Effect of Steam Explosion (SE) Pretreatment on the Contamination of Woody Biomass with Metallic Inhibitors

The aim of this study was to check the content of metal inhibitors before and after the pre-treatment of fast-growing poplar wood using steam explosion (SE) at selected temperatures (160, 175, 190 and 205 °C). An X-ray fluorescence spectrometer (XRF) was used for the analysis. The material was analysed after pre-treatment and in its native form in two variants: incinerated wood chips and incinerated wood chips dissolved in nitric acid. The analysis was intended to show the difference in the content of metals inhibiting biological processes, including enzymatic hydrolysis and fermentation (i.e., chromium, manganese, iron, nickel, copper and zinc). The study aimed to identify changes in the content of metallic inhibitors depending on the SE temperature and to demonstrate differences depending on the methodology used to measure metals in the tested material. The greatest change in metal content in the material after pre-treatment was observed for pre-treatment at 175 °C, regardless of the determination method used. Both methods allow the trend in changes in metal content in wood material to be determined. However, due to the heterogeneous structure of wood, the methods give different results, especially for iron.