|Abstract:||Recently, surface-functionalized silicon dioxide (SiO2) nanoparticles are the subject of numerous research studies, which discuss the removal of heavy metal ions from different aquatic solutions. SiO2 nanoparticles are proven to be suitable because of their inertness, biocompatibility, specific surface area and porosity, surface treatment options (functionalization), are also simple and affordable.
The research work on the preparation of amino-functionalized SiO2 nanoparticles (SiO2@NH2) was based on the Stöber method, which involves the reaction of hydrolysis and condensation of alkoxide precursors, such as tetraethoxysilane (TEOS) and 3- (trimethoxysilylpropyl) diethylenetriamine (DETA) in alcoholic media in the presence of ammonia as a catalyst. The functionality of SiO2 nanoparticles is influenced by synthesis conditions (temperature, time, molecular ratio of water:precursor, molar ration between the precursors) and selection of precursor, which with its amino (-NH2) functional groups allows to bond and remove the heavy metal ions. SiO2 and amino-functionalized SiO2 nanoparticles (SiO2@NH2) were characterized using a variety of techniques, such as FT-IR spectroscopy, specific surface area (BET), transmission electron microscopy (TEM) and zeta potential measurements. We have studied the binding efficiency (adsorption) of heavy metals ions, lead (Pb2 +) and chromium (Cr3+), by nanoparticles, from model salt solutions. Removal efficiency of heavy metal ions was calculated based on the measurements of atomic adsorption spectroscopy (AAS). The results showed a higher tendency towards synthesized SiO2 nanoparticles to Cr3 + ions (~ 60%), compared to the Pb2 + ions (~ 33%), while the tendency of functionalized SiO2 nanoparticles towards both metals was approximately similar (~ 50%).|