Synthesis of ion imprinted mesoporous adsorbent via one-pot synthesis in mild pH for removal of Cd²⁺ from water

A novel ion imprinted mesoporous SBA-15 adsorbent was fabricated via one-pot synthesis at mild pH by using Cd²⁺ as template and 3-mercaptopropyltriethoxysilane as functional monomer for removal of Cd²⁺ from water. The resultant Cd²⁺ imprinted mesoporous silica (CdIMS) exhibited a highly ordered hexagonal inner structure identified using small angle X-ray diffraction (SAXD) and transmission electron microscope (TEM). The CdIMS possessed a BET surface area of 376.2 m² g⁻¹, a pore volume of 0.71 cm³ g⁻¹ and mean pore diameter of 4.1 nm by using nitrogen adsorption–desorption measurement. The chemical composition was confirmed by Fourier transform infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX). The saturated adsorption capacity of the adsorbent toward Cd²⁺ reached up to 128 mg/g at pH 6. Langmuir isothermal adsorption model was proved to describe the adsorption data better. The adsorbent also possessed excellent kinetic property and attained equilibrium within 15 min. The adsorption process can be better described by the pseudo-second-order model than the pseudo-first-order model. Moreover, the adsorbent also exhibited specific adsorbent selectivity toward Cd²⁺ in presence of four competitor ions. The CdIMS was also capable in removing Cd²⁺ from water sample.