Shape-controlled Synthesis of Activated Bio-chars by Surfactant-templated Ionothermal Carbonization in Acidic Ionic Liquid and Activation with Carbon Dioxide

Feng Guo, Zhen Fang

Abstract


Shape-controlled bio-chars were synthesized in two steps: (i) ionothermal carbonization of biomass (e.g., glucose, cellulose, lignin, and bamboo) at low temperatures (150 to 180 °C) in an acidic ionic liquid (IL), and (ii) subsequent activation with carbon dioxide at higher temperature (500 °C). Acidic IL was used as both the medium and catalyst for advanced carbon materials production. During the first step the primary structures of spherical particles were obtained. The surfactants sodium dodecyl sulfonate (SDS), ethylene glycol (EG), and sodium oleate (SO) were also used to modify the surface morphology of bio-chars and activated bio-chars. After the second step, the primary structures of bio-chars were still preserved or improved. The Brunauer-Emmett-Teller surface area and the pore diameter of activated bio-chars were 289 to 469 m2/g and 3.5 to 3.6 nm, respectively. Scanning electron microscope and transmission electron microscope images show that after modification of bio-chars with SDS, EG, and SO, activated bio-char particles agglomerated into rod-like (~200 nm diameter), nano-membrane (~70 nm thickness), and spherical (~200 nm) morphologies, respectively. The morphology of activated bio-chars was easily controlled during the synthesis, which is important for the exploitation of their peculiar properties and unique applications.

Keywords


Bio-chars; Acidic ionic liquid; Carbonization; Modification; Surfactants; Activation

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