Treatment Of Carbon Disulfide And Toluene Gas By Low Temperature Plasma-manganese Oxide

In recent years, regional air pollution, such as haze and photochemical smog, is increasingly caused by large amounts of gaseous pollutants emission, which seriously threatens human health and ecological security. Plasma technology is commonly used in gas purification because at room temperature and under atmospheric pressure, various gaseous pollutants with different concentration can be simultaneously decomposed within a very short time by this technology. At present, in order to improve plasma energy efficiency,it is often combined with adsorbent,catalyzer, oxidizer,etc. to treat gaseous pollutants. Manganese oxide minerals have good adsorption and redox properties. At present, there are few reports about the treatment of gaseous pollutants by the combination of natural manganese oxide, cryptomelane and plasma technology.In this research, combined with cold plasma, natural manganese ore extracted from a mine in Tongling and synthesized cryptomelane are respectively employed to treat gaseous carbon bisulfide and methylbenzene. By product analysis and energy accounting,the synergistic effect of natural manganese ore,synthesized cryptomelane and plasma is evaluated. XRD, BET, SEM, EDS, TEM, FT-IR and other characterization techniques are applied to investigate the effect of manganese materials'synthesis and modification conditions on their composition, microstructure, surface property and catalytic activity; based on which the mechanism of cold plasma-manganese oxide minerals synergistic catalyzing gaseous pollutants is discussed. The main contents and conclusions of this paper are as follows:1) Natural manganese ore and its modified product are put into the plasma reactor.The effects of particle size ,position in a plasma reactor and modified methods of the manganese oxide for the removal of carbon disulfide and toluene conversion rate are studied.The result shows that carbon dioxide removal rate is gradually increased;natural with decreasing particle size of the manganese oxide, When manganese oxide is filled in reactor afterglow zone, the removal rate of carbon disulfide can reach 97.58%,compared with 65% pure plasma, carbon disulfide removal rate increased by 32%.Furthermore , adding natural manganese oxide in a plasma reactor, the energy yield of CS2 is also improved from 17% to 33% , the O3 concentration in the tail gas can be reduced by about 50%, the carbon dioxide content can be increased by 15% or so. After 4mol. L-1 sulfuric acid soaking, 500 ? calcined, microwave high fire heated for 30 min,ultrasonic 60min and 1.6g.L-1 cetyl trimethyl ammonium bromide solution modified ,the specific surface area and pore volume and the pore diameter of the modified manganese oxide are higher than that of the ore and the toluene conversion rate is increased by about 15% with the modified manganese oxide.2) Cryptomelane are synthesized by refluxing method and solid phase method.The effect of the synthesis method on the structure and properties of manganese potassium ore is investigated. The structure of cryptomelane synthesized by the reflux method (OMS-2R) is more uniform and the specific surface area is larger, OMS-2R can promote toluene completely converted to CO2 and adsorbe O3 generated by plasma and break it down to active oxygen atoms of higher oxidation, which not only improves the conversion of toluene,also it reduces O3 content in the tail gas. A comparative study is made on the degradation of toluene by plasma combine with three kinds of semiconductor minerals which are cryptomelane, goethite and anatase. The outcome suggests that cryptomelane are the best catalytic material ,whether it is for toluene conversion, the selectivity of carbon dioxide, or ozone decomposition capacity. In order to improve the catalytic performance ,cryptomelane is modified by cerium doped. The toluene conversion rate can be increased from5% to 15% by the loading of Cerium on cryptomelane. With the increase of the amount of Cerium loading, the toluene conversion is gradually increased. After the continuous use of 180min, the conversion rate of toluene decreases from 93.75% to 88.7%, which indicates that the catalyst has good stability.