Cyanide Lab Report

Introduction:

Cyanide is a known poison, inhibiting respiration. Inspite of its toxicity, it is a common industrial agent. The cyanide compounds in which cyanide can be obtained as CN- ions are classified as simple and complex cyanide. Discharge of cyanide into environmental water is a threat to living organisms. To regulate the discharge of cyanide, WHO has established standard of 50μg/L of HCN for drinking water. Water Pollution Control Law in Japan stipulates 1000μg/L of cyanide as allowed level in wastewater. Analytical methods are therefore required to monitor cyanide in environmental water and wastewater to determine contamination.

Principle: Distillation of sample for total cyanide is carried out by acidification, followed by boiling of

6 H2O) in 100 ml distilled water.

(vi) 0.2(N) Sodium Hydroxide solution: Dissolve 8.0 gm sodium hydroxide in 1 l distilled water.

(vii) Acetic acid: Dilute 1 part of glacial acid with 4 parts of water.

(viii) Stock cyanide solution: Dissolve 2.51 gm potassium cyanide (A.R. Grade) in 1 l water, standardize this solution with 0.0192(N) silver nitrate solution. The solution losses strength gradually and must be rechecked every week. 1 ml of solution = 1 mg CN

(ix) Standard cyanide solution: Dilute 10 ml stock cyanide solution to 1 litre with distilled water, mix and make a second dilution of 10 ml to 100 ml. Prepare fresh solution daily. 1 ml = 1 µg CN

(x) Chloramine –T: Dissolve 1 gm chloramine – T in 100 ml distilled water. Prepare fresh solution daily.

(xi) Pyridine

(xii) 1-phenyl–3-methyl– 5-pyrazolone solution: Prepare a saturated aqueous solution (approximately 0.5 gm / 100 ml) by adding the pyrazolone to water at 75 0 C. Agitate occasionally as the solution cools to room temperature.

(xiii) Bis–Pyrazolone (3,3-dimethyl-1-diphenyl) (4,4’-bis-2-pyrazolone)-(5,5’