Abstract ▼ AI-Helper

Air, which we breathe, has been polluted with various components, such as, toxic gases, dust, and some volatile organic solvents. It has been well known that the acidic gases, such as HCl, SO_(x) and NO_(x) , are major components of air pollution. Most of all, HCl gas is the highest risk of being ex...

Air, which we breathe, has been polluted with various components, such as, toxic gases, dust, and some volatile organic solvents. It has been well known that the acidic gases, such as HCl, SO_(x) and NO_(x) , are major components of air pollution. Most of all, HCl gas is the highest risk of being exposed to human body, and it can threaten our lives with very little amount in air. Activated carbon fibers (ACFs) are widely used in air and water purification, solvent recovery, etc. It is recognized that the pore structure and surface functional groups are the most important properties of ACFs for their applications in adsorption processes. In viewpoints of surface functionalities, the control of surface functional groups is really important because the adsorption of gas phase material is strongly depended on the functionality of the surfaces of adsorbents. The most widely used surface modification techniques involve chemical treatments, electrochemical treatment, photo-irradiation with ionized gases, and plasma. Among those, the interaction of the plasma treatment with carbon surfaces produces highly active species, such as free radicals, ions, and metastable species, depending on the nature of the gases used in the plasma zone. Many authors have reported that an oxygen plasma treatment leads to an increase of oxygen-containing functional groups on a solid surface. The addition of activated carbons treated by the oxygen plasma has been reported to enhance the properties of polarity on carbon surfaces. The objective of this study is to evaluate the efficiency of HCl removal of the oxygen plasma-treated ACFs with treatment times, and to investigate the relationships between the surface functionalities and the amount of adsorption of HCl gas. The oxygen plasma treatment of activated carbon fibers (ACFs) was carried out to introduce oxygen-containing groups on carbon surfaces. Surface properties of the ACFs were determined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). N_(2)/77K adsorption isotherms were investigated by BET and D-R plot methods to characterize specific surface area, pore volume, and pore size distribution. The efficiency of hydrochloride removal was confirmed by two kinds of methods; one is detecting tubes (range: 1-40 ppm), and the other is a gas chromatography technique. As experimental results, the hydrochloride removal efficiency of the ACFs was increased with the treatment time, resulting from newly formed phenol and carboxylic groups (C_(6)H_(5)OH and O-C=O) on carbon surfaces, in the slightly decreased specific surface areas or pore volumes. These results indicate that the plasma treatment leads to the increase of hydrochloride removal due to the improvement of surface functional groups containing oxygen on the carbon surfaces.

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