Nanocomposite ZIF-8@Active Carbon-co-Chitosan incorporated nanofiltration membrane with enhanced antifouling property and high separation efficiency to salt, heavy metals, and dye solutions

Nanocomposite Zeolitic imidazolate framework (ZIF-8)@ Active Carbon (AC)–co-Chitosan (CS) was employed to fabricate polyether sulfone-based nanofiltration membranes. The ZIF-8@(AC-co-CS) nanocomposite was synthesized using a simple co-precipitation method and examined by field emission scanning electron microscope (FESEM) images, Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis, and X-ray diffraction pattern (XRD). Membrane properties used analyses such as FESEM, ATR-FTR, atomic force microscopy (AFM), porosity, water content, contact angle measurements, roughness assessment, pure water flux (PWF), separation efficiency evaluation, and fouling analysis. The surface roughness of the membrane with 0.01 wt% ZIF-8@(AC-co-CS) was nearly half that of the pristine membrane. Investigation outcomes revealed more excellent hydrophilicity for modified membranes. The water flux measured over three times greater for modified membranes than pristine ones. All modified membranes exhibited noteworthy rejection of sodium sulfate, achieving levels exceeding >93 %. The nanocomposite membrane was also assessed for removing two heavy metal ions, i.e., Cu and Cr. The results indicated a 55.0 % removal for Cu and 62.3 % removal for Cr by the virgin membrane, while that was >94 % and >97 % for the modified membrane, respectively. Also, higher separation efficiency was achieved for chromium ions compared to copper ions by the membranes. The nanocomposite membranes exhibited impressive dye rejection rates: >97 % for Methylene Blue, >95 % for Rhodamine B, >92 % for RB50, >94 % for RB21, >89 % for RY145, and >86 % for RY39. The FRR parameter significantly increased to >97 % for the modified samples. The nanofiltration performance of ZIF-8@AC-co-CS nanocomposite membranes exhibited a remarkable improvement compared to CS-based membranes.