Abstract:

The pore structure of adsorbent plays an important role in the process of CO₂ capture. In order to improve the adsorption performance of biochar, the pore structure of biochar was modified by impregnation method using lignin as precursor, and the adsorption properties of CO₂ were studied. The results showed that the specific surface area, micropore volume and alkalinity of biochar after lignin impregnation were increased by 3.7 times, 8.3 times and 1.6 times, respectively, and the CO₂ adsorption capacity was increased from 43.15mg/g to 47.36mg/g. The linear correlation analysis showed that specific surface area, micropore volume and alkalinity were the key factors to determine the adsorption capacity of CO₂. The Avrami model and Langmuir model could well fit the adsorption process of CO₂ by biochar, which indicates that the adsorption was mainly monolayer adsorption with the combined action of physical and chemical mechanisms. When the adsorption temperature increased from 0℃ to 25℃, the adsorption capacity decreases by 46.5%—52.7%, and the adsorption of CO₂ on biochar is an exothermic process. After 10 adsorption/desorption cycles, the biochar had a high reuse rate of 97.3%—99.3%, indicating that the impregnated biochar had good reusability and was a potential CO₂ adsorbent.

Key words: biochar, CO₂ capture, lignin, impregnation

摘要：

吸附剂的孔隙结构在CO₂捕集过程中起着重要作用。本文为提高生物炭吸附性能，以木质素为前体，采用浸渍法调变了生物炭孔隙结构，并研究了其吸附CO₂特性。结果表明，木质素浸渍后生物炭的比表面积、微孔体积以及碱度分别提高了3.7倍、8.3倍与1.6倍，CO₂吸附容量从43.15mg/g提升至47.36mg/g；线性相关分析表明，比表面积、微孔体积与碱度是决定CO₂吸附容量的关键因素。Avrami模型和Langmuir模型能够较好地拟合生物炭对CO₂的吸附过程，表明该吸附由物理与化学机理共同作用，且以单层吸附为主。当吸附温度由0℃升高至25℃，吸附量降低了46.5%~52.7%，CO₂在生物炭上的吸附为放热过程。10次吸附/解吸循环后，生物炭具有高达97.3%~99.3%的重复利用率，表明浸渍生物炭具有良好的可重复使用性，是一种具有潜力的CO₂吸附剂。

关键词: 生物炭, 二氧化碳捕集, 木质素, 浸渍