Philip A. Hobson

Erratum to: Assessing dilute acid pretreatment of different lignocellulosic biomasses for enhanced sugar production

In this study, dilute acid pretreatment of five biomass feedstocks viz., sugarcane trash, sugarcane bagasse, rice straw, corn stover and palm empty fruit bunch were compared at a given combined severity factor (CSF) range of 1.4–3.2 and were characterised using an alternative Simons’ staining dye—Direct Yellow 11 fraction (DY 11, molecular weight >100,000) to better understand the correlations of pretreatment effectiveness with biomass physicochemical properties and pretreatment conditions. Good polynomial correlations (n = 2) of CSF were obtained with hemicellulose removal, cellulose digestibility and glucose yield resulting in R2 > 0.95. The results show that the total contents of extractives and ash have negative impacts on dilute acid pretreatment. Simons’ staining results show that DY 11 can also be used to estimate cellulose accessibility to cellulase enzymes. Good linear correlations of maximum adsorption capacity of DY 11 with CSF (R2 = 0.87–0.99) and cellulose digestibility (R2 = 0.91–0.99) were observed for most of the pretreated biomass samples.

Contrasting the Pyrolysis Behavior of Selected Biomass and the Effect of Lignin

This study was aimed at comparing the pyrolysis behavior of several selected biomass samples, namely, pine wood, poplar wood, wheat straw, and sugarcane bagasse, with a particular attention to the effect of lignin. Raw samples were first treated using Soxhlet solvent extraction with a 2:1 (v/v) mixture of toluene/ethanol to remove wax. Lignin was then removed by soaking the dewaxed samples in a 1.0 M sodium chlorite solution at 343 K till the solids became white. Fourier transform infrared (FTIR) spectroscopy analysis was applied to characterize the surface functional groups of the samples. The morphology of the samples before and after delignification treatment was analyzed using scanning electron microscope (SEM). The pyrolysis behavior of the raw and treated biomass samples was studied using a thermogravimetric analyzer (TGA) operating in nitrogen at a constant heating rate of 10 K min−1 from room temperature to the final temperature 823 K. The FTIR and SEM results indicated that lignin can be successfully removed from the raw biomass via the chemical treatment used. As expected, the pyrolysis behavior differed significantly among the various raw biomass samples. However, the pyrolysis behavior of the delignified samples showed almost identical thermal behavior although the temperature associated with the maximum rate of pyrolysis was shifted to a lower temperature regime by ca. 50 K. This suggests that the presence of lignin significantly affected the biomass pyrolysis behavior. Thus, the pyrolysis behavior of the biomass cannot be predicted simply from the individual components without considering their interactions.