Water washing of biomass and biochar

Abstract

To investigate the differences in organics composition between leachates of biomass and biochar, four biomass materials and the corresponding biochar are water washed. GC–MS is employed to characterize the distributions of organic components in leachates. Raw and washed biomass, and biomass leachates dried at 333 K are sent for TG/DTG analysis. The results show that corn and sorghum stalks should be washed after the high-temperature pyrolysis at 303 K, with aromatic hydrocarbon contents of 11.00 % and 29.95 %, respectively. It is proposed that wheat straw and rice husk should be washed at 303 or 333 K directly. Biomass should be pyrolyzed at a relatively low temperature and then be washed. It is recommended to wash biomass directly to inhibit the acidic organic release. Washing treatment not only reduces heat release during biomass combustion, but also increases ignition (For wheat straw from 540.9 to 583.5 K) and peak temperatures (For wheat straw from 571.8 to 618.4 K) obviously. The combustion of dried leachate is more complicated, with one or two peaks during the third stage, which corresponds to the sharp rise of the DSC curve. The activation energy follows an order of washed biomass > raw biomass > biomass leachate.