Good evening Candice! This one I am not so sure, but this is what I am thinking.

The fan aims to spread the dirty dry air around the entire space of the machine.

The thing is, we wish for the dirty air particles to all pass through the positive gauze and exit from the negative gauze (the gauzes are permeable so that particles can pass through them).

For this to happen, all the particles which approach the positive gauze must be negatively charged (so that the oppositely charged particles and plate produce the attraction force needed to force the particles through).

We need to therefore coat negative charges (from the sharp electrode which dispenses negative ions) onto the air particles. So I presume that the dirty dry air contains mostly positive charges or neutral charges (hence the need for the sharp electrode), though there should be a minority of negative charges as well.

Now, all of these charges will eventually become negative due to the coating, so it will pass through the positive gauze. Over at the other end, because now the negative particles meet the negative gauze, the repulsive forces cause the negative particles to continue moving into the rotating disc.

I'm not sure what the nano silver particles are for - maybe they are there to remove any impurity that succeeds in passing through the gauzes or to act as some catalyst.

Good evening Mr Eric :)
Thank you so much for your advice and explanation. They are certainly helpful.
I kind of got it now :D