As the worldwide population increases, maintaining a standard of public health becomes more critical. Two major concerns in this area are nosocomial infections (NI) and water contamination. Current processes in sterilization and water treatment have limitations that could be overcome using plasma techniques. The unique characteristics of plasma make it a promising alternative for energy-intensive processes. This work investigated the characteristics of plasma that have the greatest impact on sterilization and the reactivation of activated carbon. Previous studies have researched the physical and chemical surface properties of biochar but have not been able to establish an efficient process to activate biochar with desired characteristics. Plasma treatment would offer a way to etch the surface of biochar and specifically functionalize the surface. Successfully activating biochar would increase its adsorption ability and enable its use for water treatment. This project aims to harness these plasma properties and use plasmas to address three important topics related to public health: sterilization of surfaces, modulating commercial activated carbon (AC), and activations of biochar.Cold plasma sterilization offers an efficient way to sterilize medical components and instruments without the risk of deformation to heat-sensitive materials. This paper reports the use of magnetized plasma to realize low-temperature sterilization. A radio frequency dielectric barrier discharge was created in a quartz tube using a mixture of argon and oxygen gas. Glass slides inoculated with a uniform amount of Escherichia coli were exposed to the plasma afterglow at different pressures with and without a magnetic field. A global model was developed to evaluate the magnetically enhanced dielectric barrier discharges and predict species densities. Optical emission spectroscopy identified the plasma species present and validated the model. The magnetic field significantly promoted the intensity of the plasma and the sterilization efficiency. A process gas pressure of 100 mTorr presented the most effective treatment with a sterilization time less than one minute and sample temperature below 32 ℗ʻC.The effects of O2 plasma on the adsorption capacity of activated carbon (AC) was investigated by varying treatment times. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Zeta potential were used to characterize the surface properties of the AC. The carbon was then applied to remove methylene blue (MB) from an aqueous solution. The adsorption kinetics and isotherm were also studied. Results showed that pseudo-second-order kinetics was the most suitable model for describing the adsorption of MB onto AC. Equilibrium data were well fitted to the Freundlich and Langmuir isotherm models. The highest adsorption capacity resulted from 4 minutes of O2 plasma treatment. This work shows that activation of AC by plasma can open the micropore and increase the effectiveness of chemical removal.Biochar was activated using a combination of O2 plasma and KOH. The adsorption capacity was investigated for different O2 plasma treatment times, KOH concentrations, and treatment temperatures. The adsorption capacity of methylene blue (MB) by the plasma activated biochar was evaluated. The adsorption kinetics and isotherm were also investigated. Results showed that pseudo-second-order kinetics was the most suitable model for describing the adsorption of MB onto biochar. Both the Freundlich and Langmuir isotherm models fit the equilibrium data. The highest adsorption capacity resulted from 10\\% KOH + 300 ℗ʻC for 5 minutes. This work shows that activation of biochar by plasma can improve adsorption capacity.The plasma treated AC and the plasma activated biochar were applied to the removal of PFOA. It was demonstrated that plasma treatment can improve PFOA adsorption. The negative surface charge was shown to negatively impact PFOA adsorption which aligns with the hypothesis that PFOA would preferentially adsorb onto more positive surfaces due to its anionic state in water.
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