Submitted to: Modern Applied Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2014
Publication Date: 3/10/2015
Citation: Liu, Y., He, Z., Uchimiya, M. 2015. Comparison of biochar formation from various agricultural by-products using FTIR spectroscopy. Modern Applied Science. 9(4):246-253.
Interpretive Summary: Biochar is charred material produced by the pyrolysis of any biomass, including such agricultural by-products as wood scraps, grass, cottonseed hulls, wheat straws, corn stovers, and manures. To have a low-cost, rapid, and easy to use method for non-destructive screening of biochars, Fourier transform infrared (FTIR) spectroscopy could be a possible option, not only has it been used to obtain highly structural information on various biochars and starting materials, but also has been applied to investigate the structural changes of biochars as a function of pyrolysis temperatures. This study demonstrates the usefulness and effectiveness of FTIR spectroscopy in rapid, non-destructive, and direct measurement of biochar formation. With pyrolysis temperature rising, biochars underwent a number of significant changes in chemical, physical, and structural aspect. These changes can easily be revealed by FTIR spectra of samples, thus suggesting that FTIR technique can be used as an efficient tool for controlling biochar quality through production condition manipulation.
Technical Abstract: Biochar is charred material produced by the pyrolysis of organic biomass. In this work, Fourier transform infrared (FTIR) spectra of different agricultural by-products feedstock and their derived biochars were collected to explore the potential of FTIR technique as a simple and rapid method for characterizing the biochar structure. The FTIR information was also discussed for comparing the biochar formation process. Biochars became increasingly more aromatic and carbonaceous with pyrolysis temperature increasing, and these changes can easily be detected from FTIR spectral differences alone. Complementary to visual inspection of spectral variations, principal component analysis (PCA) of FTIR spectra enhanced the similarity or dissimilarity of biochars prepared at various temperatures. On the basis of spectral features in the 1750-1500 cm-1 region assignable to characteristic carboxyl and aromatic groups that existed in starting materials and also in biochars, a simple three-band ratio algorithm was developed for monitoring the biochar formation semi-quantitatively. Results indicated the feasibility of FTIR in rapid and non-destructive measurement of biochars for quality and production condition control.