Efficient Extraction of [Bmim]BF<sub>4</sub> by Organic-Aqueous\nSystem of NaBr‑H<sub>2</sub>O and CH<sub>2</sub>Cl<sub>2</sub>

The\nhomogeneous [Bmim]BF<sub>4</sub>-NaBr-H<sub>2</sub>O system\nwill be obtained in the industrial synthesis of [Bmim]BF<sub>4</sub>, and the extraction of [Bmim]BF<sub>4</sub> from such a system remains\nto be challenging. In this work, dichloromethane (CH<sub>2</sub>Cl<sub>2</sub>), is used as the organic phase to extract and separate [Bmim]BF<sub>4</sub> (1-butyl-3-methylimidazolium tetrafluoroborate) from the\nreaction solution. Dichloromethane, serving as the extracting agent,\neffectively facilitates the purification and component separation\nof the ionic liquid [Bmim]BF<sub>4</sub> postreaction, enhancing the\nreaction efficiency and product purity. The influence of operating\nparameters, including initial concentration of the ionic liquid (IL),\ntemperature, O/A ratio (the volume ratio of organic phase to aqueous\nphase), and initial concentration of NaBr, on IL separation and extraction\nwere investigated. It was found that the recovery ratio of IL and\nthe separation factor could reach 90.3% and 133.19 at optimized extraction\nconditions. Moreover, this method was appropriate for the extraction\nof [Bmim]BF<sub>4</sub> at different concentrations. As a result,\nthis work developed an optimized extraction scheme to maximize the\nyield of [Bmim]BF<sub>4</sub> using an organic and aqueous two-phase\nsystem of NaBr-H<sub>2</sub>O and CH<sub>2</sub>Cl<sub>2</sub>, which\ncould provide essential technological parameters for the efficient\nextraction of [Bmim]BF<sub>4</sub> in the NaBr-H<sub>2</sub>O-CH<sub>2</sub>Cl<sub>2</sub> two-phase system.