Activation of sawdust with eggshells
Chao Li, Shuxin Zhou, Qingyang Li, Guoming Gao, Lijun Zhang, Shu Zhang, Yong Huang, Kuan Ding, Xun Hu
Abstract
Eggshell is a kitchen waste containing abundance of calcium carbonate . The CO 2 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 900ºC was performed. The results indicated that the sawdust could be activated with only a given amount of CO 2 from eggshells, developing mainly micropores (92.0 %, 612.2 m 2 /g) and rendering the AC of the superior capability to adsorb phenol in the aqueous phase. The CO 2 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.