Removal of anionic dye using amine-functionalized mesoporous hollow shells prepared from corn cob silica

This study evaluated the performance of amine-functionalized mesoporous hollow spheres obtained using corn cob (an agriculture byproduct) nanosilica as support material for amine immobilization (NH₂-MHS) for removal of Congo Red (CR) dye from aqueous solution. Physical characteristics of adsorbents were studied using zeta potential, N₂ adsorption–desorption isotherms, surface area, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy. The effects of various physiochemical parameters such as pH (3–9), different adsorbents, temperature (15, 25, and 35 °C), initial dye concentration (10–500 mg/L), and adsorbent dosage (0.1–1.0 g) on the CR removal efficiency were investigated. The equilibrium adsorption data were well fit by the Freundlich model. The maximum adsorption capacity of CR onto NH₂-MHS according to the Langmuir isotherm model was 98.72 mg/g at 35 °C and pH 7. The adsorption kinetics were well fit using a pseudo-second-order kinetic model.