GO-PANI nanofiltration membrane with pH response for high efficiency water purification

A novel environmentally responsive membrane, which combines the advantages of traditional membrane materials and smart materials, has been widely applied in various fields. Inspired by the ability of biological cell membranes to sense environmental changes, we present an innovative pH-responsive nanofiltration membrane that selectively retains charged dye molecules by changing the environmental pH. The pH-responsive material polyaniline (PANI) was used to modify graphene oxide (GO), forming a composite material through polymerization of PANI monomer on the GO surface . This composite was then incorporated into GO nanofiltration membranes via physical intercalation, allowing the interlayer spacing to be adjusted to improve water permeability and selectivity. Our experimental results showed that the GO-PANI membrane achieved a water permeability of 40.42 L•m −2 •h −1 •bar −1 , surpassing that of pure GO membranes. Under optimal conditions, it retained over 98 % of Rhodamine B, Methyl Blue and Methyl Orange. In particular, the 5GO-PANI membrane showed excellent performance in terms of both retention rate and water permeability. The pH-responsive properties of the membrane are due to the PANI material, which undergoes molecular chain contraction and expansion at different pH levels, changing the permeability and surface charge of water molecules. Through a combination of pore size screening and electrostatic attraction, the membrane achieves selective dye molecule retention under varying pH conditions. • The GO-PANI nanofiltration membrane can be used for pH response. • Separation efficiency and selectivity can be intelligently adjusted according to pH 3,7,11. • GO-PANI nanofiltration membranes have good water flux and dye retention properties.