Showing papers on "Cyanide published in 2016"

A naked-eye chemosensor for simultaneous detection of iron and copper ions and its copper complex for colorimetric/fluorescent sensing of cyanide

Abstract: A new prototype of multifunctional chemosensor 1 has been synthesized for Fe2+/3+, Cu2+ and CN− in aqueous solution. This sensor could simultaneously detect biologically important metal ions (iron and copper) through colorimetric methods over most other competitive cations. The detection limit (2.9 μM) of 1 for Cu2+ is lower than WHO guideline (31.5 μM) in drinking water. Interestingly, the resulting 1-Cu2+ complex sensed cyanide in colorimetric and fluorometric ways, showing recovery from 1-Cu2+ to 1, over other common interference anions. These results demonstrate a novel type of versatile chemosensor for multiple target ions using two different sensing methods, simple colorimetric and sequential detections.

Chemical Inhibition Method to Synthesize Highly Crystalline Prussian Blue Analogs for Sodium-Ion Battery Cathodes

Abstract: The nucleation rate plays a critical role in the synthesis of Prussian blue analogs Rapid precipitation may lead to a large number of vacancies and a large amount of interstitial water in the material, resulting in poor electrochemical performance in batteries Hence, sodium citrate is used to compete with [Fe(CN)6]4– to slow down the coordination rates of Ni2+ and Mn2+ ions with ferrous cyanide ions The feasibility of the experiment is also confirmed by theoretical analysis Benefiting from stable crystal structure and the removal of interstitial water, the as-prepared Na2NixMnyFe(CN)6 sample exhibits a high reversible capacity of 150 mA h g–1 In addition, a high rate performance of 77 mA h g–1 is achieved at a current density of 1600 mA g–1 Most noteworthy, the Coulombic efficiency and specific capacity gradually increase in the first few cycles, which can be ascribed to the formation of a passivation layer on the surface of the electrode Continuous testing in an electrolyte solution of 1 M NaPF6 d

A Post-Synthetically Modified MOF for Selective and Sensitive Aqueous-Phase Detection of Highly Toxic Cyanide Ions.

Abstract: Selective and sensitive detection of toxic cyanide (CN(-) ) by a post-synthetically altered metal-organic framework (MOF) has been achieved. A post-synthetic modification was employed in the MOF to incorporate the specific recognition site with the CN(-) ion over all other anions, such as Cl(-) , Br(-) , and SCN(-) . The aqueous-phase sensing and very low detection limit, the essential prerequisites for an effective sensory material, have been fulfilled by the MOF. Moreover, the present detection level meets the standard set by the World Health Organization (WHO) for the permissible limit of cyanide concentration in drinking water. The utilization of MOF-based materials as the fluorometric probes for selective and sensitive detection of CN(-) ions has not been explored till now.

A highly selective and sensitive fluorescent chemosensor for detection of CN−, SO32− and Fe3+ based on aggregation-induced emission

Abstract: A novel fluorescence chemosensor 1 with aggregation-induced emission was designed and synthesized through a nucleophilic addition reaction between cyanide and triphenylamine. It exhibited remarkable selectivity and high sensitivity and was able to detect Fe3+, CN− and SO32− in almost pure aqueous solution with low detection limits of 1.44 μM, 9.88 nM and 0.107 μM, respectively. Job's plot and 1H NMR data showed that the binding stoichiometry of 1 with Fe3+, CN− or SO32− was 1:1. Further observations of 1H NMR titration suggested that a coordination bond was formed between two cyano of 1 and Fe3+ which resulted in fluorescence quenching of 1 after detection of Fe3+, whereas the nucleophilic addition of cyanide or sulfite to the vinyl group was responsible for the fluorescent quenching of CN− or SO32− toward 1. The biological applications of 1 were also evaluated and it was found to exhibit low cytotoxicity and membrane permeability. In addition, 1 could also be made into test strips to detect Fe3+ and CN− and was employed as a sensor for detection Fe3+ in living cells.

Selective Detection of Cyanide in Water and Biological Samples by an Off-the-Shelf Compound

Abstract: The simple off-the-shelf chemical 6,7-dihydroxycoumarin (1) based copper complex (1·Cu2+) has been used for the selective detection of toxic cyanide in aqueous medium. The DFT calculation confirms the binding behavior between 1 and Cu2+ (2:1) and the red shift in the UV–vis spectrum with copper ion was confirmed by the decrease in energy between HOMO–LUMO band gaps. The cyanide sensing in water was confirmed by both absorption and emission spectral studies. Cyanide ion showed 13-fold increments in fluorescent intensity in emission spectrum via displacement of copper from 1·Cu2+. The limit of detection of CN– in water is 5.77 μM; 1·Cu2+ also applicable for the detection of cyanide in fresh mouse serum with detection limit of 14.4 μM. The cell images showed that 1·Cu2+ could be used to detect intracellular CN–.

Organic chemodosimeter for cyanide : A nucleophilic approach

Abstract: Out of the all anions cyanide is one of the most threaten for environmental and social system and abundance of cyanide in environment generate not only from industrial waste but also from the biological process of fungai and algae. It has very much toxic effect, after a certain limit it may cause to death. The interest for qualitative and quantitative detection of cyanide is growing on. Detection rely on the change in absorption and emission properties of probe upon binding with cyanide is important because of its simple analysis technique. Cyanide is a good nucleophile and this property can be very much useful to develop organic probes to detect its presence. Here this review deals with the organic chemodosimetric probes for cyanide, more specifically the detection mechanism is driven by the nucleophilic attack of cyanide ion to the probe. Discussed organic probes are divided into some classes according to their structural features and functional group present in the probe.

Adsorption of cyanide from aqueous solution using calcinated eggshells: Equilibrium and optimisation studies

Abstract: Eggshells were calcined and used to adsorb cyanide from its aqueous solution. X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier Transform Infra-red (FTIR) and Scanning Electron Microscope (SEM) were used to characterize both raw and calcined eggshell (CE) while UV spectrophotometer was used to monitor the cyanide concentration. The XRD and FTIR showed the conversion of CaCO3 to CaO. Batch adsorption experiments were carried out using 10 ml each of 0.01 mol/L to 0.05 mol/L cyanide solutions at different contact times, and adsorbent dosages. To establish optimum adsorption conditions, Central Composite Design (CCD) in Response Surface Methodology (RSM) was employed using the time, concentration and adsorbent dosages as variables at a fixed pH of 7. Adsorption efficiency of 84.53% was obtained with 0.01 mol/L, 8.98 g of calcined eggshell at 26.58 min contact time using RSM. Pseudo second order kinetic model best fitted the experiment. The coefficients of determination of Langmuir and Freundlich isotherms were 0.988 and 0.650 respectively, with Langmuir isotherm giving a better fit for the adsorption. The maximum monolayer adsorption capacity from Langmuir isotherm was 3.27 mg/g at pH 7 and a temperature of 30 °C

Simultaneous removal of phenol and cyanide from aqueous solution by adsorption onto surface modified activated carbon prepared from coconut shell

Abstract: The present study is devoted to the elimination of phenol and cyanide from binary component aqueous solution by adsorption onto copper impregnated coconut shell activated carbon (Cu-CSAC). Effects of initial concentration, adsorbent dose, pH, temperature and contact time on phenol and cyanide elimination have been examined. At an optimum temperature 30 °C, pH 8, and the adsorbent dose of 40 g/L, 71.43% phenol and 86.8% cyanide were removed from binary aqueous solution comprising 300 mg/L of phenol and 30 mg/L of cyanide. The isotherm modeling study is carried out by accompanying batch experiments at range of initial concentration 100–1000 mg/L of phenol and 10–100 mg/L of cyanide. Three mono component isotherm model and six binary component isotherm models were considered. The model parameters were predicted by using non-linear regression analysis technique. It was observed that the experimental data indicate a better fit with an Extended Freundlich isotherm model for adsorption of phenol and cyanide in the binary component system. The adsorption efficiency of Cu-CSAC was observed to be 239.85 mg/g of phenol and 5.30 mg/g of cyanide. The mechanism of adsorption process was found chemisorption followed by Pseudo second order kinetics. Thermodynamic studies indicated the adsorption process onto Cu-CSAC as endothermic nature and reversible.

Two copper(i) cyanide coordination polymers modified by semi-rigid bis(benzimidazole) ligands: syntheses, crystal structures, and electrochemical and photocatalytic properties.

Abstract: Two Cu(i) cyanide coordination polymers (CPs), namely, [Cu2(L1)(CN)2]n (1) and [Cu2(L2)(CN)2]n (2) (L1 = 4,4'-bis(2-methylbenzimidazol-1-ylmethyl)biphenyl, L2 = 4,4'-bis(5,6-dimethylbenzimidazol-1-ylmethyl)biphenyl) were synthesized and structurally characterized by single crystal X-ray diffraction, IR spectroscopy, X-ray powder diffraction and elemental analysis. The cyanide ligands in these CPs are generated in situ from the C-C bond cleavage of acetonitrile under solvothermal conditions, which is environmentally friendly and used conveniently. CP 1 features a three-fold interpenetration 3D framework consisting of Cu10(CN)6(L1)4 rings, which represents the first investigation on introducing bis(benzimidazole) ligands into copper(i) cyanide CPs with ThSi2 topology, while CP 2 exhibits a two-dimensional (6,3) layered structure containing Cu6(CN)4(L2)2 rings. The thermal stabilities, and photoluminescence and electrochemical behavior in the solid state of CPs 1 and 2 have been investigated in detail. Moreover, both CP 1 and CP 2 manifest promising photocatalytic activities (photodegradation efficiency using CP 1 is 90.8% and using CP 2 is 87.2%) for the degradation of methylene blue (MB) under UV light irradiation. A possible photocatalytic mechanism is suggested by introducing t-butyl alcohol (TBA) as a widely used ˙OH scavenger.

Bioavailability of cyanide after consumption of a single meal of foods containing high levels of cyanogenic glycosides: a crossover study in humans.

Abstract: The acute toxicity of cyanide is determined by its peak levels reached in the body. Compared to the ingestion of free cyanide, lower peak levels may be expected after consumption of foods containing cyanogenic glycosides with the same equivalent dose of cyanide. This is due to possible delayed and/or incomplete release of cyanide from the cyanogenic glycosides depending on many factors. Data on bioavailability of cyanide after consumption of foods containing high levels of cyanogenic glycosides as presented herein were necessary to allow a meaningful risk assessment for these foods. A crossover study was carried out in 12 healthy adults who consumed persipan paste (equivalent total cyanide: 68 mg/kg), linseed (220 mg/kg), bitter apricot kernels (about 3250 mg/kg), and fresh cassava roots (76–150 mg/kg), with each “meal” containing equivalents of 6.8 mg cyanide. Cyanide levels were determined in whole blood using a GC–MS method with K13C15N as internal standard. Mean levels of cyanide at the different time points were highest after consumption of cassava (15.4 µM, after 37.5 min) and bitter apricot kernels (14.3 µM, after 20 min), followed by linseed (5.7 µM, after 40 min) and 100 g persipan (1.3 µM, after 105 min). The double dose of 13.6 mg cyanide eaten with 200 g persipan paste resulted in a mean peak level of 2.9 µM (after 150 min). An acute reference dose of 0.075 mg/kg body weight was derived being valid for a single application/meal of cyanides or hydrocyanic acid as well as of unprocessed foods with cyanogenic glycosides also containing the accompanying intact β-glucosidase. For some of these foods, this approach may be overly conservative due to delayed release of cyanide, as demonstrated for linseed. In case of missing or inactivated β-glucosidase, the hazard potential is much lower.

The β-cyanoalanine synthase pathway: beyond cyanide detoxification.

Abstract: Production of cyanide through biological and environmental processes requires the detoxification of this metabolic poison. In the 1960s, discovery of the β-cyanoalanine synthase (β-CAS) pathway in cyanogenic plants provided the first insight on cyanide detoxification in nature. Fifty years of investigations firmly established the protective role of the β-CAS pathway in cyanogenic plants and its role in the removal of cyanide produced from ethylene synthesis in plants, but also revealed the importance of this pathway for plant growth and development and the integration of nitrogen and sulfur metabolism. This review describes the β-CAS pathway, its distribution across and within higher plants, and the diverse biological functions of the pathway in cyanide assimilation, plant growth and development, stress tolerance, regulation of cyanide and sulfide signalling, and nitrogen and sulfur metabolism. The collective roles of the β-CAS pathway highlight its potential evolutionary and ecological importance in plants.

A highly sensitive and selective cyanide detection using a gold nanoparticle-based dual fluorescence–colorimetric sensor with a wide concentration range

Abstract: In this study, a simple analytical system is presented for the detection of cyanide with a wide concentration range, which is respectively based on the fluorescent and colorimetric properties of gold nanoparticles. This dual-functional system can work directly for aqueous medium and expand efficiently a wide detection range over three orders of magnitudes for cyanide determination. By using the fluorescence method, the lowest concentration for quantification of cyanide ions is 1.0 × 10 −7 M, and the sensitivity is good enough for the determination of cyanide in drinking water. To recognize higher concentration of cyanide for industrial sewage monitoring, the colorimetric behavior can be used as an alternating tool for field tests from naked eye. The system also provides an excellent selectivity toward cyanide over other common interfering anions and metal ions, thus enabling the ability to monitor cyanide contamination in environmental samples. Furthermore, several real water samples spiked with cyanide, including local tap water, drinking water, lake water, and sea water, were analyzed, and the experimental results demonstrated that this sensing system exhibited excellent recoveries for these practical water samples. Our attempt may provide a cost-effective, rapid and simple solution for the recognition and determination of different levels of cyanide contamination in aqueous samples.

Highly selective colorimetric/fluorometric dual-channel sensor for cyanide based on ICT off in aqueous solution

Abstract: Herein a cyanide sensor has been synthesized and evaluated by UV–vis and fluorescent method. This sensor is based on a conjugated pyrene–benzothiazol system, which was found to show rapid response, high selectivity and sensitivity for cyanide anions with significant dual colorimetric and fluorescent signal changes in aqueous solution. A large blue shift was also observed in the absorption spectra in response to CN − . The bleaching of the color could be clearly observed by the naked eye. By the nucleophilic attacking of CN − to the benzothiazol C N bond of the sensor, the intramolecular charge transfer progress was blocked with both color and fluorescence changes. The mechanism of the reaction of the sensor with the cyanide ion was established by using 1 H NMR and mass spectrometry.

Cytogenotoxic Effects of Spent Pot Liner (SPL) and Its Main Components on Human Leukocytes and Meristematic Cells of Allium cepa

Abstract: The Spent Pot Liner (SPL) is a toxic solid waste from the aluminum industry. The genotoxic potential of SPL and its main chemical components (fluoride, cyanide, and aluminum) were evaluated on vegetal (Allium cepa L. system test) and human cells (comet assay) in the present study. Meristematic cells from A. cepa submitted to the treatments presented a reduction in the mitotic index (MI) and an increase in the frequency of chromosome alterations (CA). The SPL treatment reduced MI in 50 % when compared to the negative control. In addition, there were significant reductions in MI on the cyanide and aluminum treatments. All frequencies of chromosome alterations observed to the treatments were statistically different from control, and cyanide was the most cytogenotoxic component. The exposed cells to the treatments also increased the frequency of condensed nuclei. The comet assay on human leukocytes demonstrated that all treatments induced DNA fragmentation. Fluoride and SPL showed similar damages to the positive control (doxorubicin, UA = 259.7) and higher than the negative control (CaCl2 0.01 M, UA = 16.5). The aluminum induced intermediary damage, and the cyanide was responsible for minor damage. In conclusion, both SPL and its main components presented genotoxic and mutagenic potential on evaluated cells. Fluoride was the main genotoxic component for human leukocytes while cyanide leads the higher alterations for A. cepa meristematic cells. Thus, the storage and discard of this residue should be regulated and supervised more closely in order to reduce the risk of environmental pollution and its contact with human.

A Highly Selective Chemosensor for Cyanide Derived from a Formyl-Functionalized Phosphorescent Iridium(III) Complex

Abstract: A new phosphorescent iridium(III) complex, bis[2′,6′-difluorophenyl-4-formylpyridinato-N,C4′]iridium(III) (picolinate) (IrC), was synthesized, fully characterized by various spectroscopic techniques, and utilized for the detection of CN– on the basis of the widely known hypothesis of the formation of cyanohydrins. The solid-state structure of the developed IrC was authenticated by single-crystal X-ray diffraction. Notably, the iridium(III) complex exhibits intense red phosphorescence in the solid state at 298 K (ΦPL = 0.16) and faint emission in acetonitrile solution (ΦPL = 0.02). The cyanide anion binding properties with IrC in pure and aqueous acetonitrile solutions were systematically investigated using two different channels: i.e., by means of UV–vis absorption and photoluminescence. The addition of 2.0 equiv of cyanide to a solution of the iridium(III) complex in acetonitrile (c = 20 μM) visibly changes the color from orange to yellow. On the other hand, the PL intensity of IrC at 480 nm was dramatic...

Photocatalytic degradation of methyl orange and cyanide by using TiO2/CuO composite

Abstract: In this study, the effect of adding 5–12.5 wt% CuO to TiO2 on photocatalytic properties of the nano-composite TiO2/CuO was investigated. The products were characterized by X-ray diffractometer, SEM, Brunauer–Emmett–Teller (BET), and DRS. BET-specific surface area of the TiO2/CuO composites was lower than that of the pure TiO2. Incorporation of CuO into TiO2 shifted absorption spectra to the visible region. As the CuO content increased from 0 to 12.5%, a clear decrease in optical band gap from 2.95 to 2.30 eV was observed. The photocatalytic performance was determined by methyl orange degradation and cyanide photo-oxidation under ultraviolet irradiation. However, the excessive incorporation of CuO did not improve any ability of TiO2 to degrade MeO and cyanide. The highest rate of photocatalytic degradation was found in TiO2–7.5% CuO. The rate constants of the dye degradation reaction using TiO2 and TiO2–7.5% CuO catalysts were 0.0107 and 0.0151 min−1, respectively. Corresponding results for cyanide...