Effectiveness of Chemisorption on Chlorinated Solvents
Mechanism of removing vinyl chloride in air with potassium permanganate. Activated carbon is used to remove many chlorinated solvents in air streams. If the isotherm (adsorption capacity) is good, this is the best method. In the case of low molecular weight chlorinated solvents this isotherm is not very good. In these cases, we must use other mechanism for the removal of the pollutant gas. The alternative to adsorption/absorption is to have a gas absorbed into a substrate and have a chemical reaction to neutralize or oxidize the pollutant. The mechanism is understood to be chemisorption.
Potassium permanganate is a very good chemical to perform both the neutralization and oxidization process in air. When potassium permanganate is hydrated, it will form three compounds. These compounds are potassium hydroxide, manganese tetraoxide and manganese dioxide. In the case of vinyl chloride the manganese tetraoxide will oxidize the vinyl chloride into potassium chloride and carbon dioxide. The potassium chloride will remain in the pore structure of the substrate that contains the hydrated potassium permanganate.
Hydrosil impregnates a molecular sieve of zeolite with 6% by weight potassium permanganate. The media is called HS-600. Field applications of this media in removing vinyl chloride from air streams have been proven to be efficient and economically better than that of activated carbon. In field studies, the spent media was tested and determined that it did not pose hazardous waste. The spent material was disposed in a landfill. In using this media, a representative sample should be tested for hazardous materials prior to disposal in a landfill as a non-hazardous waste.
It should be noted that if other higher molecular weight chlorinated substances are present in the air stream it is advisable to place activated carbon scrubber systems prior to the potassium permanganate system. This will increase the efficiency of the systems and result in decreased operating costs