In this study, multivariate analysis methods, including a principal component analysis (PCA) and partial least square (PLS) analysis, were applied to reveal the inner relationship of the key variables in the process of H₂O₂-assisted Na₂CO₃ (HSC) pretreatment of corn stover. A total of 120 pretreatment experiments were implemented at the lab scale under different conditions by varying the particle size of the corn stover and process variables. The results showed that the Na₂CO₃ dosage and pretreatment temperature had a strong influence on lignin removal, whereas pulp refining instrument (PFI) refining and Na₂CO₃ dosage played positive roles in the final total sugar yield. Furthermore, it was found that pretreatment conditions had a more significant impact on the amelioration of pretreatment effectiveness compared with the properties of raw corn stover. In addition, a prediction of the effectiveness of the corn stover HSC pretreatment based on a PLS analysis was conducted for the first time, and the test results of the predictability based on additional pretreatment experiments proved that the developed PLS model achieved a good predictive performance (particularly for the final total sugar yield), indicating that the developed PLS model can be used to predict the effectiveness of HSC pretreatment. Therefore, multivariate analysis can be potentially used to monitor and control the pretreatment process in future large-scale biorefinery applications.

In this study, the characteristics of nanocellulose extracted from bleached softwood and hardwood pulps by formic acid hydrolysis followed by TEMPO-mediated oxidation were compared using transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared analysis (FT-IR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The experimental results showed that the nanocellulose products derived from spruce pulp exhibited a relatively larger particle size, higher crystallinity, and higher thermal stability, compared with the corresponding products obtained from aspen pulp under the same conditions.Furthermore, the study helped establish that the properties of the nanocellulose products were highly dependent on the nature of the starting materials under identical processing conditions.

In this study, cellulose nanocrystals (CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues from acid hydrolysis were collected for producing cellulose nanofibrils (CNF) via post high-pressure homogenization. Citric acid could be easily recovered after hydrolysis reactions through crystallization due to its low water solubility or through precipitation as a calcium salt followed by acidification. Several important properties of CNC and CNF, such as dimension, crystallinity, surface chemistry, thermal stability, were evaluated.Resultsshowed that the obtained CNC and CNF surfaces contained carboxylic acid groups that facilitated functionalization and dispersion in aqueous processing. The recyclability of citric acid and the carboxylated CNC/CNF give the renewable cellulose nanomaterial huge potential for a wide range of industrial applications. Furthermore, the resultant CNC and CNF were used as reinforcing agents to make sodium carboxymethyl cellulose (CMC) films. Both CNC and CNF showed reinforcing effects in CMC composite films. The tensile strength of CMC films increased by 54.3% and 85.7% with 10 wt% inclusion of CNC and CNF, respectively. This study provides detailed information on carboxylated nanocellulose prepared by critic acid hydrolysis; a sustainable approach for the preparation of CNC/CNF is of significant importance for their various uses.