Activation of sawdust with eggshells

Eggshell is a kitchen waste containing abundance of calcium carbonate. The CO2 from decomposition of calcium carbonate can be used to activate biomass to produce activated carbon (AC) to realize full utilization of eggshells. In this study, the activation of poplar sawdust with non-contact eggshells and no carrier gas in a crucible at 900 & DEG;C was performed. The results indicated that the sawdust could be activated with only a given amount of CO2 from eggshells, developing mainly micropores (92.0 %, 612.2 m2/g) and rendering the AC of the superior capability to adsorb phenol in the aqueous phase. The CO2 mainly facilitated dehydrogenation, dehydration, deoxygenation of the C--O in esters/lactones intermediates, gasification, carbonization reactions, etc, reducing the yields of AC but enhancing C/O and C/H ratios and thermal stability of the AC. In addition, the eggshells facilitated cracking reactions at the temperatures for the pyrolysis of sawdust, producing more light aliphatic organics, heavier phenolics, and gaseous products. The non-contact activation without carrier gas eliminates the issue of post-treatment such as separation of AC and activating agent, which also features low operating cost and produces simultaneously CaO-rich material as a solid base catalyst.