An organic–inorganic bio-hybrid bead composite was fabricated through a sol–gel reaction by trappingand condensing amorphous silica into the network structures of calcium ion cross-linked alginate(CA)–xanthan gum (XG) gel beads. The reinforced silica/CA–XG composite was characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetricanalysis (TGA) and surface area measurement. Pb(II) adsorption by the composites was investigated ina batch mode by changing the relevant parameters which included solid/liquid ratio, contact time, pH,temperature, effect of co-existing metal ions and particle size. The analysis of the equilibrium data at293 K was more appropriate for the Langmuir isotherm model, with maximum adsorption capacitystanding at 18.9 mg Pb g1. It evidenced that Pb(II) adsorption was based on chemical binding process,along with intra-particle diffusion contribution. Experiments carried out at 293 and 313 K enabled theevaluation of the thermodynamic parameters of the adsorption process, namely DG0 (5 kJ mol1),DH0 (7.20 kJ mol1) and DS0 (18.0 J mol1 K1); it was revealed as a spontaneous and endothermic process.0.5 mol L1 HCl was recommended for composite regeneration and Pb(II) recovery. Fixed bed experimentwas attempted for treatment of Pb(II)-bearing battery industrial wastewater with an efficient levelof reversible performance through an extended period of time. Overall, the proposed silica/CA–XG compositewould be a very promising adsorbent for lead removal and recovery from aqueous solutions, withremarkable advantages in terms of biocompatibility, recyclability, ease of operation and low cost.

Silica modified calcium alginate–xanthan gum hybrid bead composites for the removal and recovery of Pb(II) from aqueous solution

Pepe F.
2013

Abstract

An organic–inorganic bio-hybrid bead composite was fabricated through a sol–gel reaction by trappingand condensing amorphous silica into the network structures of calcium ion cross-linked alginate(CA)–xanthan gum (XG) gel beads. The reinforced silica/CA–XG composite was characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetricanalysis (TGA) and surface area measurement. Pb(II) adsorption by the composites was investigated ina batch mode by changing the relevant parameters which included solid/liquid ratio, contact time, pH,temperature, effect of co-existing metal ions and particle size. The analysis of the equilibrium data at293 K was more appropriate for the Langmuir isotherm model, with maximum adsorption capacitystanding at 18.9 mg Pb g1. It evidenced that Pb(II) adsorption was based on chemical binding process,along with intra-particle diffusion contribution. Experiments carried out at 293 and 313 K enabled theevaluation of the thermodynamic parameters of the adsorption process, namely DG0 (5 kJ mol1),DH0 (7.20 kJ mol1) and DS0 (18.0 J mol1 K1); it was revealed as a spontaneous and endothermic process.0.5 mol L1 HCl was recommended for composite regeneration and Pb(II) recovery. Fixed bed experimentwas attempted for treatment of Pb(II)-bearing battery industrial wastewater with an efficient levelof reversible performance through an extended period of time. Overall, the proposed silica/CA–XG compositewould be a very promising adsorbent for lead removal and recovery from aqueous solutions, withremarkable advantages in terms of biocompatibility, recyclability, ease of operation and low cost.
Aqueous solution; Pb(II); Removal
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12070/5004
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