Extraction of lignin from pecan nutshell using the Organosolv process: characterization and potential applications as biomaterials

Lignin is the second most abundant biopolymer in nature, after cellulose, and is found in the cell walls of various plant species (particularly in wood), agricultural residues, fruit peels, and other biopolymeric sources. This biopolymer has antioxidant and biodegradable properties, making it a valuable raw material for the development of highly functional bio-based materials. Therefore, this study focuses on the extraction of lignin from pecan nutshell (Carya illinoinensis) using the Organosolv technique. Additionally, its potential applications in the development of superhydrophobic surfaces are explored. The extracted lignin was characterized using UV-Vis spectrophotometry and scanning electron microscopy (SEM), which allowed the analysis of both its spectral composition and morphology. For the characterization of the superhydrophobic surfaces, optical microscopy and contact angle measurement techniques were employed to assess their surface structure and water repellency. The results showed that the extracted lignin presented well-defined bands in the wavelength range of 280 to 312 nm, similar to those of reference lignin. Furthermore, this lignin exhibited a morphology with poorly defined shapes and varying sizes. On the other hand, the superhydrophobic surfaces presented a heterogeneous structure and high contact angle values (> 150.10 ± 0.21), indicating high water repellency. Based on these results, it can be concluded that the extraction of lignin from agroindustrial residues, such as nutshells, is a sustainable and efficient strategy that not only enables the valorization of agroindustrial waste but also the production of a versatile biopolymer with potential applications in various fields. This approach promotes the use of more eco-friendly materials and contributes to the development of functional products, advancing towards a circular economy and reducing dependence on non-renewable resources.