基于稻壳基活性炭吸附焦油类挥发性苯系物的研究

The emission of VOCs not only influences human heath, but causes photosomg and haze, which makes the air pollution more serious. On the basis of the 13th Five Year Plan in China, the gross of the VOCs emission must be controlled by the combination of key region and key industries. In addition, the VOCs emission control must increase the differentiation, the pertinency and the operability. Carbon adsorption is one of the widely used recycle technologies. Its principle is the adsorbents including activated carbons, activated carbon fibers with porous structures can be used for the capture of VOCs in waste gases. Because of the relatively high expense of adsorbents and high energy consumption, seeking low-cost sustainable technologies has become an inevitable route for controlling the VOCs pollution. This project aims to remove the VOCs in the industrial tar and the discharged gas (namely model compounds of the typical benzene series) by using the low-temperature carbon adsorption technology. Through the physical and chemical activation, the pore structures of rice husk char could be regulated in order to improve its BET surface areas, thereby enhancing its adsorption performance. Furthermore, the surface functional groups of rice husk char would be analyzed to study the influence on the adsorption behavior. Besides, the mechanisms and kinetics would be studied on the activated rice husk char for the adsorption of the single-mode and mixed-mode volatile benzene series. Finally, the saturated rice husk char would be regenerated and activated for further use.

VOCs的排放不仅严重威胁着人类健康，其导致的光化学烟雾、城市雾霾等复合大气污染问题亦日趋严重。根据“十三五规划”基本思路，对VOCs实施重点区域与重点行业相结合的总量控制，增加差别化、针对性和可操作性。炭吸附是最广泛使用的回收技术，其原理是利用吸附剂（粒状活性炭和活性炭纤维等）的多孔结构，将废气中的VOCs捕获。由于吸附剂成本较高且能耗大、寻求因地制宜的可持续治理技术已然成为控制VOCs污染的必由之路。本项目针对工业焦油和排放的废气中VOCs，以典型的苯系物为模型化合物，采用低温炭吸附技术对其进行净化处理。通过物理和化学活化，调控稻壳炭的空隙结构，提高稻壳炭的比表面积，从而强化稻壳炭对挥发性苯系物的吸附性能。进一步，研究稻壳炭的表面官能团对挥发性苯系物吸附行为的影响。同时，深入分析活性稻壳炭吸附单一型和复合型挥发性苯系物的机制及其动力学模型。此外，饱和的炭吸附材料可以脱附-活化再生。

挥发性有机物(VOCs)的排放不仅严重威胁着人类健康，其导致的光化学烟雾、城市雾霾等复合大气污染问题亦日趋严重。根据“十三五规划”基本思路，对VOCs实施重点区域与重点行业相结合的总量控制，增加差别化、针对性和可操作性。炭吸附是最广泛使用的回收技术，其原理是利用吸附剂（粒状活性炭和活性炭纤维等）的多孔结构，将废气中的VOCs捕获。由于吸附剂成本较高且能耗大、寻求因地制宜的可持续治理技术已然成为控制VOCs污染的必由之路。本项目针对工业焦油和排放的废气中VOCs，以典型的挥发性苯系物为模型化合物，采用低温炭吸附技术对其进行净化处理。通过物理和化学活化，调控稻壳炭的空隙结构，提高稻壳炭的比表面积，从而强化稻壳炭对挥发性苯系物的吸附性能。进一步，研究稻壳炭的表面官能团对挥发性苯系物吸附行为的影响。同时，深入分析活性稻壳炭吸附单一型和复合型挥发性苯系物的机制及其动力学模型。研究表明，苯酚/甲苯大多数吸附在生物炭表面结构而非孔道中。含氧官能团会增强生物炭表面亲水性，有利于小分子和极性焦油分子的吸附。该作用并不是生物炭吸附极性焦油分子的主导机制，且水分子能够参与竞争结合生物炭表面含氧官能团，占据生物炭表面部分吸附位点，抑制焦油吸附。经KOH活化后，生物炭具有高的比表面积和丰富的微孔/介孔，形成多级孔道结构。该多级孔道结构大大增强生物炭对焦油分子的吸附性能。物理和化学活化可调控生物炭的物化特性(提高比表面积、优化孔隙结构和表面有机官能团等)，强化其焦油吸附性能。最后，饱和的炭吸附材料可以脱附-活化再生。