Fabrication of the composite sepiolite@polyethyleneimine/sodium alginate and its excellent adsorption performance for heavy metal ions

In order to explore more excellent heavy metal adsorbents with clay mineral sepiolite (Sep), this work was carried out and presented the novel design and fabrication processes of the composite Sep@polyethyleneimine/sodium (SEP@PEI/SA), which were characterized by SEM, EDX, FT-IR, XPS, TGA, and porous analysis, and were efficiently utilized for heavy metal ions adsorption. The adsorption properties of SEP@PEI/SA for Pb(II), Cu(II), Au(III), Ag(I), Pd(IV), Pt(IV), Hg(II), Cr(VI), Cr(III), Co(II), Zn(II), and Ni(II) were investigated, and it was employed to remove lead ions from the simulated lead-containing industrial wastewater through adsorption method. The adsorption properties of lead ions on SEP@PEI/SA were thoroughly investigated in this study, and the results demonstrated that the adsorption kinetics of SEP@PEI/SA for lead ions at different temperatures could be modeled closely by a pseudo second-order rate equation, Langmuir isotherm model was the best fit one and the maximum adsorption capacity was could reach 1094.86 mg/g at 25 °C. Adsorption thermodynamic parameters, standard Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) changes, were −6.29 KJ·mol−1 (35 °C), 30.81 KJ·mol−1, 0.12 KJ·(K·mol)−1, respectively, suggesting the spontaneous and endothermic nature of the adsorption process with the increase of the randomness. All these research work results showed that the novel adsorbent SEP@PEI/SA has promising potential to removal lead ions from water body efficiently.