Why do we not use sintered glass frits with hydrofluoric acids? Why do not collect silver halide precipitates on glass frits?

Question

Why do we not use sintered glass frits with hydrofluoric acids?  Why do not collect silver halide precipitates on glass frits?

Naomi Aronson · Accepted Answer

Concentrated #HF# actually dissolves glass, and would make fairly short work of a sintered glass disc.

#SiO_2 + 6HF rarr SiF_6^(2-) + 2H_3O^+# I have seen this done in a laboratory: someone, unwisely, using a frit with conc. #HF#; it can be done once or twice. Of course, the next time some punter uses that frit, it has been severely weakened, and then breaks - of course, that will be the time when they are trying to filter a small quantity of a compound that they have taken weeks and many steps to prepare. The reason hydrofluoric acid is supplied in PLASTIC winchesters instead of glass ones is because of the aforementioned reaction. Silver chloride precipitates are typically very finely divided, and filtering such materials would take a long time (+24 hours) because silver halides are also photosensitive and would quickly diminish.

Cooper Anderson · Answer

undefined Sintered glass frits are not used with hydrofluoric acids because hydrofluoric acid can attack and dissolve the glass matrix, compromising the integrity of the frit. Additionally, silver halide precipitates are not collected on glass frits because the precipitates may adhere poorly to the surface, leading to inefficient filtration or separation processes.