Impacts of partial removal of lignin on development of pore structures in activation of Chinese parasol.

[Display omitted] • NaOH disrupts entangled structure in Chinese parasol (CP), releasing more volatile. • Activation of CP-NaOH increased permeability and yield of activated carbon (AC). • Activation of CP-NaOH with ZnCl 2 renders AC of more developed pores. • Reduced stability and aliphatic content form less pores in activation with K 2 C 2 O 4. • In-situ IR confirms enhanced condensation by ZnCl 2 and reduced cracking by K 2 C 2 O 4. Pore structures of activated carbon (AC) is determined not only by activation conditions but also by biomass composition. Alkaline treatment removes lignin and hemicellulose structures, which is expected to impact subsequent activation. This was investigated herein by activation of NaOH-treated Chinese parasol (CP) with ZnCl 2 and K 2 C 2 O 4 , respectively. The results indicated that pyrolysis of CP-NaOH (with NaOH treatment) enhanced pyrolysis to form more bio-oil (increase of yield by 39.0 %) but less gases (decrease by 62.5 %), due to increased mass transfer of volatiles via destructing winding structure. Activation of CP-NaOH with ZnCl 2 also generated higher yield of AC than that of activation of CP (40.5 % versus 31.5 %), because of enhanced permeability of ZnCl 2 after the NaOH treatment for catalyzing condensation of cellulose derivatives. The NaOH treatment also rendered AC-NaOH-ZnCl 2 (NaOH treatment followed by activation) with more developed pores than AC-ZnCl 2 (specific surface area: 1531.5 versus 1281.8 m2g−1), with also more abundant micropores (97.1 % versus 94.1 %), due to the higher accessibility of ZnCl 2 to cellulose structure in CP-NaOH. However, activation of CP-NaOH produced AC-NaOH-K 2 C 2 O 4 with less developed pore structure than AC-K 2 C 2 O 4 (863.2 versus1062.9 m2g−1). This was due to the lowered structural stability of AC and consequently merge of micropores from reduced content of lignin and less pores generated from cracking of aliphatic structures from partial hemicellulose removal. The in-situ IR characterization confirmed accelerated dehydration and condensation of unsaturated aldehydes/ketones in activation of CP-NaOH with ZnCl 2 and the reduced abundance of aliphatic structures and decreased intensity for cracking for generating pores with K 2 C 2 O 4. [ABSTRACT FROM AUTHOR]