Ball-milled biochar incorporated polydopamine thin-film composite (PDA/TFC) membrane for high-flux separation of tetracyclic antibiotics from wastewater

Nowadays, attempts emerge in an endless stream to explore an efficient active interlayer to break the "trade-off" relationship between permeability and rejection of conventional thin-film composite (TFC) membrane. Biochar, which is often used as an economically efficient material in soil remediation and wastewater treatment, however, is usually neglected in the application of TFC membrane. This study fabricated a series of polydopamine (PDA)/TFC membranes incorporated with different concentrations of ball-milled biochar (BMBC) interlayer by the combination of conventional interfacial polymerization and bar coating method and employed them in antibiotics wastewater removal. Results indicated that water permeability of the optimized membrane (PDA/TFC-2) improved nearly two-fold (32 ± 1.8 LMHB (L.m−2·h−1·bar−1) versus 18.6 ± 1.6 LMHB for control membrane), and the rejection rates were also the highest (91.9% for chlortetracycline, 90.3% for tetracycline, 81.8% for Ciprofloxacin and 91.3% for oxytetracycline). Furthermore, the fouled PDA/TFC-2 membrane could be easily regenerated by NaOH washing and remained ~70.6% permeability flux of that of fresh membrane even after five times washing, while the rejection rate was still more than 60%. The findings of our study not only provide a promising material for the separation of antibiotic wastewater but also give a new sight towards the application of biochar in wastewater treatment.