| Summary: | 碩士 === 明志科技大學 === 材料工程系碩士班 === 106 === Atmospheric pressure plasma jet techniques developed rapidly during the last decades and widely used in biomedical and material processing. Atmospheric pressure plasma jet generates various kinds of radicals among them hydroxyl (OH) radical plays very important role in various biological applications such as device sterilization, chronic wound healing, diabetic treatment, dental care, dermatological therapy and cancer treatment. In this study, we designed and built a customized atmospheric plasma system with frequency varying power supply, optical spectrometer of emission/transmission, customized charge-coupled device camera and high precision mass flow controllers. The gas mixture of He/Ar and He/Ar/H2O were chosen for the generation of plasma. Besides testing He/Ar plasma, two sets of experiments were designed to study the variation of emission spectra. The first is varying He flow rate (30 - 45 sccm) for water vapor carrying into plasma under 100 sccm Ar an the second is varying Ar flow rate (200 - 3000 sccm) with fixed He flow (35 sccm) for water carrying. Quantitative results from optical emission indicates that both water vapor and Ar can effectively boost atmospheric plasma, nonetheless the increase of Ar supply is much more efficient in plasma generation. More importantly, the spectroscopic analysis also indicates that large quantities of OH radicals can be generated in atmospheric plasma if suitable Ar and He are supplied. Following this, the APPJ system was used to study its efficiency in degrading methylene blue as a function of radical and ozone density by using He/Ar/O2、Ar/Ar/O2、He/Ar、He/Ar/H2O. According to the results, it was found that the degradation of methylene blue was directly related to the ozone concentration and, perhaps, OH radical density. Complete degradation of MB can be achieved in 60 minutes.
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