A process for impregnating zeolite with quaternary ammonium cation (QAC) (6A) and then coating the zeolite with permanganate (such as potassium permanganate) (8), and for impregnating zeolite with permanganate and then coating the impregnated zeolite with a QAC, and coated, impregnated zeolite crystals resulting from either process. Either coating acts as a protective agent for the impregnating substance in each zeolite crystal's interior, and allows regulated time release control of the impregnating substance, thus permitting a controlled diffusion (or absorption) rate in applications in which the coated, impregnated zeolite is employed to absorb contaminants from air or water. Other embodiments of the invention are methods for producing zeolite crystals impregnated with manganese dioxide, and for using such manganese dioxide-impregnated crystals to absorb contaminants from fluid.