Extractive removal and recovery of bisphenol A from aqueous solutions using terpenoids and hydrophobic eutectic solvents

Abstract

Bisphenol A (BPA) is a widely used chemical that is found in wastewaters and surface water due to its ineffective removal by conventional water treatment processes. BPA being an endocrine disruptor, regulations and different technologies have been proposed for its treatment. In this work, the use of natural solvents such as terpenoids and eutectic solvents is presented, envisioning a BPA extraction from aqueous solutions based on the hydrophobicity of these sustainable solvents. First, an initial screening of 43 solvents was performed by molecular simulation using the COSMO-RS method. BPA extraction from aqueous solutions was experimentally evaluated with initial BPA concentrations of 5–100 mg/L, and several solvent-to-feed ratios at 303.2 K. Extraction yields > 99% were obtained with eucalyptol, geraniol, and (menthol + camphor) eutectic solvent outperforming conventional solvents. Eucalyptol, geraniol, and (menthol + camphor) have been used in a scaling-up evaluation and reuse in 6 consecutive cycles observing yields in all stages above 98.5% at solvent-to-feed ratios ranging 0.01–0.05. Besides, the solvents were regenerated using back-extraction with NaOH, providing yields above 99.5%. The regenerated solvents showed similar yields to those obtained with fresh solvent, and their chemical stability was checked through FTIR analysis. BPA was recovered by precipitation from the aqueous back-extraction solution, showing by FTIR that no degradation occurs during the extraction, back-extraction, and precipitation processes. For the first time, the complete cycle of extraction with solvent reuse, back-extraction, and precipitation of BPA using eutectic solvents and terpenoids has been studied.