photometric method with high accuracy and precision for measuring trace amounts of free cyanide ion in aqueous solution is demonstrated. Under the evaluated conditions, we could determine CN− concentration in the range of 5–70 ppm easily. The work is based upon the photometric titration of CN− with Co(II) in the presence of 2,6-dichlorophenolindophenol (DCPIP) at λmax = 602 nm in aqueous solution. The optimal conditions, such as pH, ionic strength, and concentration of chromopher were evaluated. The interence effect of many other cations and anions studied and the results are given here. The optimized titration was successfully used to determine the concentration of free cyanide ion in aqueous solutions.

Cyanide ions transport from aqueous solutions by using quaternary ammonium salts through bulk liquid membranes

Extraction experiments were carried out to determine the suitable solvent and carrier type. Five different solvents and carriers were used and verified. Trichloromethane and tetraoctyl ammonium chlorides were found to be the most appropriate solvent and carrier type for this study. The coupled transport of cyanide ions in aqueous solutions through bulk liquid membrane (BLM) was investigated using various stirring speeds and temperatures. Cyanide ion transport through BLM technique was analyzed according to coupled non-steady state kinetics of two consecutive irreversible first order reactions. The influences of the kinetic parameters ( k 1 d , k 2m , k 2a , R m max, t max, J d max, J a max) for the various stirring speeds in the system were established. The removal and recovery efficiencies of the cyanide ions transported from aqueous solutions in 360 min were 99.4 and 82%, respectively. As the stirring speed was increased, both the efficiency of transport and recovery of cyanide ions from aqueous solutions were increased. On the other hand, for maximum membrane entrance ( J d max) and exit ( J a max) fluxes the activation energies were calculated as 21.6 kcal/mol and 10.5 kcal/mol, respectively.

Photocatalytic oxidation of cyanide ions by alkoxy-derived titanium oxide coatings

Nano-porous titanium oxide coatings were produced on titanium of commercial purity by anodization in methanolic electrolytes. The structure of the oxide was found to be amorphous. Following heat-treatment at 400°C for 20 min the amorphous oxide crystallized and was transformed into anatase. Application of this coating as a catalyst for the destruction of cyanide ions in aqueous solutions under ultraviolet radiation was investigated. The effects of process parameters, such as oxide crystallinity (amorphous versus anatase), ultraviolet intensity and oxygen exposure, on the rate of cyanide destruction were studied. Anatase exhibited superior photocatalytic activity to the amorphous form of TiO2. The poor activity of amorphous TiO2 was attributed to the recombination of photo-excited electrons and holes at defects located on the surface and in the bulk of the coatings. As expected, oxygen was found to play a critical role in the destruction of the cyanide.

A molecular dynamics study of the vibrational energy relaxation of the cyanide ion in aqueous solution

A molecular dynamics study of the vibrational energy relaxation of the cyanide ion in aqueous solution has been accomplished by applying normal mode analysis to our recently derived influence functional theory for multi-phonon processes where both the solute and solvent were treated quantum mechanically. It was found that two-phonon coupling between two rotational librational modes of water molecules and the coupling between the bending and rotational librational modes are mostly responsible for the relaxation. The calculated relaxation time, based upon Fermi's golden rule, gave the same order of relaxation time as the experimental one.

Dissociation kinetics of [Fe(phen)3]2+, [Fe(bipy)3]2+ and [Fe-(4,4?-Me2bipy)3]2+ in the presence of cyanide ion in aqueous solution at pressures up to 1 kilobar

Rate constants for dissociation, in aqueous solution at 25° C, of [Fe(phen)3]2+, [Fe(bipy)3]2+, and [Fe(4,4′-Me2bipy)3]2+ in the presence of cyanide, and of the last-named complex also in the presence of hydroxide, are significantly decreased by the application of pressure (up to 1 kbar). Kinetic measurements were carried out using a high pressure cell of improved design to that used in our earlier investigations. Volumes of activation, ΔV*, are scarcely sensitive to ligand or to attacking nucleophile, being in the range of 10–12 cm3 mol−1. An explanation of these results resides in an associative mechanism, a scheme invoked for similar reactions reported previously.

Determination of microgram amounts of cyanide by the induced iodine-azide reaction with the use of sodium tetrathionate

The iodine-azide reaction induced by sulphur(−II) compounds was applied to the determination of cyanide ions in aqueous solution. The method is based on the conversion of cyanide by an excess of tetrathionate into thiosulphate and thiocyanate followed by the determination of the products by the iodine-azide reaction. The method allows the determination of 0.05 μg of cyanide in a 5-ml sample.

The effect of copper and iron complexation on removal of cyanide by ozone

not detected during ozonation of iron-cyanide complex. Complete destruction of free cyanide ion in aqueous solution has been reported unanimously by numerous re- searchers (Gurol and Bremen, 1985; Rowley and Otto, 1980; Zeelvalkink et al., 1979; Matsuda et al., 1975a,b; Balyanskii et al., 1972; Sondak and Dodge, 1961a,b; Khandelwal et al., 1959; Selm, 1959; Walker and Zabban, 1953). However, there is disagreement as to the effects of metal complexation

Vibrational energy relaxation of the cyanide ion in aqueous solution

Vibrational energy relaxation (T1) of the CN− ion is reported for NaCN in saturated H2O/D2O and dilute H2O solutions at room temperature. Time domain measurements of the v = 1, 2080 cm−1 vibration shown T1 is on the order of a few picoseconds. The relaxation time increases with dilution and is apparently sensitive to cation (Na+,K+) and local solution structure.

Kinetic and equilibrium study of the reaction of meso-tetra (4-N-methylpyridyl) porphinediaquochromium (III) with thiocyanate and cyanide ions in aqueous solution

Abstract The reactions of CN − and NCS − with meso-tetra(4 - N - methylporphinediaquochromium(III), CrP(H 2 O) 2 5+ , have been studied at different temperatures in the pH range 1–13. The kinetic and equilibrium properties are adequately described by the following scheme: The values of pK a 1 at 25°C are 6.74 and 10.66 respectively. The values of k 1 , k −1 , k 2 and k −2 for NCS − and of k 2 and k −2 for CN − have been determined at three different temperatures. The values of ΔH ∗ and ΔS ∗ for all the reactions have also been determined. ΔS ∗ was negative for all the reactions. The presence of the porphine and specially the presence of the porphine and the OH − ligands in the complex greatly labilizes chromium (III) toward substitution.