free cyanide
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2022 ◽  
Vol 175 ◽  
pp. 107289
Author(s):  
Xiaoxia Yang ◽  
Yufan Mu ◽  
Yongjun Peng
Keyword(s):  

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1410
Author(s):  
Anastasia Sedova ◽  
Lenka Rucká ◽  
Pavla Bojarová ◽  
Michaela Glozlová ◽  
Petr Novotný ◽  
...  

Industries such as mining, cokemaking, (petro)chemical and electroplating produce effluents that contain free cyanide (fCN = HCN + CN−). Currently, fCN is mainly removed by (physico)chemical methods or by biotreatment with activated sludge. Cyanide hydratases (CynHs) (EC 4.2.1.66), which convert fCN to the much less toxic formamide, have been considered for a mild approach to wastewater decyanation. However, few data are available to evaluate the application potential of CynHs. In this study, we used a new CynH from Exidia glandulosa (protein KZV92691.1 designated NitEg by us), which was overproduced in Escherichia coli. The purified NitEg was highly active for fCN with 784 U/mg protein, kcat 927/s and kcat/KM 42/s/mM. It exhibited optimal activities at pH approximately 6–9 and 40–45 °C. It was quite stable in this pH range, and retained approximately 40% activity at 37 °C after 1 day. Silver and copper ions (1 mM) decreased its activity by 30–40%. The removal of 98–100% fCN was achieved for 0.6–100 mM fCN. Moreover, thiocyanate, sulfide, ammonia or phenol added in amounts typical of industrial effluents did not significantly reduce the fCN conversion, while electroplating effluents may need to be diluted due to high fCN and metal content. The ease of preparation of NitEg, its high specific activity, robustness and long shelf life make it a promising biocatalyst for the detoxification of fCN.


2021 ◽  
Vol 924 (1) ◽  
pp. 012031
Author(s):  
A R Pramitha ◽  
H Harijono ◽  
S N Wulan

Abstract Arbila beans contains cyanogenic compounds in the form of linamarin (cyanoglucosides), acetone cyanohydrin, and free cyanide, all together constitute total cyanide content. The objective of this study was to compare the cyanide content in arbila beans analyzed by picrate and acid hydrolysis methods. Picrate method measures total cyanide only. Cyanide content was identified by using a picrate paper, which turned into yellow. The absorbance was measured by a spectrophotometer at 510 nm. Acid hydrolysis method measures cyanide in arbila beans in the form of linamarin, acetone cyanohydrin, and free cyanide. Linamarin wa hydrolyzed in H3PO4 solution. Estimated cyanide levels was measured by using a colorimetric procedure. Data was analyzed using Independent sample t-test (SPSS v.16). The results showed that, there was no difference in the total level of cyanide in both methods. Total cyanide measured by picrate and acid hydrolysis method was 2705.17 ppm and 2693.29 ppm, respectively. In addition, the three forms of cyanide content were as follows: linamarin 926.22 ppm, cyanohydrin 556.01 ppm, and free cyanide 1211.06 ppm. Based on the results, both methods can be used for total cyanide analysis. To determine the form of cyanide other than total cyanide, it is recommended to use the acid hydrolysis method.


Author(s):  
Mercedes SALAZAR-HERNÁNDEZ ◽  
Enrique ELORZA-RODRÍGUEZ ◽  
Juan Manuel MENDOZA-MIRANDA ◽  
Lucia G. ALVARADO-MONTALVO

This paper shows the syntheses and use of hybrid porous silica materials (UGM-triamin) in the adsorption of Cu (I) of the cyanidation effluents of gold and silver. Studies of adsorption of Cu (I) in synthetic solutions of Cu-CN a pH of 11 and at a concentration ratio of 1: 5 Cu: CN, simulating the effluents of cyanide process gold and silver ores, showed maximum adsorption capacity of 7.54 mg of Cu (I) per gram of material and favorable adsorption according to the Langmuir model (RL of 0.31 to 0.41). The evaluation of the adsorption capacity of the material with real solutions of cyanide, showed 95% removal of copper in the effluent cyanide and 68.5% selectivity for the adsorption of copper. It has been observed free cyanide destruction in the system during adsorption of copper, so that the oxidation of free cyanide may be linked to the mechanism of adsorption of copper.


2021 ◽  
Vol 170 ◽  
pp. 107031
Author(s):  
Valentina Satizabal-Gómez ◽  
Manuel Alejandro Collazos-Botero ◽  
Efraím A. Serna-Galvis ◽  
Ricardo A. Torres-Palma ◽  
Juan J. Bravo-Suárez ◽  
...  

2021 ◽  
Author(s):  
Daniel Guck ◽  
David Kim ◽  
Brian Logue ◽  
Nesta Bortey-Sam ◽  
Nicole Tubbs ◽  
...  

Abstract Background: Cyanide (CN) has been shown to be chronically present in the airways of cystic fibrosis (CF) patients, as a byproduct Pseudomonas’ metabolism. We sought to determine the concentrations of CN in the sputum of CF patients, who were admitted to the hospital with acute clinical exacerbations using 2 different approaches. Methods: Sputum was collected within 1 day (median) of admission and immediately analyzed for the presence of total and free CN. Results: We found 1) toxic levels of CN in the sputum of our patients, ranging from 27 to 401 µM, 2) the majority of the cyanide was in the form of free, thus diffusible, CN and 3) no cyanide in the blood. Conclusions: While the chronic presence of CN in patients colonized with pseudomonas is not a new concept, the present data support the view that very high levels of free cyanide are present in the airways of CF patients during an acute clinical exacerbation, i.e. levels compatible with concentrations of CN able to virtually stop the mitochondrial activity. It becomes therefore urgent to investigate whether, in CF patients, cyanide is a significant factor affecting the short and long-term outcome and whether a specific treatment of CN intoxication of the airways is warranted during an exacerbation.


Author(s):  
Congying Wen ◽  
Yuzhu Chen ◽  
Rongsheng Liu ◽  
Jiankun Huang ◽  
Dawei Wang ◽  
...  

Although colorimetry has found broad application, its deficiency in the distinguishment of analytes within close concentrations remains a long-standing issue. Herein, Au@Au-Ag yolk-shell nanoparticles were synthesized and utilized to develop...


Author(s):  
Burkhard Knopf ◽  
Heinz Rüdel ◽  
Dirk Hansknecht ◽  
Thorsten Klawonn ◽  
Knut Kreuzer

AbstractCyanide compounds are naturally emitted into the environment in low levels by degradation processes or emitted from anthropogenic sources. In surface water, complex cyanide compounds as well as “free cyanide” are present. The latter term covers hydrogen cyanide and cyanide compounds which easily liberate hydrogen cyanide under slightly acidic conditions. Especially free cyanide may cause adverse effects in the environment. To exclude negative impacts on freshwater systems, in the context of the European Water Framework Directive (WFD), preventive regulatory activities for free cyanide are currently under discussion. However, established analytical methods for quantification of free cyanide only obtain limits of quantification (LOQs) in the range of 1 μg L−1. Thus, these methods are not sufficiently sensitive for a potential environmental quality standard (EQS) compliance monitoring at water concentrations below the current predicted no effect concentration (PNEC) level of free cyanide. In the present study, a standardized continuous flow analysis (CFA) method for quantification of low free cyanide concentrations was adapted by applying a special system which allows an ultra-sensitive photometric detection of a colored cyanide derivative. By this means, LOQs in a range of one magnitude below the PNEC are achievable. The method was validated according to ISO/IEC 17025 requirements. Free cyanide concentrations in tested surface water samples from a small river and a barrier lake with low anthropogenic influences were very low and clearly below the PNEC. The results prove that the adapted CFA method is suitable for the analysis of low concentration free cyanide in freshwaters and appropriate for a possible EQS compliance monitoring.


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