چكيده به لاتين
In recent years, the tendency to use surface adsorption with solid adsorbents has increased due to the need for low energy, low cost, and ease of use. In the present study, raw activated carbon adsorbent and modified activated carbon with nickel oxide and magnesium oxide to adsorb carbon dioxide were investigated. The goal is to optimize the operating conditions of carbon dioxide uptake and optimize the adsorption direction to improve adsorption capacity. After conducting initial experiments and achieving optimal conditions for adsorption modification, the adsorbent structural characteristics are provided by XRD, SEM, and BET analyzes. To optimize the adsorption operating conditions using the experimental design of the response surface method, three factors include temperature, pressure, and adsorption type, have been investigated. Absorption experiments have been performed on a discontinuous reactor in the temperature range of 25-80 °C and in the pressure range of 1-9 bar. Modification of active carbon adsorbent with the optimal amount of nickel oxide and magnesium oxide (3% by weight) led to a 57% and 41% increase in adsorption capacity at ambient temperature.
Optimal conditions were considered for the maximum possible adsorption capacity and the highest possible temperature. Based on the desirability function for adsorption of activated carbon with nickel oxide, the temperature conditions were 62.7 °C and the pressure was 7.8 bar for the input variables, and the amount of 121.3 mg/g for the response. Also, for adsorption of activated carbon modified with magnesium oxide, the temperature conditions of 57.1°C and the pressure of 7.8 bar for the input variables and the amount of 105.2 mg/g for the response were obtained. Additional tests have been performed to evaluate isothermal, kinetic, and thermodynamic models. Given the R2 values for the unmodified activated carbon adsorbent, the Fendelich model, which expresses the physical multilayer absorption, is appropriate. Also, for modified activated carbon, the isothermal models are the best, according to the Sips model, which combines the isotherm of Langmuir and Freundlich. Also, after the Sips model, the Langmuir model, which is the best description of the chemical reaction due to being limited to one layer, is the appropriate model. The results of the kinetic study showed for raw AC the first-order model is the best and for modified activated carbon showed the second-order model and the Elovich model was appropriate.
