Physical Changes in Softwood and Hardwood Through Different Stages of Thermo-chemical Treatment Monitored by Scanning Electron Microscope.

Two types of biomass, namely Hybrid poplar and Douglas fir were studied under scanning electron microscope before and after thermo-chemical pretreatment. It was evident that the thermo-chemical pretreatment of hot water treatment and torrefaction changes the surface topography of both the biomass following the same trend. It was also found that acid and salt pretreatments that do not use mechanical stress has no effect on the physical surface observed after hot water treatment.