Advancing Direct Air Capture via Wood-Derived Biochar: Catalytic Enhancement of CO2 Adsorption Performance and Regeneration Stability - Thesis

[Geoengineering News]

https://www.proquest.com/openview/cd0c64016a7762395c43a639a987d7f4/1?pq-origsite=gscholar&cbl=18750&diss=y

Authors: Eshita, Jannatul Adnin

2025

Abstract 

Wood-derived biochar offers a sustainable and cost-effective method for direct air cap-

ture (DAC) of CO2. This study comprehensively examines the impact of operating

temperature, gas flow rate, and prolonged saturation on CO2 adsorption performance.

A biochar-packed fixed bed column was subjected to synthetic air (400 ppm CO2 and

balanced N2) at various flow rates (35–80 mL/min) and temperatures (5°C to 20°C).

The biochar exhibits a highly alkaline nature (pH 10.23), high specific surface area, and

a rich microporous structure. Maximum CO2 removal occurred at lower temperatures

and flow rates, resulting in a CO2 removal rate of up to 91.8% and an adsorption capac-

ity of 0.014 mmol/g at 5°C. Although higher flow rates enhanced adsorption capacity,

they reduced removal efficiency. After 12 hours of continuous exposure, saturation be-

havior was observed, resulting in a total adsorption capacity of nearly 0.055 mmol/g

(2.42 mg/g). Kinetic analysis revealed good agreement with both pseudo-second-order

(PSO) and pseudo-first-order (PFO) models, indicating the coexistence of physisorp-

tion and chemisorption mechanisms. The adsorbent consistently demonstrated stable

performance across several regeneration cycles, highlighting its reusability. These re-

sults highlight the promise of wood biochar as a viable, renewable DAC sorbent capable

of capturing low-concentration CO2 across different environmental conditions.

Source: ProQuest