Preparation of nanocellulose/filter paper (NC/FP) composite membranes for high-performance filtration

A layer deposition method was developed to prepare a series of nanocellulose/filter paper (NC/FP) composite filtration membranes by vacuum filtration of an aqueous nanocellulose dispersion on a filter paper substrate. The deposited NC networks and the final pore structure of the NC/FP composite were affected by the size and the amount of the nanocellulose. Drying methods further influenced the filtration performance of the membranes. With a greater NC aspect ratio and an increasing amount of added NC, NC/FP composite membranes exhibited better rejection rates with lower water flux. Two types of NC were chosen with different sizes as follows: (1) cellulose nanocrystals prepared from microcrystalline cellulose, which are characterized by their small size, and (2) cellulose nanofibers (CNFs) prepared from hardwood bleached Kraft pulp, which are characterized by their large size. Varying filtration performance was also achieved by altering the drying conditions (temperature, pressure and solvents) during the manufacturing process of NC/FP composite filtration membranes. In particular, NC/FP composite membranes obtained by vacuum drying at 60 degrees C with 0.1% CNFs demonstrated excellent ultrafiltration properties with retention rates as high as 97.14% and an acceptable flux (46,279Lm(-2)h(-1)). Furthermore, NC/FP composite membranes demonstrated good tolerance to acidic and alkaline conditions, but their performance was weakened when treated with high or low temperatures. NC/FP composite membranes have promising potential for use as advanced separation membranes for water purification. [GRAPHICS] .