拓展分子筛功能的新途径：在活性炭类粗孔材料里构筑选择性吸附位

This project tries to fabricate the zeolite-like selective adsorption sites in unordered porous material like activated carbon in order to expand the function of molecular sieves and to conquer the challenge in environment protection. It is necessary to selectively adsorb tobacco-specific N-nitrosamines (TSNA) in tobacco extract solution, which is crucial to control the carcinogens pollution in environment. However, industrial tobacco extract solution is the viscous one with a complex composition hence various zeolites and mesoporous molecular sieves are deactivated. Fabrication of new functional material becomes the key step of expanding the application of molecular sieves, especially endowing the unordered porous materials to have the adsorptive function of zeolite to efficiently capture the carcinogen with a trace amount in the complex solution. For this propose, we try to incompletely disperse some metal oxides inside the pore of activated carbon based on the special surface property of the support and the guest-host interaction, piling up the quest particles to divide the narrow pore of host and form a kind of short channel with fine geometric confinement. These short channels will exhibit the selective adsorption towards TSNA with the assistance of metal cations that attract the TSNA by electrostatic interaction, grafting the function of molecular sieve on the normal unordered porous material. This project aims the famous environment problem characterized with a complex solution and the strict demands, and constructs the new material by controlling the distribution of metal oxides in porous support and exploring the extra-fine structure of obtained composite with different spectroscopy's, plus careful adsorption tests and strict application for industrial product line. Moreover, a new way is proposed in this project to expand the new application of molecular sieves, that is, grafting the unique selectivity on more unordered porous sorbents.

尝试在活性炭等粗孔材料里构筑选择性吸附位，拓展分子筛功能解决环境保护难题。控制烟草特有亚硝胺TSNA污染需要吸附烟叶萃取液中的TSNA从源头控制其致癌性危害。工业浓缩萃取液成分复杂而且发粘，致使沸石和介孔分子筛失去吸附能力。应对环境保护需求研制捕获痕量致癌物的新功能材料，赋予粗孔材料选择性吸附新性能，成为开拓分子筛新应用的关键环节。拟在活性炭的特定区域利用其特殊表面性质，使金属氧化物不完全分散-堆砌构筑成狭窄通道、分割载体原有孔穴的纳米空间，形成具有几何精细约束效应的微环境，辅以金属阳离子的静电吸引作用，搭建出选择性吸附位、使之兼有类似分子筛吸附TSNA的性能。针对环境保护难题中的溶液复杂组分和特殊要求，控制金属氧化物在粗孔载体里的分布，精细剖析复合材料的微细结构，检验新生的选择性吸附性能并评价应用前景，将分子筛的“功能”拓展到非规整孔材料的更广阔领域。

复杂体系里选择性吸附去除诸如烟草特有亚硝胺（TSNA）之类强致癌物是环境保护的难题，吸附剂需要“大海捞针”般去除致癌物的高选择性和大通量能力；其关键在于控制活性位的分布和微环境，形成毒物的理想陷阱而不拘泥于规整孔结构。2017年1月至2020年12月，在国家自然科学基金的资助下，选择碳和无定形氧化硅为基质，通过“改性修饰”和“纳米铸型”两条技术路线进行了构筑选择性吸附位研究。.氧化锌精细修饰促成活性炭像沸石一样吸附TSNA，证实粗孔材料中能构筑选择性吸附位。醋酸铁碳化法在椰壳活性炭上生成无数氧化铁与碳混杂的微粒附着孔壁，加大粗糙度并缩小原有孔径；吸附量超过沸石和分子筛，还具有形状选择性、优先吸附细长的强致癌物NNK，去除率达84%。新材料凭借静电吸引力区分TSNA分子及其前驱体烟碱。发现石墨烯凭借与靶标之间π-π 相互作用差异也形成选择性并不受扩散影响。“一釜法”将烟蒂转变为TSNA液相捕获新材料，将金属盐加入碳前驱体，碳化中裁剪孔结构和形貌并构筑复合吸附位，如同鱼鳃吸收水中氧气般高效去除烟草萃取液的TSNA，NNK去除率达83-93%。以“静电吸引”产生选择性吸附、氧化锌经碳粒粘合与氧化铁复合后成为高效吸附剂：水溶液中吸附 TSNA达 3.84 mg g-1，在模拟地表水和烟草萃取液中分别去除了 99%和 40%的 TSNA；铅离子吸附量为 150 mg g -1。揭示沸石精准捕获TSNA的超精细筛分效应、最佳Hβ沸石以及“自活化”再生效应，及其替代沸石类型。尝试超疏水硅气凝胶及分散于介孔孔道后捕捉水中亚硝胺；采用“含铝介孔氧化硅的扭曲孔道”、“金属氧化物修饰”以及“碳粒子原位生成”三因素构筑MCM-41介孔孔道内优化微环境以捕获TSNA。金属盐碳化及外加碳结合裁剪SBA-15介孔壁上的微孔缝隙，原位聚合苯胺构筑TSNA介孔吸附剂。发明MgO覆盖辅以碱腐蚀剪裁硅胶孔结构，使之成为高效率、低成本的水体农残净化材料。.合同任务完成，4年发表SCI论文18篇（包括ACS Appl. Mater. Interf. 一篇，Chem. Eng. J.五篇，J. Hazard. Mater.三篇， Micropr. Mesopr. Mater. 五篇），培养研究生6名，毕业博士生1名和硕士生4名。

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