Amphiphilic cellulose nanofiber-interwoven graphene aerogel monolith for dyes and silicon oil removal

Abstract Monolithic graphene oxide (GO) and reduced GO (rGO) aerogel is recently receiving a great deal of concern as a promising adsorbent, whose structure and surface properties, however, are anticipated to be improved and adapted to the adsorption of organic contaminants with various polarities and ionic properties. Herein, super strong and hydrophilic cellulose nanofiber (CNF) was exploited as a cross-linker to interweave in between rGO layers so as to tune and balance the structural and surface properties (hydrophilicity and hydrophobicity) of the monolith. It was found that mechanical property of the monolith changes stepwise with the addition of CNF and can be greatly improved by proportion with CNF irrespective of a little sacrifice in electrical conductivity. Filling and further formation of aggregating bundle structure of CNFs in rGO monolith gradually decreases porosity at compensation of a slight increase in monolithic volume. CNF plays a critical role in separating rGO layers, leading to formation of the exposed and uniformly dispersed rGO layers in the monoliths. It can increase the amount of oxygen containing groups at the same time to generate carbonized moieties, thus ameliorating both hydrophilicity and hydrophobicity of the monolithic aerogel. The unique structural change and improved amphiphile surface property due to the addition of CNF can greatly enhance affinity of the hybridized monolith toward the adsorption of not only hydrophilic (both anionic and cationic) dyes but also hydrophobic organic oil.