Abstract:

Biomass charcoals were made from 3 kinds of biomass wastes, maize straw, branches and leaves trees at 350,550,750 ℃, respectively. The
 structure and composition characteristics of biomass charcoals were characterised by thermogravimetric analysis, FTIR analysis, Boehm titration and X-ray diffraction analysis. The results show that maize straw has the lowest thermal stability and the highest mass loss, followed by those of the branches and leaves. Compared with branches and leaves, maize straw has the greatest dispersion degree in Xray diffraction with a less layer number of microcrystalline. The total quantity of surface functional groups in biomass charcoals made from different feedstocks at the same temperature is similar, the pH value has larger differences and biochars derived from maize straw have the highest pH value. Results of characterization of biochars derived from the same feedstock show that with the increase of pyrolysis temperature, the aromatization degree of biochars increases; the content of surface functional groups decreases; pH value increases; the characteristic peaks of cellulose and hemicellulose disappear; the structure of biomass charcoals tends to graphite crystallite structure.

Key words: biochar, pyrolysis temperature, characterization, maize straw, branches of wood, leaves