Ultrasonic-assisted synthesis of Bio-MOF-based cobalt-glutamic acid for CO2/CH4 adsorption: Experimental and isotherm modeling

Abstract

The natural gas and carbon capture industries require sustainable solutions, therefore producing eco-friendly materials is important. The Bio-Metal Organic Framework (Bio-MOF) of cobalt chloride and L-glutamic acid (Co-Glu) produced ultrasonically in this research captures and stores CO₂ and CH₄ sustainably. For industrial applications, the Bio-MOF reduces energy usage, improves material characteristics, and scales for mass manufacturing. The synthesis was improved using several reactant molar ratios, and SEM, XRD, TGA, FTIR, and BET were used to analyze the material's structure and stability. Post-combustion experiments evaluated CO₂ and CH₄ gas adsorption ability from ambient pressure up to 3.0 MPa. The research found that the Bio-MOF had high uptake capacity for CO₂ and CH₄ at 27 °C, with CO₂ uptakes of 0.51 kg/kg and CH₄ uptakes of 0.12 kg/kg, demonstrating excellent performance at moderate pressures. Isotherm modelling were also undertaken with the langmuir, toth, and langmuir-freundlich (Sips) model to simulate adsorption isotherms with R² values of 0.99 and AARE values of 0.05 observed in most regressions. The Clausius-Clapeyron and Chakraborty-Saha-Koyama (CSK) equation was used to compute the enthalpy of adsorption up to 700 kJ/kg, highlighting the energy-efficient potential of Bio-MOFs in gas storage applications.