Green synthesis approach using deep eutectic solvents to enhance the surface functional groups on porous carbon for CO₂ capture

This study explores the potential of green solvents using amino acids-based deep eutectic solvents to alter surface functionality of activated carbon thus enhancing the carbon dioxide (CO₂) adsorption capacity. Green solvent is prepared by mixing an amino acid (L-Arginine) with ethylene glycol to form amino acid-based deep eutectic solvents. Amino acid-based deep eutectic solvents were used to modify the surface functionalities of activated carbon derived from palm shell waste. The change in surface functional groups and surface morphology of the modified activated carbon samples were characterized by Fourier-transform infrared spectroscopy and Scanning electron microscopy-energy dispersive X-ray analysis. Then, CO₂ removal performance was performed using a packed-bed CO₂ adsorption reactor to evaluate CO₂ breakthrough time and adsorption capacity. CO₂ adsorption experiments were measured at a certain temperature (25-45°C), at a fixed feed flow rate and CO₂ concentration of 200 mL/min and 15%. It was observed that modified activated carbon showed the highest breakthrough time (15.2 min) compared to raw palm shell (5.2 min) at an adsorption temperature of 25°C. CO₂ breakthrough times significantly decreased with increasing adsorption temperature because of physical adsorption.