Method for producing chlorine dioxide using calcium chloride impregnated zeolite or aqueous calcium chloride

摘要

A method for producing chlorine dioxide by activating zeolite crystals (which have been impregnated with metal chlorite such as sodium chlorite, and a water-retaining substance such as magnesium sulfate, potassium chloride, or potassium hydroxide, or calcium chloride) with an acid, or activating an aqueous solution of metal chlorite (preferably sodium chlorite) and such a water-retaining substance. Acids useful for performing the activation are acetic acid, phosphoric acid, and citric acid. The activation can be performed by causing fluid to flow through a bed of zeolite crystals impregnated with calcium chloride (or another water-retaining substance) and sodium chlorite, and a bed of zeolite crystals impregnated with the acid. The two beds can be physically mixed together, or the fluid can be caused to flow sequentially through distinct first and second beds (preferably first through the bed containing acid-impregnated zeolite). The activation can also be performed by immersing impregnated zeolite crystals in (or spraying them with) acid. To produce chlorine dioxide using the sodium chlorite- containing aqueous solution of the invention, the solution is mixed (or otherwise combined) with acid. Other embodiments of the invention are impregnated zeolite crystals (or other substances), which are useful for producing chlorine dioxide and are stable until activated with acid. The presence (in a sufficient amount) of calcium chloride (or another water- retaining substance) in the unactivated composition reduces the rate of chlorine dioxide outgassing to no more than a negligible amount at times prior to activation of the composition with acid.