Worldwide demand for man-made cellulosic fibres (MMCF) are increasing as availability of cotton fibre declines due to climate change. Feedstock for MMCF include virgin wood, agricultural residues (e.g., straw), and pre- and post-consumer cellulosic materials high in alpha-cellulose content. Lyocell MMCF (L-MMCF) offer large advantages over other MMCF processes in terms of both environmental and social impacts: the solvent for cellulosic dissolution, n-methyl-morpholine-n-oxide, can be recycled, and the process utilizes non-toxic chemicals and low amounts of water. Hemp can be a preferential cellulosic feedstock for L-MMCF as hemp cultivation results in carbon dioxide sequestration, and it requires less water, fertilizers, pesticides, and herbicides than other L-MMCF feedstock crops. These factors contribute to hemp being an environmentally conscious crop. The increased legalization of industrial hemp cultivation, as well as recent lifts on cannabis restrictions worldwide, allows accessibility to local sources of cellulose for the L-MMCF process. In addition, hemp biomass can offer a much larger feedstock for L-MMCF production per annum than other cellulosic sources, such as eucalyptus trees and bamboo. This paper offers perspectives on the agricultural, manufacturing, and economic opportunities and challenges of utilizing hemp biomass for the manufacturing of L-MMCF.

Lyocell man-made cellulosic fibres (L-MMCF) have been commercially available since the mid-1990’s, with the typical feedstock prepared from tree pulp or cotton linters. In recent years, there have been advancements in the utilisation of high alpha-cellulose agricultural biomass for L-MMCF feedstock. Industrial hemp stalks offer a unique opportunity for L-MMCF since hemp is considered an environmentally conscious crop that can also help to bridge the gap in worldwide cellulose shortages; additionally, industrial hemp stalks are high in alpha-cellulose, making this an ideal feedstock for L-MMCF manufacturing. This review paper outlines the lyocell process in detail, including processes for preparation of feedstocks, pulp processing, removal of contaminants and nonessential plant components, pulp dissolution, dope preparation, and fibre spinning. Opportunities and challenges associated with the utilisation of industrial hemp stalks as an alternative feedstock are addressed through all steps of the manufacturing process. Incorporating alternative feedstock opens new perspectives for manufacturing sustainable L-MMCF.

The lyocell process offers an environmentally friendly strategy to produce regenerated cellulose fibre from biomass. However, it is critical to recover and reuse the N-methyl-morpholine-N-oxide (NMMO) solvent to maximize the environmental benefits and lower the cost. This article reviews NMMO recovery and characterization techniques at the lab and industrial scales, and methods to limit the NMMO degradation during the process. The article also presents the results of a pilot study investigating the recovery of NMMO from lyocell manmade cellulosic fibre (L-MMCF) manufacturing wastewater. The work described includes the development of a calibration curve for the determination of NMMO content in aqueous solutions using Fourier Transform Infrared Spectroscopy (FTIR). Successful NMMO recovery from the wastewater was achieved using a rotary evaporator: the final NMMO concentration was 50, i.e., ready for use in the lyocell process, and no NMMO degradation was observed. The knowledge in this paper will support advances in L-MMCF manufacturing and the reduction in textile environmental footprint.