Facile preparation of quaternary ammonium graft-modified PVDF nanofiltration membrane with excellent antibiotic desalination and antibacterial performance

Nanofiltration can be used to concentrate antibiotics and separate inorganic salts in the antibiotic fermentation process, replacing traditional evaporation and concentration methods and saving energy. To address the issues of poor separation selectivity for antibiotics and susceptibility to biofouling in traditional separation membranes, quaternized poly(vinylidene fluoride) (QPVDF) nanofiltration membrane was prepared with immersion phase inversion method by grafting allyltrimethylammonium chloride (ATAC) onto PVDF using atom transfer radical polymerization (ATRP) technology. This process creates a nanofiltration membrane that exhibits a synergistic effect of permselectivity and hydrophilicity enhancement. The modified membrane shows a 2.6-fold increase in water flux (up to 45.9 L·m −2 ·h −1 ) with a water contact angle reduction of about 20°. Experimental results showed that the QPVDF membrane retained 91 % of tetracycline hydrochloride (TC) and only 4.7 % of NaCl, with an antibiotic/salt separation coefficient of 10.6. The QPVDF membrane showed excellent antibacterial properties and inhibited more than 98 % of Escherichia coli ( E. coli ). It also experienced stable rejection to TC in 10 h of continuous operation, demonstrating good antifouling performance. The QPVDF membrane has significant potential applications in the field of efficient antibiotic desalination in wastewater.