Abstract:
The main anthropogenic greenhouse gas (GHG) which immensely leads to global warming is CO2 and it is primarily emitted through fossil fuel combustion practices. To avoid the climatical adversities, CO2 capturing, and utilization is requisite for sustainable development. In this study, activated carbon (AC) based adsorbents were synthesized from biomass-derived hydro-char (HC) through modified hydrothermal carbonization (HTC) process coupled with H3PO4 (PA), ZnCl2, (ZnCl), and KOH thermochemical activation with a specific impregnation ratio of 1:3 (HC/activating agent) at 600 °C. The prepared ACs were characterized through CHN-S analyser, XRD, SEM/EDS, BET, TGA, and FTIR analysis which revealed the modification in textural and surface morphology. Thermochemical activation results in surface modification of AC samples with a higher specific (SBET) surface area having range 650-1225 m2/g and 68-90% micro-porosity. The CO2 adsorption capacity was examined through a high-pressure gas sorption analyser at a pressure of 0-16 bar (15, 30, and 45 C). At 15 C of temperature AC-PA showed CO2 adsorption capacity of 130 and 958 mg/g, while AC-ZnCl exhibited 160 and 836 mg/g of adsorption at 1 and 16 bar of pressure respectively. Whereas AC-KOH exhibited a notable CO2 adsorption capacity of 198 and 1560 mg/g at 1 and 16 bars of pressure (15 C). Furthermore, experimental data of CO2 adsorption were applied in Freundlich and Langmuir isotherm models and validate by calculating regression coefficient R2 and standard deviation, Δq (%). Finally, the thermodynamics parameters were evaluated and concluded that the adsorption of CO2 (adsorbate) on adsorbent is spontaneous and exothermic.
