Fabrication of a ternary biocomposite membrane based on chitosan, cellulose nanocrystals and Ag nanoparticles for water treatment

Abstract

The paper presented the preparation of a ternary biocomposite membranes based on chitosan (CS) with cellulose nanocrystals (CNC) and silver nanoparticles (Ag) with the aim for water treatment. The mCS/CNC/Ag membranes were fabricated using a two-stage process. Initially, mCS/CNC membranes were synthesized by the cryogenic gelation method. The mCS/CNC membrane morphology was studied by scanning electron microscopy (SEM). SEM results indicated that the mCS/CNC semi-permeable membrane had a porous structure with pore size of 50–200 µm. The morphology of the pores on the two sides of the membrane's surface showed significantly different in which one surface of the membrane had less pores and a smaller pore size than the other. This proved that the obtained mCS/CNC membrane had an asymmetrical structure. Then, Ag nanoparticles (Ag NPs) were attached to the mCS/CNC membrane by UVC irradiation. The presence of Ag in the mCS/CNC membrane structure was confirmed through the results of X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The SEM image results showed that after the Ag NPs were formed, they were then inserted into the mCS/CNC membrane, breaking the pore structure to form the mCS/CNC/Ag membrane. The mCS/CNC/Ag biocomposite membrane had a high methylene blue removal efficiency (more than 90%) in 1 minute in the presence of NaBH4. The presence of CNC improved the mechanical properties of the membrane and could help to reuse the membrane after processing.