Imaging and spectroscopic techniques for microstructural and compositional analysis of lignocellulosic materials: a review

Selection and characterization of biomass feedstocks with the maximum biomaterial or biofuel yields need the accessibility of reliable and efficient methods for structural and compositional characterization of plant material. Understanding microstructure of lignocellulosic fibre is required to evaluate the heat and mass transfer phenomena, bond formation, fibre alignment and orientation, structural architecture and modelling of structure-property relationship, which are necessary for designing and developing cellulose-based products. Furthermore, the microstructural and compositional information can determine distribution of lignin, hemicellulose and cellulose in the biomass, interaction of reinforced fillers and polymer matrix in the bio-composites. Many conventional standard analytical methods for biomass study are laborious, slow and use harsh chemical reagents that need certain remediation. This paper reviews the microstructural and compositional analyses of lignocellulosic materials through imaging and spectroscopic techniques (I&ST) such as X-ray micro-computed tomography (X-ray mu CT), scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM), Fourier transform infrared (FTIR) spectroscopy and near infrared spectroscopy (NIRS). This review attempts to provide fundamental backgrounds, basic working principles, applications and technical limitations and possible solutions of I&ST for analysing lignocellulosic biomass, their products and changes acquired during processing.