Separation and Recycle of Phenol from Wastewater by Liquid–Liquid Extraction

Laboratory-scale experiments and pilot scale experiments were performed to study the separation and recycle of phenol from wastewater with 200 to 6000 mg/L phenol and 5% salt. Liquid–liquid extraction (LLE) was an efficient means to separate phenol from wastewater. Some commercial extraction reagents, such as N-503, ABK, and QH1, were used to compare the extractive efficiency. The extraction time, mixed intensity, and separated factor were the key factors during the process of extraction and reverse extraction. In this work, the conditions of extraction were studied, and optimum conditions were obtained, except for conditions of pH 3.0, 1 atm, and ambient temperature. Stirred time (t1) and separated time (t2) were 3 seconds and 6 seconds, respectively. The optimum mixed Renault's value was in the range of 309,000 to 367,000, and the mass ratio of extraction reagent to wastewater was 1 to 3. A pilot-scale extractive system was designed based on the laboratory-scale experiment, which has been working for 5 years in a plant located in China.