Adsorption Properties of Thiol-Functionalized Silica Nanoparticles Prepared for Application in Poly(ether sulfone) Nanocomposite Membranes

Thiolfunctionalized silica nanoparticles (SiO2– SH) were prepared by sol-gel method through using 3- mercaptopropyltrimethoxysilane and nanosized silica. The effect of the pH of the silane solution on grafting efficiency of silica nano-particles was scrutinized. It was found that the reaction between silane and silica nanoparticles was more effective at low pH. The FTIR spectroscopy and CHNS analyses were used to study the chemistry of the modified nanoparticles. It was found that the SiO2–SH groups could effectively remove the heavy metal ions (Pb2+, Ni2+, and Hg2+) in the solution through electrostatic and chemical interactions. The adsorption isotherm and adsorption capacity of the functional nanoparticles for different metal ions, and its selectivity were investigated. Similarly, the effect of the pH values on the adsorption of metal ions was studied. The strong adsorption ability of SiO2–SH can be attributed to the functional nonoparticles with rich thiol groups facilitating the mass transport of metal ions to the active sites. These functional nanoparticles were blended in poly(ether sulfone) membranes as an adsorbent to improve the membranes separation and selectivity properties for removal of heavy metal ions.