Potential of NIR spectroscopy for predicting cellulose nanofibril quality in commercial bleached Kraft pulp of eucalyptus

Authors: COSTA, LÍVIA RIBEIRO - Secretaria De Estado De Meio Ambiente E Desenvolvimento Sustentável (SEMAD MINAS GERAIS); DOS SANTOS, ALLAN DE AMORIM - Universidade Federal De Lavras; DIAS, MATHEUS - Federal University Of Amapá; SILVA, LUIZ EDUARDO - Universidade Federal De Lavras; Wood, Delilah - De; Williams, Tina; HEIN, PAULO - Universidade Federal De Lavras; TONOLI, GUSTAVO - Universidade Federal De Lavras

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2024
Publication Date: 1/11/2024
Citation: Costa, L., dos Santos, A., Dias, M.C., Silva, L., Wood, D.F., Williams, T.G., Hein, P.R., Tonoli, G.H. 2024. Potential of NIR spectroscopy for predicting cellulose nanofibril quality in commercial bleached Kraft pulp of eucalyptus. Carbohydrate Polymers. 329. Article 121802. https://doi.org/10.1016/j.carbpol.2024.121802.
DOI: https://doi.org/10.1016/j.carbpol.2024.121802

Interpretive Summary: Nanomaterials are used to lend superior properties to many types of materials. Nanofibers made from cellulose are renewable, biodegradable, and biocompatible. Cellulose-based nanomaterials have a high specific surface area, translucency, high rigidity and tensile strength, and have available hydroxyl groups allowing bond formation with other materials in many applications. However, manufacture of cellulosic nanofibrils can require an enormous amount of energy because they’re made by intense milling and shearing. Thus, we set out to maximize size reduction while minimizing energy use. Quality control measures were established using standard laboratory techniques and relating the results to those obtained using near infrared spectroscopy (NIRS). We successfully developed a method where NIRS alone could be used to predict performance of cellulose nanofibrils reliably and effectively at the industrial level.

Technical Abstract: Multivariate models were used to classify cellulose nanofibril (CNF) fibrillation quality from NIR spectra. Commercial pulps of Eucalyptus spp. were used to produce cellulose nanofibrils by means of a fibrillator mill. Samples were collected following each of five successive passes through the mill. Energy consumption and fiber classification was assessed following each pass through the mill. As a standard, pulps were oxidized with TEMPO (2,2,6,6-tetramethypiperidine-1-oxyl) reagent followed by a single pass through the mill to compare the resulting quality of CNF produced by each method. NIR spectra of CNF were associated with quality indices determined by conventional laboratory analyses that included morphology, turbidity, mechanical properties, X-ray diffraction and quality index measurements. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to the spectral and experimental data. Fibrillator milling to obtain CNF was efficient and resulted in gel formation following the third pass through the mill. Gel formation is indicative of excellent formation of CNF. NIR spectroscopy combined with PLS-DA were used successfully to classify CNF quality with 96% certainty in 3% (w/v) solutions. Results indicate that NIR spectroscopy has promise in the estimation of the quality of CNF in suspension. This model has potential in industrial applications in situations that require reliable and real-time estimates of CNF quality.