Abstract To develop a greener method to separate phenols from oils, four kinds of halogen-free zwitterions, including 1-(propyl-3-sulfonate)-triethylaminium (TEA-PS), 1-(propyl-3-sulfonate)-tripropylaminium (TPA-PS), 1-(butyl-4-sulfonate)-triethylaminium (TEA-BS) and 1-(butyl-4-sulfonate)-tripropylaminium (TPA-BS), were designed and synthesized to separate phenols from model oils via forming deep eutectic solvents (DESs) based on the formation of hydrogen bonding between OH group on phenol and the oxygen atom on SO3− group of the zwitterions. The effects of time, temperature, dosage of zwitterions, initial phenol content, and structure of zwitterions were investigated. The results show that the extraction process can reach equilibrium within 2 min and the extraction efficiency is not sensitive to temperature. The zwitterions separate well phenol from model oils at room temperature, and the minimum phenol contents follow the order: TEA-PS > TPA-PS > TEA-BS > TPA-BS. The minimum phenol content and the maximum extraction efficiency at 25 °C can reach 4.8 g dm−3 and 98.6%, respectively, by using TPA-BS. All the maximum extraction efficiency can be obtained with nzwitterions:nphenol of less than 0.4, which greatly reduces the dosages of extractants. Importantly, these zwitterions can avoid the introduction of halide ion, which can seriously corrode the process equipment. All these zwitterions can be easily regenerated by an anti-solvent method without an obvious mass loss and a decrease in phenol extraction efficiency. Lastly, the extraction mechanism was studied with FT-IR and the freezing points of DESs indicate that the DESs are formed through hydrogen bonding.

中文翻译：

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磺酸盐基两性离子：一种新型萃取剂，可通过形成深共熔溶剂从油中高效分离酚类

摘要 为了开发一种更环保的分离油中酚类物质的方法，包括 1-(丙基-3-磺酸盐)-三乙基胺 (TEA-PS)、1-(丙基-3-磺酸盐)-三丙基胺 (TEA-PS) 四种无卤两性离子 ( TPA-PS)、1-(4-磺酸丁酯)-三乙胺 (TEA-BS) 和 1-(4-磺酸丁酯)-三丙胺 (TPA-BS) 被设计和合成用于从模型油中分离苯酚基于苯酚上的 OH 基团与两性离子 SO3- 基团上的氧原子之间形成氢键，形成深共熔溶剂 (DES)。研究了时间、温度、两性离子用量、初始苯酚含量和两性离子结构的影响。结果表明，提取过程可在2 min内达到平衡，提取效率对温度不敏感。两性离子在室温下将井酚与模型油分离，酚含量最低的顺序为：TEA-PS>TPA-PS>TEA-BS>TPA-BS。通过使用TPA-BS，在25°C下的最小苯酚含量和最大提取效率可以分别达到4.8 g dm-3和98.6%。当nzwitterions:nphenol小于0.4时，可以获得最大的萃取效率，大大减少了萃取剂的用量。重要的是，这些两性离子可以避免引入卤离子，从而严重腐蚀工艺设备。所有这些两性离子都可以通过反溶剂方法轻松再生，而不会出现明显的质量损失和苯酚提取效率的降低。最后，