Showing papers on "Cyanide published in 2002"
TL;DR: In this paper, two separate fixed bed modified activated carbon columns were used; TBA-carbon column for cyanide removal and SDDC-column for multi-species metal ion removal.
617 citations
TL;DR: This work represents the first example of a direct method for the luminescence lifetime-based sensing of anions for fluoride and cyanide anions.
Abstract: A new Ru(II) complex is described which serves as a luminescence lifetime-based sensor for fluoride and cyanide anions (KF = 640 000 mol-1, KCN = 430 000 mol-1). This chromophore displays observable changes in its UV−vis and steady-state luminescence spectra upon cyanide binding. Prior to cyanide addition, this complex exhibits a single-exponential lifetime (τ = 377 ± 20 ns). With increasing cyanide concentrations, the intensity decays are composed of two exponentials: long τ (320−370 ns) and short τ (13−17 ns). The average lifetimes shorten as a function of cyanide concentration since the fractional intensity shifts from an initial dominant long lifetime component to the short lifetime component. This work represents the first example of a direct method for the luminescence lifetime-based sensing of anions.
433 citations
TL;DR: A chromogenic reagent for cyanide determination in water based on the reaction of this anion with a squaraine derivative functionalized with ether chains has been developed.
218 citations
TL;DR: In this article, a general method has been developed for determination of the total cyanide content of all cyanogenic plants and foods, including cassava roots and cassava products, flax seed, bamboo shoots and cyanide containing leaves.
215 citations
TL;DR: In this paper, the photocatalytic activity of the CuO loaded TiO 2 catalysts was measured to determine their ability to oxidize cyanide, and it was found that the rate of photooxidation of cyanide assisted with the doped catalyst was improved slightly at 0.10 at.% Cu.
160 citations
TL;DR: In this paper, the authors evaluate treatment strategies involving some indigenous adsorbents and a low-cost chelating agent for treatment of a simulated wastewater containing copper and zinc, complexed with cyanide.
150 citations
TL;DR: In this article, the impregnated activated carbons were packed in fixed bed columns and used for cyanide removal from aqueous solutions and the adsorbed capacity was monitored from the breakthrough, which indicates that the carbon is not longer adsorbing effectively.
Abstract: Impregnated activated carbons are carbonaceous adsorbents which have silver and nickel distributed on their surface. The impregnation optimises the existing properties of the activated carbon giving greater cyanide removal capacity to the carbon. This facilitates the cost-effective removal of cyanide impurities from aqueous effluent. The adsorption isotherms of the impregnating elements (Ag and Ni) from aqueous solutions on plain activated carbon was measured. The amount of adsorbed silver on plain carbon reached 45.7 mg g−1 carbon and for nickel was 4.3 mg g−1 carbon. These impregnated materials were packed in fixed bed columns and used for cyanide removal from aqueous solutions. The adsorbed capacity was monitored from the breakthrough, which indicates that the carbon is not longer adsorbing effectively. The results indicates that carbon–Ag impregnation was shown to have a cyanide removal capacity of nearly two times that of carbon–Ni impregnation and of four times that of plain activated carbon. These suggest that cyanide was probably eliminated in the forms Ag(CN)2− and Ni(CN)4 complexes. However, calcination of impregnated activated carbon under nitrogen at 300°C showed similar results to impregnated non-calcinated ones.
138 citations
TL;DR: It was concluded that NF‐κB‐mediated up‐regulation of Bcl‐XS and Bax is involved in regulating cytochrome c release in cyanide‐induced apoptosis.
Abstract: Cyanide induces apoptosis through cytochrome c activated caspase cascade in primary cultured cortical neurons. The underlying mechanism for cytochrome c release from mitochondria after cyanide treatment is still unclear. In this study, the roles of endogenous Bcl-2 proteins in cyanide-induced apoptosis were investigated. After cyanide (100–500 µm) treatment for 24 h, two pro-apoptotic Bcl-2 proteins, Bcl-XS and Bax were up-regulated as shown by western blot and RT-PCR analysis. The expression levels of two antiapoptotic Bcl-2 proteins, Bcl-2 and Bcl-XL, remained unchanged after cyanide treatment, whereas the mRNA levels of Bcl-XS and Bax began to increase within 2 h and their protein levels increased 6 h after treatment. NF-κB, a redox-sensitive transcription factor activated after cyanide treatment, is responsible for the up-regulation of Bcl-XS and Bax. SN50, which is a synthetic peptide that blocks translocation of NF-κB from cytosol to nucleus, inhibited the up-regulation of Bcl-XS and Bax. Similar results were obtained using a specific κB decoy DNA. NMDA receptor activation and reactive oxygen species (ROS) generation are upstream events of NF-κB activation, as blockade of these two events by MK801, l-NAME or PBN inhibited cyanide-induced up-regulation of Bcl-XS and Bax. Up-regulation of pro-apoptotic Bcl-XS and Bax contributed to cyanide-induced cytochrome c release, because SN50 and a specific Bax antisense oligodeoxynucleotide significantly reduced release of cytochrome c from mitochondria as shown by western blot analysis. It was concluded that NF-κB-mediated up-regulation of Bcl-XS and Bax is involved in regulating cytochrome c release in cyanide-induced apoptosis.
113 citations
TL;DR: In this article, a batch photoreactor with immersed lamp was used for treating aqueous suspensions containing polycrystalline TiO2 powders irradiated in the near-UV region.
Abstract: The ozonization and the heterogeneous photocatalytic method are contemporarily applied for the oxidation of free cyanide ions. A batch photoreactor with immersed lamp was used for treating aqueous suspensions containing polycrystalline TiO2 powders irradiated in the near-UV region. Air or ozone–air mixtures were used as oxidation reactants. At the used experimental conditions, the photoreaction proceeds at a measurable rate until low values of cyanide concentration. In the presence of ozone (O3) several parallel reaction routes are contributing to the overall cyanide degradation: (i) homogeneous oxidation by ozone; (ii) heterogeneous catalytic reaction by ozone; (iii) photocatalytic degradation with oxygen; and (iv) photocatalytic degradation with ozone. The rate of cyanide oxidation by heterogeneous photocatalytic mechanism is enhanced by ozone with respect to that observed in the presence of neat oxygen. A kinetic model based on Langmuir–Hinshelwood equations describes adequately the photoreactivity results and provides the values of the kinetic constants and equilibrium adsorption constants for the catalytic and photocatalytic reactions contributing to cyanide oxidation. In order to gain further information on the interaction of ozone with TiO2 surfaces, either in the dark or under UV-irradiation, an ESR study has been also carried out. The results indicate that ozone strongly interacts with TiO2, leading mainly to the formation of ozonide radicals.
110 citations
TL;DR: In this paper, a critical literature survey was conducted to examine the stability constants of copper cyanide species and the equilibrium potentials of these species depend on the mole ratio of cyanide to copper, total cyanide concentration, pH and temperature.
90 citations
TL;DR: Experiments conducted with cyanide addition to the medium to assess whether the enzymes were induced in the presence of cyanide failed to show any statistically significant increase, which suggests a constitutive nature of both the enzymes in all the selected strains of Trichoderma used in this study.
Journal Article•
TL;DR: This case shows pseudolaminar necrosis along the central cerebral cortex 3 weeks after cyanide poisoning, showing that the sensorimotor cortex is also a site for toxic necrosis because of its high oxygen dependency.
Abstract: We describe MR changes that occurred 3 and 6 weeks after a suicide attempt with cyanide. The toxicity of cyanide causes damage, primarily to the basal ganglia, and those changes were visible as altered signal intensity on the first MR images. Extensive areas of hemorrhagic necrosis were seen 6 weeks later. Our case shows pseudolaminar necrosis along the central cerebral cortex 3 weeks after cyanide poisoning, showing that the sensorimotor cortex is also a site for toxic necrosis because of its high oxygen dependency.
TL;DR: All data unequivocally show a linear geometry and that the carbon of cyanide is bound to copper with a Cu-C distance of 1.82962(4) A in the r(m)((2)) structure, which is likely to be closest to the equilibrium geometry.
Abstract: Copper(I) cyanide is an important reagent in organic, organometallic, and supramolecular chemistry because of both the copper center and the versatile cyanide ligand. Solid-phase CuCN and many of its derivatives show oligomeric or polymeric structures, a trait shared by other metal cyanides. Often, it is difficult to specify the orientation of the cyano ligand in an X-ray structure. Here the first preparation and precise structure of a monomeric transition metal cyanide is reported. Gas-phase reaction between copper vapor and cyanogen (NCCN) clearly gives CuCN (not CuNC). The precise structure of CuCN so produced is determined by millimeter/submillimeter-wave spectroscopy. Because of the highly efficient synthesis and the presence of significant amounts of two copper isotopes, such strong signals were seen that natural-abundance materials allowed observation of transitions for the four isotopomers (63)Cu(12)C(14)N, (65)Cu(12)C(14)N, (63)Cu(13)C(14)N, and (63)Cu(12)C(15)N and the determination of r(o), r(s), and r(m)((2)) structures. All data unequivocally show a linear geometry and that the carbon of cyanide is bound to copper with a Cu-C distance of 1.82962(4) A in the r(m)((2)) structure, which is likely to be closest to the equilibrium geometry.
TL;DR: It is concluded that AN metabolism to CEO is a prerequisite for cyanide formation, and this pathway is exclusively catalyzed by CYP2E1.
Abstract: Acrylonitrile (AN) is a rodent carcinogen and suspected human carcinogen. Metabolism of AN proceeds via conjugation with glutathione or epoxidation via cytochrome P4502E1 (CYP2E1) to cyanoethylene oxide (CEO). It was hypothesized that CEO metabolism via epoxide hydrolase (EH) is the primary pathway for cyanide formation. The objective of this work is to assess the enzymatic basis of metabolism to cyanide. Male wild-type and CYP2E1-null mice received 0, 2.5, 10, 20, or 40 mg of AN/kg by gavage, and cyanide was measured in blood and tissues. CYP2E1 and EH expression were assessed using Western blot analyses. Present results demonstrated that cyanide concentrations in blood and tissues of AN-treated wild-type mice were higher at 1 versus 3 h, increased in a dose-dependent manner, and were significantly higher in AN-treated versus vehicle-treated mice. In contrast, cyanide concentrations in the blood and tissues of AN-treated CYP2E1-null mice were not statistically different from those of vehicle-treated mice. Furthermore, this work showed that EH is expressed in CYP2E1-null and wild-type mice. In conclusion, under the current experimental conditions using CYP2E1-null mice, current work demonstrated for the first time that CYP2E1-mediated oxidation is a prerequisite for AN metabolism to cyanide. Since earlier studies showed that CYP2E1 is the only enzyme responsible for AN epoxidation, it is concluded that AN metabolism to CEO is a prerequisite for cyanide formation, and this pathway is exclusively catalyzed by CYP2E1. Finally, this work confirmed that cyanide plays an essential role in the causation of the acute toxicity/mortality of AN.
TL;DR: A (salen)titanium catalyst has been found to induce the asymmetric addition of potassium cyanide and acetic anhydride to aldehydes, giving enantiomersically enriched cyanohydrin esters with up to 92% enantiomeric excess using just 1 mol% of the catalyst.
TL;DR: Acremonium strictum, capable of degrading 7.4 g thiocyanate l−1, was isolated from wastewater condensate from coke-oven gas.
Abstract: Acremonium strictum, capable of degrading 7.4 g thiocyanate l−1, was isolated from wastewater condensate from coke-oven gas. Ammonia and sulfate were the final products from thiocyanate degradation with a stoichiometric ratio of near 1:1. The highest degradation activity was at pH 6. Although the degradation rate started to be inhibited above 4 g thiocyanate l−1, thiocyanate was completely degraded up to 7.4 g l−1 within 85 h in shake-flask cultures. The degradation of thiocyanate was inhibited by phenol above 625 mg l−1, by cyanide above 16 mg l−1, and by nitrite above 100 mg l−1. However, ammonia and nitrate had negligible inhibition on thiocyanate degradation up to 3 g l−1 and 1.5 g l−1, respectively.
TL;DR: The decrease in E degrees ' of the Fe3+/Fe2+ couple on cyanide binding turns out to be a fullyEntropic effect, unequivocally demonstrating the importance of entropic effects in determining the E degrees " values of redox metal centers.
Abstract: The thermodynamics of Fe3+ to Fe2+ reduction for the five-coordinate high-spin native form of horseradish peroxidase and for its six-coordinate low-spin cyanide adduct have been determined from variable-temperature UV−vis spectroelectrochemical experiments. In both cases, the ΔH°‘rc and ΔS°‘rc values are positive. Hence, the negative reduction potentials turn out to be the result of two opposing and partially compensating contributions: a large enthalpic term, which is the determinant of the negative E°‘ values for both species, and a smaller, yet relevant, entropic contribution. The decrease in E°‘ of the Fe3+/Fe2+ couple on cyanide binding turns out to be a fully entropic effect, unequivocally demonstrating the importance of entropic effects in determining the E°‘ values of redox metal centers.
TL;DR: In this paper, a systematic investigation of the electrochemical oxidation of copper cyanide was carried out, and the transition point between low and high pH as a function of cyanide and copper concentrations was discussed.
TL;DR: The purpose of this work was to characterize the extent of leaching of cyanides and fluorides from SPL, as a function of the number of years the material was present in an operating electrolytic cell, and there did not appear to be a correlation between the fractions of fluoride and cyanide leached from the samples and the operating life of the potliner materials.
Journal Article•
TL;DR: In this article, the authors developed a sensitive, rapid, simple, and fully automated method for measuring cyanide in whole blood, which is based on the use of gas chromatography (GC) with nitrogen-phosphorus detection and acetonitrile as an internal reference.
TL;DR: Octahedral coordination of molybdenum(III) is achieved by limiting the amount of cyanide available upon complex formation, resulting in the strongest antiferromagnetic coupling yet observed through a cyanide bridge.
Abstract: Octahedral coordination of molybdenum(III) is achieved by limiting the amount of cyanide available upon complex formation. Reaction of Mo(CF3SO3)3 with LiCN in DMF affords Li3[Mo(CN)6]·6DMF (1), featuring the previously unknown octahedral complex [Mo(CN)6]3-. The complex exhibits a room-temperature moment of μeff = 3.80 μB, and assignment of its absorption bands leads to the ligand field parameters Δo = 24 800 cm-1 and B = 247 cm-1. Further restricting the available cyanide in a reaction between Mo(CF3SO3)3 and (Et4N)CN in DMF, followed by recrystallization from DMF/MeOH, yields (Et4N)5[Mo2(CN)11]·2DMF·2MeOH (2). The dinuclear [Mo2(CN)11]5- complex featured therein contains two octahedrally coordinated MoIII centers spanned by a bridging cyanide ligand. A fit to the magnetic susceptibility data for 2, gives J = −113 cm-1 and g = 2.33, representing the strongest antiferromagnetic coupling yet observed through a cyanide bridge. Efforts to incorporate these new complexes in magnetic Prussian blue-type solids...
TL;DR: Cyanide-induced necrosis of MC cells involved generation of excessive amounts of nitric oxide and superoxide accompanied by mitochondrial depolarization, whereas cyanide causes a lower level of oxidative stress in CX cells, and a moderate change in mitochondrial membrane potential that lead to cytochrome c release, caspase activation, and apoptosis.
Abstract: A comparative study was conducted in rat primary cortical (CX) and mesencephalic (MC) neurons to investigate intracellular cascades activated during cyanide-induced injury and to determine the point at which the cascades diverge to produce either apoptosis or necrosis. Cyanide treatment (400 M) for 24 h produced primarily apoptosis in CX cells, whereas the same concentration of cyanide induced predominantly necrosis in MC cells as indicated by increased propidium iodide staining and cellular lactate dehydrogenase efflux. Cyanide increased generation of cellular reactive oxygen species (ROS) in both CX and MC cells, but the rate of formation and nature of the oxidative species varied with cell type. Catalase decreased cyanide-induced ROS generation in CX but not in MC cells. Nitric oxide generation was more prominent after cyanide treatment of MC compared with CX cells. N-Methyl-D-aspartate receptors were more involved in CX apoptosis than in MC necrosis. Mitochondrial membrane potential decreased moderately in CX cells on exposure to cyanide, whereas MC cells responded with a more pronounced reduction in potential. In CX cells cyanide produced a concentration-dependent release of cytochrome c from mitochondria and increased caspase activity, whereas little change was seen in MC neurons. Thus, cyanide-induced necrosis of MC cells involved generation of excessive amounts of nitric oxide and superoxide accompanied by mitochondrial depolarization. In contrast cyanide causes a lower level of oxidative stress in CX cells, involving mainly hydrogen peroxide and superoxide, and a moderate change in mitochondrial membrane potential that lead to cytochrome c release, caspase activation, and apoptosis.
TL;DR: In this paper, the simultaneous biosorption of iron (III) (ferric) cations and iron(III)-cyanide complex anions to Rhizopus arrhizus from binary mixtures was studied and compared with single metal and metal cyanide complex ion situation in a batch stirred system.
TL;DR: A review of the cyanidation and cyanide destruction processes at the Ovacik Gold Mine is presented in this article, where it has been shown that an effluent quality (CN WAD ) between 0.06 ppm (min) and 1 ppm (max) was achievable after cyanide removal with the Inco Process.
TL;DR: In this paper, a flow reactor using the Ti/70TiO2/30RuO2 (w/w) DSA-type electrode was designed for the electrooxidation of cyanide in batch recirculating mode.
Abstract: In this paper, a flow reactor using the Ti/70TiO2/30RuO2 (w/w) DSA-type electrode was designed for the electrooxidation of cyanide in batch recirculating mode. The device performance was evaluated in terms of the decay of the cyanide concentration as a function of the current density, flow rate, and initial pollutant concentration. The experiments show that cyanide electrooxidation presents pseudo-first-order kinetics with respect to CN- ions. For the operational conditions used in the experiments, the rate constant for cyanide oxidation was in the range from 3 × 10-5 to 2 × 10-4 m s-1, with an optimum value of 1.5 × 10-4 m s-1 for a current density of 10 mA cm-2 and a linear speed of 0.22 m s-1. Using these parameters, 12 kWh is consumed for the oxidation of 1 kg of cyanide.
13 Feb 2002
TL;DR: In this paper, gold nanostructured films are used as highly sensitive surface-enhanced Raman spectroscopy (SERS) substrates for the detection of chemical agents.
Abstract: Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive technique for quantifying trace amounts of analyte adsorbed at a roughened metal surface. Many techniques, including electrochemical etching and e-beam lithography, have been used previously to produce roughened metallic surfaces. In this work we demonstrate how novel gold nanostructured films, which are simply fabricated using gold nanoparticles and latex microspheres, can be used as highly sensitive SERS substrates. The gold films are templated by 3D colloidal crystals and display long ranged ordered regions. Since the films are porous on two length scales and, therefore, possess a high surface area, we have investigated their SERS activity using sodium cyanide as a model compound. We have integrated these substrates into a flow chamber and demonstrated the quantitative detection of sodium cyanide form 5 to 500 ppb. Our results also reveal that cyanide detection can be significantly enhanced by lowering the pH after cyanide adsorption, likely indicating a conformational change of the bound cyanide. This study illustrates how novel materials formed by simple wet chemistry techniques can be used in practical devices for the detection of chemical agents, and, more generally, illustrates how material design and spectroscopic evaluation can be rapidly integrated.
TL;DR: It is concluded that melatonin protects against DNA damage induced by the *OH produced by cyanide or hydrogen peroxide, suggesting that reactive oxygen species including the * OH may play a cardinal role for mtDNA damageinduced by potassium cyanide.
TL;DR: In this paper, structured porous gold films have been fabricated using colloidal crystals to template gold nanoparticles and integrated into an online flow chamber and used to study the effects of pH and other additives on the detection of sodium cyanide.
Abstract: To implement surface-enhanced Raman spectroscopy as a practical detection method, highly enhancing, stable, and reproducible substrates need to be fabricated in an efficient manner, and their performance in different solution environments should be well characterized. In this work structured porous gold films have been fabricated using colloidal crystals to template gold nanoparticles. These films were integrated into an online flow chamber and used to study the effects of pH and other additives on the detection of sodium cyanide. The gold films proved to be highly enhancing and were used to detect cyanide over a wide range of pH values in the concentration range of ~2 to 200 ppb. The Raman signal intensity could be increased by lowering the pH after the adsorption of cyanide, which was likely due to both a change in the ionization state and a conformational change of the bound molecules. The peak intensity could also be enhanced multifold by treating the substrate with silver nitrate. Cyanide could be removed from the substrates using hydrochloric acid, although this also passivated the structures, and the activity could only be restored partially with tannic acid. These results provide a rational method to optimize the online detection of cyanide in water.
TL;DR: In the presence of a catalytic amount (5 mol%) of a platinum complex, tributyltin cyanide reacts with dimethyl- or diethyl acetylenedicarboxylate (2b ) to afford cyanostannylation adducts (3a, b ) in excellent yields as mentioned in this paper.