| SO2and NO from fossil fuels combustion are major air pollutants and the key precursors to acid rain. As SO2, CO2, and NO not only pollute the environment but also harmful to humans. CO2is a ubiquitous species that has received much attention recently because of its greenhouse gas effect. Therefore, it is necessary to study the SO2, CO2, and NO pollution control technology to protect air environment. Much more research work had been done for them in wordwide. In the paper, the SO2, CO2, and NO co-adsorption processs had been discussed on the organic solvent method. It paid more attention to the adsorption activity of SO2, CO2, and NO on ACF in static volumetric adsorption and dynamic adsorption. The preparation condition, operation condition and regeneration methods were investigated, then the mechanisms of co-adsorption SO2, CO2, and NO were discussed based on the thermodynamics, kinetics, experimental study and literatures. In this study, the main results are as follows:(1) The adsorption characteristics of pure component on activated carbon fiber (ACF) at temperatures ranging from323K to363K had been experimentally measured by a volumetric apparatus. The equilibrium data were analyzed by the Langmuir and Freundlich model, which revealed that Freundlich model was more suitable to describe the adsorption of the three gases than Langmuir model. The Henry’s Constant was investigated based on the adsorption isotherms. The results showed that adsorption affinity follows the order SO2> NO> CO2on ACF. Thermodynamic functions integral Gibbs’free energy, enthalpy and entropy were calculated to characterize adsorption behaviors. Finally, a classical micropore diffusion model was used to extract the crystallite diffusivity for SO2, CO2, and NO in adsorbents.The diffusion time constants of SO2, CO2, and NO for the adsorbent at323K were estimated from the adsorption breakthrough curves by a micropore diffusion model. The diffusion time follows the sequence:CO2>NO> SO2.(2) In order to study the adsorption performance of modified ACF, a series of activated carbon fibers loaded on metal ions were prepared by impregnation method. The effects of conditions including the precursors, types and concentrations of nitrates, adsorption reaction temperatures, oxygen and moisture on adsorption abilities were investigated. The co-adsorption properties of the prepared samples were examined. Among the sorbents, ACF-Cu exhibited the best result to remove SO2, CO2, and NO all together. The results showed that ACF prepared by impregnating0.3M Cu(NO3)2was the best adsorbent for co-adsorption, under condition of323K and5%v oxygen, the adsorption effect of SO2, CO2, and NO were best. The effect of humidity is diverse for different adsorbates, the CO2and NO is better in anhydrous condition, but different in SO2,30%relative humidity was the best.(3) The effects of the different regeneration methods (alkali regeneration, thermal regeneration, NTP regeneration) were researched on co-adsorption influence of SO2, CO2and NO in this study. The result showed that alkali regeneration using the0.1mol/L KOH boil10min was the best for the adsorption of SO2, CO2and NO. After second base regeneration still have certain adsorption removal ability of SO2, CO2and NO.(4) Possible mechanism of the SO2, CO2and NO removal process is proposed on the basis of FTIR and XPS spectroscopy measurements. In a dry condition, adsorption of CO2on ACF was physical absorption, but SO2and NO were chemical absorption, NO was Oxidized to NO2, While SO2was changed to SO42". Under the presence of water, the chemisorption of the three gases is significant and the final products are H2CO3, HNO3and H2SO4... |
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