NER: Fractal Nanoagglomerates: A New Filter Media For HEPA Filters

本项目旨在确定由纳米颗粒的分形凝聚体组成的介质是否将作为从气流中去除超细气溶胶颗粒的高效且经济高效的过滤器，并评估这种过滤介质在提供低压降、高过滤效率和高容量方面的性能是否与基于纤维的高效空气过滤器一样好或更好。这项工作还将开发预测纳米团聚过滤介质的过滤效率、压降和容量的模型。研究发现，在干态下，纳米颗粒是由具有分级分形结构和高孔隙率(0.99)的多孔团聚体组成的。这种结构导致了团聚体内的多模式孔径分布，这与广泛使用的基于纤维的高效空气过滤器中发现的单峰孔径分布有很大不同。初步证据表明，这种纳米团聚过滤器起到了深度过滤器的作用，因此比传统的基于纤维的高效空气过滤器具有更大的容量(高达两个数量级)。高效空气过滤器被广泛应用于许多工业过程中，甚至在家庭中，如果成功，这项工作可能会产生显著的经济效益。

This project seeks to determine whether a medium made of fractal agglomerates of nanoparticles will act as an efficient and cost-effective filter for removing ultra-fine aerosol particles from gas streams and to evaluate whether such a filter medium can perform as well or better than fiber-based HEPA filters with respect to providing low pressure drop, high filtration efficiency, and high capacity before clogging. The work also will develop models to predict filtration efficiency, pressure drop, and capacity of the nano-agglomerate filter medium. Nanoparticles in the dry state have been found to consist of porous agglomerates with a hierarchical fractal structure and a high porosity ( 0.99). This structure results in a multi-modal pore size distribution within the agglomerates, which is very different from the unimodal pore-size distribution found in widely used fiber-based HEPA filters. Preliminary evidence has shown that such nano-agglomerate filters act as a depth filters and thus have significantly greater capacity (up to two orders of magnitude) than traditional fiber-based HEPA filters. HEPA filters are widely used in many industrial processes and even in homes, and if successful, this work could have significant economic benefits.