Cadmium sulfide is toxic, especially dangerous when inhaled as dust, and cadmium compounds in general are classified as carcinogenic. (…) en.m.wikipedia.org/wiki/Cadmium_sulfide
ideally you will hope to have a process in which this powder will be supported on a stable substrate … but eventually, if you don’t use pure water, any impurity can have any chemical composition … so, if you are working in the real world with a mix of unknown soup, you will end up with chemical reactions … especially if there is some acids you will leach out the cadmium as soluble compounds or you may get fragmentation and powder coming out, going to the environment, pickied up by wind, creating dust in the air (…) .
Still, the process might be viable if well controlled and if the gain by eliminating PFAS is great enough.
P.S. this process involves liberation of fluoride so you will get :
Cadmium fluoride : Solubility in water 4.35 g/100 ml en.m.wikipedia.org/wiki/Cadmium_fluoride