Browsing Theses and Dissertations by Author "Le, Khang Nguyen"
Water Purification And Antibacterial Effects Of Metallic Nanoparticles Deposited Using Dc High Vacuum Magnetron Sputtering On Filtering MaterialsLe, Khang NguyenWater and water purification is an important problem that is confronting our generation at a global level. Our research tested the antibacterial effects of Silver, Copper, Titanium, Zirconium and Aluminum metallic nanoparticles deposited on microsize filtration materials. The DC High Vacuum Magnetron Sputtering Equipment was used for the deposition of metallic nanoparticles. The thickness of the coatings was in-situ monitored using a quartz crystal microbalance and ex-situ evaluated using a profilometer. The chemical composition of the structures was characterized using the X-Ray diffraction analysis and their surface morphology was investigated using digital optical microscopy and scanning electron microscopy. Each metallic material was deposited on 3M filter paper with different thicknesses. The antibacterial effect was tested were using mBlue-E.coli 24 media, the membrane filtering technique, and an incubator which was set at 35 Celsius degrees, according to standardized methods for the examination of water and wastewater. The testing media containing the bacterial samples was contaminated water collected from the wastewater basins. The water was initially tested for the bacterial content as collected and then exposed to metallic deposited filtering materials; the remaining targeted bacteria was quantified. The antibacterial effects of metallic nanoparticles were observed and analyzed. Deactivation rates for fecal coliform and Escherichia coli were measured for different metals with varying metallic thickness coatings. All metallic nanoparticles showed a good adhesion at microscopic level to water filter paper as observed by digital microscopy and scanning electron microscopy examination. Titanium nanoparticles did not have antibacterial effect showing no change in time evolution of E. Coli and Total Coliforms as well as control samples. Zirconium and Aluminum nanoparticles had some antibacterial effect showing a small change in time evolution of E. Coli and Total Coliforms for the control and coated samples. Silver and copper nanoparticles coated filters gradually removed both E. Coli and Total Coliforms. Various thickness of silver and copper nanoparticles coated filters were investigated, and it was observed that the thickness of coatings does not have significant impact on their antibacterial activity. Additionally, this research is investigating the synergistic antibacterial effect obtained by using silver and copper thin films deposited on water filter paper and the effect of the potential applied to the electrically conductive structures. It was observed that silver nanoparticles had high antibacterial effects when a high power is applied to its conductive structures.