Adsorption and Removal of Cadmium Ions from Simulated Wastewater Using Commercial Hydrophilic and Hydrophobic Silica Nanoparticles: a Comparison with Sol–gel Particles

Abstract

Adsorption and removal of cadmium ions from simulated industrial wastewater using hydrophilic and hydrophobic commercial silica nanoparticles are reported. These results are compared with those obtained using sol–gel silica nanoparticles. Two types of dense commercial pyrogenic silica nanoparticles with different chemical groups on the surface were used to adsorb cadmium ions: Aerosil A130VS and R972. The pore absence in these particles reduces the surface area and, consequently, the concentration of active chemical groups appropriated for adsorption, as compared with the sol–gel particles that are highly porous; this effect is partially compensated by the small sizes available for these commercial particles. The concentration of cadmium ions was reduced: from 109 to 0.01 ppm for A130VS, from 138 to 1.44 ppm for R972, and from 123 to 0.005 ppm for sol–gel. The flocculation kinetics was obtained using dynamic light scattering and the amount of adsorbed cadmium in the sediment using atomic absorption spectroscopy.