Citric acid-silane modified zirconia nanoparticles: Preparation, characterization and adsorbent efficiency

This work demonstrates the development of novel adsorbent of 3-aminopropyltriethoxysilane (APTES)/citric acid (CA) modified zirconia nanoparticles (APTESCAZNs) for removing of Pb(II) and Cd(II) as heavy metal ion models from the water. The physical properties of as-prepared nanoparticles were investigated and compared with primary unmodified and APTES-modified ones using thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) analysis, zeta potential, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and N2 adsorption-desorption isotherms. The synthesized APTESCAZNs particles had a quasi-spherical, mesoporous shape with the particle size prominently in 21.4 nm. The adsorption ability of the as-prepared particles was investigated in the different experiment condition (pH, time and Pb and Cd ion concentration). The results showed that APTES and CA surface modification improved adsorption properties of primly zirconia nanoparticles. The optimum adsorption of the APTESCAZNs occurred at pH = 6.0. The kinetic studies revealed that a pseudo-second-order kinetic model was involved in the ions adsorption and the maximum adsorption capacity of 172.4 and 90.9 mg/g were obtained for Pb2+ and Cd2+ ions, respectively. The regeneration study showed that the synthesized nanoadsorbent was effectively regenerated using acid treatment.