Mensuração in situ da variação espacial e cinética da dessorção de água na madeira de Eucalyptus sp. por meio da espectroscopia NIR

Abstract

Near-infrared spectroscopy (NIR) has emerged as an efficient tool for the non-destructive analysis of wood properties. This study aimed to 1) Analyze the panorama of scientific production on topics related to the application of near-infrared spectroscopy in wood research; 2) Evaluate the effect of sample thickness on the calibration performance of NIR-based models for estimating the moisture content of Eucalyptus sp. wood; 3) and Evaluate the robustness and reliability of models based on NIR spectra in estimating the moisture content of Eucalyptus wood of different densities, dried naturally and in an oven, by means of independent validation. Between 2015 and 2024, investigating the trend in publications, international collaborations and academic impact, 819 eligible articles were identified in the Scopus-Elsevier database, with China standing out in terms of number of publications and total citations, while the USA had the highest average number of citations per document. For the most prominent author on the subject, we recorded the H index (13) and the most cited article, published in the Chemical Engineering Journal. In order to assess the influence of wood thickness on the performance of NIR models in estimating moisture content, 250 specimens of Eucalyptus sp. wood with thicknesses of 5.0, 7.5, 10.0, 12.5 and 15.0 mm were made and subjected to NIR spectral measurements at five drying stages. The models generated by partial least squares regression (PLS-R) showed coefficients of determination (R²cal) between 0.83 and 0.91, indicating that thickness has an impact on the estimation of moisture by NIR spectroscopy, but not proportionally. In addition, a model was developed to predict the moisture content of Eucalyptus sp. wood at different densities, considering the spatial variation of the water desorption gradient. Specimens were made radially in the bark-medulla direction and subjected to natural and oven drying. During the process, spectra were collected at each drying stage at approximately 10% loss of initial mass, while adjacent samples were used to determine initial humidity. demonstrating that NIR can accurately monitor moisture variation within specimens. The results showed that NIR spectroscopy is an effective tool for estimating wood moisture during drying, allowing detailed analysis of the moisture gradient without the need for destructive methods. In addition, the bibliometric review reinforces the growing interest of the scientific community in the application of NIR for wood studies, with significant international collaborations and relevant impact in the field.