Direct air capture of CO2 by KOH-activated bamboo biochar.

Direct air capture (DAC) of CO 2 is considered one of the most promising carbon capture methods to reduce ambient CO 2 concentration for climate change mitigation. Biochar represents an attractive adsorbent for DAC because it is environmentally friendly and cost-effective. In this work, KOH-activated bamboo biochar shows the CO 2 capture capacity of 3.49 mmol g⁻¹ (25 °C, 1 bar), and it is used as an adsorbent to perform direct air capture using a fixed-bed reactor with an ambient CO 2 capture capacity of up to 51.74 μmol g⁻¹. Furthermore, the effect of relative humidity on CO 2 adsorption by biochar was investigated and exhibited promising stability under 2.7% relative humidity. However, the biochar activity for CO 2 capture is reduced to 63.88% under 67.1% humidity after 50 cycles. [Display omitted] • KOH was used to activate bamboo-derived biochar. • Bamboo biochar was investigated in direct air capture of CO 2. • Gas selectivity of biochar during direct air capture. • Effect of relative humidity on direct air capture efficiency. [ABSTRACT FROM AUTHOR]