Investigation of the Amine-Functionalized Silica Material for Capture of CO₂ by Adsorption

Abstract

CO₂ emissions are of serious concern due to their negative effect on climate change. As emissions from various industrial processes continue to rise, the need to capture and utilize CO₂ becomes increasingly important. This paper examined the applicability of amine-functionalized silica material for the capture of CO₂. Commercially sourced silica gel was modified with an amino group and used as a solid support substrate. The substrate, silica, was suspended in dimethylformamide solution and reacted with a chlorinating reagent, phosphorous pentachloride, followed by substitution of the chloride atom with the amino group from ethylenediamine. The modified silica and CO₂-treated samples were analyzed using Fourier-transform infrared spectroscopy and thermogravimetric analysis. It was observed from the Thermal analysis that the silica framework was stable between 0°C and 100°C, and the mass loss observed near this temperature is due to the decomposition of the grafted ethylenediamine and not of the silica support. The modified silica was applied for the removal of a laboratory-prepared CO₂ gas. An excess of CO₂ was bubbled into a 1M calcium hydroxide solution, and turbidity measurements were recorded to determine removal efficiency. The regeneration of the amino-modified silica was confirmed using dilute hydrochloric acid, which stripped the attached CO₂. The contact time was evaluated, and an optimum duration of 35 minutes yielded the highest removal efficiency. Adsorption followed pseudo-first-order kinetics, indicating a chemisorption process. This study reported an adsorption capacity of 0.3558 g/g of CO₂, demonstrating that the modified material is effective for CO₂ capture.