Flotation deinking of old newsprint (ONP) using polydiallyldimethylammonium chloride (polyDADMAC) as the only deinking agent was studied. The results demonstrate that polyDADMAC can neutralize dissolved anionics to form small particles. These small particles, together with ink, filler, and fines, strongly adsorbed onto air bubble surfaces and functioned as particle foaming agents. Therefore, no...