Sol–gel derived poly(vinyl alcohol)-3-(2-aminoethylamino) propyl trimethoxysilane: Cross-linked organic–inorganic hybrid beads for the removal of Pb(II) from aqueous solution

This manuscript reports sol–gel derived cross-linked poly(vinyl alcohol) (PVA)-3-(2-aminoethylamino) propyl trimethoxysilane (AEAPTMEOS) beads with low degree of swelling as a new adsorbent for the removal of Pb(II) from aqueous solution. Beads were prepared by condensation polymerization followed via acid-catalyzed sol–gel process in presence of non-ionic surfactant. Cross-linking was achieved by glutaraldehyde. Presence of –NH/–NH2 groups in beads provide active sites for Pb(II) adsorption, and were responsible for high adsorption capacity. SEM/TEM studies confirmed the spherical and rough surface morphology, which was changed after Pb(II) adsorption. For the removal of Pb(II) in aqueous solution, effect of equilibrium time, temperature, pH, adsorbent dose and adsorbate concentration were investigated in batch process. Pseudo-first- and pseudo-second-order kinetics were also evaluated. The equilibrium adsorption followed Langmuir and Freundlich isotherms. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° revealed endothermic and spontaneous adsorption. Monolayer adsorption capacity (Q0) value for the developed PVA-AEAPTMEOS beads was 67.56 mg g−1 at pH: 5.0, much higher as compared to other adsorbents reported in literature. Desorption studies also suggested that cross-linked PVA-AEAPTMEOS beads can be effectively utilized for the removal of Pb(II) from wastewater.