Artículos de revistas: "Cyanide proces"

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Luque-Almagro, Víctor M., María-J. Huertas, Manuel Martínez-Luque, Conrado Moreno-Vivián, M. Dolores Roldán, L. Jesús García-Gil, Francisco Castillo y Rafael Blasco. "Bacterial Degradation of Cyanide and Its Metal Complexes under Alkaline Conditions". Applied and Environmental Microbiology 71, n.º 2 (febrero de 2005): 940–47. http://dx.doi.org/10.1128/aem.71.2.940-947.2005.

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ABSTRACT A bacterial strain able to use cyanide as the sole nitrogen source under alkaline conditions has been isolated. The bacterium was classified as Pseudomonas pseudoalcaligenes by comparison of its 16S RNA gene sequence to those of existing strains and deposited in the Colección Española de Cultivos Tipo (Spanish Type Culture Collection) as strain CECT5344. Cyanide consumption is an assimilative process, since (i) bacterial growth was concomitant and proportional to cyanide degradation and (ii) the bacterium stoichiometrically converted cyanide into ammonium in the presence of l-methionine-d,l-sulfoximine, a glutamine synthetase inhibitor. The bacterium was able to grow in alkaline media, up to an initial pH of 11.5, and tolerated free cyanide in concentrations of up to 30 mM, which makes it a good candidate for the biological treatment of cyanide-contaminated residues. Both acetate and d,l-malate were suitable carbon sources for cyanotrophic growth, but no growth was detected in media with cyanide as the sole carbon source. In addition to cyanide, P. pseudoalcaligenes CECT5344 used other nitrogen sources, namely ammonium, nitrate, cyanate, cyanoacetamide, nitroferricyanide (nitroprusside), and a variety of cyanide-metal complexes. Cyanide and ammonium were assimilated simultaneously, whereas cyanide strongly inhibited nitrate and nitrite assimilation. Cyanase activity was induced during growth with cyanide or cyanate, but not with ammonium or nitrate as the nitrogen source. This result suggests that cyanate could be an intermediate in the cyanide degradation pathway, but alternative routes cannot be excluded.

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RAMIREZ, CARLOS DARIO LOPEZ, DAIRO E. CHAVERRA y OSCAR JAIME RESTREPO BAENA. "Obtaining Urea from Effluents of Gold Cyanidation Process". Material Science Research India 16, n.º 1 (23 de abril de 2019): 43–47. http://dx.doi.org/10.13005/msri/160106.

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Cyanide is one of the most used reagents in the precious metal extraction process; as well as the most efficient from the point of view of the dissolution process, but it is also a toxic product that requires a lot of care in handling. Likewise, the residual solutions of the process must be followed because they can be a risk of contamination of water, animals and human health. In the artisanal processes of obtaining gold and silver, neutralization of the residual solutions is used to passivate the present cyanide. During this process ammonium cyanate is formed which decomposes rapidly in the presence of air and sunlight in carbon dioxide and ammonia gas, contributing to the greenhouse effect. In this work, the use of the ammonium cyanate obtained in the process of neutralization of the cyanide solutions as a reagent to obtain urea is proposed. Urea was obtained indirectly through the use of the reagent kit UREA/BUN-COLOR. The process is effective at pH ≤ 4.5 with a rapid increase in solution temperature and the addition of hydrogen peroxide. The urea crystals begin to form at 50°C. The cyanide/urea ratio obtained was 1/7.5.

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Mitsudo, Koichi, Kazuki Yoshioka, Takayuki Hirata, Hiroki Mandai, Koji Midorikawa y Seiji Suga. "1,10-Phenanthroline- or Electron-Promoted Cyanation of Aryl Iodides". Synlett 30, n.º 10 (11 de abril de 2019): 1209–14. http://dx.doi.org/10.1055/s-0037-1611793.

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A 1,10-phenanthroline-promoted cyanation of aryl iodides has been developed. 1,10-Phenanthroline worked as an organocatalyst for the reaction of aryl iodides with tetraalkylammonium cyanide to afford aryl cyanides. A similar reaction occurred through an electroreductive process.

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Simovic, L. y W. J. Snodgrass. "Natural Removal of Cyanide in Gold Milling Effluents - Evaluation of Removal Kinetics". Water Quality Research Journal 20, n.º 2 (1 de mayo de 1985): 120–35. http://dx.doi.org/10.2166/wqrj.1985.023.

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Abstract Research using synthetic solutions was conducted to examine factors influencing the natural removal of cyanides from gold mill lagoons. Factors examined included: pH, temperature, ultraviolet irradiation and degree of aeration. Temperature was the principal factor affecting the rate of cyanide loss from solution. UV irradiation had some effect while the effect of aeration was limited. The dominant mechanism for cyanide removal from solution was volatilization. Cyanide degradation was found to follow a first order reaction with respect to free cyanide and metallo-cyanide complexes of Zn, Ni, Cu and Fe. Data from each single metallo-cyanide solution were fitted to a mathematical model which considered volatilization of free cyanide, dissociation of the metallo-cyanide species, and one cyanide complex per metal. The best estimates of the rate constants found for the single metallo-cyanide solutions were used to simulate the removal characteristics of cyanide in a synthetic mixed solution of four metals. The coefficient of determination ranged from 0.93 to 0.99 for model predictions fitted to data from single metallo-cyanide solutions. Estimates for volatilization coefficients varied widely with some of the variation resulting from data which did not completely describe the decay process. The simulation of cyanide removal from the synthetic mixed solution suggested the need to recalibrate the model or to examine the formation of more than one metallo-cyanide species.

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Beattie, JK y GA Polyblank. "Copper-Catalyzed Oxidation of Cyanide by Peroxide in Alkaline Aqueous Solution". Australian Journal of Chemistry 48, n.º 4 (1995): 861. http://dx.doi.org/10.1071/ch9950861.

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The oxidation of cyanide by peroxide in alkaline aqueous solution is catalysed by copper complexes. In the presence of excess cyanide, copper(II) is reduced to form the tricyanocuprate (I) complex. The cyanogen oxidation product is hydrolysed with disproportionation to cyanate and cyanide:2CuII+2CN-→ 2CuI+(CN)2(CN)2+2OH- → OCN-+CN-+H2OCuI+3CN- ↔ Cu(CN)32-The stoichiometry and kinetics of the catalysed oxidation have been investigated. Hydrogen peroxide oxidizes coordinated cyanide with a rate that is first order in peroxide and first order in copper but independent of cyanide concentration in the presence of excess cyanide. Cu(CN)32-+H2O2→ Cu(CN)2-+OCN-+H2O Cu(CN)2-+CN-↔ Cu(CN)32- When the excess cyanide is consumed and Cu(CN)2- becomes the dominant species, the reaction becomes more complex and less efficient. Under certain conditions the stoichiometry revealed a peroxide-to-Cu(CN)2- ratio of about 6 : 1, instead of the minimum of 2.5:1 required for the oxidation of the coordinated cyanide to cyanate and the CuI to Cu(OH)2. This suggests that peroxide is consumed by a copper- catalysed disproportionation, in competition with oxidation of the coordinated cyanide. An intermediate yellow complex forms while peroxide is present, before Cu(OH)2 finally precipitates. The consequence of this mechanism is that the most efficient process for the destructive oxidation of cyanide has a high cyanide-to-copper ratio, to minimize the final concentration of Cu(CN)2- which consumes peroxide inefficiently. The rate of the reaction depends on the concentration of copper, however, which must be large enough for a satisfactory turnover.

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Dong, Kaiwei, Feng Xie, Wei Wang, Yongfeng Chang, Chunlin Chen y Xiaowei Gu. "Calcination of Calcium Sulphoaluminate Cement Using Pyrite-Rich Cyanide Tailings". Crystals 10, n.º 11 (26 de octubre de 2020): 971. http://dx.doi.org/10.3390/cryst10110971.

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Pyrite-rich cyanide tailings (CTs) are industrial hazardous solid wastes arising from the gold mining industry. Every year, hundreds of millions of tons of cyanide tailings are produced and discharged to tailings dams. It is of great significance to dispose of cyanide tailings harmlessly and resourcefully. The feasibility of calcination of calcium sulphoaluminate (CSA) cement clinker using pyrite-rich cyanide tailings as Fe2O3 and SO3 sources was investigated for this paper. The behavior of pyrite during the calcination of cyanide tailings under various calcination conditions and the properties of calcium sulphoaluminate cement clinker were examined. The results show that it is feasible to produce calcium sulphoaluminate cement clinker using pyrite-rich cyanide tailings. The optimal conditions for the calcination of calcium sulphoaluminate cement using pyrite-rich cyanide tailings are confirmed. During the calcination process, the cyanides decompose into carbonate, CO2, and N2. The pyrite decomposes into Fe2O3 and SO2, and they react with CaO and Al2O3 to form the intermediates of CaSO4, 2CaO·Fe2O3, and CaO·2Al2O3, which further react to form 3CaO·3Al2O3·CaSO4, 4CaO·Al2O3·Fe2O3, and 12CaO·7Al2O3. The calcium sulphoaluminate cement prepared by pyrite-rich cyanide tailings exhibits excellent mechanical properties and meets the compressive strength criteria of 42.5 grade calcium sulphoaluminate cement.

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Singh, Hariraj y Brijesh Kumar Mishra. "Degradation of cyanide, aniline and phenol in pre-treated coke oven wastewater by peroxide assisted electro-oxidation process". Water Science and Technology 78, n.º 10 (10 de diciembre de 2018): 2214–27. http://dx.doi.org/10.2166/wst.2018.503.

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Abstract The present study explored the feasibility of using graphite electrodes for the electrochemical oxidation of cyanide, thiocyanate, phenol and aniline with hydrogen peroxide. The dosing effects of hydrogen peroxide and current density were examined in the pre-treated coke oven wastewater. It was found that 0.025 M hydrogen peroxide and 13.63 mA/cm2 of current density were more favorable for the removal of 100%, 90%, 71% and 40% cyanide, thiocyanate, phenol and aniline respectively. The increased removal of phenol in the coke oven wastewater was attributed to the pre-treatment of wastewater. Initially, 28% phenol was converted to phenolate ion by air stripping process, which increased the removal rate of phenol by the electro-oxidation process as the removal of phenolate is quite easy compared to phenol. The advanced oxidation process degrades the more toxic cyanide into less toxic intermediate cyanate ions (CNO─), which further cut down into nontoxic end products such as N2, HCO3 and CO2. The experimental results show that the primary mechanisms in the oxidation of cyanide and phenol are mediated electro-oxidation by hydroxyl radicals and hypochlorite ions. The operating cost under the optimized conditions for the removal of 100% cyanide and 71% phenol was estimated to be 616.95 INR/m3.

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Levitus, Marcia y Suman Ranjit. "Cyanine dyes in biophysical research: the photophysics of polymethine fluorescent dyes in biomolecular environments". Quarterly Reviews of Biophysics 44, n.º 1 (26 de noviembre de 2010): 123–51. http://dx.doi.org/10.1017/s0033583510000247.

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AbstractThe breakthroughs in single molecule spectroscopy of the last decade and the recent advances in super resolution microscopy have boosted the popularity of cyanine dyes in biophysical research. These applications have motivated the investigation of the reactions and relaxation processes that cyanines undergo in their electronically excited states. Studies show that the triplet state is a key intermediate in the photochemical reactions that limit the photostability of cyanine dyes. The removal of oxygen greatly reduces photobleaching, but induces rapid intensity fluctuations (blinking). The existence of non-fluorescent states lasting from milliseconds to seconds was early identified as a limitation in single-molecule spectroscopy and a potential source of artifacts. Recent studies demonstrate that a combination of oxidizing and reducing agents is the most efficient way of guaranteeing that the ground state is recovered rapidly and efficiently. Thiol-containing reducing agents have been identified as the source of long-lived dark states in some cyanines that can be photochemically switched back to the emissive state. The mechanism of this process is the reversible addition of the thiol-containing compound to a double bond in the polymethine chain resulting in a non-fluorescent molecule. This process can be reverted by irradiation at shorter wavelengths. Another mechanism that leads to non-fluorescent states in cyanine dyes is cis–trans isomerization from the singlet-excited state. This process, which competes with fluorescence, involves the rotation of one-half of the molecule with respect to the other with an efficiency that depends strongly on steric effects. The efficiency of fluorescence of most cyanine dyes has been shown to depend dramatically on their molecular environment within the biomolecule. For example, the fluorescence quantum yield of Cy3 linked covalently to DNA depends on the type of linkage used for attachment, DNA sequence and secondary structure. Cyanines linked to the DNA termini have been shown to be mostly stacked at the end of the helix, while cyanines linked to the DNA internally are believed to partially bind to the minor or major grooves. These interactions not only affect the photophysical properties of the probes but also create a large uncertainty in their orientation.

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Rader, W. Scott, Ljiljana Solujic, E. B. Milosavljevic, J. L. Hendrix y J. H. Nelson. "Photochemistry of Aqueous Solutions of Dicyanomercury(II) and Potassium Tetracyanomercurate(II)". Journal of Solar Energy Engineering 116, n.º 3 (1 de agosto de 1994): 125–29. http://dx.doi.org/10.1115/1.2930070.

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Photochemically induced reactions of dicyanomercury(II) and potassium tetracyanomercurate(II) in alkaline aqueous solutions were investigated in detail. The studies were conducted in the presence or absence of a titanium(IV) oxide semiconductor photocatalyst utilizing sunlight as the irradiation source. It was established that the cyanide ion liberated from the thermodynamically stable mercury-cyano species can be photocatalytically oxidized via cyanate and nitrite to nitrate. In addition, the process removes over 99 mol% of mercury from the solution. In the absence of the photocatalyst, no photoproducts were detected and mercury remained in solution. The results obtained may have ramifications for the use of solar power for the efficient treatment of large quantities of precious metals mill tailings wastes containing various cyanide species. In addition, in order to follow the fate of cyanide in these experiments, a novel gas-diffusion flow injection analysis system for the determination of cyanide from the thermodynamically stable mercury-cyano complexes was utilized.

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Ofori-Sarpong, G., A. S. Adam y R. K. Amankwah. "Detoxification of Cyanide Wastewater by Cyanotrophic Organisms: the case of Phanerochaete chrysosporium". Ghana Mining Journal 20, n.º 1 (7 de julio de 2020): 34–44. http://dx.doi.org/10.4314/gm.v20i1.4.

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Abstract Cyanide, a carbon-nitrogen radical, is a major building block in many industries including pharmaceuticals, petrochemical and gold processing. In the gold extraction industry, cyanide has been the universal lixiviant for over a century due to better understood process chemistry, among others. Industries that discharge cyanide-laden effluents are mandated to keep concentrations below 0.2 mg/L to prevent death by cyanide-intoxification, which occurs when cyanide binds to key iron-containing enzymes and prevent them from supplying oxygen-containing blood to the tissues. Techniques used to attenuate cyanide in wastewater can broadly be grouped into chemical, physical and biological methods. In recent times, attention has been placed on biotechnological methods, which make use of cyanotrophic microorganisms to clean up cyanide-contaminated environments. This paper reports on studies set out to assess the ability of Phanerochaete chrysosporium to degrade cyanide under different conditions including changes in cyanide concentration, culture mass, time, closed system and open system. At the end of 24-hour contact in an open agitated system with initial pH of 11.5, a control experiment using 100 mg/L cyanide revealed a natural attenuation of 15% with pH decreasing to 9.88, while the best myco-detoxification of 85% was achieved by contacting 100 mg/L cyanide with 0.5 g culture mass, translating into degradation capacity of 17.2 mg/g (milligram of cyanide per gram of culture) with pH reducing to 8.4 in 24 hours. The degradation could be based on a number of mechanisms including hydrolysis to HCN, oxidation to cyanyl radical and cyanate due to natural attenuation through atmospheric contact, and secretion of organic acid, oxidative enzymes, and hydrogen peroxide by the fungus. Keywords: Cyanotrophic Organism, Myco-Detoxification, Cyanide-Laden Effluents, pH

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Szpyrkowicz, L., F. Zilio-Grandi, S. N. Kaul y S. Rigoni-Stern. "Electrochemical treatment of copper cyanide wastewaters using stainless steel electrodes". Water Science and Technology 38, n.º 6 (1 de septiembre de 1998): 261–68. http://dx.doi.org/10.2166/wst.1998.0260.

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A study was carried out to define the best conditions for the simultaneous electroxidation of cyanides and recovery of copper as a metallic deposition on the cathode from weak concentration rinse wastewaters, using plate stainless steel electrodes. A direct electroxidation process and an indirect electroxidation in a chloriderich medium were tested at pH from 10 to 13. The results show that the process of the direct electroxidation is feasible and economically convenient if conducted at pH 13. It was possible to reduce copper concentration from 470 mg−1 by 79% in 1.5 h, at an energy consumption of 17 kWh kg−1 and to recover 335.3 mg of Cu as pure metal, electrodeposited on the cathode. The CuO film formed simultaneously on the anode had catalytic properties for CN− electroidation. The efficiency of the destruction of cyanides was in the same order of magnitude, with kinetics being of first order with respect to cyanide concentration (first order reaction rate k = 0.007 min−1).

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Suponik, Tomasz y Marcin Lutyński. "IN-SITU TREATMENT OF GROUNDWATER CONTAMINATED WITH UNDERGROUND COAL GASIFICATION PRODUCTS / OCZYSZCZANIE IN-SITU WÓD PODZIEMNYCH ZANIECZYSZCZONYCH PRZEZ PRODUKTY PODZIEMNEGO ZGAZOWANIA WĘGLA". Archives of Mining Sciences 58, n.º 4 (1 de diciembre de 2013): 1263–78. http://dx.doi.org/10.2478/amsc-2013-0087.

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Abstract In the paper the contaminants that may be generated in Underground Coal Gasification (UCG) process were listed and include mainly mono- and polycyclic aromatic hydrocarbons, phenols, heavy metals, cyanides, ammonium, chloride and sulphate. As a method of UCG contaminated groundwater treatment a Permeable Reactive Barrier technology was proposed. To assess the effectiveness of this technology two tests were carried out. Granulated activated carbon (GAC) and zeolite, and granulated activated carbon and scrap iron were applied in the first and second test respectively. For these materials the hydro geological parameters called reactive material parameters were determined and discussed. The results of the experiments showed that GAC seems to be the most effective material for phenols, BTX, PAH, cyanides and slightly lowers ammonia removal, while zeolites and scrap iron removed free cyanide, ammonia and heavy metals respectively.

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Iciek, Małgorzata, Anna Bilska, Elżbieta Lorenc-Koci, Lidia B. Włodek y Maria M. Sokołowska. "The effect of uremic toxin cyanate (OCN--) on anaerobic sulfur metabolism and prooxidative processes in the rat kidney: A protective role of lipoate". Human & Experimental Toxicology 30, n.º 10 (22 de diciembre de 2010): 1601–8. http://dx.doi.org/10.1177/0960327110394225.

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Cyanate and its active form isocyanate are formed mainly in the process of nonenzymatic urea biodegradation. Cyanate is capable of protein S- and N-carbamoylation, which can affect their activity. The present studies aimed to demonstrate the effect of cyanate on activity of the enzymes implicated in anaerobic cysteine metabolism and cyanide detoxification and on glutathione (GSH) level and peroxidative processes in the kidney. In addition, we examined whether a concomitant treatment with lipoate, a dithiol that may act as a target of S-carbamoylation, can prevent these changes. The studies were conducted in Wistar rats. The animals were assigned to four groups, which received injections of physiological saline, cyanate (200 mg/kg), cyanate (200 mg/kg) + lipoate (100 mg/kg) and lipoate alone (100 mg/kg). The animals were killed 2 h after the first injection, the kidneys were isolated and kept at −80°C until biochemical assays were performed. Cyanate inhibited rhodanese (TST) and mercaptopyruvate sulfotransferase (MPST) activity, decreased GSH level and enhanced peroxidative processes in the kidney. All these changes were abolished by cyanate treatment in combination with lipoate.

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Alarcón, Alejandro, Carlos Segura, Carlos Gamarra y Juan Carlos F. Rodriguez-Reyes. "Green chemistry in mineral processing: chemical and physical methods to enhance the leaching of silver and the efficiency in cyanide consumption". Pure and Applied Chemistry 90, n.º 7 (26 de julio de 2018): 1109–20. http://dx.doi.org/10.1515/pac-2017-0904.

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Abstract The leaching of valuable metals from mineral ores is the basis of several extractive economies around the world, but the strategies employed often need to rely on dangerous compounds such as cyanides. Due to the complex nature of most ores, leaching processes are slow and have a low efficiency in noble metal extraction, which is usually improved by fine-milling the mineral. In this manuscript, we consider this strategy, demonstrating that it may increase the amount of silver leaching, but at the expense of a higher consumption of cyanide, which renders the process inefficient (only 2% of consumed cyanide is employed to complex silver). The increase in the yield of the desired product without the smarter use of dangerous compounds is shown as a paradigm of the need to insert green chemistry principles in industrial processes. We further present the result of two potential strategies for greener mineral processing: the use of ultrasound to eliminate passivating layers formed during the leaching process and the use of chemical pretreatments to eliminate possible sources of passivation. These strategies can increase the amount of silver extraction and simultaneously increase the efficiency in cyanide consumption. The convenience of these pretreatments in the framework of the green chemistry principles, as well as the challenges towards their implementation at industrial scale, is discussed.

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Berger, Ute y Wolfgang Schnick. "Ba2Na(CN2)(CN)3, ein neues Cyanamid-cyanid mit interpenetrierenden Teilstrukturen / Ba2Na(CN2)(CN)3, a Novel Cyanamide Cyanide with Interpenetrating Substructures". Zeitschrift für Naturforschung B 51, n.º 1 (1 de enero de 1996): 1–8. http://dx.doi.org/10.1515/znb-1996-0102.

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Abstract Ba2Na(CN2)(CN)3 was obtained by the reaction of Ba2N with melamine and NaCN at 700 °C. The compound was structurally characterized by single-crystal X-ray investigations (Fd3̄m, a = 1518.8(3) pm, Z = 16). In the crystal structure the Ba2+ ions form a cubic close packed arrangement, the Na+ and the CN2-2 ions occupy the octahedral interstices. The CN-ions are located within the close packed Ba2+ layers. The unit cell of Ba2Na(CN2)(CN)3 contains two interpenetrating substructures of the zinc-blende structure type, building up a variant of NaTl. A reversible phase transition has been observed during cooling of the compound. Whereas the Ba2(CN2)(CN)3 sublattice remains nearly unaffected in this process, the Na+ ions of the low-temperature phase are statistically distributed on two crystallographic positions.

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Badugu, Ramachandram, Joseph R. Lakowicz y Chris D. Geddes. "Cyanide-sensitive fluorescent probes". Dyes and Pigments 64, n.º 1 (enero de 2005): 49–55. http://dx.doi.org/10.1016/j.dyepig.2004.04.002.

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Majalis, Asep Nurohmat, Sri Lusiani y Yeni Novitasari. "Proses untuk Menurunkan Konsentrasi Sianida Bebas dalam Air Limbah Pertambangan Emas Skala Kecil". Jurnal Teknologi Lingkungan 20, n.º 1 (31 de enero de 2019): 73. http://dx.doi.org/10.29122/jtl.v20i1.3214.

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ABSTRACTThe processing of gold by cyanidation has an impact on the release of free cyanide into the environment contained in the tailings. Free cyanide is very dangerous because it has very high toxicity. The process to remove free cyanide from tailings is the oxidation-precipitation using a mixture of sulfur and oxygen catalyzed by copper (II). This process can reduce the concentration of free cyanide as well as heavy metals. Free cyanide is oxidized to cyanate and heavy metals are deposited as metal-hydroxide. The optimum parameter of these methods on tailing cyanidation from gold ore Lebak Situ Village-Lebak Gedong District-Lebak Regency-Banten province are the ratio of the weight of SO2/CN- is 7; the catalyst dose is 75 mg/L; pH is 9 and the processing time is 4 hours. Application tests of the optimum parameter were able to reduce free cyanide concentration from 95.8 mg/L to 0.25 mg/L. Wastewater from the processing with this process has fulfilled the specified Quality Standards. The wastewater pollution index value before the treatment process is 136.32, changing to 0.36 after processing. These changes indicate that the oxidation-precipitation process has been able to change the condition of cyanidation wastewater from heavily polluted to better conditions.Keywords: cyanidation, tailing, oxidation, optimum parameter, aplication test, pollution index ABSTRAKPengolahan emas dengan sianidasi berdampak pada pelepasan sianida bebas ke lingkungan yang terkandung di dalam tailing. Sianida bebas sangat berbahaya karena mempunyai toksisitas yang sangat tinggi. Salah satu proses untuk menghilangkan sianida bebas dari tailing adalah oksidasi-presipitasi menggunakan campuran gas sulfur dan oksigen terkatalisis tembaga (II). Proses ini mampu menurunkan konsentrasi sianida bebas sekaligus logam berat. Sianida bebas dioksidasi menjadi sianat dan logam berat diendapkan sebagai logam-hidroksida. Parameter optimum proses tersebut pada tailing sianidasi bijih emas Lebak Situ Kecamatan Lebak Gedong Kabupaten Lebak Provinsi Banten adalah rasio berat SO2/CN- 7; dosis katalis 75 mg/L; pH pengolahan 9 dan waktu pengolahan 4 jam. Uji aplikasi parameter optimum tersebut mampu menurunkan konsentrasi sianida bebas dari 95,8 mg/L menjadi 0,25 mg/L. Air limbah hasil pengolahan dengan proses tersebut telah memenuhi Baku Mutu yang ditetapkan. Nilai indeks pencemaran air limbah sebelum proses pengolahan adalah 136,32 berubah menjadi 0,36 setelah dilakukan proses pengolahan. Perubahan tersebut menunjukkan bahwa proses oksidasi-presipitasi telah mampu mengubah kondisi air limbah sianidasi dari tercemar berat menjadi kondisi lebih baik.Kata kunci: sianidasi, tailing, oksidasi, parameter optimum, uji aplikasi, indeks pencemaran

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Goodarzvand Chegini, Zahra, Hessam Hassani, Ali Torabian y Seyed Mehdi Borghei. "Enhancement of PMS activation in an UV/ozone process for cyanide degradation: a comprehensive study". Pigment & Resin Technology 49, n.º 5 (3 de agosto de 2020): 409–14. http://dx.doi.org/10.1108/prt-05-2020-0044.

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Purpose This paper aims to study peroxymonosulfate (PMS) activation in the ultraviolet (UV)/ozone process for toxic cyanide degradation from aqueous solution by a novel and simple method. Design/methodology/approach Photocatalytic degradation of cyanide (CN-) was carried out using a bench-scale photoreactor. Optimization of the UV/ozone process for the highest removal of cyanide was obtained. The effect of parameters such as ozone concentration, PMS concentration, temperature, cations (Cu2+, Co2+ and Fe2+), cyanide concentration, anions (bicarbonate, carbonate, chloride, nitrite, nitrate and sulfate [SO42−]) and scavengers (ethanol [EtOH], humic acid, TBA and NaN3) was investigated for CN- degradation. Findings Complete removal of 50 mg/L cyanide was obtained in 4 min in an ozone/UV/PMS process. The cyanide removal increased from 49.3% to 100% by adding the persulfate dosage up to 100 mg/L. The effect of various cations (II) on the cyanide degradation was enhanced in the order Cu2+ > Co2+ > Fe2+. Hydroxyl radical based on different radical quenchers such as salicylic acid proved as the main oxidizing radical for oxidation. The application of ozone/UV/PMS to treat wastewater containing cyanide shows high degradation efficiency. Research limitations/implications The ozone/UV/PMS system could be a process for degradation and detoxification of cyanide. Practical implications This study provided a simple and effective method for degradation of cyanide from aqueous solution. This method was applicable to protect environment from a huge amount of toxic cyanide wastewater produced by different industrial processes. Originality/value The PMS activation is done via a simple and effective method, which is carried out with the ozone/UV system. There are two main innovations. One is that the novel catalytic role of bimetallic ions in the ozone reaction with cyanide and the further decomposition of intermediate products is investigated. The other is that the optimized conditions were obtained for the removal of cyanide as a water contaminant. Furthermore, predominant oxidizing species by PMS activation are identified.

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Rojas Ch., Olga, Didier Alazard, Leonardo Aponte R. y Luis F. Hidrobo. "Influence of Flow Regime on the Concentration of Cyanide Producing Anaerobic Process Inhibition". Water Science and Technology 40, n.º 8 (1 de octubre de 1999): 177–85. http://dx.doi.org/10.2166/wst.1999.0416.

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A study was conducted to analyze the effects of cyanide on methanogenic bacterial populations in both continuous and batch reactors. The appropriate toxicity assays were divided into two parts, i.e. 1) batch assays, and 2) continuous flow assays, using a 6.5-litre up-stream anaerobic sludge blanket reactor (UASB). A synthetic substrate was used as feed for both assays using 99% sucrose as a carbon source, and potassium cyanide (KCN) as a free cyanide source. In the first part, the treatments with the lowest and highest percentages of Specific Methanogenic Activity (SMA %) were 3 and 10 mg CN−/l. A 0.96 mg/l concentration of cyanide caused methanogenic activity inhibition by 50% during the exposure stage. During the recovery stage, Methanogenic Activity of treatments had a considerable increase compared to the results from direct cyanide exposure, except for treatments of 7 and 10 mg CN−/l. The concentration of cyanide that inhibits Specific Methanogenic Activity by 50% was 6.1 mg CN−/l during this stage. In the second part, the reactor was continuously fed with a synthetic substrate (COD≈ 1500 mg/l). After the anaerobic sludge became acclimated, cyanide concentrations from 0.5 and 130 mg CN−/l were progressively added. The hydraulic retention time remained constant at 12 hours throughout the entire experiment. Results indicated that while partial inhibition occurred for concentrations of 3, 20 and 100 mg CN−/l, severe inhibition occurred for 130 mg CN−/l.

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Pueyo, N., N. Miguel, J. L. Ovelleiro y M. P. Ormad. "Limitations of the removal of cyanide from coking wastewater by ozonation and by the hydrogen peroxide-ozone process". Water Science and Technology 74, n.º 2 (25 de mayo de 2016): 482–90. http://dx.doi.org/10.2166/wst.2016.227.

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The purpose of this study is to compare the efficiency of ozonation and the hydrogen peroxide–ozone process for the removal of cyanide from coking wastewater. The most efficient oxidation process is combined with coagulation–flocculation–decantation and lime–soda ash softening pretreatments. The oxidation in aqueous solution and industrial wastewater (at pH 9.5–12.3) by O3 was carried out using a range of concentration of consumed O3 from 10 to 290 mg/L. A molar ratio of H2O2/O3 from 0.1 to 5.2 with different concentrations of O3 constants was used for the H2O2-O3 process. The maximum cyanide removal obtained in coking wastewater was 90% using a mass ratio of O3/CN– of 9.5. Using lower concentrations of O3, cyanide is not removed and can even be generated due to the presence of other cyanide precursor organic micropollutants in the industrial matrix. The concentration of O3 is reduced to half for the same cyanide removal efficiency if the pretreatments are applied to reduce the carbonate and bicarbonate ions. The cyanide removal efficiency in coking wastewater is not improved if the O3 is combined with the H2O2. However, the preliminary cyanide removal treatment in aqueous solution showed an increase in the cyanide removal efficiency for the H2O2-O3 process.

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Chao, Xu, Cai Mingming, Gao Tengyue, Li guangsheng, Zhu xingfu, Lu Zhongbo, Chen Yanbo et al. "Study on Technological Process Innovation of Non-Cyanide Leaching". E3S Web of Conferences 267 (2021): 02064. http://dx.doi.org/10.1051/e3sconf/202126702064.

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Nowadays, there are many gold leaching processes, and the dominant one is cyanidation, but the virulence of cyanidation seriously endangers the environment and human health. In order to reduce environmental pollution and improve the recovery rate of gold, metallurgical workers put forward a variety of new gold leaching methods, which can be roughly divided into two types: one is to develop pretreatment technology on the basis of traditional cyanidation method; The other is non-cyanide leaching of gold. Based on the existing Non-Cyanide leaching technology, this paper puts forward the process innovation of Non-Cyanide leaching technology, thiourea method and dilute nitric acid pre-oxidation treatment process. The thiourea non-cyanide leaching system was investigated. According to the leaching situation of gold and silver in raw ore, the innovative scheme of gold and silver leaching technology was selected. Compared with other treatment methods, thiourea method and dilute nitric acid pre-oxidation treatment technology overcome the danger of high pressure, and the nitrogen oxide gas produced in the dilute nitric acid oxidation process can be recycled, which basically does not pollute the environment.

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Hori, Yuichiro, Shinya Hirayama y Kazuya Kikuchi. "Development of cyanine probes with dinitrobenzene quencher for rapid fluorogenic protein labelling". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, n.º 2107 (16 de octubre de 2017): 20170018. http://dx.doi.org/10.1098/rsta.2017.0018.

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A multicolour protein labelling technique using a protein tag and fluorogenic probes is a powerful approach for spatio-temporal analyses of proteins in living cells. Since cyanine fluorophores have attractive properties for multicolour imaging of proteins, there is a huge demand to develop fluorogenic cyanine probes for specific protein labelling in living cells. Herein, we develop fluorogenic cyanine probes for labelling a protein tag by using a dinitrobenzene fluorescence quencher. The probes enhanced fluorescence intensity upon labelling reactions and emitted orange or far-red fluorescence. Intramolecular interactions between the cyanine fluorophores and the dinitrobenzene quencher led not only to fluorescence quenching of the probes in the free state but also to promotion of labelling reactions. Furthermore, the probes successfully imaged cell-surface proteins without a washing process. These findings offer valuable information on the design of fluorogenic cyanine probes and indicate that the probes are useful as novel live-cell imaging tools. This article is part of the themed issue ‘Challenges for chemistry in molecular imaging’.

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23

Anning, Cosmos, Junxiang Wang, Ping Chen, Idermunkh Batmunkh y Xianjun Lyu. "Determination and detoxification of cyanide in gold mine tailings: A review". Waste Management & Research 37, n.º 11 (11 de octubre de 2019): 1117–26. http://dx.doi.org/10.1177/0734242x19876691.

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Cyanide is among the most toxic chemicals widely employed in the cyanidation process to leach precious minerals, such as gold and silver, by the minerals processing companies worldwide. This present article reviews the determination and detoxification of cyanide found in gold mine tailings. Most of the cyanide remains in the solution or the slurries after the cyanidation process. The cyanide species in the gold tailings are classified as free cyanide, weak acid dissociation, and metallocyanide complexes. Several methods, such as colorimetric, titrimetric, and electrochemical, have been developed to determine cyanide concentrations in gold mine effluents. Application of physical, natural, biological, and chemical methods to detoxify cyanide to a permissible limit (50 mg L−1) can be achieved when the chemical compositions of cyanide (type of species) present in the tailings are known. The levels of cyanide concentration determine the impact it will have on the environment.

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Lin, Mingguo, Qiyuan Gu, Xinglan Cui y Xingyu Liu. "Cyanide Containing Wastewater Treatment by Ozone Enhanced Catalytic Oxidation over Diatomite Catalysts". MATEC Web of Conferences 142 (2018): 01003. http://dx.doi.org/10.1051/matecconf/201814201003.

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Cyanide containing wastewater that discharged from gold mining process creates environmental problems due to the toxicity of cyanide. As one of the promising advanced oxidation process, catalytic oxidation with ozone is considered to be effective on the purification of cyanide. Diatomite, a natural mineral, was used as catalyst in this study. The effect of O3 dosage, salinity, initial cyanide concentration and initial pH condition were investigated. It was observed that the removal rate of cyanide was much higher in the catalytic oxidation with ozone process than the one in zone alone process. Alkaline condition was especially favorable for cyanide in catalytic oxidation with ozone. The ozone and catalytic oxidation with ozone were simulated by pseudo-first-order kinetics model. The apparent first-order rate constant contribution of the diatomite catalyst was 0.0757 min-1, and the contribution percentage was 65.77%.

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Faiberg, Anna A., Aleksandra N. Mikhailova, Vladimir E. Dementiev y Sergey S. Gudkov. "Biogenic Hydrogen Sulfide for Cyanide Regeneration in Solutions during Cupriferous Gold Ores Processing". Solid State Phenomena 262 (agosto de 2017): 131–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.131.

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An optimal approach to the problem of cupriferous gold ores hydrometallurgical processing is the recycling of process solutions after copper recovery and regeneration of cyanide bound in complexes. The study focuses on the copper-cyanide solutions processing technology using biogenic hydrogen sulfide for copper recovery in the form of сhalcocite, and cyanide regeneration. The strains of anaerobic sulfidogenic thermophilic microorganisms Desulfurella acetivorans and Desulfurella Kamchatkensis were used for producing hydrogen sulfide. The studies on copper precipitation and cyanide regeneration were conducted on copper-cyanide process solutions which were obtained during cyanidation of refractory cupriferous gold-bearing flotation concentrates from one of the deposits in the South Ural (Russia). Ten cycles of "Cyanidation-Regeneration" were carried out in total. The copper recovery was 86–96 %; the cyanide regeneration obtained 96 %. On an average 8.9 kg of sodium cyanide and 4.6 kg of copper sulfide were recovered from 1 m3 of solution. The sodium cyanide consumption decreased from 25.0 kg/t to 6.0 kg/t without reducing gold recovery during the CIL (carbon-in-leach) recycling process. The gold recovery was the same 63–68 %.

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Fu, Pingfeng, Zhenyu Li, Jie Feng y Zhenzhong Bian. "Recovery of Gold and Iron from Cyanide Tailings with a Combined Direct Reduction Roasting and Leaching Process". Metals 8, n.º 7 (21 de julio de 2018): 561. http://dx.doi.org/10.3390/met8070561.

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Cyanide tailings are the hazardous waste discharged after gold cyanidation leaching. The recovery of gold and iron from cyanide tailings was investigated with a combined direct reduction roasting and leaching process. The effects of reduction temperature, coal dosage and CaO dosage on gold enrichment into Au-Fe alloy (FexAu1−x) were studied in direct reduction roasting. Gold containing iron powders, i.e., Au-Fe alloy, had the gold grade of 8.23 g/t with a recovery of 97.46%. After separating gold and iron in iron powders with sulfuric acid leaching, ferrous sulfate in the leachate was crystallized to prepare FeSO4·7H2O with a yield of 222.42% to cyanide tailings. Gold enriched in acid-leaching residue with gold grade of 216.58 g/t was extracted into pregnant solution. The total gold recovery of the whole process reached as high as 94.23%. The tailings generated in the magnetic separation of roasted products, with a yield of 51.33% to cyanide tailings, had no toxic cyanide any more. The gold enrichment behaviors indicated that higher reduction temperature and larger dosage of coal and CaO could promote the allocation of more gold in iron phase rather than in slag phase. The mechanism for enriching gold from cyanide tailings into iron phase was proposed. This work provided a novel route to simultaneously recover gold and iron from cyanide tailings.

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Panay, Aram Joel, Claudia Liliana Vargas-Serna y Maria Lorena Carmona-Orozco. "Biodegradation of cyanide using recombinant Escherichia coli expressing Bacillus pumilus cyanide dihydratase". Revista Colombiana de Biotecnología 22, n.º 1 (1 de enero de 2020): 27–35. http://dx.doi.org/10.15446/rev.colomb.biote.v22n1.79559.

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Despite its high toxicity, cyanide is used in several industrial processes, and as a result, large volumes of cyanide wastewater need to be treated prior to discharge. Enzymatic degradation of industrial cyanide wastewater by cyanide dihydratase, which is capable of converting cyanide to ammonia and formate, is an attractive alternative to conventional chemical methods of cyanide decontamination. However, the main impediment to the use of this enzyme for the biodegradation of cyanide is the intolerance to the alkaline pH at which cyanide waste is kept and its low thermoresistance. In the present study, the catalytic properties of whole E. coli cells overexpressing a cyanide dihydratase gene from B. pumilus were compared to those of the purified enzyme under conditions similar to those found in industrial cyanide wastewater. In addition, the capacity of whole cells to degrade free cyanide in contaminated wastewater resulting from the gold mining process was also determined. The characteristics of intracellular enzyme, relative to purified enzyme, included increased thermostability, as well as greater tolerance to heavy metals and to a lesser extent pH. On the other hand, significant enzymatic degradation (70%) of free cyanide in the industrial sample was achieved only after dilution. Nevertheless, the increased thermostability observed for intracellular CynD suggest that whole cells of E. coli overexpressing CynD are suited for process that operate at elevated temperatures, a limitation observed for the purified enzyme.

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Qiu, Dali, Yijiang Liu, Mengnan Li, Hongbiao Chen y Huaming Li. "Near-infrared chemodosimetric probes based on heptamethine cyanine dyes for the “naked-eye” detection of cyanide in aqueous media". Journal of Luminescence 185 (mayo de 2017): 286–91. http://dx.doi.org/10.1016/j.jlumin.2017.01.038.

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Kamrani, M. S., K. Seifpanahi-Shabani, A. Seyed-Hakimi, G. A. M. Al, Sh Agarwa y V. K. Gupta. "Degradation of cyanide from gold processing effluent by H2O2, NaClO and Ca(ClO)2 combined with sequential catalytic process". Bulgarian Chemical Communications 51, n.º 3 (2019): 384–93. http://dx.doi.org/10.34049/bcc.51.3.5052.

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This work investigates the removal of cyanide as a noxious pollutant in the gold processing effluent (Aq-Dara mine, Takab, Iran) using H2O2, H2O2+Fe(II) (Fenton), H2O2+Cu(II), NaClO and Ca(ClO)2 oxidants. Implementation of purification operation was carried out by varying the parameters including pH, oxidant dosage, temperature and time of the reaction. The results show that the oxidants have the highest efficacy at pH 10-12, while the Fenton process has the highest efficiency at pH 8. The results confirm that Ca(ClO)2 is the best oxidant due to the shorter time, low reaction rate, high degradation of cyanide and low cost. The obtained results of response surface methodology optimization show that cyanide degradation has a direct relation to temperature, amount of oxidant, time and catalyst dosage parameters and has an inverse relation to pH. Also, the cyanide elimination efficiency is more than 99.5% and residual cyanide less than Environmental Protection Agency standards and 40% of the consumed water can be compensated by the effluent treatment and its return to the factory's processing circuit. Keywords: Oxidation Process; Gold Processing Effluents Treatment; Cyanide Degradation; Non-linear Kinetic Modeling, Response Surface Method.

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Hidayat, Diky. "PENGARUH SIANIDA PADA FOTOREDUKSI Hg(II) YANG DIKATALISIS TiO2". Molekul 6, n.º 1 (1 de mayo de 2011): 40. http://dx.doi.org/10.20884/1.jm.2011.6.1.90.

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Influence of cyanide on the photoreduction of Hg(II) catalyzed by TiO2 had been studied. Photoreduction process was carried out in a closed reactor equipped with UV lamp The process was done by radiated and stirred a mixture of Hg(II) solution, TiO2, and cyanide for a certain period of time. The amount of reduced Hg(II) by photoreduction was calculated by the substracting initial Hg(II) concentration with unreduced one, which was determined by usedcold vapor atomic absorption spectrophotometer method. In this research influences of solution concentration and pH solution in the presence cyanide were also evaluated.The result of this research indicated that the presence of cyanide lead to decrease Hg(II) photoreduction, and a drastical drop was observed when more than 2 mmole cyanide was added for each mmole of Hg(II). Increased pH solution from 2 to 4 in the presence of cyanide can improve photoreduction process, but further increased of pH solution higher than 4 lead to decrease photoreduction of Hg(II).

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Moradkhani, Mahboubeh, Soheila Yaghmaei y Zahra Ghobadi Nejad. "Biodegradation of Cyanide under Alkaline Conditions by a Strain of Pseudomonas Putida Isolated from Gold Mine Soil and Optimization of Process Variables through Response Surface Methodology (RSM)". Periodica Polytechnica Chemical Engineering 62, n.º 3 (8 de agosto de 2017): 265–73. http://dx.doi.org/10.3311/ppch.10860.

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In regard to highly poisonous effects of cyanide ion, concerns have been focused recently on treatment of such compounds in different ways. Four bacterial strains (C1-C4) capable of using cyanide as nitrogen source were isolated from contaminated gold mine soil samples under alkaline conditions at 30 °C, pH 9.5-10.5, and agitation speed 150 rpm. The gram-negative bacterium C3 (identified as Pseudomonas parafulva NBRC 16636(T) by 16S rRNA gene sequencing) was able to tolerate cyanide up to 500 ppm besides removing 93.5% of 200 ppm cyanide in 13 days which was confirmed by microorganisms growth. The addition of basal salts enhanced the removal efficiency of C3 by 16%. Cyanide removal efficiency of co-culture was 30% less than C3. Optimization of three significant parameters including temperature, pH, and glucose concentration for cyanide biodegradation was studied using response surface methodology (RSM). The optimum conditions for maximizing cyanide biodegradation were temperature (32.23 °C), pH (9.95), and glucose concentration (0.73 g/l).

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Yanbo, Chen, Qin Guanglin, Li Guangsheng, Zhu Xingfu, Yu Congquan, Lu Zhongbo, Ji Qiang et al. "Experimental study on thiosulfate leaching of gold from a high copper gold concentrate". E3S Web of Conferences 271 (2021): 04001. http://dx.doi.org/10.1051/e3sconf/202127104001.

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The conventional cyanide leaching process is used to extract gold from a high copper gold concentrate. Because the copper associated minerals consume sodium cyanide in large quantities, the cost of the reagents is high and the economic benefit is not ideal. At the same time, a large number of cyanide tail slag are produced, which brings a series of environmental problems. In order to solve the environmental problems caused by excessive sodium cyanide consumption and cyanogen slag, the feasibility of leaching gold by thiosulfate in copper ammonia system was studied. The gold leaching rate of thiosulfate was increased to more than 90% by using the direct thiosulfate leaching process and pretreatment thiosulfate leaching process, which was close to the gold leaching index of sodium cyanide at the production site.

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M. Cardoso, Luciana, Fernando B. Mainier y José A. P. Itabirano. "Analysis Voltammetry of Cyanide and Process Electrolytic Removal of Cyanide in Effluents". American Journal of Environmental Engineering 4, n.º 6 (1 de diciembre de 2014): 182–88. http://dx.doi.org/10.5923/j.ajee.20140406.07.

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Osathaphan, K., T. Boonpitak, T. Laopirojana y V. K. Sharma. "Removal of Cyanide and Zinc–Cyanide Complex by an Ion-Exchange Process". Water, Air, and Soil Pollution 194, n.º 1-4 (20 de abril de 2008): 179–83. http://dx.doi.org/10.1007/s11270-008-9706-z.

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BOUZIDA, SAMIRA, EL BACHIR BENAMAR, MANALE BATTAS, GUY SCHMERBER, ZOUHEIR SEKKAT, AZIZ DINIA, ABDELILAH SLAOUI, MOHAMMED ABD-LEFDIL y MOHAMMED REGRAGUI. "EFFECT OF POTASSIUM CYANIDE ETCHING ON STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF Cu2ZnSnS4 THIN FILMS DEPOSITED BY A MODIFIED SPRAY PROCESS". Surface Review and Letters 26, n.º 09 (17 de octubre de 2019): 1950053. http://dx.doi.org/10.1142/s0218625x19500537.

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We report the effect of potassium cyanide etching treatment on structural, optical and electrical properties of Cu2ZnSnS4 thin films prepared by a spray-assisted chemical vapor deposition process. Raman spectroscopy and X-ray diffraction measurements before and after potassium cyanide etching have confirmed the kesterite structure of Cu2ZnSnS4 films. Potassium cyanide treatment led to the elimination of [Formula: see text]S secondary phase. Optical measurements showed that the band gap value was about 1.52[Formula: see text]eV. The best electrical resistivity and Hall mobility values were reached for a deposition temperature of 450∘C in both cases without and with potassium cyanide treatment.

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Yan, Jingmin, Yanhua Wang, Yubo Tu, Peiwei Han, Xiang Liu y Shufeng Ye. "Green Treatment of Cyanide Tailings Using a “Filter Press BackWash–Chemical Precipitation–Gaseous Membrane Absorption” Method". Applied Sciences 11, n.º 5 (26 de febrero de 2021): 2091. http://dx.doi.org/10.3390/app11052091.

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Based on a “filter press backwash–chemical precipitation–gaseous membrane absorption” process, treatment of harmless cyanide tailings was conducted using cyanide tailings from a gold smelting enterprises (Yunnan Province, China) as the research object. The effects of air-drying time, backwash water parameters, initial pH of acidification, NaHS dosage, cyanide-containing water flow rate, and gaseous membrane stages on the process were investigated. Chemical composition, X-ray diffraction, and X-ray photoelectron spectroscopy analyses of the copper products were carried out. Results showed that the copper content in the copper product was 54.56%, and the chemical composition was mainly CuSCN, CuS, Cu2S, and CaSO4. Five cycles of experiments were carried out under optimal conditions; the results showed that the process can make the treated cyanide tailings meet the requirements of the technical specification for pollution control of cyanide leaching residue in the gold industry (TSPC) standard for storage in a tailings pond and a have certain stability. The average recovery rate of copper and total cyanide in elution water was 97.8% and 99.89%, respectively, and the average removal rate of thiocyanate was 94.09%.

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Purwati, Yeni, Anny Thuraidah y Dinna Rakhmina. "Kadar Sianida Singkong Rebus dan Singkong Goreng". Medical Laboratory Technology Journal 2, n.º 2 (31 de diciembre de 2016): 46. http://dx.doi.org/10.31964/mltj.v2i2.93.

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<p style="text-align: justify;">Cassava is the third staple food often used by people to make a variety of products. Carbohydrates from cassava also contains toxic compound such as cyanide which can inhibit the action of respiratory enzymes. Cyanide in cassava can be removed by boiling or frying process. The aim of research was to find out the cyanide level differences between boiled cassava and fried cassava. This type of research was experiment, with design of comparative studies approach. Cyanide levels were examined in 10 samples with 2 treatments using Argentometry Volhard titration method. The result showed the average of cyanide levels in boiled cassava was 0.772 ppm and in fried cassava was 1.069 ppm. The percentage of cyanide levels reduction in boiled cassava was 28,78%, while for the fried cassava was 0%. The statistical test obtained the value of p <0.05, that showed there was significant difference of cyanide level between boiled cassava and fried cassava. Based on these results, it is advisable to choose the boiling process for cassava consumption. Next research can be conducted on comparative levels of cyanide in the cassava root and cassava leaves.

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Pereira, Pablo Tavares, Margarida Monteiro de Carvalho, M. T. Amaral-Collaço, J. Carlos Roseiro y João Daniel Arrabaça. "Alternative respiratory system and formamide hydro-lyase activity as the key components of the cyanide-resistance mechanism inFusarium oxysporum". Canadian Journal of Microbiology 43, n.º 10 (1 de octubre de 1997): 929–36. http://dx.doi.org/10.1139/m97-134.

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A strain of Fusarium oxysporum, isolated from an industrial effluent containing a high cyanide concentration, detoxifies cyanide via formamide hydro-lyase (FHL). The importance of the coexistence of the alternative (cyanide insensitive) respiratory system and the synthesis of FHL was assessed. This enzyme, induced by cyanide, converts this compound to formamide and is partially responsible for the tolerance of F. oxysporum to high cyanide concentration. The FHL induction for cyanide detoxification depends on the alternative respiratory system when the terminal oxidase of the electron transport chain is blocked by cyanide used during the induction process. The respiratory metabolism of a F. oxysporum strain was studied. Whole cells exhibited a cyanide-sensitive respiration but developed a partially cyanide-resistant respiration under certain physiological conditions, namely, in the stationary phase of growth, in the presence of chloramphenicol in the growth medium, or upon aeration in the absence of nutrients (starvation conditions). Cycloheximide prevented the appearance of cyanide-insensitive respiration when the cells were aerated under starvation conditions. This fact suggested some form of induction involving de novo protein synthesis.Key words: cyanide tolerance, cyanide-resistant respiration, formamide hydro-lyase, Fusarium oxysporum.

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Yi, Wuzhong, Xiaoqing Yan, Renhong Li, Jian-Qiang Wang, Shihui Zou, Liping Xiao, Hisayoshi Kobayashi y Jie Fan. "A new application of the traditional Fenton process to gold cyanide synthesis using acetonitrile as a cyanide source". RSC Advances 6, n.º 20 (2016): 16448–51. http://dx.doi.org/10.1039/c6ra01025c.

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We introduced a general Fenton-reaction synthesis of metal cyanide solids using acetonitrile as a green cyanide source. This Fenton-improved cyanation method gets rid of CN⁻ ions and UV-light efficiently, which is green and facile.

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Igeño, María Isabel, Daniel Macías, María Isabel Guijo, Rubén Sánchez-Clemente, Ana G. Población, Faustino Merchán y Rafael Blasco. "Bacterial Consortiums Able to Use Metal-Cyanide Complexes as a Nitrogen Source". Proceedings 2, n.º 20 (22 de octubre de 2018): 1284. http://dx.doi.org/10.3390/proceedings2201284.

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Most cyanide-containing industrial effluents also contain other cyano-derivatives and high amounts of metals and metal-cyanide compounds. For this reason, the biotreatment of these wastes requires the use of microorganisms capable to degrade all these different cyano-compounds and to tolerate metals. Pseudomonas pseudoalcaligenes CECT 5344 is a cyanotrophic bacterium capable of metabolize cyanide in its free form, but it is not very efficient at degrading metal-cyanide complexes. Therefore, for the optimization of the cyanide biodegradation process it is essential to find and characterize new bacterial strains, capable of assimilating metal cyanide-complexes, to complement the capacities of P. pseudoalcaligenes CECT 5344.

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Zhao, Xu, Haidong Wang, Fayuan Chen, Ran Mao, Huijuan Liu y Jiuhui Qu. "Efficient treatment of an electroplating wastewater containing heavy metal ions, cyanide, and organics by H2O2 oxidation followed by the anodic Fenton process". Water Science and Technology 68, n.º 6 (1 de septiembre de 2013): 1329–35. http://dx.doi.org/10.2166/wst.2013.296.

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A real electroplating wastewater, containing heavy metals, cyanide, and organic contaminants, was treated by electrocoagulation (EC), H2O2 oxidation, H2O2 pre-oxidation followed by EC, and the anodic Fenton process and the efficacy of the processes was compared. Concentration of cyanide, Cu, Ni, Zn, and Cr was largely decreased by EC within 5 min. When the reaction time was extended, removal of residual cyanide, Cu, and Ni was limited. In H2O2 oxidation, the concentration of cyanide decreased from initial 75 to 12 mg L−1 in 30 min. The effluents from the H2O2 oxidation were further treated by EC or anodic Fenton. In EC, the concentration of total cyanide, Ni, and Cu decreased to below 0.3, 0.5, and 1.5 mg L−1, respectively. Removal efficiency of chemical oxygen demand by EC was less than 20.0%. By contrast, there was 73.5% reduction by the anodic Fenton process with 5 mM H2O2 at 30 min; this can be attributed to the oxidation induced by hydroxyl radicals generated by the reaction of H2O2 with the electrogenerated Fe2+. Meanwhile, residual cyanide, Cu, and Ni can also be efficiently removed. Transformation of organic components in various processes was analyzed using UV-visible and fluorescence excitation-emission spectra.

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Yang, Dong Fang, Xin Huai He, Jie Gao, Fei Juan Wang y Ping Wang. "Transfer Processes of Cyanide in Jiaozhou Bay". Advanced Materials Research 1092-1093 (marzo de 2015): 992–95. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.992.

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This paper analyzed the seasonal and vertical variations of cyanide in Jiaozhou Bay, and tried to reveal the transfer processes based on investigation data in different seasons in 1982. Results showed that cyanide contents in surface waters were showing obvious seasonal variations, and were in orders of spring < summer < autumn, due to the inputs of cyanide were mainly occurred in wet season. The vertical variations seem to be not regular, and the influences of cyanide contents in surface waters to bottom waters were not significant, because the degradation of cyanide were rapid in summer and early autumn, leading to most of the cyanide was degraded before or in the process of sedimentation.

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Beneto, Arockiam Jesin y Ayyanar Siva. "Highly selective colorimetric detection of cyanide anions in aqueous media by triphenylamine and phenanthro(9,10-d)imidazole based probes". Photochemical & Photobiological Sciences 16, n.º 2 (2017): 255–61. http://dx.doi.org/10.1039/c6pp00345a.

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Two novel triphenylamine based fluorescent probes TPC and PITP have been synthesized and studied as an effective cyanide selective indicator in aqueous media. Complete colour bleaching and visible colour changes was observed upon addition of cyanide to fluorophores TPC and PITP respectively.

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Vasyunina, N. V., I. V. Dubova, S. P. Baksheev, M. R. Kovel y V. V. Makarova. "Generation of sodium cyanide by coal gasification for gold recovery factories". Proceedings of Irkutsk State Technical University 25, n.º 4 (1 de septiembre de 2021): 488–97. http://dx.doi.org/10.21285/1814-3520-2021-4-488-497.

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The aim was to assess the technological feasibility of generating sodium cyanide by coal gasification, to study the effects of the process parameters (temperature, experiment duration, coal type) on the concentration of sodium cyanide in the resulting solutions, as well as to identify optimal modes of the process. Experiments were carried out on a laboratory setup consisting of a tubular cylindrical furnace equipped with a working compartment in the form of a corundum tube. Lignite and charcoal, preliminarily crushed to increase the specific surface area, were investigated. A solution of sodium cyanide was produced by sorption of gaseous hydrocyanic acid (a syngas component) with a sodium carbonate solution. A NaOH solution (pH = 10) installed in an ice bath was used in the system of absorbers. The content of sodium cyanide in the solution was determined by the titrimetric method. The HSC Chemistry 5.1 software package was used for thermodynamic calculations. During the gasification of charcoal in the temperature range 600–800oC, sodium cyanide solutions with a concentration of 0.03–0.08 wt% were obtained. An increase in temperature from 600 to 900oC led to a 4-fold decrease in the concentration of sodium cyanide in an alkaline solution, under the same duration of the experiments. A regression equation was derived for the dependence of the NaCN concentration in solution on the temperature of coal gasification and the duration of the process. It was shown that the generation of sodium cyanide by coal gasification under laboratory conditions yields sodium cyanide concentrations in solution comparable to those used for gold cyanidation at gold recovery plants. The installation of sodium cyanide generation lines directly at the production areas of gold recovery plants will reduce the production costs by eliminating expenses for purchasing, transporting and storing reagents.

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Astier, Alain y Frederic J. Baud. "Complexation of intracellular cyanide by hydroxocobalamin using a human cellular model". Human & Experimental Toxicology 15, n.º 1 (enero de 1996): 19–25. http://dx.doi.org/10.1177/096032719601500104.

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1 The rational for administering hydroxocobalamin (OHCbl) as an antidote to cyanide poisoning is based on the high affinity ofCN ion for cobalt compounds. However, only few data are available on the influence of OHCbl on the intracellular cyanide pool. 2 In human fibroblasts incubated for 10 min with 500 μM of [14C] cyanide, the accumulation ratio was 25 at 37°C (10.45 ± 1.51 mM) and 11.9 at 4°C. 3 Using the monoblastic U-937 cell line, a rapid uptake of radioactive cyanide was observed with a maximum accumulation ratio of 1.97 at 5 min. 4 A linear relationship between cyanide uptake by U-937 cells and cyanide concentration in incubation medium (10-500 μM; 5 min) was found suggesting a first order process (k= 0.25 min-1). 5 After incubation of fibroblasts with 500 μM of OHCbl, a 75% decrease of intracellular cyanide was observed, with concomittant formation of intracellular cyanocobalamin CNCbl (intracellular/extracellular ratio: 158). 6 These findings suggest that OHCbl is able to penetrate into heavily cyanide loaded cells and to complex cyanide to the non-toxic CNCbl form.

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46

Li, Guang-Yue, Wen-Liang Li, Hang Zhang y Xiao-Ran Sun. "Theoretical study on phthalocynine-Fe(II)-based fluorescent sensors for cyanide anion". Journal of Theoretical and Computational Chemistry 13, n.º 01 (febrero de 2014): 1450006. http://dx.doi.org/10.1142/s0219633614500060.

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Three fluorescent sensors bearing phthalocynine- Fe ( II ) moiety were designed specifically for detecting cyanide anions, and investigated by DFT/TDDFT method. Comparison of the geometrical and photophysical properties of these sensor molecules, equipped with H -, carbamoyl and phthalimino groups, provided a deep insight into the sensor–cyanide interactions. The binding energy calculation shows that all the three sensors have good selectivity to the cyanide anion. Especially, frontier molecular orbital analysis confirmed that there was a photoinduced electron transfer (PET) process in the sensor with phthalimino group upon the addition of cyanide anion. This process could cause the fluorescence change. As a result, the sensor with phthalimino group displayed several favorable sensing properties.

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Zeng, Jing-bin, Ying-ying Cao, Jing-jing Chen, Xu-dong Wang, Jian-feng Yu, Bin-bin Yu, Zi-feng Yan y Xi Chen. "Au@Ag core/shell nanoparticles as colorimetric probes for cyanide sensing". Nanoscale 6, n.º 17 (2014): 9939–43. http://dx.doi.org/10.1039/c4nr02560a.

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48

Gao, Teng-Yue, Chao Xu y Guang-Lin Qin. "Recovery of Copper and Cyanide from Copper-cyanide Solution by Direct Electrolysis". E3S Web of Conferences 261 (2021): 02052. http://dx.doi.org/10.1051/e3sconf/202126102052.

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Using direct electrolysis method, the recovery of copper and cyanide from high concentration copper cyanide solution was researched. The distribution of copper cyanide species was calculated by stability constants and balance equation. The results showed that the cupric ion was confirmed to generate at low potential (<0.4V) on the titanium electrode coated with iridium and tantalum oxides during the electrolysis process, which led to the oxidation of cyanide and the precipitate obtained on the anode was proved to be cupric hydroxide by XRD at high potential. The copper was recovered by direct electrowinning, the recovery of copper increased with increasing temperature, which reached 80% at 70°C; but the loss of cyanide was serious, the free cyanide concentration was significantly lower than original value.

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Atwood, D. A. "Mercury removal in the gold-cyanide process". Mining, Metallurgy & Exploration 20, n.º 4 (noviembre de 2003): 211–12. http://dx.doi.org/10.1007/bf03403179.

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Oleson, J. L., H. K. Lin y D. E. Walsh. "Modeling of SO2/air cyanide destruction process". Mining, Metallurgy & Exploration 22, n.º 4 (noviembre de 2005): 199–204. http://dx.doi.org/10.1007/bf03403323.

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