Four biomass including pine, poplar, maize straw and rice husk were selected as raw materials. After washing and ash removal with 3 vol.% acetic acid solution, a fast pyrolysis experiment was conducted to compare the effects of acid washing pretreatment on the physical and chemical properties of char during pyrolysis of the four biomass. The results show that the acetic acid can effectively remove the pine, poplar, maize straw and rice husk ash content of inorganic elements, so as to promote the release of volatile matter in the process of pyrolysis, significantly improve the surface chemistry characteristic of the bio-char. Acid washing can promote the formation of pore structure of bio-char and improve the specific surface area and total pore volume. However, the average pore size decreased, indicating that acid washing can improve the micropore rate and promote the formation of micropores. At the same time, the acid washing keeps more oxygen containing functional groups in the surface of bio-char, which is especially significant for maize straw and rice husks. The adsorption experiment results of gasified tar showed that the adsorption capacity of pyrolysis char increased after washing.
Key words
biomass /
pyrolysis /
adsorption /
acid washing /
bio-char /
physical and chemical properties
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