A new eco-friendly method for efficient recovery and reuse of phenols in a semi-coke wastewater

Phenols in wastewater (WWSCP) from semi-coke production pose a serious threat to human health and ecological environment due to its high concentration, high toxicity, and difficult-to-degrade characteristics. Single treatment method, such as extraction or catalytic conversion, has the problems of secondary pollution, high processing cost, and low catalytic efficiency. In light of the problems, this study developed an ecofriendly WWSCP treatment by the synergistic process of extraction and catalytic conversion, which can convert phenols in a WWSCP into anisoles. Using response surface method (RSM), the wastewater treatment process was optimized. The concentration of phenols in the WWSCP was optimally reduced from 5509 mg L-1 to 105 mg L-1 after three times of extraction with cyclohexane/dimethyl carbonate (DMC) as the extractant at 25 degrees C for 1 min of each extraction and the extract yield of phenols up to 98%. The phenols extracted from the WWSCP were completely converted over Na-CH3ONa/gamma-Al2O3 at 213.48 degrees C for 2.00 h with phenols/DMC molar ratio of 1 : 4.00. Therefore, the synergistic process of extraction and catalytic conversion provides a pollution-free and more economic strategy for treating WWSCP.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).