Extraction of cellulose nanofibrils and nanocrystals from a new cultivar of pineapple ( <i>Ananas comosus</i> ‘Vitória’) from the Amazon region

Abstract The expansion of the agroindustrial sector has led to a significant increase in crop residues, particularly from large‐scale pineapple production. Pineapple leaves, a major byproduct, are often burned in plantations or improperly discarded, causing environmental harm. As lignocellulosic materials, rich in cellulose, these leaves present an opportunity for value‐added applications. This study aimed to extract and characterize lignocellulosic components from pineapple leaves, including moisture content, ash, extractives, holocellulose, cellulose, alpha‐cellulose, and cellulose nanofibrils (CNFs) via mechanical milling, as well as cellulose nanocrystals (CNCs) via acid hydrolysis (H 2 SO 4 , 60% m/m). Characterization techniques included X‐ray fluorescence (XRF), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic light scattering (DLS), and atomic force microscopy (AFM). The results showed that pineapple leaves contain approximately 55% cellulose, a significant proportion for CNC and CNF extraction of Type I cellulose. The crystallinity index was 48% for cellulose, 71% for CNFs, and 84% for CNCs, demonstrating the effectiveness of the methods used. Fourier transform infrared spectra confirmed the presence of cellulose and revealed reduced lignin‐related bands (1620 and 1606 cm −1 ) in nanocellulose samples. Thermogravimetric analysis indicated lower thermal stability in CNCs due to sulfate groups introduced during acid hydrolysis. Scanning electron microscopy imaging showed that fresh samples exhibited a lamellar structure with smooth surfaces due to waxes and amorphous materials, where as extracted cellulose had a rougher texture following their removal. The Dynamic light scattering and AFM confirmed the nanoscale dimensions of CNCs and CNFs, validating the extraction process.