Influence of the interaction between activation conditions on the pore structure and CO2 uptake of the prepared macadamia nutshell-based activated carbon

Renewable carbon materials are attractive materials with great potential for many applications. Macadamia nutshell is a by-product of the nut industry, with high yield and fast regeneration. It is a potential precursor for biomass-based activated carbon. In this study, we prepared an adsorbent using macadamia nutshell as a precursor and KOH as an activator. To prepare the samples with the highest CO2 uptake, the preparation process was optimized by response surface methodology (RSM). Interactions between different activation conditions were investigated, and their effects on CO2 uptake were explored. Meanwhile, visual three-dimensional images were used to describe the effects of activation conditions and interactions on adsorption capacity. It was found that the activation conditions affected the location of the central region (high CO2 uptake region) of the carbon material. Meanwhile, the interaction between different activation conditions has a significant influence on the growth of pores during the activation process. The preparation conditions optimized by RSM in this study are as follows: activation temperature is 771 degrees C, KOH/C is 1.7, and time is 2.3 h. At 0 degrees C and 1 bar, the carbon sorbent prepared under optimized conditions has a CO2 adsorption capacity of 6.58 mmol/g. This study confirms that RSM is an effective method to optimize the preparation process of high-efficiency carbon adsorbents for CO2 uptake.