Upcycling of Hemp Hurds into High-Value Cellulose Nanomaterials: Nanofibrillated Cellulose and Nanocrystalline Cellulose Production and Characterization

Abstract

This study focused on the production and characterization of nanocellulose derived from hemp hurd, a highly valuable lignocellulosic natural resource. The holocellulose, alpha-cellulose, and lignin contents of the hemp hurd were determined as 83.3%, 39.1%, and 15.7%, respectively. The hemp hurd fiber had a length of 0.6 mm and a width of 19.1 µm. Following maceration and delignification pretreatments, bleached hemp hurd fibers were converted into nanofibrillated cellulose (NFC) by high-pressure homogenization, whereas nanocrystalline cellulose (NCC) was produced via sulfuric acid hydrolysis. The width of NFC was found to be 26.7 nm, while the width of NCC was determined to be 3.7 nm. The length of the NCC was confirmed to be 44.6 nm. The crystallinity indexes of NFC and NCC were found as 85.6% and 93.7%, respectively. The thermal decomposition of NFC occurred between 220 and 340 °C, whereas the thermal decomposition of NCC occurred between 170 and 550 °C. The residual material ratio was 25% for NFC and 28% for NCC. Moreover, the chemical bonds that form NFC and NCC, such as C–H, O–H, C–O–C, etc., were identified.