超细颗粒物对活性炭吸附去除室内有机气态污染物影响研究

Organic gaseous pollutants represented by formaldehyde and VOCs seriously deteriorate indoor air quality. It is important to remove gaseous pollutants from indoor air for protecting occupants’ health. Gas adsorption technology is regarded as the most reliable and the safest method for air purification. Activated carbon is one of adsorbent which has been widely used for indoor air purification due to its good adsorption capacity and low price. However, gaseous pollutants and particles coexist in the air. Even the front high efficiency particulate air filter cannot remove the ultrafine particles. The adhesion of ultrafine particles on the porous surface of activated carbon affects the removal of gaseous pollutants and shortens its service life. Since the indoor ultrafine particles have large number and diverse components in China, the effect of ultrafine particles on the gas adsorption by activated carbon is not sufficiently studied. Therefore, this study will experimentally investigate the performance of activated carbon for indoor gaseous pollutants removal as well as with effect of ultrafine particles, analyze the interaction between ultrafine particles, gaseous pollutants and activated carbon surface by means of molecular simulation, and finally reveal coupled mass transfer mechanism of gaseous pollutants and ultrafine particles on activated carbon surface. The research will be of important significance to develop the theory of combined gas-particle pollutants removed on the surface of porous materials, and useful for guiding the application of porous materials in the field of indoor environmental pollution control.

以甲醛和VOCs为代表的有机气态污染物严重恶化室内空气品质，去除气态污染物对于保护居民健康至关重要。吸附技术被认为是最安全可靠的空气净化方法，活性炭由于良好的吸附能力和低廉的价格得到广泛应用。然而，实际空气中气相、颗粒相污染物共存，即使前置高效过滤器也无法有效去除超细颗粒物，颗粒物在活性炭多孔表面粘附占据气态污染物吸附空间，缩短其使用寿命。我国室内超细颗粒物数量多、成分复杂，超细颗粒物对活性炭气相吸附的影响并不明确。针对这一问题，本项目结合实验和分子模拟的方法，确定不同结构活性炭对室内典型有机污染物的吸附特性，探讨超细颗粒物的成分、形状和粒径对活性炭气相吸附的影响，剖析气态污染物、颗粒物和活性炭表面之间相互作用关系，揭示有机气态污染物和超细颗粒物在活性炭表面耦合传质机理。研究结果对发展气、固两相介质在多孔材料表面传质理论具有重要意义，为多孔材料在室内环境污染控制领域的实际应用提供科学基础。

吸附是室内有害气体污染控制的重要方法之一。实际室内环境中普遍存在大量的超细颗粒物，它们粘附在吸附剂表面会对吸附剂的吸附位、孔道以及吸附行为造成影响，缩短吸附剂的使用寿命。探究超细颗粒物对吸附剂气相吸附的影响关键是解释气、固两相介质在吸附剂表面耦合传质的机理。基于此，本项目以活性炭为研究对象，通过动态吸附实验明确了活性炭吸附ppm浓度水平的甲苯和丙酮的性能，并建立了活性炭吸附ppb浓度有害气体的预测方法，使得活性炭使用寿命的预测偏差小于7%。以NaCl为超细颗粒物的代表，通过气、固两相介质吸附实验，针对不同结构的活性炭、有害气体的极性，明确了超细颗粒物浓度对活性炭气相吸附量的影响程度。研究进一步建立了纳米多孔碳、有害气体和颗粒物的分子模型，采用了蒙特卡洛方法（GCMC）和分子动力学（MD）方法，从吸附量、自扩散系数、吸附位、径向分布函数、吸附热和能量分布等角度对气、固两相介质在活性炭表面耦合传质机理进行解析。通过分子模拟，揭示了超细颗粒物的浓度、成分、形状和粒径对活性炭气相吸附的影响，发现有害气体浓度越低，吸附过程越容易受到颗粒物影响；在颗粒物四类属性中，颗粒物浓度是影响气相吸附的最主要因素，与气体亲和力强的颗粒物如炭黑，对气相吸附的影响较小。本项目的研究成果有助于阐明在超细颗粒物影响下低浓度有机污染物吸附的科学问题，为吸附材料在室内污染控制领域的应用提供基础数据，还有助于为清除和防止颗粒物影响措施的制定提供理论参考。