Heiji Enomoto*, Atsushi Hatakeyama** and Yoshishige Kato***

*Tohoku University, Faculty of Engineering
**Tohoku University, Graduate Student
***National Institute for Resources and Environment

+ Correspondence should be addressed to Heiji Enomoto:
Tohoku University, Faculty of Engineering
(Aramaki aza Aoba, Aobaku, Sendai-city 980 Japan)

Abstract

As one of the new means of safe treatment of polyvinyl chloride wastes, reaction conditions of dechlorination in hot water at up to 400*C[Celsius degeree] were investigated. Results may be summarized as follows. 1) Dechlorination can be done by a one hour reaction in hot water at sub-critical conditions over300*C[Celsius degeree],andbya20hourreactionat250*C[Celsius degeree],withpresenceofmetaliron,orinalkalinesolution. 2) With metal iron, the dechlorination reaction is dominant and decomposition reaction seems not to proceed, so that the residue is a dechlorinated solid. 3) In alkaline solution, dechlorination and hydration reactions proceed simultaneously so that the main reaction products are water-soluble or in-soluble liquids, and little solid residue remains. 4) With metal iron in alkaline solution, the dechlorination reaction is dominant, but at supercritical conditions decomposition reaction easily occurs.

Key words: polyvinyl chloride, subcritical condition, hydrothermal reaction, disposal, medical wastes