Shell-in-shell monodispersed triamine-functionalized SiO2 hollow microspheres with micro-mesostructured shells for highly efficient removal of heavy metals from aqueous solutions

Abstract

For the first time, triamine-functionalized SiO2 hollow microspheres (TAS-HMSs) with shell-in-shell morphology and micro-mesoporous walls were utilized to remove some heavy metal cations namely Pb(II), Cu(II), Cd(II), and Cr(III) from aqueous solution. Moreover, a facile one-pot co-condensation methodology was applied for preparing the TAS-HMSs. Adsorption kinetics fitted by both pseudo-first-order and pseudo-second-order models (their nonlinear regressions ∼ 0.98). The equilibrium data fitted better with the Langmuir model for TAS-HMSs and the sequence of maximum adsorption capacities under optimal conditions (pH: 5.0; adsorbent dose: 5.0 mg; contact time: 120 min) was as follows: Pb(II) (295.36/mg g–1), Cu(II) (275.88/mg g–1), Cd(II) (251.67/mg g–1), and Cr(III) (192.87/mg g–1). Thermodynamic parameters, i.e. ΔG°, ΔS°, and ΔH° suggested that heavy metals adsorption onto TAS-HMSs is a spontaneous, endothermic, and physicochemical adsorption process. These findings highlight the potential usefulness of TAS-HMSs as a high efficient adsorbent for heavy metals removal.