活性炭/三维石墨烯复合高效吸氡材料的研究与应用

Activated carbon is the main material for radon absorption, but its adsorption capacity is low because of the low ratio of micro-porewith the adsorption effect. Three-dimensional graphene porous material with high specific surface area can significantly improve the mass absorption rate for radon, but its volume absorption rate is lower than that of activated carbon, which is not conducive to the miniaturization of radon adsorption devices. Combined with the structure and adsorption property characteristics of activated carbon and three-dimensional graphene, design and construction of activated carbon/three-dimensional graphene composites, which make hierarchical pores formed from graphene into surface macro-pore of activated carbon or its inter-granular space, can realize the high efficient adsorption for radon. In addition, the composites has good electrical conductivity, thermal conductivity and wave absorption properties, which are also conducive to rapid radon desorption and material regeneration. Therefore, this project attempts to prepare activated carbon/three-dimensional graphene composites using activated carbon as base material and skeleton material, graphene oxide as precusor; then systematically study the relationship between the composition, morphology structure, properties of radon absorption and material regeneration; further investigate the adsorption dynamics and thermodynamics characteristics to explore the adsorption mechanism; at last establish the corresponding experimental device of radon remove, to verify the feasibility of the composites for realizing the device miniaturization and high efficiency. Hence, the research has important scientific significance and outstanding application prospect.

活性炭是目前商用的主要吸氡材料，但因具有吸附阻滞效果的微孔占比较低，导致其吸附容量不高。具有高比表面积的三维石墨烯多孔材料能显著提高对氡的质量吸收率，但其体积吸收率低于活性炭，不利于除氡装置小型化。结合活性炭与三维石墨烯各自结构与吸附性能的特点，设计和构筑活性炭/三维石墨烯复合材料，使活性炭表面大孔以及活性炭颗粒空隙间形成新的石墨烯多级孔洞结构，可实现对氡高效吸附。此外，复合材料具有优良的电导率、热导率及吸波性能，还利于吸氡材料的快速解吸再生。故本项目拟以活性炭为基料和骨架材料，以氧化石墨烯为前驱体制备活性炭/三维石墨烯复合材料，系统研究材料的组成、形态结构与吸氡性能、再生性能之间的关系，考察吸附动力学与热力学特征并探讨其吸附机理，建立相应的除氡实验装置，验证利用复合材料实现连续除氡装置的小型化和高效化的可行性。因此，本项目研究具有重要的科学意义和突出的应用前景。

氡是仅次于吸烟的致肺癌因素，被世界卫生组织列为19种致癌物质之一。吸附除氡是有效的控氡手段。活性炭是目前唯一大规模工业应用的吸氡材料，尤其是优质椰壳活性炭对氡有较强的吸附能力，但其仍无法满足研制高效连续吸附除氡装置的需要。所以有必要研究优质椰壳活性炭吸氡的机制、配制以活性炭为基料和骨架材料的高效吸氡材料。主要研究内容包括：（1）采用巨正则系综的蒙特卡罗方法，理论计算得到了影响活性炭吸氡能力的主要孔径分布范围，找到了活性炭吸氡能力与其0.55 nm的微孔孔容密切相关的实验现象的原因。（2）研制了氧化石墨烯/活性炭复合吸氡材料对氡吸附系数达到5.98±0.18 m3•kg-1，相比于活性炭提升35%。发现浸渍-低温冷冻的过程过中，形成了新的对吸氡有利的微孔，羟基对氡有强的相互作用，羟基与活性炭0.55 nm孔径的协同作用实现了氧化石墨烯/活性炭复合材料对氡的高效吸附。（3）研制了液氮改性活性炭对氡吸附系数达到5.99 m3•kg-1，且其的比表面积较原活性炭的提高了24％。（4）研制了活性炭/凹凸棒土复合吸氡材料对氡的吸附系数从4.28 m3•kg-1提升到5.35 m3•kg-1。凹凸棒土能容易地扩散进入活性炭大孔和介孔，形成新的富微孔的互穿网络，显著提高活性炭比表面积和微孔占比。（5）研制了水浸泡冻融改性活性炭对氡的吸附系数提升了24%达到5.42 m3•kg-1，改性活性炭的0.55nm左右的孔容显著增加，且与吸氡能力的提高呈正相关性。（6）研制了纳米镍/活性炭复合吸氡材料对氡吸附系数达到6.56±0.14 m3•kg-1，相比于活性炭的氡吸附系数提升48%。发现其吸氡能力与Ni0的正相关。（7）研制了氢氧化钾改性活性炭对氡吸附系数达到6.50±0.13 m3•kg-1，比活性炭提升46.7%，增加了活性炭0.55 nm的微孔孔容，提升了活性炭的氡吸附能力。研究成果将为实现除氡装置的小型化和高效化，实现核电站运行周期延长和废物最小化提供技术基础，具有重要的科学意义和应用前景。