Preparation, characterization and lead sorption performance of alginate-SBA-15 composite as a novel adsorbent

Alginate-SBA-15 (ALG-SBA-15) was synthesized by encapsulation of the nanoporous SBA-15 in the biopolymeric matrix of calcium alginate. This adsorbent was characterized using powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), nitrogen adsorption-desorption and Fourier transform infrared (FT-IR) spectroscopy. Tests were then conducted to study the adsorption of lead ions onto ALG-SBA-15 from an aqueous solution for the effect of pH, contact time and temperature in batch systems. Freundlich and Langmuir models were used for a mathematics description of the adsorption isotherm. The equilibrium process was described well by the Langmuir isotherm model with the maximum sorption capacity of 222.22 mg g−1 of lead on ALG-SBA-15. The kinetics analysis revealed that the overall adsorption process was successfully fitted with the pseudo-second-order kinetic model. The values of calculated thermodynamic parameters (ΔG∘ΔG∘, ΔH∘ΔH∘ and ΔS∘ΔS∘) indicated the endothermic and spontaneous nature of adsorption. All the results validated the feasibility of ALG-SBA-15 for highly effective removal of lead from an aqueous solution.