生物质基温敏性固态胺吸附纤维的设计及其吸附性能的研究

In this project, the vegetable fibers, which are abundant, cheap, low-density and recoverable, such as sisal fiber, cotton fiber, bagasse fiber, bamboo shell and corncob, are applied as substrates. After grafting with amine-contained and thermo-sensitive monomers, the thermo-sensitive solid amine adsorbents can be prepared. The grafting of thermo-sensitive monomers on aminated vegetable fibers could endow the fibers with thermosensitivity, and in this way the prepared adsorbents could be able to shrink or stretch reversibly in response to temperature, which would make efficient CO2 adsorption and thorough desorption with low energy consumption become a reality. Meanwhile, a series of thermo-sensitive solid amine adsorbents with different lower critical solution temperatures and amine densities will be prepared, and through comparing their CO2 adsorption performance, the impact of the adsorbent structures on their CO2 adsorption behavior could be clarified, therefore a proven preparation system of promising thermo-sensitive solid amine adsorbents can be set up. To better investigate the CO2 adsorption-desorption behavior, the adsorption process will also be optimized. Moreover, the adsorption thermodynamic model will be used to interpret the obtained CO2 adsorption data, and an adsorption bed will be designed to test the dynamic CO2 adsorption ability of the adsorbents, and thus the CO2 adsorption-desorption regulation mechanism of the thermo-sensitive solid amine adsorbents could be completely elucidated. It is worth noting that this project will lay a solid foundation for further research of intelligent high-performance fibrous adsorbent and demonstrate its desirable application in reduction of greenhouse gas emission and national defense field.

本项目创新性地以来源广泛、价格低廉、密度较低且可降解回收的生物质原料，如剑麻纤维、棉纤维、蔗渣纤维、竹笋壳、玉米芯为基体，通过与含胺基功能单体和温敏功能单体接枝反应，制备具温敏响应特性的胺基密度不同的生物质基固态胺纤维吸附材料。在生物质固态胺纤维上接枝不同的温敏响应特性调控单体，可赋予接枝纤维以温敏性能，使其接枝链段在较窄温度范围内发生可逆收缩和伸展，从而实现其对CO2快速吸附和低能耗完全脱附。通过比较不同低临界溶解温度、不同胺基密度的温敏性固态胺纤维材料对CO2的吸附和脱附行为的影响，筛选高吸附容量、低再生能耗的温敏性固态胺纤维材料，优化其吸附和脱附工艺。同时，本项目采用吸附热力学模型对吸附数据进行拟合、设计CO2吸附床测试其吸附与脱附性能并进行数值模拟，全面阐明温敏固态胺纤维对CO2吸附和脱附的温敏调控机理，为温敏固态胺纤维在温室气体减排和国防领域的应用奠定基础。

本研究将多种植物纤维通过接枝反应性功能单体，随后进一步胺化，制备了一系列固态胺吸附剂。探究了制备条件对纤维接枝率及功能化效率的影响，评价了固态胺吸附剂的CO2吸附行为及其与吸附材料结构之间的关系。. 以剑麻纤维(SF)，蔗渣纤维，竹笋壳纤维，玉米芯纤维为基体，通过接枝丙烯酰胺得到接枝纤维SF-AM，随后分别以乙二胺、二乙烯三胺、三乙烯四胺及四乙烯五胺对SF-AM进行胺化修饰，制备了剑麻基固态胺吸附纤维。优化条件下，该类吸附材料对CO2吸附容量可达5 mmol/g。植物纤维的植物孔结构和亲水特征有利于CO2与纤维表面的烷基氨充分接触，从而提高植物纤维基固态胺吸附剂的吸附量。该类固态胺纤维对CO2的吸附主要是化学吸附，水的存在能显著提高该类吸附剂对CO2的吸附量。. 在前述研究的基础上，本项目利用PNIPAAM及其衍生共聚物在其低临界溶解温度（LCST）上下会发生亲/疏水性变化的特点，制备一类温敏性固态胺吸附材料，使其既具有CO2吸附能力，又能够在较低温度下脱附再生，达到降低再生能耗，提高CO2脱附速率的目的。. 以PP纤维、粘胶纤维为基体，通过接枝引入温敏性单体NIPAAM和亲水性单体AM，制备了一系列具有不同NIPAAM/AM比例的温敏性纤维。再利用酰胺取代反应将三乙烯四胺结合到纤维表面，制得一种具有温敏响应性能的固态胺纤维。在该反应体系条件下，NIPAAM和AM具有不同的竞聚率，NIPAAM的竞聚率低于AM的竞聚率，因此想要得到更高NIPAAM/AM摩尔比的产品，需要提高投料量中NIPAAM的含量。接触角测试表明，所制备的纤维具有不同程度的温敏响应性，NIPAAM/AM的比例越大，其在293K和343K时的接触角差值也越大，说明接枝的NIPAAM含量越高，纤维的温敏性越明显。通过对比纤维在80℃时的吸附-脱附曲线表明，温敏固态胺纤维能够在80 oC完全脱附，具有比传统固态胺纤维VF-AM-TETA更优良的再生性能。. 上述研究成果对进一步优化固态胺吸附材料的结构，设计并制备具有高吸附容量，低再生能耗低的吸附纤维，奠定了重要的基础。