A purifying device provided with a device for collecting particles, such as dust includes a chamber having an inner wall that is generally cylindrical around a central axis (X), the inner wall extending parallel to the central axis between first and second substantially parallel faces, wherein the chamber has an inlet opening and an outlet opening. The collecting device also includes a rotor which is rotatable around the central axis, and which includes at least three blades, each of which extend radially from a rotary shaft to the inner wall while defining, within the chamber, compartments which are sized such that the inlet and outlet openings are in constant communication with separate compartments. The inlet opening is provided in the first base and the outlet opening is provided in the second base.