Estimation of energy properties of wood from Brazilian Cerrado biome by NIR spectroscopy

Knowledge of the technological properties of wood is important for its use and the quality of its products. The aim was to assess the quality of charcoal produced from wood grown in the Cerrado biome. Wood samples of Handroanthus roseoalba (ip & ecirc; branco), Handroanthus heptaphyllus (ip & ecirc; roxo) and Piptocarpha rotundifolia ('blackheart') were selected. Charcoals from these samples were produced at two charring temperatures (500 and 550 degrees C). Basic density, total extractives, lignin and holocellulose, gravimetric yield, higher calorific value and immediate chemical properties of the charcoals were determined. Near infrared (NIR) spectra were obtained on the transverse and longitudinal faces of the wood using a DLP (R) NIRscan (TM) portable spectrometer. Partial least squares regression was used to adjust predictive models of charcoal properties using the NIR spectra measured in the precursor wood. The coefficients of determination in the cross-validation (R2cv) ranged from 0.49 to 0.87 for volatile materials, from 0.48 to 0.88 for fixed carbon and from 0.49 to 0.85 for higher calorific value of charcoal. The spectra generated better models for properties of charcoals produced at 500 degrees C. The models generated were satisfactory, indicating that the NIR spectrometry can predict the quality of charcoal before it is produced.