Sol-gel silica doped with 3-(2-naphthoyl)-1,1-dibutylselenourea, an efficient precursor for removal of Pb(II) and Zn(II) from water samples

Abstract

ABSTRACT 3-(2-naphthoyl)-1,1-dibutylselenourea was prepared and Sol-gel silica was doped with it. The selenourea organic derivative was characterised in solid state by single-crystal X-ray diffraction, and doped sol-gel materials were characterised by FT-IR and SEM. The doping results were verified from their characteristic prominent bands v(cm−1) = 1753 and 1199 predominantly assigned to C = O and C = Se, respectively. The processed sol-gel was used as adsorbent to investigate its efficiency for removal of M(II) ions from aqueous solution using batch techniques (M = Pb and Zn). The porosity study reveals that the doped sol-gel contains pores which are responsible for the adsorption of metal ions, besides pores present in the material, the ligand possesses active sites (-NH, = O, = Se) readily available for coordination with metal ions, and the material thus acts as efficient chelating agent. Adsorption kinetics, isotherm, effect of equilibration time, initial concentration of adsorbate, and pH on the metal extraction were studied and conditions were optimised. Metal remediation capacity of the hybrid material i.e. sol-gel is pH dependent, and maximum removal was obtained at pH 5 (Pb) and pH 6 (Zn) with in 35 and 15 minutes, respectively. The prepared adsorbent shows rapid equilibrium and enough stability at elevated temperature in the given medium. Desorption of metal ions was carried out in 0.1 M HNO3 solution, and thereafter, sol-gel silica adsorbent was successfully regenerated and reused.