Fabrication of methyl acrylate modified silica aerogel for capture of Cu²⁺ from aqueous solutions

With SiO₂ gel as the main skeleton material, the surface modification with methyl acrylate (MA) and tetraethylenepentamine (TEPA) was carried out by Michael addition and substitution reaction, after CO₂ supercritical drying TEPA and MA modified SiO₂ aerogel (TEPA–MA–SA aerogel) was obtained. The sample exhibited selectivity and enormous adsorption capacities for Cu²⁺ (218.57 mg g^–1). The removal rate of Cu²⁺ in ternary-mixed metal solution reached 49.29%, ranking first among the materials we have known. MA and TEPA both contain rich groups such as –NH₂ and –NH–, which provide abundant adsorption sites for adsorbing heavy metal ions. BET test showed that the specific surface area, the pore volume, and the pore diameter was 190.2 m² g⁻¹, 4.426 cm³ g⁻¹ and 9.306 nm respectively. The above properties facilitated capture for Cu (II). The adsorption data were fitted with Langmuir and Freundlich adsorption isotherm models, and both models could describe the adsorption process. However, according to the fitting parameters, Langmuir adsorption isotherm model explicates the adsorption process better. Although the pore structure and specific surface area are beneficial to the physical adsorption, chemical chelation still plays a major role. XPS analysis further proved the possible adsorption mechanism that N and O atoms adsorb Cu (II) ions through chelation. Altogether, TEPA–MA–SA aerogel is suitable as an auxiliary adsorbent to purify contaminated water.