Treatment of model wastewater contaminated with reactive acid dyes using ionic liquids

Abstract

The paper focuses on the simple separation of reactive acid dyes dissolved in aqueous solution using low-melting quaternary ammonium salts (ionic liquids). The effect of bulkiness of quaternary ammonium cations added in the form of readily applicable ionic liquids on the removal efficiency was studied. Especially benzyldimethylhexadecylammonium chloride combines acceptable aqueous solubility and high removal efficiency for all tested dyes. Rapid removal of dyes Reactive Orange 16, Reactive Blue 4, Reactive Orange 12, Reactive Black 5 and Reactive Black 39 from diluted aqueous solution was successfully tested using cheap and readily commercially available ionic liquid benzalkonium chloride as substitute of expensive benzyldimethylhexadecylammonium chloride liquid ion exchanger with co-action of inorganic coagulant (Al(III) or Fe(III) sulfate. The obtained removal efficiency of tested dyes from model aqueous solutions using aqueous mixture of 0.1 mol L-1 benzalkonium chloride and 0.4 mol L-1 Al2(SO4)3 is higher than 88 %, in most cases over 97 %.The removal efficiency of benzalkonium chloride mixed with aqueous Fe2(SO4)3 is less effective.