Sodium alginate intercalated 2D g-C3N4 membrane: Efficient dye removal and photocatalytic self-cleaning

[Display omitted] •A g-C3N4-SAx self-cleaning membrane was prepared by the blending method.•The interlayer spacing is increased by using SA as an interlayer support.•The composite membrane showed high flux and rejection for dyes.•The composite membrane exhibits stable self-cleaning cycle performance. Two-dimensional material membranes have excellent separation and permeation properties. However, membrane fouling will inevitably occur during the continuous filtration process and reduce the membrane performance. As a 2D layered material with light response characteristics, graphitic carbon nitride (g-C3N4) can be used to effectively construct self-cleaning membranes; however, its narrow interlayer channel limits its mass transfer rate. In this study, sodium alginate (SA) molecules and g-C3N4 nanosheets were stably anchored via electrostatic forces and hydrogen bonding to prepare high-performance g-C3N4-SAx membranes with high flux and self-cleaning. As an interlayer support, SA molecules expanded the interlayer spacing and accelerated the molecular transport efficiency. The –OH in the SA promoted the transportation of photogenerated carriers, effectively improving the photodegradation rate of the pollutants by the composite membranes. Therefore, the membrane exhibited an excellent rejection rate, water flux and stable self-cleaning; furthermore, the membrane could achieve cyclic and efficient water purification processes.