Selective removal of copper (II) ions from aqueous solution using pyridyl-bridged mesoporous organosilica hybrid adsorbent

The incorporation of active functional groups into the mesoporous organosilica hybrid materials is efficient for various applications. A newly designed mesoporous organosilica adsorbent was prepared using diaminopyridyl groups bridged-(bis-trimethoxy)organosilane (DAPy) precursor by using Pluronic P123 as structure directing template via sol-gel co-condensation method. The hydrolysis reaction of DAPy precursor and tetraethyl orthosilacate (TEOS) with a DAPy content of about 20 mol% to TEOS were incorporated into the mesopore walls of the mesoporous organosilica hybrid nanoparticles (DAPy@MSA NPs). Low-angle XRD and FT-IR, N₂ adsorption-desorption analysis, SEM, TEM, and TG analysis were used to characterize the synthesized DAPy@MSA NPs. The DAPy@MSA NPs exhibit an order mesoporous structure with a high surface area, mesopore size and pore volume of approximately ∼465 m²/g, 4.4 nm and 0.48 cm³/g, respectively. The pyridyl groups integrated DAPy@MSA NPs showed the selective adsorption of Cu²⁺ ions from the aqueous medium by metal-ligand complex coordination of Cu²⁺ ions with the integrated pyridyl groups and the pendant hydroxyl (-OH) functional groups present into the mesopore walls of the DAPy@MSA NPs. In the presence of other competitive metal ions (Cr²⁺, Cd²⁺, Ni²⁺, Zn²⁺, and Fe²⁺), the DAPy@MSA NPs showed relatively high adsorption of Cu²⁺ ions (276 mg/g) from aqueous solution as compared to the other competitive metal ions at the same concentration (100 mg/L) of initial metal ion solution.