Temperature-Assisted Removal of Triphenylmethane Dyes from Water with Novel Hydrophobic Benzothiazolium Ionic Liquids

In this work, a simple and effective extraction method for triphenylmethane dyes from their aqueous solution was developed. Three novel task-specific ionic liquids based on N-alkylbenzothiazolium cations were prepared and their extraction performance in this new method was evaluated in self-prepared and real water samples. Through the control of temperature, the ionic liquids could be dispersed into the aqueous solution, first, to fully contact with the dyes and then easily recovered as tiny particles enriching these target compounds. Parameters of the extraction conditions including the amount of the ionic liquid, volume of the dispersing solvent, dissolving temperature, extraction time, pH value, and ionic strength have been investigated. The results showed that the major driven forces for the extraction were hydrogen bonding and hydrophobic interactions between the ionic liquids and the dyes. The proposed method combined the advantages of both homogeneous mixing and heterogeneous solid-liquid separation in extraction process, which was expected to lay the foundation for actual application in future.