Semester of Graduation

Summer 2026

Degree

Master of Science in Biological and Agricultural Engineering (MSBAE)

Department

Biological and Agricultural Engineering

Document Type

Thesis

Abstract

This study investigates the separation of lignin from biomass using deep eutectic solvents (DES) in combination with microwave radiation and evaluates the effects of process conditions on lignin yield and other characteristics of lignin. All experiments were conducted in a batch microwave system to provide controlled and consistent heating. In the first study, three DES systems were examined, including formic acid choline chloride DES, oxalic acid ethylene glycol choline chloride DES, and acetic acid choline chloride DES. Experiments were carried out at temperatures of 80, 100, and 120 °C, with DES-to-biomass ratios of 4:1, 6:1, and 8:1. A constant reaction time was maintained, and two particle size ranges of less than 1 mm and between 1–2 mm were evaluated. Statistical analysis showed that temperature and DES type significantly affected lignin extraction, while particle size and solvent ratio did not have a significant impact. Based on these results, an optimized process was identified using formic acid choline chloride DES at a 6:1 ratio and 100 °C, with biomass particle sizes less than 2 mm.

The second study applied these optimized conditions to compare lignin extraction across six biomass types: Hem-Fir chips and sawdust, Douglas fir chips and sawdust, and Southern Yellow Pine chips and sawdust. This allowed for evaluation of how biomass type influences lignin separation under consistent processing conditions. Differences in lignin yield were observed between biomass types and forms, indicating that feedstock characteristics affect extraction performance even under optimized conditions.

Overall, this work demonstrates that DES composition and temperature are key factors in lignin separation, and that a batch microwave system can be effectively used to apply optimized conditions across multiple biomass sources to assess variability in extraction efficiency.

Date

7-27-2026

Committee Chair

Boldor, Dorin

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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Available for download on Friday, July 27, 2029

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