Efficient Removal of Tartrazine from Aqueous Solutions Using Eco-Friendly Aqueous Two-Phase Systems (ATPSs)

Synthetic dyes are widely used in industry; however, their release into the environment without adequate treatment poses serious risks because of their toxicity and adverse effects on human health and aquatic ecosystems. Although conventional methods are effective, they are often costly and have limited sustainability. In this context, ATPSs are proposed as an environmentally friendly alternative aligned with the principles of green chemistry, offering an efficient and cost-effective route. In this study, Tartrazine (Tart), an azo model dye, was used to evaluate the efficiency of an ATPS formed by PEG + salt + H2O. The effects of the cation and anion nature, PEG molar mass, and pH on Tart partitioning were investigated by determining the partition coefficient of Tart (KTart) and the Gibbs free energy of transfer (ΔtrG°). The PEG 1500 + Na2SO4 + H2O ATPS at pH 3.0 exhibited the best performance among the systems evaluated, with a spontaneous transfer process evidenced by ΔtrG° values as low as −21.62 kJ mol−1. The extraction efficiency exceeded 99%, and the ATPS was successfully applied to the removal of Tart from river water and wastewater samples, demonstrating high performance and considerable potential as an alternative technology for the removal of this dye from industrial aqueous solutions.