Study of the Interactions between Simple Coacervates and Chemicals for Water Depollution by Self-coacervation

The use of microextraction or sequestration offers a promising method for removing chemicals from polluted water. Simple coacervates, which are water-in-water droplets, present the advantage of being formed at a given pH while being destroyed upon pH-change. Theoretically, such stimuli-responsiveness could be leveraged to recover the pollutant. Coacervates have shown exceptional capability in sequestering diverse chemicals and colloids. In this paper, we seek to understand more in-depth the sequestration mechanisms occurring with a variety of usual ionic pollutants, both qualitatively and quantitatively, since the presence of ions can affect the coacervate formation. By combining microscopy observations with spectroscopic analysis, we have precisely defined the nature and strength of the interactions between coacervates and chemicals. Our findings indicate that polluted solutions treated with coacervates show removal efficiencies ranging from 30% to 90%. We highlight that factors such as charge, concentration, solubility, and process play critical roles in the sequestration efficiency of these coacervates. Understanding these interactions is crucial for advancing several fields, particularly in water purification processes.