Regulable surface hydroxyl group content in disperse ultrafine amorphous SiO2 nanoparticles

Abstract Amorphous silica (SiO 2 ) nanoparticles (NPs) can be applied in environmental pollutant remediation, element removal, and water purification. The content of surface silanol groups in amorphous SiO 2 NPs affects the characteristics of SiO 2 NPs. However, the regulation of surface silanol group content in amorphous SiO 2 NPs below 10 nm remains a challenge. Herein, tunable surface silanol group content was achieved in disperse ultrafine amorphous SiO 2 NPs by controlling calcination and rehydroxylation. The surface silanol group content in amorphous SiO 2 NPs is low (10 nm) and can be tuned from 0% to 2.5%. The amount of naphthalene adsorbed by the SiO 2 NPs increases with increasing surface silanol group content. The surface silanol group content in SiO 2 NPs can be an effective means to tune their adsorption performance and applications.