Silica nanoparticles have been successfully synthesized by a modified sol-gel auto combustion synthesis method using
silica gel and PEG 4000. The as-prepared silica was calcined at 800 oC for 4 h following by the characterization using
various tools such as XRD, FT-IR, and FE-SEM. The average crystallite size of the calcined Silica was determined to be 3-
7.5 nm. FTIR spectroscopy confirmed the presence of a silica sample according to the presence of the peaks at 468, 665, 811,
and 1064 cm-1. The FE-SEM photograph displayed that the calcined silica nanoparticles are agglomerated in spherical shapes
and the average agglomerated particle size in the range of 91 nm. The batch adsorption was applied for the removal of congo
red dye over the fabricated silicon oxide adsorbent under various experimental conditions. The extracted adsorption data
applied for the investigation of adsorption isotherm and kinetic models. Also, the thermodynamic parameters were examined
for the removal of congo red dye over silicon oxide nanoparticles.