Adsorption of lead ions in contaminated water using commercial hydrophilic silica nanoparticles

Abstract

The adsorption of lead ions from simulated industrial wastewater using hydrophilic commercial silica nanoparticles (Aerosil A130VS) is reported. These results were compared with those obtained using sol-gel silica nanoparticles prepared in our laboratory. Hydrated commercial silica nanoparticles have, on their surface, silanol groups (≡Si-OH) that are appropriated for the adsorption process. The commercial particles are dense because they are produced by a pyrogenic process. The absence of pores means a smaller internal surface area and, consequently, a smaller number of silanol groups available for adsorption; as compared with the highly porous sol-gel silica nanoparticles. This effect is partially compensated by the small particle size that can be obtained from these commercial particles. Different concentrations of lead ions in aqueous solution were added to a suspension of commercial particles until the critical flocculation concentration was reached. The flocculation kinetic was obtained using dynamic light scattering and the amount of adsorbed lead ions using atomic absorption. The lead concentration was reduced from 65.9 ppm to 0.2 ppm using Aerosil A130VS.