Near Infrared Spectroscopy: Rapid and Simultaneous Approach to Predict the Fixed Carbon, Volatile Matter and Ash Contents in Biochar Produced from Agricultural Residues

Abstract Presented paper aimed to employ the near infrared spectroscopy (NIRS) as a rapid and simultaneous method for quality assessment of biochar samples made of agricultural waste materials (chatter bamboo; firewood; coconut shell). Spectral data were obtained in the wavelength range of 1000–2500 nm, while actual fixed carbon, volatile matter and ash contents were observed using standard chemical analysis. Moreover, prediction models were established using two different regression approaches: principal component regression and partial least square regression. Prediction performances were evaluated by assessment of several statistical indicators, such as correlation coefficient and ratio of prediction to deviation index. The results showed that PLS generated a better prediction performance with maximum r coefficient and RPD index – 0.89 and 2.26 for fixed carbon; 0.93 and 2.84 for volatile matter; 0.90 and 2.30 for ash content. Based on the results acquired, it can be concluded that NIRS is usable for the purposes of a rapid and simultaneous approach to biochar quality determination.