| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 148064 | Chemical Engineering Journal | 2013 | 10 Pages |
•Silica/CA–XG templated by bonding of alginate–xanthan gum of complex network.•Silica synthetically entrapped and condensed into the networks of CA–XG gel bead.•Silica/CA–XG composite of optimal stability, binding capability, macro/mesoporosity.•Pb(II) removal by chemical bonding process and intra-particle diffusion process.•Efficient Pb(II) removal and recovery from battery wastewater in China.
An organic–inorganic bio-hybrid bead composite was fabricated through a sol–gel reaction by trapping and 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), thermogravimetric analysis (TGA) and surface area measurement. Pb(II) adsorption by the composites was investigated in a 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 at 293 K was more appropriate for the Langmuir isotherm model, with maximum adsorption capacity standing at 18.9 mg Pb g−1. 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 the evaluation of the thermodynamic parameters of the adsorption process, namely ΔG0 (−5 kJ mol−1), ΔH0 (7.20 kJ mol−1) and ΔS0 (18.0 J mol−1 K−1); it was revealed as a spontaneous and endothermic process. 0.5 mol L−1 HCl was recommended for composite regeneration and Pb(II) recovery. Fixed bed experiment was attempted for treatment of Pb(II)-bearing battery industrial wastewater with an efficient level of reversible performance through an extended period of time. Overall, the proposed silica/CA–XG composite would be a very promising adsorbent for lead removal and recovery from aqueous solutions, with remarkable advantages in terms of biocompatibility, recyclability, ease of operation and low cost.
