pH-responsive BNNS/PAA nanofiltration membrane for tunable water permeance and efficient dye separation

Two-dimensional lamellar nanofiltration membranes have great application potential for water purification. Here, in order to achieve tunable water permeance and efficient dye separation, we reported a pH-responsive boron nitride nanosheets (BNNS)-based nanofiltration membrane by introducing polyacrylic acid (PAA). The strong hydrophilicity and electronegativity of PAA endow BNNS/PAA membrane with a fast water flux of 228 L·m−2·h−1 and a high methylene blue (MLB) rejection of 98%, increased by 235% and 4% compared to the neat BNNS membrane, respectively. Owing to the size sieving effect, the BNNS/PAA membrane possesses the better selectivity for the different types of dyes and dye/salt mixture from the potential pollutants in the water. Meanwhile, it exhibits diverse and tunable nanofiltration performances at different pH, implying excellent pH-responsive ability of BNNS/PAA membrane. In addition, the BNNS/PAA membranes also display the exceptional separation and long-term stability at different environments. This work provides a novel and simple strategy for designing the BNNS-based nanofiltration membrane with the pH-responsive ability, the tunable water permeance and selectively.