Cyanide Analyzer (3S-CL-XCN) Determination of Cyanide Content in Water Quality
Cyanides are organic and/or inorganic compounds containing a cyano-CN group. Cyanide is a common industrial chemical used in nitrile and methacrylate fibers and other organic nitrile compounds; in electroplating and metal production (e.g. steel) to extract gold and silver from low-grade ores. Cyanide also has other uses in pesticides. It is a by-product of coke and natural gas production and can be found naturally in certain plants such as bitter almonds, lima beans, and cassava. Cyanide present in wastewater can be in different forms such as hydrocyanic acid HCN, the cyanide ion CN-, which is stable across a wide range of metal-cyanide complexes ([M(CN)n]m-), cyanide (CN)2, cyanate (containing -OCN), thiocyanate (-SCN) and nitrile (RCN, R is an alkyl group). Free cyanide exists as cyanide as the sum of molecular HCN and ionic CN - while total cyanide also includes cyanide measurable from the breakdown of metal cyanide and organic complexes. Different forms of cyanide have different chemical properties and are therefore toxic to aquatic life to varying degrees. HCN and CN - present or derived from the dissociation of complexed or bound cyanides are the main toxic forms, the former being more toxic due to its ability to cross biofilms. The toxicity of cyanide is mainly through the inhibition of cellular respiration. The binding of cyanide to the heme iron(III) of enzymes such as cytochrome oxidase prevents the transfer of electrons to the molecule O2. The form of cyanide in water is affected by pH, temperature, dissolved oxygen, salinity, other ions, complexing agents and sunlight. HCN is a diffusible, volatile and highly reactive substance. It is a weak acid in aqueous solution, and the proportion of cyanide present as free cyanide depends on pH and temperature. Cyanide combines with various heavy metal ions to form metal cyanide complexes with different stabilities. For example, Pb(II), Zn(II), Cd(II) cyanide complexes are unstable in aqueous solution and thus dissociate easily, forming CN-HCN and HCN in greater proportions than the complex ions themselves. big. The more stable complexes of Ni(II), Cu(II) and Ag(I) experienced less dissociation. The degree of dissociation increases with decreasing complex concentration, decreasing pH and decreasing complex stability. Toxicity to aquatic organisms may be due in part to compound ions, although they are much less toxic than HCN. Ferric cyanide and ferric cyanide, which have a wide range of industrial uses, are stable complexes, but readily release cyanide when exposed to ultraviolet light. Thus, sunlight causes the mobilization of free cyanide in water containing ferricyanide complexes. Cyano(CN)2 and cyanohydrin RR'C(OH)CN decomposes in water releasing free cyanide and is therefore toxic. Cyanogen chloride (CNCl) is the chlorination/oxidation product of the different cyanide forms, and this chemical is highly toxic. Other forms of cyanide such as thiocyanate, cyanate and nitrile do not form free cyanide (except thiocyanate in acidic media) and are therefore much less toxic. Volatilization is an important method to remove high-concentration free cyanide, but the removal method for low-concentration cyanide is not clear. Complexation and oxidation, as well as microbial decomposition, may also be important processes for the removal of free cyanide. The residence time of cyanide in the environment is not necessarily short. The typical analysis procedure of the analyzer is set inside the system, such as: flush the optical reaction cell with the sample, extract a part of the sample at the same time, add one or more reagents, such as buffer or masking agent, and then perform a second measurement as a reference measurement value. Reference measurements can be disturbed by factors such as sample color and turbidity, as well as various colors from pharmaceuticals and refracted light. After obtaining the reference value, the color changes after adding potions. The sample is mixed and allowed time for the color to fully stabilize, and a second measurement is taken to obtain a second reading. The reference measurement value and the second measurement value are used to calculate the concentration value under certain process coefficients. The reaction cell is then emptied and rinsed several times before the next cycle of measurement is performed. Application field of cyanide online analyzer 3S online cyanide analysis instrument has a wide range of application fields, and many environmental protection enterprises are involved. For example, many domestic wastewater treatment plants and industrial applications are aimed at underground surface water monitoring, ultra-pure water detection, and online detection of steam and condensed water. Osmotic plants, ion exchange systems, process optimization of boiler feed water wastewater treatment plants, monitoring of sewage treatment plant outlet system detection, surface water analysis and treatment, etc. 3S cyanide online analysis instruments can meet the detection data of the above enterprises.