Treatment of pyridine in industrial liquid waste by atmospheric DC water plasma.

Pyridine is a basic heterocyclic compound with high toxicity, widely found in liquid waste from industrial processes. The treatment of highly-concentrated pyridine was demonstrated using a novel mist-type water thermal plasma torch. Decomposition rate and TOC removal rate were more than 94% in all conditions, while the max energy efficiency reached about 23 g/kWh. With a high temperature of 5500-7500 K, more than 95% of carbon content in pyridine was converted into valuable gas products, while a little amount of formic acid and acetic acid were observed as liquid by-products. The production of hydrogen cyanide (HCN) during the thermal decomposition of pyridine was observed, which can be inhibited by increasing the input power. Based on the experimental results, detailed decomposition mechanisms in the high-temperature and the downstream region were discussed respectively. Water plasma shows significant potential in the treatment of non-biodegradable industrial liquid waste.