Biomimetic hybrid membranes with covalently anchored chitosan – Material design, transport and separation

Abstract New hybrid membrane was inspired by biomimicking the water harvesting system in the back of fogstand beetle. Therefore, efficient hydrophobic material with hydrophilic chitosan (CS) islands was produced by the covalent attachment of chitosan to the hydrophobic surface of PVDF membranes. The attachment of CS molecules allows upgrading the membrane permeability and antifouling properties. Employing the “grafting to” approach, CS was anchored to pre-activated PVDF-membranes by urea linker via silanization. Materials were used for different separation processes, including membrane distillation (MD) for the removal of hazardous volatile organic compounds, desalination, and concentration of raw juices. Material physiochemical features, wettability, stability, tribology, and morphology, were assessed with respect to transport and separation. The hybrid-material possessed improved thermal stability and water resistance. The process separation index increased from ~6.8 kg m−2 h−1 to 90 kg m−2 h−1 for pristine and hybrid-material, respectively. During the juice concentration, the normalized flux decline for pristine was ~50%, whereas for hybrid material below 10%. On the pristine material, a visible layer of foulant was found after the separation, whereas the hybrid membrane shows a relatively clean surface. The developed strategy offers several distinct advantages for generating new materials having potential applications in water oil separation and wastewater treatment.