Green nanosilica@folic Acid (VB9) nanocomposite for engineered adsorptive water remediation of bivalent lead, cadmium and copper

Abstract

Folic acid (VB9) was used as an eco-friendly sequestering chemical compound to modify and develop a novel nanocomposite via surface immobilization and chemical bonding with nanosilica (Nano-SiO2) in the chloride form to generate Nano-SiO2@VB9. The synthesized materials were investigated and characterized by several means of SEM, HR-TEM, TGA, FT-IR, XRD and surface area determination. The tendency of Nano-SiO2@VB9 nanocomposite to extract and remove bivalent lead, cadmium and copper ions was studied and optimized under various variables including pH of contact medium, nanocomposite dose, contact time, effect of metal ion concentration and interfering cations-anions. The highest determined capacity values were 562.1, 973.8 and 152.1 mg g−1 for Cd(II), Pb(ІІ) and Cu(II), respectively. The optimum contact time for sorption of metal ions was identified as 25 min, while 10.0 mg of Nano-SiO2@VB9 nanocomposite was the optimum dosage to establish the maximum capacity values. The adsorbed ions were arranged in a multilayer surface and the equilibrium up-take of metal ions by Nano-SiO2@VB9 nanocomposite was favorably characterized by the Freundlich adsorption isotherm model. The potential applications of Nano-SiO2@VB9 for removal and preconcentration of Cu(II), Pb(II) and Cd(II) from real water samples using multistage microcolumn were also studied to confirm excellent percentage extraction values 94–100%, 100% and 57–81%, respectively.