A new type of DC atmospheric pressure glow discharge combined with thermal catalyst was applied to the removal of toluene. Our plasma reactor closed in the discharge chamber consists of a rectangular shaped duct, in which five pins and a plate with spherical craters are positioned. The inter-electrode distance is 12.7 mm. The discharge was initiated at high voltage up to 20 kV and applied current up to 3 mA. A Cu-Mn/Al 2 O 3 thermal catalyst (operated temperatures up to 300 • C) is placed in series with a discharge chamber. In this study, inlet concentration range of toluene was stable at 45 ppm. No influence of the toluene admixture was observed on the threshold currents. The highest removal efficiency detected was about 96 % (temperature 300 • C; voltage 17.9 kV; current 2.5 mA). The energy efficiency of the toluene removal process and the existence of a synergistic effect of the combined application of plasma and catalysis were investigated, with the aim to operate the catalyst at a lower temperature, i.e. at a lower energy cost. We tried to explain some plasmochemical processes, such as consignable influence of generated ozone on the final Volatile organic compounds (VOC) concentration as well.
The low-temperature low-pressure hydrogen based plasmas were used to study the influence of processes and discharge conditions on corrosion removal. The capacitive coupled RF discharge in the continuous or pulsed regime was used at operating pressure of 100−200 Pa. Plasma treatment was monitored by optical emission spectroscopy. To be able to study influence of various process parameters, the model corroded samples with and without sandy incrustation were prepared. The SEM-EDX analyzes were carried out to verify corrosion removal efficiency. Experimental conditions were optimized for the selected most frequent materials of original metallic archaeological objects (iron, bronze, copper, and brass). Chlorides removal is based on hydrogen ion reactions while oxides are removed mainly by neutral species interactions. A special focus was kept for the samples temperature because it was necessary to avoid any metallographic changes in the material structure. The application of higher power pulsed regime with low duty cycle seems be the best treatment regime. The low pressure hydrogen plasma is not applicable for objects with a very broken structure or for nonmetallic objects due to the non-uniform heat stress. Due to this fact, the new developed plasmas generated in liquids were applied on selected original archaeological glass materials.
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