Chlorine-based or per-oxygen-based decontaminants could be used for destruction of cyanide ion in the emergency management of leakage. During destruction, poisonous gases like ClCN and HCN were often produced. It may lead to serious damage for personal safety and quality of environment. In this study, the amount of gaseous products of ClCN and HCN during destruction of KCN by hypochlorite solutions and peroxyl acid were first measured. And quantitative risks assessments correspond to different damage criterions were established. Results showed that toxic HCN gas would form once KCN aqueous exposed to atmosphere. And different decontaminants would result in different hazardous gasses. Chlorine-based decontaminants reacted with KCN would cause toxic gas of ClCN, and it lead to relatively larger depth of damage. It would cause medial lethal depth of damage under certain conditions, such as higher concentration of decontaminant, lower flow speed, higher temperature and large volume of KCN being destructed. For per-oxygen-based decontaminants, toxic HCN gas produced would cause relatively smaller depth of damage.

Three oxidant decontaminants, including NaClO, H2O2 and an organic peroxyl acid, were introduced to destroy the cyanide ion. The residual cyanide ion concentrations in different decontamination water were detected by a cyanide ion selective meter. Before the detection process, the oxidants left in the cyanide decontamination water were pretreated by adding a certain amount of Na2SO3. Results showed that starch-iodide solution indicator method presented a perfect function on determining the dosage of Na2SO3. Values of the relative mean deviations on residual cyanide detection were below 5%. After the decontamination water was deoxidized by Na2SO3, whether the sample distillated or not could not affect the value of CN- quite much. Non-distillation was confirmed alternative in the detection of cyanide ion decontamination water. Too much standing time would lead to a relatively lower CN- concentration, especially in that of non-distillation.