Novel method for the preparation of lignin-rich nanoparticles from lignocellulosic fibers

Nanoparticle research in the field of biopolymers is significant from the perspective of efficient utilization of sustainable resources. The most abundant biopolymer in nature, cellulose, has been extensively studied. Lignin is the second most abundant natural renewable biopolymer that has immense potential and is undervalued largely due to structural and morphological heterogeneity. This limitation of lignin can be addressed by efficient methods; one of which could be conversion of lignocellulosic fibers to lignin nanoparticles. In this research work, we have prepared lignin-rich nanoparticles from lignocellulosic fibers of Indian ridge gourd (Luffa cylindrica) by the breakdown of the lignin-cellulose complex by specific enzymes. These nanoparticles are characterized by electron microscopy,X-Ray diffraction, thermal studies and spectroscopic measurements. Microscopy results indicate that the particle size is around 20-100 nm with a cuboidal shape. The X-ray diffraction data indicate reduced crystallinity upon enzymatic hydrolysis. The thermal and spectroscopic studies confirm that upon enzymatic hydrolysis, cellulosic content in nanoparticles is substantially reduced. The work highlights a method for obtaining unique cuboidal shaped lignin-rich nanoparticles that are uniform in size and shape. These lignin-rich nanoparticles have a potential for various applications across fields including automobile, pharmaceutical and polymer industries. (C) 2017 Elsevier B.V. All rights reserved.