Efficient Removal of Microcystin Toxins in Contaminated Fresh Water by Biocompatible Polymer Complex Coacervates

Microcystins (MC) are one of the most commonly found cyanotoxins in the U.S. freshwater sources, which are released from the blue-green algae blooms into the surrounding water and harmful to human and animal health. The safe level of MC concentration in drinking water is regulated to be more than 1-1.6 μg/L, yet its concentration in natural freshwater could reach to up to 1800 μg/L, making it a hazard for consumption and daily uses. Among  different toxin chemical structures (congeners) that are released during the algae blooms, microcystin-LR (MC-LR) is the most abundant and toxic. In this study, we demonstrate the exploration of spontaneous liquid-liquid separating polymer coacervation of biocompatible polyethylene oxide (PEO) and polyacrylic acid (PAA) via hydrogen bonding to rapidly and effectively remove MC-LR and other congeners from aqueous solutions. The efficiency of MC-LR removal strongly depends on the composition of PEO-PAA complex coacervates, where an optimal composition is defined. Moreover, gel-like PEO-PAA complexes could reach near 90-97% MC toxins, far exceeding the reported performance of polymer membrane separation or other methods. Such biocompatible polymer coacervates could be further developed into a safe and scalable treatment to remove harmful cyanotoxins for drinkable fresh water.