Silica nanoparticles (SiO2 NPs) are a material that is used in many areas and are obtained by various methods and attracts the attention of researchers with its many properties such as photocatalysis, adsorbent and non-toxicity. In this study, sodium bentonite was used as a raw material to synthesize silica nanoparticles. In the FTIR results of the prepared SiO2 NPs, the Si-O-Si band indicating the formation of NPs is remarkable. The morphology structure was determined to be an agglomerated structure similar to a spherical form in SEM images. In the other part of the study, the photocatalytic degradation of methylene blue (MB) dye was investigated with SiO2 NPs. The results revealed that 80% degradation was achieved in 60 min and the process complied with the second order reaction kinetics. The effect of MB in aqueous solution was investigated for its use as an adsorbent. After 60 minutes, 90% dye removal was achieved and it was determined that the process fit pseudo-second-order kinetic model (PSO).