TY - JOUR

T1 - Isotherms, Thermodynamics and Regeneration Studies of CO 2 Adsorption on Activated Carbon Impregnated With Waste‐Sourced Natural Amino Acids

AU - Mohammed Hatta, Nur Syahirah

AU - Hussin, Farihahusnah

AU - Gew, Lai Ti

AU - Aroua, Mohamed Kheireddine

PY - 2025/6/9

Y1 - 2025/6/9

N2 - This study investigated the CO2 adsorption isotherms, thermodynamic properties and regeneration efficiency of palm shell activated carbon (AC) impregnated with waste‐sourced natural amino acids from egg white (EW), namely, ACEW‐30. Initially, the performance of ACEW‐30 was compared with AC impregnated with fresh EW and synthetic amino acids using fixed‐bed adsorption system. The results revealed that ACEW‐30 prepared from waste sources demonstrated comparable performance with other adsorbents tested, suggesting its potential for waste valorisation. Afterwards, the data were fitted to various adsorption isotherm models, namely, Langmuir, Freundlich, Sips, Toth, Dubinin–Radushkevich and Temkin, to characterise the adsorbate‐adsorbent interaction between CO2 molecules and ACEW‐30 at different adsorption temperatures (25–50°C) and CO2 partial pressures (0.15–0.30 vol.%). The isotherm results were used to evaluate thermodynamic properties using Van't Hoff and Clausius–Clapeyron equations. The effect of regeneration conditions (desorption temperatures and nitrogen purging flow rate) have also been investigated prior to cyclic adsorption–desorption experiments. Overall findings indicate that CO2 adsorption on ACEW‐30 was best fitted to Freundlich isotherm, spontaneous and exothermic in nature. The isosteric heat of adsorption was within 20–24 kJ/mol, suggesting that the adsorption mechanism lies within the intermediate region between purely physical and purely chemical. Remarkably, the results obtained from regeneration studies reveal that ACEW‐30 exhibited high regeneration stability at 25°C and 800 mL/min purging flow rate, with more than 87% efficiency even after 20 cyclic adsorption–desorption.

AB - This study investigated the CO2 adsorption isotherms, thermodynamic properties and regeneration efficiency of palm shell activated carbon (AC) impregnated with waste‐sourced natural amino acids from egg white (EW), namely, ACEW‐30. Initially, the performance of ACEW‐30 was compared with AC impregnated with fresh EW and synthetic amino acids using fixed‐bed adsorption system. The results revealed that ACEW‐30 prepared from waste sources demonstrated comparable performance with other adsorbents tested, suggesting its potential for waste valorisation. Afterwards, the data were fitted to various adsorption isotherm models, namely, Langmuir, Freundlich, Sips, Toth, Dubinin–Radushkevich and Temkin, to characterise the adsorbate‐adsorbent interaction between CO2 molecules and ACEW‐30 at different adsorption temperatures (25–50°C) and CO2 partial pressures (0.15–0.30 vol.%). The isotherm results were used to evaluate thermodynamic properties using Van't Hoff and Clausius–Clapeyron equations. The effect of regeneration conditions (desorption temperatures and nitrogen purging flow rate) have also been investigated prior to cyclic adsorption–desorption experiments. Overall findings indicate that CO2 adsorption on ACEW‐30 was best fitted to Freundlich isotherm, spontaneous and exothermic in nature. The isosteric heat of adsorption was within 20–24 kJ/mol, suggesting that the adsorption mechanism lies within the intermediate region between purely physical and purely chemical. Remarkably, the results obtained from regeneration studies reveal that ACEW‐30 exhibited high regeneration stability at 25°C and 800 mL/min purging flow rate, with more than 87% efficiency even after 20 cyclic adsorption–desorption.

KW - regeneration

KW - eco‐friendly adsorbent

KW - thermodynamic

KW - natural amino acid

KW - CO2 capture

U2 - 10.1002/ghg.2354

DO - 10.1002/ghg.2354

M3 - Journal article

JO - Greenhouse Gases: Science and Technology

JF - Greenhouse Gases: Science and Technology

SN - 2152-3878

ER -