Bioinspired PDA/PVDF composite membrane with excellent antibiotic desalination properties

In the production process of antibiotic drugs, a certain amount of inorganic salt needs to be added due to the needs of microbial growth environment and biological activity in the fermentation broth, so the drug desalination technology is an essential and important part of the pharmaceutical process. This work used KMnO₄-catalyzed oxidative self-polymerization of dopamine hydrochloride to deposit polydopamine (PDA) onto porous polyvinylidene fluoride (PVDF) membranes, resulting in the production of PDA/PVDF composite nanofiltration membranes with high flux and separation selectivity in a fast and easy-to-use manner. The uniformly deposited polydopamine nanospheres on the surface of the PVDF membrane form a dense separation layer ≈25 µm thick with a water contact angle of 35.6°. The prepared composite membranes have high rejection to antibiotics such as tetracycline hydrochloride (TC, 90%) and ciprofloxacin (CIP, 92%), and low rejection to NaCl (9.8%) and MgCl₂ (7.8), while the membrane show high flux exceeding 20 L/(m²·h·bar). Due to the hydrophilic properties of the functional layer, the membrane flux decreased by only about 12.5% during the 120 min TC solution filtration process. The high selectivity and antifouling properties of the composite membrane make it an ideal choice for antibiotic desalination.