Optimization of delignification and cellulose isolation process from Natural cotton pods and preparation of its nanofibers with choline chloride–lactic acid eutectic solvents

• Published in: Biomass conversion and biorefinery Vol. 15; no. 2; pp. 2063 - 2079
• Main Authors: Soleimanzadeh, Hamid, Salari, Dariush, Olad, Ali, Ostadrahimi, Alireza
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.01.2025; Springer Nature B.V
• Subjects: Biomass; Biorefineries; Biotechnology; Cellulose; Cellulose fibers; Chlorides; Choline; Cotton; Energy; Fibrillation; Field emission microscopy; Fourier transforms; Infrared spectroscopy; Lactic acid; Lignin; Lignocellulose; Mechanical properties; Optimization; Original Article; Renewable and Green Energy; Scanning electron microscopy; Solvents; Transmission electron microscopy; X-ray diffraction; Natural cotton po ds; Eutectic solvents; Delignification; Cellulose isolation; Cellulose nanofibers
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-023-04141-9

Recently, eutectic solvents (ESs) green treatment of lignocellulose biomasses attracted vast attention due to their properties. Concerning the subject, this paper aims to apply choline chloride lactic acid-based ESs for delignification and cellulose isolation optimization from extractive-free natural cotton pods (EFNCPs) to achieve the highest cellulose extraction and purity and also, consumption of ES-treated cotton pods (ESTCPs) for nano-fibrillation. The structure of each step product was characterized by applying Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric (TG), derivative thermogravimetric (DTG), field emission scanning electron microscopy (Fe-SEM), and transmission electron microscopy (TEM) methods. As the FTIR diagram shows, respectively decreasing the strength around 1515 and 1740 cm −1 and increasing the intensity of bands at 890, 1030, and 1210–1490 cm −1 are attributed to lignin removal and increasing the cellulose amount during isolation. XRD analysis results show in the extraction and nano-fibrillation process the small peaks, which were related to the lignin and other impurities eliminated and the crystallinity enhanced. The TG and DTG results indicate that during the cellulose isolation process, the narrowness of peak at 200–400 °C increased which is due to the lignin removal. Also, the results of TG and DTG show that during the isolation process by ES, the structure of cellulose fibers is almost unchanged. Also, Fe-SEM and TEM images show that during the isolation process, due to the removal of the non-cellulosic layer surface, roughness increased. The result of this study can be used for cellulose isolation optimization with unique chemical and mechanical properties.