How does something acquire postive charges?

Question

I understand that an object becomes postively charged when it looses electrons. I was curious, at 5:45 of this video Electronics at Work - 1943 (https://www.youtube.com/watch?v=hwutHPYGgfU), how does the particles loose their electrons and acquire their positive charge by passing through a parallel 1300V plate?

Answer 1

The film shows particles in the air blowing past wires at $-13000$ Volts. These wires have a negative charge. Electrons are repelled strongly enough that some escape from the wire into the air. Some will land on dirt particles in the air.

Then the air blows past plates with at $+6500$ Volts. These attract the electrons and negatively charged dirt particles.