功能化还原性纤维素基气凝胶的制备及其对无机微污染物的作用机制

In consideration of the health risk caused by micro-pollutants in drinking water and their treatment limitation, the adsorption-coupled reduction method is thus adopted in this proposal. Additionally, the advantages of aerogels, i.e., high specific surface area and surface simple modification etc. are also introduced to overcome the above problems. Cellulose, as a natural abundant biomass, is used as raw material to prepare the functional reductive cellulose based areogels by coupling techniques of dissolution, drying, modification and surface embellishment etc. And, they will be used to remove the inorganic micro-pollutants in the drinking water with high performance. During the whole process, the assembly and modification conditions of the characteristic functional groups from the cellulose based aerogels are optimized to verify the interaction rules among the cellulose matrix, modifiers and reducing functional groups under different reaction conditions. Modern analytical methods are adopted to comprehensively characterize the functional groups, micro-surface and pore structure characteristics of the obtained aerogels to reveal the relationship between their structures and performance. Studies are also conducted regarding the adsorption-coupled reduction behaviors of bromate, chlorite and chlorate in drinking water on the aerogels as well as their reusability by systematic experiments of adsorption-coupled reduction kinetics, and thermodynamics and repeated use etc. Then the mechanisms are illuminated regarding the transportation and transformation of bromate, chlorite and chlorate from drinking water into the surface and inside pores of the cellulose based aerogels by spectrum analysis from molecular level. Ultimately the correlated mathematical models are established to explore the action mechanisms of adsorption-coupled reduction, which will provide the theoretical basis and technical support for the micro-pollutants treatment from drinking water.

鉴于饮用水中微污染物所带来的健康安全威胁及其处理方法的局限性，本项目采用还原吸附法，结合气凝胶高比表面积和表面修饰简单易行等优点，以纤维素为原料，将溶解、干燥、改性与表面修饰等技术耦合，制备出功能化还原性纤维素基气凝胶，用于饮用水中无机微污染物的高效去除。优化纤维素基气凝胶特征官能团的组装和修饰方法，探明不同反应条件下纤维素基体、改性剂与还原性官能团之间的相互作用规律；采用现代分析手段，对气凝胶的官能团、微观形貌及孔结构特征等进行表征，揭示其构-效关系；系统开展还原吸附动力学、热力学和重现性等实验，研究气凝胶对溴酸盐、亚氯酸盐和氯酸盐等微污染物的还原吸附行为及其使用稳定性；通过光谱分析，从分子水平上着手，研究溴酸盐、亚氯酸盐和氯酸盐等无机微污染物在饮用水中、气凝胶表面及内部的迁移转化机制，建立相关的数学模型，探索其还原吸附作用机理，为饮用水中微污染物的处理提供一定的理论依据和技术支持。

鉴于饮用水中微污染物所带来的健康安全威胁及其处理方法的局限性，本项目以纤维素为原料，采用还原吸附法，结合气凝胶自身的优点，通过溶解、还原改性、干燥、表面修饰等技术耦合，制备出叔胺基纤维素基气凝胶（CAA）和氨基纤维素基气凝胶（ATC）等系列功能化还原性纤维素基气凝胶，并将其应用于溴酸盐、亚氯酸盐和氯酸盐等无机微污染物的还原去除，研究其还原吸附作用机制，为饮用水中微污染物的处理提供一定的理论依据和技术支持。研究的重要结果及关键数据如下：（1）采用4种不用纤维素溶解体系溶解纤维素，再通过再生和冷冻干燥制备纤维素基气凝胶，发现纤维素的晶型均由Ⅰ型结构转变为Ⅱ型结构，结晶度均有不同程度的下降，并形成了较致密的孔洞结构；（2）利用甲基丙烯酸二甲氨乙酯（DMAEMA）作为胺源，可制备叔胺基纤维素基气凝胶（CAA），其孔隙发达，比表面积为90.75 m2/g，孔容为0.24 cm3/g；（3）以丙烯酰胺、氨基硫脲作为改性剂，通过二步改性法可制备出氨基纤维素基气凝胶（ATC），其表面分布着纳米微球结构，平均孔径为26.26 nm；（4）CAA对亚氯酸根ClO2-和ClO3-的吸附均符合准一级动力学与准二级动力学方程，吸附过程均呈两段式分布，吸附同时符合Langmuir和Freundlich等温模型，且为放热反应；（5）CAA对ClO3-的作用机理：ClO3-先行吸附在CAA表面，而后被大部分还原成Cl-，产生的Cl-最终也大部分被吸附在CAA上，溶液中的总氯含量呈不断下降的趋势，溶液中的氧化还原电位呈快速上升而后变缓的趋势，在整个吸附-还原过程中，吸附作用占据主导地位；（6）在最优条件下，ATC对溴酸根BrO3-的去除率可达99.82%，其去除过程受到吸附和还原双重作用。本项目共申请国家发明专利6件（其中已授权3件），学术论文11篇（其中SCI收录8篇，中文核心2篇），组织学术会议3场（其中国际会议1场、全国会议2场），参加国内外学术会议32人次，已培养硕士研究生2名，在读博士研究生2名，硕士研究生5名。