Novel highly efficient ionic liquid-functionalized silica for toxic metals removal

Abstract Novel ionic liquid-functionalized mesoporous silicas were synthesized using triblock copolymer Pluronic F127 as a template and I. (3-chloropropyl)trimethoxysilane, which then reacted with the appropriate pyridine derivatives (Q-pSZ series), or II. 1-[3-(trimethoxysilyl)propyl]-3- or -4-undecanoylpyridinium chloride, and 3- or 4-[1-(hydroxylimine)undecyl]-1-[3-(trimethoxysilyl)propyl]pyridinium chloride (SZ series), as a source of IL functional groups. The synthesized materials were characterized by FT-IR, Raman, SEM, XPS, low temperature N2 sorption, and IGC technique. The ability of the fabricated materials as adsorbents was investigated for the removal of Pb(II), Cd(II) and Zn(II) from aqueous solutions and compared with the nonmodified silica. Sorption optimization experiments were performed by changing the factors affecting the metals ions removal, such as pH, temperature, time, metals ions concentration. The optimum pH range for adsorption of Pb(II), Cd(II) and Zn(II) was found to be 4-6 and, the optimum contact time was found to be 15 min and 45 min, for the series materials “Q-pSZ” and “SZ”, respectively. The adsorption isotherms were obtained using concentrations of the metals ions ranging from 50 to 200 mg/L. The adsorption process followed pseudo-second-order reaction kinetics, as well as Langmuir and Freundlich adsorption isotherms. Q-pSZK3 possessed adsorption capacities of 202.3 mg/g for Pb(II), SZ-Ox3 148.6 mg/g for Cd(II) and SZ-Ox4 133 mg/g for Zn(II).This study revealed that the fabricated materials were promising adsorbents for removal especially Pb(II), Cd(II) and Zn(II) from aqueous solutions.