Cellulose nanofibre composite membranes – Biodegradable and recyclable UF membranes

• A simple and quick method to prepare composite silica nanoparticle–cellulose nanofibre membranes was developed.
• Cellulose nanofibre membranes are recyclable.
• Silica nano particles controlled the pore size of nanofibre membranes.

Polymeric membranes are widely used in filtration applications because of their excellent mechanical properties and chemical resistance. Unfortunately they pose environmental problems during the production and particularly in the disposal stages of their life cycle. Cellulose nanofibre membranes, which are recyclable, have the potential to mitigate these problems. In this work cellulose nanofibre composite membranes are prepared using suspensions of cellulose nanofibres, silica nanoparticles (22 nm) and polyamide-amine-epichlorohydrin (PAE) via filtration. Here silica nanoparticles act as spacers to the control pore size of the nanofibre network. PAE was added to adhere the negatively-charged nanoparticles to the nanofibres and also to improve the wet strength of the membrane. Membranes prepared with nanofibres alone showed high flux but low rejection due to large pore size. In contrast, nanofibre composite membranes showed water flux of 80 LMH and MWCO of 200 kDa. Addition of silica nano particles controlled the pore size. These results demonstrate the potential of cellulose nanofibre composite membranes in ultrafiltration. The produced membranes are readily recyclable as a feed stock to a conventional paper making process.