Enhanced CO2 adsorption on graphene oxide via mangosteen peel extract impregnation: Effect of synthesis temperature variation

By altering the preparation temperature (60, 80, and 100°C), this study explores the impregnation of mangosteen peel extract (MP) onto graphene oxide (GO) in order to enhance the quality of GO surface functional groups and CO 2 adsorption. The adsorbent was prepared using the modified Hummer's method and subsequently characterized by its surface and chemical characteristics. Nitrogen adsorption-desorption analysis revealed that GO 60 + MP exhibited a type IV isotherm with an H 2 hysteresis loop, indicating dominant mesoporous characteristics, whereas GO 80 + MP and GO 100 + MP showed type III isotherms with weaker adsorption-desorption interactions. The BET surface area of GO 60 increased from 52.64 m 2 /g to 71.27 m 2 /g after mangosteen peel impregnation. The CO 2 adsorption capacity of GO 60 increased from 0.51 mmol/g to 1.86 mmol/g after impregnation. In addition, the energy gap decreased from 3.29 eV to 3.04 eV after surface modification. The adsorbent also demonstrated preliminary regeneration capability and relatively stable adsorption performance during the investigated adsorption-desorption cycles under fixed-bed conditions. Furthermore, adsorption kinetic analysis showed that the Avrami fractional-order model better described pristine GO, suggesting relatively heterogeneous adsorption behavior, whereas the impregnated samples exhibited more consistent fitting with pseudo-first-order and pseudo-second-order models after surface modification.