Characterization of a bacterial cellulose-silica nanocomposite prepared from agricultural waste products

Bacterial cellulose (BC) has attracted considerable scientific interest and can be modified, making it more widely useful in composites with guest nanoparticles. In this study, silica nanoparticles obtained from rice husks were used to prepare BC-silica composite aerogels (CAs) via a sol-gel method. Various amount of silica nanoparticles (3, 6, 9 and 12% w/v) dissolved in 2.5 M NaOH were used as a precursor for inclusion into BC. Subsequently, it was employed to form a SiO2 gel skeleton in a BC matrix by adding 2 M H2SO4, as a catalyst. Increasing levels of silica nanoparticles led progressively lower transmittance values of BC-silica CAs. SEM images revealed a surface morphology of spheroid particles with little agglomeration. The XRD diffraction peaks were gradually covered by a broad peak of silica as increasing silica content. Similarly, FTIR spectroscopy results also indicate the presence of silica in proportion to its content. Furthermore, addition of silica nanoparticles improved the thermal properties using TGA analysis, shifting the decomposition temperature of BC up to 550 °C and retaining of BC weight at least 60% with the BC sample with 3% of silica. This unique characteristic implies that silica had a stabilizing effect on polymeric cellulose. These results demonstrate an economical and environmentally friendly preparation of BC-silica CAs that can benefit material applications.