Removal of potassium chloride by nanofiltration from ion-exchanged solution containing potassium clavulanate

In this study, nanofiltration with NF200 membrane was employed to remove KCl from ion-exchanged solutions containing potassium clavulanate. The pore radius of NF200 membrane was estimated to be around 0.39 nm. The effects of operating pressure on separation performance were investigated in a range of 100–400 psig. The influences of cross-flow velocity (0.14–0.70 cm/s), temperature (4–25 °C), and feed composition were also investigated. In all experiments, clavulanate rejection showed high levels from 0.91 to 0.99, while chloride rejection ranged from 0.06 to 0.54. In a case at an operating pressure of 50 psig and 25 °C, as much as 94% of clavulanate was retained while 94% of chloride was removed, indicating that NF200 membrane was a suitable choice for selectively removing KCl. NF200 membrane also showed a stable performance in the operational stability test with an ion-exchanged solution obtained by treating actual fermentation broth.