Preparation of a novel polymer microspheres and application in solid phase extraction combined with hollow fiber membrane system for capturing lactic acid from simulated fermentation broth

Abstract

To separate the fermentation products in real time and improve the fermentation yield, a novel poly-4-vinylpyridine-vinylbenzeneboronic acid polymer microspheres (p4VP-VPBA) with bifunctional groups was prepared by suspension polymerization. The spherical p4VP-VPBA was 5–20 μm and thermally stable below 355.4 °C. The elemental contents of N and O were 1.36% and 5.72%, respectively, and the content of boronic acid was 0.1357 mmol/g. Its adsorption performance to lactic acid was satisfactory. Under pH 4 and 20 °C, the maximum static adsorption of p4VP-VPBA was up to 185.31 mg/g in 3 h. Its selectivity on lactic acid to glucose was 70.05 at pH 2, 7.71 at pH 4, and only 0.81 at pH 10, which indicated a good selectivity to lactic acid at low pH fitting to fermentation process. Furthermore, a p4VP-VPBA-combined with hollow fiber membrane (HFM) separation system was proposed and the removal rate of 5 mg/mL lactic acid was maintained at about 90% after 5 consecutive cycles. These data showed a huge potential for future real-time capturing lactic acid from fermentation, which also was a reference for other fermentation inhibited by product concentration.