Valorization of argan paste cake waste: Enhanced CO2 adsorption on chemically activated carbon

Abstract

This study addresses the critical need to reduce energy penalties in CO2 capture processes by exploring the potential of activated carbons derived from argan paste cake for post-combustion CO2 capture applications. Leveraging their cost-effectiveness, stability in humid conditions, and microporous structure, a series of activated carbons with diverse textural characteristics were synthesized through a two-step chemical activation process employing a KOH: biochar ratio of 1:1. Activation temperatures ranged from 700 to 850 °C. Characterization techniques such as Raman spectroscopy, X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, elemental analysis, and Fourier-transform infrared spectroscopy were employed to analyze the structural and chemical properties of the synthesized activated carbons. Remarkably, all synthesized samples exhibited excellent CO2 adsorption properties. Notably, the activated carbon sample prepared at 700 °C (APC-500–700) demonstrated the highest CO2 adsorption capacity, reaching up to 4.89 mmol/g at 0 °C and 2.98 mmol/g at 25 °C. Additional samples, including APC-500–800 and APC-500–850, exhibited CO2 adsorption capacities of 4.89 mmol/g and 4.83 mmol/g, respectively, at 0 °C, with corresponding values of 2.74 mmol/g and 2.60 mmol/g observed at 25 °C. Selectivity and stability tests were conducted to evaluate the adsorption performance under varied conditions, further highlighting the potential of activated carbon derived from argan paste cake in contributing to efficient CO2 capture processes. These findings underscore the significance of synthesis conditions in tailoring adsorption performance and pave the way for the sustainable utilization of waste biomass for environmental applications.