Green Micellar Extraction of Phenol from Wastewater Using Eco-Friendly Hydrophilic Deep Eutectic Solvents

Phenol, an extremely toxic wastewater pollutant, adversely affects animals, plants, and aquatic life. Its accumulation in aquatic and terrestrial ecosystems affects nutrient recycling and their long-term stability. Industrial wastewaters constitute a major source of phenol, and its removal is a major concern of researchers and governments across the world. In the current research work, green extraction of phenol from model industrial wastewater was studied by using Aquoline, a new type of eco-friendly deep eutectic solvent (DES), prepared from choline chloride as an H-bond receiver and water as an H-bond contributor. Separation of phenol from wastewater is facilitated by micelles formed in Aquoline due to the CTAB surfactant. The prepared DES was characterized by UV, FTIR, and NMR spectroscopy. Maximum phenol extraction efficiency of 93.27 % was obtained with Aquoline DES + CTAB under optimized conditions (initial phenol concentration = 5000 ppm, temperature = 301 K, pH =10, CTAB concentration = 0.9 mM.L-1, volume ratio of wastewater to solvent = 10:1). The recovered solvent was reused four times after removal of phenol. FTIR studies on recovered solvent showed no change in its structure. This is the first research to use a hydrophilic deep eutectic solvent in the extraction of phenol from wastewater. The research will pave the way for the use of a new type of eco-friendly solvent while adhering to principles of green chemistry