Cellulose in biomass is a renewable, sustainable, and abundant polymer that has tremendous potentials in a variety of applications. Nanocellulose can be derived by defibrillation of any lignocellulosic biomass. For example, when lignin and hemicellulose are removed, the TEMPO-oxidation method can be used to convert the hydroxyl group in the 6<sup>th</sup> position on the cellulose chain into the carboxylate group with a negative change. The charge repulsion forces can overcome the interfibrillar hydrogen bonds resulting in a well-dispersed nanocellulose in suspension. In this study, we have developed a hierarchical antifouling membrane using cellulose nanofiber (CNF) to construct the barrier layer. The negatively-charged CNF surface exerted repulsion forces between the membrane and protein foulant. In addition, the high affinity of CNF to water enabled the formation of a superhydrophilic membrane surface, which increased the water flux through the membrane and lowered the biofouling tendency when compared with commercial ultrafiltration membranes with similar pore sizes. In specific, the fluxes of the CNF-coated membranes at the operating conditions were 30-50 LMH depending on the thickness of the CNF nanolayer thickness, whereas the commercial membranes exhibited fluxes in the range of 3-10 LMH only. Membranes with thinner CNF layer thickness showed higher water flux, but when the layer thickness decreased to around 100 nm, fouling started to occur due to the surface roughness due to the fibrous support. At an optimum CNF thickness, biofouling was shown to be as low as 5%, whereas commercial membranes exhibited fouling as high as 30-40% under the same protein concentration.

Sustainable biomass-derived nanocellulose as anti-biofouling layer for membranes

256th National Meeting (2018)

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