Pilot‐scale Ultrasonic Assisted Cloud Point Extraction of Polycyclic Aromatic Hydrocarbons from Polluted Water

Abstract

Cloud point extraction (CPE) has been proved to be an efficient and environment‐friendly separation technology for polycyclic aromatic hydrocarbons from polluted water in many related researches. However, its traditional phase separation process, based on throughput‐limited centrifugation or low‐efficient heating, limited the scaling up and continuous operation of CPE process to a large extent. In our previous study, an efficient and easy‐scaling up CPE process, namely ultrasonic assisted cloud point extraction (Us‐CPE), was developed by performing the CPE process in an ultrasonic environment. The introduction of an ultrasonic environment successfully accelerated the phase separation; and due to that the ultrasonic effect was free from throughput limitation, the process was of a good potential in the scaling up and continuous operation. In this paper, a pilot‐scale Us‐CPE process of three polycyclic aromatic hydrocarbons (PAHs), anthracene, phenanthrene, and pyrene from polluted water was performed in a pilot‐scale extraction column with a volume up to 500 mL, and the treatment was operated continuously with pumps. The steady state time of the continuous system was determined, and the influence of operation parameters including ultrasonic power, temperature, extraction column volume, flow rate, and PAHs initial concentration, were evaluated by determining the PAHs concentrations in the treated water and the corresponding distribution coefficients. Comparing with the batch operation in our previous study, a comparable high performance was able to be obtained by the continuous process in a PAHs initial concentration range lower than 20 mg/L, which means that the continuous process was feasible in the treatment of common PAHs polluted water. And the results that the extractability of the system increased with the ultrasonic power and system volume indicated that a high performance was expectable in a further scaling up process with a higher column volume, given a suitable ultrasonic power.