**1. Introduction**

The comprehensive use of lignocellulosic waste coincides with the concept of circular economy because these wastes are renewable, abundant in nature, and generated in large volumes. In addition, they are a main source of natural fibers, chemical compounds, and other industrial products. Lignocellulosic residues are used in various applications depending on their composition and physical properties. Generally, lignocellulosic residues are constituted of cellulose, hemicellulose, lignin, pectin, waxes, and ash [1]. One of its main applications is the production of biofuels, where cellulose is subjected to various physical (mechanical, ozonolysis, pyrolysis), chemical

(acid, alkali, organosolv), and biological (commonly used white-rot fungi) pretreatments. However, this review is focused on the different treatments used on the surface of natural fibers in order to improve their compatibility with a polymeric matrix and thus obtain materials with ecological, lightweight, and excellent mechanical properties, called biocomposites. It is important to mention that when carrying out some of these treatments, residues are generated, which can be processed to recover some high value-added compounds (antioxidants, sugars, bioactive phenols, organic acids, polysaccharides, and polyphenolics). Furthermore, the different types of biomaterials that can be obtained from cellulose (MCF, NFC, CNC, BNC) are described. Finally, an investigation of the market size of some of the products derived from lignocellulosic residues was carried out.
