Removal of Acid Orange 7 Dye from Water Via Plasma-Polymerized Allylamine-Coated Quartz Particles

Abstract

A novel method of acid orange 7 (AO7) removal has been developed via the deposition of plasma-polymerized allylamine (ppAA) films on quartz particles. ppAA films were deposited at a power of 25 W, allylamine flow rate of 4.4 sccm and polymerization time of 5 to 60 min. Polymerization time had a significant effect on surface chemistry where the XPS nitrogen concentration, XPS C-O, C-N concentration, isoelectric point and the number of positively charged groups per nm2 all increased with increasing polymerization time. Increasing polymerization time increased AO7 adsorption due to greater concentrations of positively charged amine groups on the surface. The pH and initial AO7 concentration were varied to investigate their effect on AO7 adsorption. Increasing the initial AO7 concentration increased adsorption for all polymerization times. pH had a significant effect on AO7 adsorption with maximum adsorption at pH 3 and significantly less at pH values of 5–9. Regeneration of ppAA-coated quartz particles for up to 4 cycles using pH 12 Milli-Q water resulted in only slight losses in adsorption capacities. ppAA-coated particles have shown to successfully remove AO7 dye from solution and therefore demonstrate potential for use in the treatment of industrial dye wastestreams.