Carbon nanofibers/chitosan nanocomposite thin film for surface modification of poly(ether sulphone) nanofiltration membrane

In this study, carbon nanofibers (CNFs) assisted chitosan (Cs) was utilized to surface modification of poly(ether sulphone) (PES) nanofiltration membranes. The effect of CNFs-co-Cs nanocomposite layer on physical/chemical properties and separation performance of prepared membranes was investigated. The ability of membranes in heavy metal ions removal from water was studied. Scanning electron microscopy (SEM), Scanning optical microscopy (SOM), Fourier transform infrared spectroscopy (FTIR) and 3D surface images were employed for the membranes characterization. Moreover membrane porosity, mean pore size, water content, water contact angle, flux, salt rejection and tensile strength of fabricated membranes measured. The FTIR analysis verified formation of CNFs-co-Cs layer on the membrane surface. SOM images revealed relatively uniform surface for the prepared membrane. Introducing of CNFs-co-Cs on the PES substrate led to decline of water contact angle from 62.66° to 43.86° sharply. Modified membranes showed higher porosity and water content than virgin PES membrane. The Na2SO4 rejection was measured >66% for PES membrane while it was >82% for PES/CNFs-co-Cs membrane containing of 0.5 wt% CNFs. Pure water flux also enhanced from 4.25 (L/m2.h) for virgin PES membrane up to 13.58 (L/m2.h) for the surface modified membranes. Mechanical tensile strength was also increased considerably for the PES/CNFs-co-Cs membrane containing of 0.5 wt% CNFs that were 3.5 times more than the tensile strength for PES membrane. The Cu, Cr and Pb rejections measured 97.86%, 98.40% and 96.54% for the PES/CNFs-co-Cs membrane with 0.5 wt % CNFs while they were 45.3%, 48.46% and 38.02 for PES substrate respectively.