Activated char is one of the most cost-effective absorbents for low-temperature CO2 capture. Rather than disposing of corncob residues by open-air burning, this study focused on improving corncob residues through pretreatment with low-transition temperature mixtures (LTTM) of choline chloride and glycerol combined with hydrothermal carbonization before being converted to CO2 capture activated char. Compared to raw corncob residues, cellulose-rich materials (CRMs) from the pretreatment had less thermal stability and substantial changes in cellulose crystallinity and surface functional groups relative to cellulose and lignin, thus differently resulting in surface morphologies of activated biochars and hydrochars. The crystallinity of cellulose was still maintained in CRMs but not when the CRMs were hydrothermally carbonized. All hydrochars mainly contained aromatic compounds of lignin. The presence of choline chloride in LTTM pretreatment caused activated hydrochar to increase the specific surface area (from 25.4 to 64.0 m2/g) while reducing the total pore volume (from 1.2 to 0.7 m3/g) and pore size (from 184.3 to 34.3 nm). The activated CRM hydrochar had a CO2 adsorption capacity of over ten times that of the activated biochar (no pretreatment and hydrothermal carbonization were applied). After 20 cycles of regeneration, it maintained >97 % of the initial CO2 adsorption capacity. This finding pointed out that pretreatment and hydrothermal carbonization can potentially enhance the CO2 adsorption performance of activated hydrochar from corncob residues.

中文翻译：

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用于 CO2 捕集材料的玉米芯残渣的低温混合物预处理和水热碳化


活性炭是低温 CO2 捕获中最具成本效益的吸收剂之一。本研究不是通过露天焚烧来处理玉米芯残留物，而是通过氯化胆碱和甘油的低转变温度混合物 （LTTM） 结合水热碳化在转化为 CO2 捕获活性炭化之前进行预处理来改善玉米芯残留物。与原料玉米芯残留物相比，预处理过程中的富含纤维素的材料 （CRMs） 的热稳定性较低，相对于纤维素和木质素，纤维素结晶度和表面官能团发生了实质性变化，因此导致活化生物炭和水炭的表面形态不同。纤维素的结晶度在 CRM 中仍然保持，但在 CRM 进行水热碳化时保持不变。所有水炭均主要含有木质素的芳香族化合物。LTTM 预处理中氯化胆碱的存在导致活化水炭增加比表面积（从 25.4 到 64.0 m2/g），同时减少总孔体积（从 1.2 到 0.7 m3/g）和孔径（从 184.3 到 34.3 nm）。活性 CRM 水炭的 CO2 吸附能力是活性生物炭的十倍以上（未进行预处理和水热碳化）。经过 20 次再生循环后，它保持了初始 CO2 吸附容量的 >97 %。这一发现指出，预处理和水热碳化可以潜在地增强玉米芯残留物中活性水炭的 CO2 吸附性能。