Kode Technology Modification of Nanofibres to Capture Particulates

Poudyal, Ankita
Henry, Stephen
Williams, Eleanor
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Doctor of Philosophy
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Auckland University of Technology

With the continual rise in the levels of urban and industrial pollution, there is increased contamination of air and water by small particulate matter. Most of the current filtration methods can capture such particles by trapping through size exclusion, that is by filtration through membranes, which have pores smaller than the particles. This approach is problematic because small pore dimensions block flow. If particles could be captured by surfaces with larger pores, it would be possible to achieve a membrane that could remove pollutants and have a good flow characteristic at the same time. Attempts to make such activated capture membranes have been done earlier but are limited. Nanofibre mats made up of fibres less than 1000 nanometres in diameter are one of the extensively used advanced materials for air and water filtration. However, surface functionalization of nanofibres is complicated. Most procedures are complex involving multiple steps that can damage surfaces.

Kode Technology is a surface engineering technology that has the potential to modify membranes in a single step without significantly changing the structure of the surface. The extension of this technology to modify nanofibre surfaces could potentially create high-efficiency filters capable of capturing air and water particulates with minimal compromise in flow characteristics. The main aim of this research was to establish whether coating nanofibres with Kode constructs could enhance the adsorption and filtration of air and water particles. The research included a study of the modification mechanism, comparison of various functional heads and construct designs, limitations and extension to capture cells such as red cells and bacteria. A variety of Kode constructs were applied to nanofibres made from various polymers. For water particle capture, in-house synthesised silver nanoparticles were used as surrogates of pollutants. UV-Vis spectroscopy was used as a main quantitative tool and SEM, EDS and FTIR were used for qualitative analysis. For air particle capture, aerosols were generated using sources such as diesel combustion, wood-burning and incense combustion. Laser particle counters were used for quantification and size distribution analysis and were further analysed by SEM and EDS for morphological and chemical signatures. Additionally, modification of nanofibres was studied by applying Kode constructs during fabrication (electrospinning) and after electrospinning.

It was observed that surface modification of nanofibres by Kode constructs can significantly enhance the adsorption and filtration efficiencies of nanofibres and that the technology has the potential to be utilised for the capture of nanoparticles as compared to aerosols. After the successful coating and capture of air and water particles, the research was proof-of-concept, extended to capture biological particles such as microbes and RBCs. The conclusions from this research are that Kode Technology has the potential to be used for actively capturing pollutants and other contaminants.

Kode , FSL , Surface-modification , Nanofibres , Particulates , Filtration
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