Removal of acid dyes from aqueous effluents using ionic liquids

Abstract

The decolorization efficiency of three anionic dyes dissolved in aqueous solution using four quaternary phosphonium salts with bulk cation has been investigated by spectroscopic measurements. The NMR spectroscopy suggests formation of ion pairs by complete replacement of sodium cations bound to sulfo groups in anionic dyes with tetrasubstituted phosphonium cations in structure of isolated ion pairs. According to obtained results, the tetraphenylphosphonium salt, which contain a more hydrophobic and bulky cation, exhibited a lower aqueous solubility of produced ion pair.