Degree
Doctor of Philosophy (PhD)
Department
Biological Engineering
Document Type
Dissertation
Abstract
Lignin stands out as a potential, renewable resource for the sustainable manufacture of aromatic chemicals, which provides a viable alternative to petroleum-based products. Despite its vast potential, the use of lignin is limited due to the unwanted effects of certain extraction/isolation processes on its quality and structure. The goal of this study is to investigate the application of a continuous process in the extraction of lignin using microwave irradiation and DES. To also study the feasibility of a large-scale lignin extraction process using DES and conventional heating methods, comparing the physicochemical characteristics of the lignin extracted with that of commercial lignin. Lignin was extracted on a large-scale using DES at two temperatures (80 and 100 ℃) and a constant residence time of 4 hours. Two different lignin (AL & DL) were obtained from the study. The sample AL had better purity than the DL and commercial lignin samples. The AL samples were also lighter in color and showed less occurrence of repolymerization reactions. As the temperature increased, the yield of the lignin samples also increased. The continuous extraction of lignin was carried out at four different temperatures (60, 70, 80, and 90 ℃) and flow rates (108, 141, 173, and 207 ml/min). The lignin yield increased with an increase in temperature and residence time. At 80 ℃, a higher lignin yield was obtained with good properties, therefore, 80 ℃ was chosen as the critical temperature for the process. A kinetic study was also carried out, and the activation energy of the process was recorded as 107 KJ/mol. A numerical model studying the continuous microwave heating of the reactant mixture was developed using COMSOL Multiphysics. The model was in good agreement with the experimental results, and the configuration of the reactor was found to influence the microwave heating of the reactant samples. Additionally, a parametric sensitivity analysis was carried out and showed that mild changes in the relative permittivity influence the microwave heating of the DES: biomass mixtures. These studies help to advance the understanding of lignin extraction using microwaves and DES, it also helps the commercialization of lignin extraction using DES for further valorization. The model developed can be used to simulate and optimize the continuous extraction of the lignin using microwaves
Date
3-19-2025
Recommended Citation
Adewumi, Adejoke Deborah, "Extraction of Lignin Using DES: Effect of Heating Methods and Process Design" (2025). LSU Doctoral Dissertations. 6690.
https://repository.lsu.edu/gradschool_dissertations/6690
Committee Chair
Boldor, Dorin
Included in
Biological Engineering Commons, Bioresource and Agricultural Engineering Commons, Polymer and Organic Materials Commons, Polymer Science Commons, Process Control and Systems Commons, Wood Science and Pulp, Paper Technology Commons
