The journal article is open access and available through the DOI link. Short version, as I understand it (take with more than a grain of salt): the mechanical

The journal article is open access and available through the DOI link. Short version, as I understand it (take with more than a grain of salt): the mechanical process does not degrade the C-F bonds at all, but when you grind quartz that is already sufficiently fine it produces some highly reactive species on fresh surfaces which chemically attack the PFAS. At least some of the C-F bonds are replaced with Si-F bonds, though I'm not sure exactly what the products are.