Selenium modified graphitic carbon nitride membrane with improved antibacterial properties against Bacillus cereus and Escherichia coli

Abstract

In this study a nanocomposite membrane, consisting of hyperbranched polyethyleneimine (HPEI) and graphic carbon nitride (g-C3N4) embedded with selenium nanoparticles (SeNPs), was used in the removal of Bacillus cereus (B. cereus) and Escherichia coli (E. coli) in water. The prepared Se/g-C3N4/HPEI nanocomposite was incorporated into a polyethersulfone (PES) matrix through the phase inversion method. The synthesized nanocomposite and membranes were characterized using transmission electron microscopy (TEM), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), contact angles, water intake capacity, water flux and filtration studies. The TEM micrographs of the Se/g-C3N4/HPEI nanocomposite showed a typical rippled 2D flat layered structure with dispersed Se nanorods with an average diameter of 37.60 nm. The hybrid membranes exhibited lower pure water flux (40.28–26.53 Lm−2 h−1), improved hydrophilicity (63.21–35.54°) and higher bacteria rejection (28.03–100%) as compared to the pristine PES (127.36 Lm−2h−1, 67.75° and 19.67%). The modified nanocomposite membranes displayed improved antibacterial properties against B. cereus and E. coli achieving an inhibition of growth rate of approximately 100% at the highest concentration (0.9%). The SEM analysis of the modified membrane after bacteria filtration shows that the cell morphology of the B. cereus and E. coli was damaged and the cell membrane lost its integrity. This was due to the bactericidal effect of the modified membrane.