The FTIR spectrum of NSi looks very different from cellulose, Figure 1, since it only shows a very intense band in 1052 cm−1, due to asymmetric mode of Si–O–Si correlated with the next intense band due to symmetric mode of the same Si–O–Si found in 800 cm−1 while the weak band in 1741 cm−1 is related to C=O group vibration since NSi is a modified silica .