Study of membrane separation processes of a betaine-like medicinal solution

Betaine is a medicine with the molecular formula of C24H26N2O13 extracted from plants. A betaine-like solution from present extraction processes contains large amounts of inorganic salts, water and foreign substances. A betaine-like solution is processed by early and subsequent filtering for foreign substance removal — electrodialysis (ED) for desalination and nanofiltration (NF) for concentration. The results showed that, after ED for 20–30 min, the salt rejection of the betaine-like solution reached 99.4%. As operating pressure rose, the water flux of NF increased; at lower operating pressure (0.8 MPa) the flux of NF process was stable within 35–40 L/m2.h. As the concentrating times increased, NF flux was sharply lowered. The permeates from the ED and NF processes were determined at a wavelength of 480 nm with UV spectrophotometry, and the betaine-like concentrations in the permeates reached zero, showing that the optional membranes for separation of a betaine-like solution possess excellent retention.