A comprehensive review of recent advances in delignification technology

Due to the growing interest in lignocellulosic natural fibers, delignification has become a widely discussed research area. However, conventional degradation methods often involve high energy consumption and the use of potentially harmful substances, such as chlorine and heavy metals. These pollutants not only pose risks to the environment but also conflict with the principles of sustainable development. This paper provides a comprehensive review of various lignin removal technologies, including alkali treatment, organic solvent treatment, ionic liquid treatment, and biological treatment. The technological conditions, lignin removal rate, and reaction mechanism were compared. Alkali treatment is frequently combined with oxidants or physical methods to enhance the effectiveness of lignin removal. Most organic solvent treatments can be recycled through distillation. The relatively new ionic liquid treatment has shown promising results in terms of high lignin removal rates and minimal cellulose loss. However, due to its high cost, it is not widely adopted in industrial applications. Biological treatment, which does not involve chemical agents, however, tends to have a longer process duration compared to chemical treatments. Overall, delignification treatments facilitate the transformation of lignocellulosic fiber into high-value products.