Chitosan tailored SiO₂ aerogel for efficient removal of copper ions

Copper ions pollution is a severe problem for the health of human beings worldwide, while the removal of copper ions with high-efficient and low-cost method remains a challenge. Herein, chitosan and tetraethyl orthosilicate (TEOS) were used as precursors to prepare SiO₂/chitosan hybrid aerogel. The effects of chitosan content on the density, porosity, and adsorption property of the composite aerogel were investigated by means of structure and performance characterization. The results showed that SiO₂/chitosan hybrid aerogel possesses a uniform porous structure. With the increase of chitosan content below 20 wt%, the bulk density of hybrid aerogel decreased while the porosity increased. The adsorption tests for Cu²⁺ ions showed that the adsorption capacity of the composite aerogel increased with the increase of chitosan content, and was up to 35.72 mg/g when the chitosan content was 40 wt% with a high copper ions removal efficiency (81 %), exhibiting the superior adsorption performance. Adsorption kinetics show that ΔH° was found to be -13.1 kJ/mol, indicating that the reaction was exothermic. ΔG° values for different were below zero, which shows that the adsorption process occurs spontaneously. FTIR and XPS spectra show that the adsorption mechanism of aerogel includes the electrostatic attraction between aerogels and Cu²⁺, and the chemical interaction of C-O-Cu and Cu-NH₂. Our work presents a promising strategy for the highly efficient removal of copper ions for environmental remediation.