PECASE: Kinetics of Adsorption in Nanoporous Structures

化学和生物分离计划的职业奖支持南伊利诺伊大学卡本代尔分校的Maria Mercedes Calbi教授的工作，以开发理论模型和方法，这些模型和方法可以提供对不同原子或分子如何以及如何快速进入纳米多孔结构并结合（吸附）到其表面的基本理解。由于不同的原子在结构上的吸附不同（因为它们以不同的强度被吸引到其表面，或者它们以不同的速度被吸附，或者两者兼而有之），吸附过程已被广泛用于从混合物中分离气体。该项目的重点是一种特殊的纳米结构，即碳纳米管束，它是一种中空的、非常长的管的集合，这些管自发地聚集在一起形成束或绳。管的小直径和不同种类的吸附空间的存在使纳米管束成为研究这些吸附过程的独特纳米结构。此外，碳纳米管最近已成为分离和膜应用的有前途的材料。气体分离设备由于其广泛用于气体回收（包括H2生产，这是对氢基经济的重大挑战）、空气净化系统和环境修复而对社会产生广泛影响。在本项目中，将实施计算机模拟和统计力学模型，以便：1）探索导致纳米多孔结构中的吸附位点的实际可及性的条件并识别参数，2）评估基于纳米管的系统用于分离和运输应用的能力，以及3）阐明了作为对吸附原子的限制的结果而预期的独特的动力学行为，以有效地在低维空间（表面和通道）中移动。从更广泛的角度来看，这些结果将提供基础，以了解这些现象在更复杂的系统（其他多孔材料和/或更复杂的吸附物），并设想新的类型的结构与分离和运输应用的最佳性能。 该项目还包括一个重要的教育组成部分，通过以下活动：1）参与该项目的学生在学习特定理论和计算技术的同时获得基本的研究技能，2）PI参与材料研究的跨学科计划，该计划将来自代表性不足的群体的学生带到SIUC从事研究项目，3）一门新课程，题为"纳米结构中的表面现象"，旨在填补当前课程的教育空白，并加强最近批准的应用物理学博士课程。作为一项外联活动，旨在增加STEM（科学、技术、工程和数学）职业的女性入学率，PI领导了一个讲习班，对初中女生进行重要干预，以提高对基于数学的职业的认识，提供有关这些职业道路的信息，最重要的是，提供成功的职业榜样。

This CAREER award by the Chemical and Biological Separations program supports work by Professor Maria Mercedes Calbi at Southern Illinois University at Carbondale to develop theoretical models and methods that can provide a basic understanding of how and how fast different atoms or molecules can gain access into nanoporous structures and become bound (adsorbed) to their surfaces. Since different atoms adsorb differently on a structure (either because they are attracted to its surfaces with different strength, or they are adsorbed at different speeds, or both), adsorption processes have been widely used for separating gases from a mixture. This project is focused on a particular nanostructure, a carbon nanotube bundle, which is a collection of hollow, very long tubes that gather spontaneously forming bundles or ropes. The small diameter of the tubes and the presence of different kinds of adsorbing spaces make a nanotube bundle a unique nanostructure in which to study these adsorption processes. Moreover, carbon nanotubes have recently emerged as promising materials for separation and membrane applications. Gas separation devices have an extensive impact on society due to their wide use for gas recovery (including H2 production, a significant challenge toward a hydrogen-based economy), air purification systems and environmental remediation. In this project, computer simulations and statistical mechanical models will be implemented in order to: 1) Explore the conditions and identify the parameters that lead to the actual accessibility of adsorption sites in nanoporous structures, 2) Assess the ability of nanotube-based systems for separation and transport applications, and 3) Elucidate the unique dynamical behavior that is expected as a consequence of the restriction on the adsorbed atoms to move in effectively lower dimensional spaces (surfaces and channels). From a wider perspective, these results will provide the basis to understand these phenomena in more complicated systems (other porous materials and/or more complex adsorbates) and to envision new kinds of structures with optimal performance for separation and transport applications. This project also comprises an important educational component through the following activities: 1) Students participating in the project acquire basic research skills while learning specific theoretical and computational techniques, 2) The PI participates in an interdisciplinary program in Materials Research that brings students from underrepresented groups to engage in research projects at SIUC, 3) A new course, entitled "Surface Phenomena in Nanostructures", is implemented to fill educational gaps in the current curriculum and strengthen the recently approved doctoral program in Applied Physics. As an outreach activity, aimed at increasing the female enrollment in STEM (Science, Technology, Engineering and Math) careers, the PI leads a workshop to make a critical intervention in junior high school girls to increase the awareness of math-based careers, to present information about the paths to those careers and, most importantly, to provide successful career role models.