1. Free cyanide When pH ≤ 8, free cyanide is present as HCN molecule, and the measurement can be carried out by solvent extraction or collecting HCN bubbles in the solution. Seamless Steel Tubes,Galvanized Steel Pipe,Steel Tube,Steel Pipes,Steel Tubes Shandong Rizhaoxin Metal Products Co., Ltd. , https://www.rizhaoxinsteel.com
2. Total cyanide The total amount of cyanide. Including the free cyanide ion (CN -), hydrocyanic acid molecules (HCN) and all metal cyanide complex. It is generally measured by acid fractionation or distillation analysis, that is, the hydrocyanic acid released from the distillation absorbs the liquid amount with caustic, and then the content thereof is determined by a titration method, a colorimetric method, an ion selection method, or the like.
3. Less than total cyanide The free cyanide is determined by cyanide separation of the metal from the cyano complex under specific conditions.
The measurement methods are as follows:
1) The cyanide chloride method is used to determine the principle of total cyanide difference before and after chlorination, that is, one sample is taken for common cyanide analysis by the common method, and the other sample is treated with sodium hypochlorite under alkaline conditions. The remaining chlorine is removed, and the difference in the total value of the two samples is analyzed according to the total cyanide determination procedure, that is, the cyanide is suitable for the chlorination treatment mark.
2) Weak acid decomposition method Similar to the method for measuring total cyanide, the difference is that the reagents used in the distillation are different. The weak acid decomposition method uses an acetic acid-sodium acetate buffer solution, pH=4.5.
3) Determination of picric acid The reagent is directly added to the sample to determine the concentration of cyanide in terms of color change.