Air Purifiers

are air purfiers any good. do they also collect dust in the air, because i want one that will collect dust. any models or ideas. thanks again.
or what is a good one

I have 2 large air purifiers in my room and a small one. One is a big HEPA which is rated for a room much bigger than mine and the other is an ionic one that seems to collect some dust. I keep my door closed all the time to keep dust out.

I still notice dust floating in the air when i look at light hitting the air. Are these purifiers even practical? Is it possible to eliminate all of the dust in the air?