Liquid-liquid extraction of sinapic acid from a mustard seed by-product using a hollow fiber membrane contactor

This study focuses on the recovery of sinapic acid using liquid-liquid extraction (LLE) assisted by a hollow fiber membrane contactor (HFMC) from an aqueous feed obtained through the hydrolysis of mustard bran. The hydrolyste contains 230 +/- 36 mg/L of sinapic acid, with a natural pH of 4. A screening was performed with solvents of different chemical nature (alcohol, ester, ketone, ether, cyclic ether). Data showed that all the solvents tested gave an extraction efficiency of more than 80 % for pH < 5, whereas the initial concentration of sinapic acid in the aqueous feed has little impact on the extraction efficiency. Four of the solvents tested were selected for use in the HFMC: two volatile (CPME, MIBK) and two non-volatile (octanol, octyl acetate). The solubility of the volatile solvents in the feed phase was found to be an important factor to consider in evaluating the HFMC (2.6 +/- 0.5 % and 1.07 +/- 0.05 % v/v with MIBK and CPME, respectively). Mass transfer coefficients with volatile solvents (25 +/- 1 x10(-6) and 15.3 +/- 0.5 x10(-6) m/s for MIBK and CPME, respectively) exceeded those of non-volatile solvents (4.1 +/- 0.2 x10(-6) and 4.5 +/- 0.5 x10(-6) for octanol and octyl acetate, respectively) by 4-to 6-fold. Extraction was intensified by increasing the initial concentration of sinapic acid in the feed phase and by increasing the feed-to-solvent ratio. CPME demonstrated optimal recovery efficiency at a phase ratio of 8:1 (v/v), yielding 0.9 g of sinapic acid per liter of CPME used.

Automated summary

This study focuses on the recovery of sinapic acid using liquid-liquid extraction assisted by a hollow fiber membrane contactor from an aqueous feed obtained through the hydrolysis of mustard bran. The screening of solvents of different chemical nature showed that all tested solvents had an extraction efficiency of more than 80% for pH < 5. Four solvents were selected for use in the hollow fiber membrane contactor, and the volatile solvents showed higher mass transfer coefficients compared to non-volatile solvents. The extraction efficiency was intensified by increasing the initial concentration of sinapic acid and the feed-to-solvent ratio. CPME was found to have optimal recovery efficiency at a phase ratio of 8:1, yielding 0.9 g of sinapic acid per liter of CPME used.