Amino acid-imprinted polymers as highly selective CO₂ capture materials

Abstract

The recent atmospheric concentration of CO₂ increase to 400 ppm is a cause of global climate change. There is therefore an urgent need for selective and cost-effective CO₂ capture technologies. Fossil fuel consumption during energy production and transportation are two major sources of CO₂ emission into the atmosphere. The capture of CO₂ selectively from gaseous mixtures using reusable adsorbent is thus a challenge. In this article, we report that nanoparticles functionalized with imprinting of amino acids exhibit a significant increase in the selective adsorption capacities of CO₂ in a gaseous mixture. Molecular imprinting of taurine in the vinylbenzyl chloride-co-divinyl benzene polymer formed cavities of 1–3 nm size and introduced –SOOH and –N–H functionalities, resulting in a very high CO₂ adsorption capacity of 5.67 mmol g⁻¹ at 30 °C/1 bar. The selectivity of CO₂ over N₂ and CH₄ was 87–91% and 83–87%, respectively. The isosteric heat of adsorption (Q_st) for CO₂ at 298 and 303 K showed an increase in Q_st from 36.8 to 47.6 K kJ mol⁻¹, and this would be responsible for high CO₂ adsorption energies and faster kinetics. This study reports first-time imprinting of CO₂-philic templates in the polymers to capture small gas molecules at ambient conditions, and the results demonstrated that the polymers have a wide scope for real-life applications of CO₂ capture.