High flux and adsorption based non-functionalized hexagonal boron nitride lamellar membrane for ultrafast water purification

Water pollution has prejudicial effects on human health and ecosystems. An advanced membrane technology, which uses less energy for pollutants removal from water, is strongly desired for improving cost efficiency. This study demonstrates a high-flux enabled non-functionalized hexagonal boron nitride (h-BN) lamellar membrane, which retains pollutants through adsorption mediated filtration system–a phenomenon that is not yet studied. The membrane is found to be pH responsive, and acidic solution increases anionic methyl orange (MO) and direct red-80 (DR-80) dyes retention up to ≥90%. It also improves permeance fluxes by ~15 and 61-folds for MO and DR-80, respectively, as compared with the previous studies. Next, the membrane qualifies to be a good adsorbent for pollutants removal. The maximum adsorption capacities of this h-BN membrane for bisphenol A, MO and DR-80 are 125.7, 120.8, and 328.2 mg g⁻¹, respectively. Furthermore, the anti-fouling performance of the membrane has been studied. The membrane exhibits normal fouling tendency, but could be recovered to 80% after washing. The membrane is very stable, and no swelling is observed even in extremely high acidic and basic conditions. The membrane could be regenerated with ethanol treatment and retained dye removal efficiency (around 90%) after four consecutive cycles test.