Chemical oxygen demand (COD) measurement：

According to GB-11914

2Cr2O72- + 16H+ + 3C(organic matter) → 4Cr3+ +8H2O +3CO2  

Chemical used for the measurement:

Ag2SO4 (Catalysts);

HgSO4 (Masking agent);

Fe(NH4)2·(SO4)2·6H2O (Standard Titration Solution);

H2SO4 (pH<2)

Equipment for the measurement：

Reflux device; heating equipment; Acid burette.