Many halogenated compounds are employed for a variety of practical uses, e.g., as pesticides, soil fumigants, solvents, etc.. Many escape into the environment, as for example in manufacturing or application wastes and spills. Some, such as pesticides, are applied in such a manner as to become part of the environment. It has been found that a number of such compounds, particularly though not necessarily polyhalogenated compounds, are toxic to plant and animal life. Although some of the compounds are bio- and/or photo-degradable so that they soon disappear from the environment, a substantial number are resistant to environmental degradation and remain in poisonous form for periods as long as many months or years. As a result, a good deal of research has been done to find reliable and economical treatment methods to degrade such compounds into environmentally safe products.
Some work has been done with treatment of certain halogenated compounds variously with UV radiation or with UV radiation and oxygen, air or ozone. To inventor's knowledge, there have been no prior teachings of the use of a chemical reduction treatment employing UV and hydrogen free from any added oxidizer, such as air or oxygen per se, or the use of UV alone in which the compound is in aqueous alkaline solutions. U.S. Pat. No. 3,977,952 teaches the required use of oxygen (or air) plus UV, preferably in the presence of HCl catalyst. In column 1, the patent mentions the use of carbon dioxide, water vapor, air or hydrogen as carrier gases for gas phase reaction. The reference to hydrogen appears to be inadvertent since no one skilled in the art would use hydrogen within the context of an oxygen oxidation process. The hydrogen would oxidize to water and present a serious hazard of explosion.