Biomass is regarded as a promising low-cost precursor for the preparation of activated carbons. However, direct carbonization of biomass usually produces a low-surface-area or even non-porous carbons that are useless for CO₂ capture. In this work, garlic peel was first transformed to a hydrochar by hydrothermal carbonization and then chemically activated by KOH to obtain activated carbons with high-surface-areas and large pore volumes. The microstructure and morphology of the activated carbons were characterized by N₂ adsorption, SEM and XRD. Results indicate that their surface area and pore volume are mainly determined by the activation temperature and KOH/hydrochar mass ratio. Activated carbon (AC-28) obtained by KOH activation with a KOH/hydrochar ratio of 2 at 800 °C has a well-developed porosity with a surface area and pore volume of 1 262 m²/g and 0.70 cm³/g, respectively, while a reduction of the activation temperature to 600 °C (AC-26) results in a material whose corresponding values are 947 m²/g and 0.51 cm³/g. Although AC-26 exhibits a much lower surface area and pore volume compared with AC-28, it has the larger CO₂ uptake of up to 4.22 mmol/g at 25 °C and 1 bar due to its higher microporosity of up to 98% and abundant narrow micropores, implying that the microporosity is one of the main factors for CO₂ capture besides the traditionally-believed surface area and pore volume. The isosteric heat of CO₂ adsorption indicates that the affinity between the activated carbon and CO₂ molecules increases with the volume of narrow micropores less than 0.8 nm and the number of surface oxygen-containing functional groups.

生物质被认为是制备活性炭的有前途的低成本前体。然而，生物质的直接碳化通常会产生低表面积或什至无孔的碳，这些碳对于捕获CO ₂毫无用处。在这项工作中，首先将大蒜皮通过水热碳化转化为水焦，然后通过KOH化学活化，以获得具有高表面积和大孔体积的活性炭。用N ₂表征了活性炭的微观结构和形貌。吸附，SEM和XRD。结果表明，它们的表面积和孔体积主要由活化温度和KOH /烃质量比决定。在800°C下通过KOH /烃类比率为2的KOH活化获得的活性炭（AC-28）具有良好的孔隙度，表面积和孔体积为1 262 m ² / g和0.70 cm ³ / g，分别将活化温度降低至600°C（AC-26）会得到一种材料，其相应值为947 m ² / g和0.51 cm ³ / g。尽管与AC-28相比，AC-26的表面积和孔体积低得多，但其CO ₂较大由于其高达98％的较高微孔率和丰富的狭窄微孔，因此在25°C和1 bar下的最大吸收量为4.22 mmol / g，这意味着除传统认为的表面之外，微孔率也是捕获CO ₂的主要因素之一面积和孔体积。CO ₂吸附的等排热表明，活性碳与CO ₂分子之间的亲和力随窄微孔的体积（小于0.8 nm）和表面含氧官能团的数量而增加。