CO2 adsorption by coal-based activated carbon modified with sodium hydroxide

This paper used sodium hydroxide to improve the CO 2 adsorption capacity of coal-based activated carbon. The effect of several modification parameters, including sodium hydroxide concentration (0.01–8 M), impregnation time (4–7 h), drying duration (4–7 h), the effect of washing, and the impact of fixed bed operating conditions such as inlet flow rate, the height of the adsorption column, and operating pressure on CO 2 adsorption capacity were investigated. The plain and impregnated adsorbents were thoroughly characterized by several instrumental analyses. With increasing NaOH loading, CO 2 adsorption capacity improved until its maximum value at 1 M NaOH concentration. Washing the samples was an important parameter on CO 2 uptake in the fixed bed when samples were impregnated with high concentration NaOH solution. The mechanisms of modification and CO 2 adsorption process on the modified activated carbon were carefully studied. The dynamic adsorption capacity for the plain and impregnated AC at optimum conditions were 21.20 and 51.41 mg/g, respectively, which indicates that the capacity for CO 2 adsorption increased by more than 142%. According to the findings, NaOH-modified activated carbon can efficiently capture CO 2 .