Rapid characterization of biochar for energy and ecological purpose utilization is fundamental. In this work, visible and near-infrared (vis-NIR) spectroscopy was used to measure ash, volatile matter, fixed carbon contents, and calorific value of three types of biochar produced from pine wood, cedar wood, and cotton stalk, respectively. The vis-NIR spectroscopy was also used to discriminate biochar feedstock types and pyrolysis temperature. Prediction result shows that partial least squares (PLS) regression calibrating the spectra to the values of biochar properties achieved very good or excellent performance with coefficient of determination ( ) of 0.86~0.91 and residual prediction deviation (RPD) of 2.58~3.32 for ash, volatile matter, and fixed carbon, and good prediction with of 0.81 and RPD of 2.30 for calorific value. Linear discrimination analysis (LDA) of the principal components (PCs) produced from PCA of wavelength matrix shows that three types of biochar can be successfully discriminated with 95.2% accuracy. The classification of biochar with different pyrolysis temperatures can be conducted with 69% accuracy for all three types and 100% accuracy for single type of cotton stalk. This experiment suggests that the vis-NIR spectroscopy is promising as an alternative of traditionally quantitative and qualitative analysis of biochar properties. 1. Introduction Biochar is the product of thermal degradation of organic materials in the absence of air (pyrolysis). Except for being an excellent material for energy purpose utilization, biochar has also been described as a possible means to improve soil fertility as well as other ecosystem services and sequester carbon (C) to mitigate climate change [1, 2]. Conversion of agricultural wastes into biochars not only can save natural resources but also protect environment. Biochar quality is mainly influenced by its feedstock type as well as pyrolysis conditions. However, it is very cost- and time-consuming to determinate biochar properties, for example, to measure calorific value, by using conventionally physic-chemical means in laboratory. Thus, it is necessary to develop an alternative for rapid characterization of biochar properties. Recently, near-infrared reflectance spectroscopy (NIRS) has received increasing attention because it is characteristic of rapid measurement, ease to use, and absence of agents. This technology has been used for the analysis of biomass feedstock properties. Sanderson et al. [3] used the NIRS to determine the chemical compositions of several woody and herbaceous feedstocks,
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