Aqueous Biphasic Systems Composed of Random Ethylene/Propylene Oxide Copolymers, Choline Acetate, and Water for Triazine-Based Herbicide Partitioning Study

Aqueous biphasic systems comprising ethylene/propylene oxide copolymer (EOPO-2500) and choline acetate ([Cho][OAc]) were used for extraction of three herbicides (simazine, cyanazine, and atrazine) from aqueous samples. The influence of phase composition and temperature on phase separation as measured by tie-line lengths (TLLs) and thus, on the partition coefficient (K), of the herbicides was investigated. The herbicides preferred the EOPO-rich phase. The partition coefficients decreased with higher concentrations of EOPO-2500 and [Cho][OAc] and with increasing temperatures (i.e., K decreases with higher TLLs). The proposed system was more environment-friendly and fast compared to traditional liquid-liquid extraction, considering that no organic solvent was consumed.