Rice straw agri-waste for water pollutant adsorption: Relevant mesoporous super hydrophobic cellulose aerogel

A simplistic synthesis approach for fabrication of ultra-light density (2.2 to 24 mg. cm^-3), highly porous (98.4%-99.8%), and cross-linked natural cellulose aerogel from rice straw was developed via a freeze-drying process. The obtained natural cellulose aerogels exhibited porous network structure with specific areas of 178.8 m². g^-1 and mesopore volumes of 0.8 cm³. g^-1. The cellulose aerogel with 1.3 wt% displayed the highest Young's modulus and compressive strength. Subsequent hydrophobic coating with methyltrimethoxysilane, the super-hydrophobic and oleophilic cellulose aerogel (water contact angle as high as 151 ± 7°) were capable of adsorbing a wide range of organic solvents and oils with adsorption capacities up to 170 g. g^-1 based on the density of the liquids. Furthermore, the adsorbed organic solvent could be desorbed by means of simple mechanical squeezing. These results suggested that the super-hydrophobic natural cellulose aerogel can be used as a precious sorbents for adsorption of oil and organic solvents.