Performance evaluation of phosphonium based deep eutectic solvents coated cerium oxide nanoparticles for CO2 capture

Abstract

The critical challenge being faced by our current modern society on a global scale is to reduce the surging effects of climate change and global warming, being caused by anthropogenic emissions of CO₂ in the environment. Present study reports the surface driven adsorption potential of deep eutectic solvents (DESs) surface functionalized cerium oxide nanoparticles (CeNPs) for low pressure CO₂ separation. The phosphonium based DESs were prepared using tetra butyl phosphoniumbromide as hydrogen bond acceptor (HBA) and 6 acids as hydrogen bond donors (HBDs). The as-developed DESs were characterized and employed for the surface functionalization of CeNPs with their subsequent utilization in adsorption-based CO₂ adsorption. The synthesis of as-prepared DESs was confirmed through FTIR measurements and absence of precipitates, revealed through visual observations. It was found that DES6 surface functionalized CeNPs demonstrated 27% higher adsorption performance for CO₂ capturing. On the contrary, DES3 coated CeNPs exhibited the least adsorption progress for CO₂ separation. The higher adsorption performance associated with DES6 coated CeNPs was due to enhanced surface affinity with CO₂ molecules that must have facilitated the mass transport characteristics and resulted an enhancement in CO₂ adsorption performance. Carboxylic groups could have generated an electric field inside the pores to attract more polarizable adsorbates including CO₂, are responsible for the relatively high values of CO2 adsorption. The quadruple movement of the CO₂ molecules with the electron-deficient and pluralizable nature led to the enhancement of the interactive forces between the CO₂ molecules and the CeNPs decorated with the carboxylic group hydrogen bond donor rich DES. The current findings may disclose the new research horizons and theoretical guidance for reduction in the environmental effects associated with uncontrolled CO₂ emission via employing DES surface coated potential CeNPs.

Keywords: CO(2) adsorption; Cerium oxide nanoparticles; Deep eutectic solvents; Hydrogen bond acceptor; Hydrogen bond donor.