NC State
Li, K., Chen, H., Yu, H., Zhu, H., Mao, Q., Ma, X., Zhao, Z., and Xiao, T. (2014). "Study on the comprehensive utilization of bitter almond shell," BioRes. 9(3), 4993-5006.


A comprehensive process was developed to make full use of the solid and liquid products during the production of activated carbon. Almond shell waste was modified with phosphoric acid and thermally treated to give activated carbon. Wood vinegar was generated and collected within the temperature range of 90 to 500 °C, and the maximum amount of the wood vinegar was in the range of 170 to 370 °C, which also gave the strongest anti-pathogens activities with the lowest pH and the highest organic acid content. The remaining residue after wood vinegar generation was further calcined in inert atmosphere to obtain high surface area activated carbon. The pre-treatment of almond shell with H3PO4 leads to the higher surface area, but H3PO4 solution with concentration more than 40% does not increase the surface area further. The impregnation of H3PO4 helps the formation of pores in the almond shell during the calcination, and gives higher iodine number and methylene blue sorption capacity of the resultant activated carbon materials.
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