Conversion of de-ashed cocoa pod husk into high-surface-area microporous carbon materials by CO2 physical activation
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In this work, the de-ashed cocoa pod husk (CPH) was reused as an excellent precursor for preparing high-surface-area activated carbons (ACs) by physical activation with carbon dioxide (CO2) as a gasifying agent. A series of experiments were accomplished at different activation temperatures (i.e., 600, 700, 800, and 900 °C) and holding times (i.e., 0, 30, 60, 90, and 120 min). Results indicated that the yields of the resulting ACs showed a decreasing trend with increasing both the activation temperature and holding time, but their pore properties and true densities led to an increasing trend. The lowest yield (about 10 wt%) was obtained at 900 °C for holding 120 min, showing that the resulting AC had the highest Brunauer–Emmet–Teller (BET) surface area (over 1300 m2/g). Furthermore, the resulting ACs were mainly microporous based on the Type I of the nitrogen (N2) adsorption–desorption isotherms. On the other hand, the chemical compositions of the resulting ACs contained about 88 wt% carbon, 8 wt% oxygen and 3–4 wt% hydrogen/nitrogen/sulfur according to the elemental analysis and scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS).
KeywordsCocoa pod husk Activated recycling Carbon material Pore property Elemental analysis
The authors thank Li-Jing Viscarb Co. (Pingtung, Taiwan) for offering a project grant. We also appreciate the Instrument Centers at National Chung Hsing University and National Pingtung University of Science and Technology for elemental analysis (EA) and scanning electron microscopy—Energy Dispersive Spectroscopy (SEM-EDS), respectively.
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