چكيده به لاتين
Today there is growing concern about the increasing greenhouse gas emissions, especially carbon dioxide. Carbon dioxide gas has been the main source of greenhouse gas. Different processes have been proposed for the removal of carbon dioxide. Recently, carbon dioxide adsorption with recyclable solids has been studied using the selective low-energy carbon dioxide adsorption method. Merits for solid adsorbents include high chemical adsorption capacity, low thermal capacity, the ability to produce pure carbon dioxide, and environmental benefits as well. It is necessary to identify adsorption capacity, behavior and mechanism for absorbent In adsorption processes. In this study, silica gel adsorbents, lithium hydroxide, actived carbon before reforming and after modifying with lithium hydroxide solution were investigated for carbon dioxide adsorption. The adsorption experiments were carried out in a batch reactor at a temperature of 30-90 ° C and a pressure range of 1 to 9 bars to examine adsorption kinetics, isotherms and thermodynamics of the adsorption process. Activated carbon adsorbents has been compared with silica gel. The results showed that surface modification of activated carbon using lithium hydroxide led to the correction of activated carbon levels using lithium hydroxide at concentration of about 12 to 48%. The effect of temperature, pressure, adsorbent amount, particle size, agitation rate, solution pH and activated carbon type were evaluated to determine the optimal operating conditions. The results showed that modified activated carbon with 24% lithium hydroxide concentration (24Li-AC) provides the best performance for absorbing carbon dioxide. Also, kinetic studies showed that, the second order model was suitable at temperatures of 30 and 50 ° C for modified activated carbon, the Elovich model was suitable at temperatures of 70 and 90 ° C. the second order model was suitable for lithium hydroxide. The thermodynamic parameter was used to determine the type of physical and chemical adsorption, thermostable and thermosetting. Using isotherm models of adsorbent reactions was possible after identification of monolayer and multilayer adsorption. The isotherm sips model was very suitable for carbon dioxide adsorption.
Key words: Adsorption, Activated carbon, Lithium hydroxide, Isotherm, Carbon dioxide, Thermodynamics, Kinetics
