Stiff and tough hydrophobic cellulose-silica aerogels from bacterial cellulose and fumed silica

This work reports hydrophobic and compressible cellulose- silica composite aerogels prepared by freeze drying fumed silica (FS) infiltrated bacterial cellulose (BC) hydrogels. Compression modulus of cellulose silica (BC-FS) aerogels increase from 0.22 MPa up to 3.83 MPa with respect to pure freeze dried BC. BC with 8% silica (BC-FS-8) aerogel demonstrated excellent robustness and is compressible with full elastic recovery for 50 cycles without any substantial drop in mechanical strength. All aerogels exhibit more than 96 % porosity, specific surface up to 420 m2/g, density ranging from 0.01 to 0.04 g/cm3 and thermal conductivity less than 0.04 W/mK. Hydrophobic aerogels demonstrated excellent oil absorption properties from oil/water mixture, with an oil uptake up to 28 times of its original weight. The cyclic test conducted for oil absorption shows that the aerogel can be used at least 10 times for oil recovery without any substantial reduction in the uptake capacity.