Ionizers?

So i have this massive ionizer sitting next to me, it was meant for night club sized operation. I have no electrochemical knowledge apart from simple electrolysis of solutions. I'm wondering how this device charges particles... does it actually add or remove electrons from orbit therefore giving a charge or does it simply use eletrostatic energy generated from electrical current to grab the dust?

Adds an electron for a negative charge. Dust particles that pick up a static charge like that stick to things, coming out of suspension in the air. Some have a plate of opposite charge inside the ionizer itself which is more effective and keeps it from making a dirty smear over the nearest wall.

Ionizers try to keep the voltage low enough that they do not create ozone (O3 instead of O2), which is irritating to the lungs and eyes so it's bad even though it oxidizes contaminants in the air which is a useful cleaning action.

It's pretty simple like Oznog said. Air particles near the charged plate are ionized and either exausted via a fan, or an oppositly charged plate is placed near it, the charged partcles are attracted to it and stick. Air molecules will tend to blow past the plate while charged dust/polutant partciles will stick to it. Even without an oppositly charged exit plate the ionized exaust air will tend to attract other molecules of dust and act to precipitate particle in the air into large enough chunks that gravity starts working on them better.