Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor/Mentor

Walters, Keisha B.

Abstract

Lignin is an abundant naturally occurring plant-based polymer that is branched, highly unsaturated, and rich in aliphatic and aromatic hydroxyl groups. Lignin is a significant byproduct of the wood pulp and paper industries; however, it has yet to be widely utilized in commercial applications due to its non-linear structure, broad range of molecular weights, hydrophobicity, high rigidity, and brittleness. Recent investigations into modifying lignin to broaden its potential uses have shown promising results. This thesis explores different modification techniques of the naturally occurring hardwood lignin polymer for specific applications in areas of water treatment and polyurethane (PU) production. The first project utilized lignin phenolation and subsequent amination for the removal of toxic anionic azo dyes from solution. Each reaction step characterized by Fourier transform infrared (FTIR) spectroscopy to confirm chemical reaction, and ultraviolet-visible light spectroscopy (UV-vis) to monitor dye removal over time throughout multiple dye removal tests. The second project aimed to modify lignin to act as the foundational polyol and isocyanate precursors of PU synthesis, for ultimate use in a completely lignin-based PU product. Building upon the successful results in the synthesis of two modified lignin-based polyols, these polyols were employed to develop three partially lignin-based PUs. Each of the lignin-based PU products were characterized by FTIR spectroscopy, and both water contact angle goniometry and thermogravimetric analysis (TGA) to assess wettability and thermal stability of the final PU products respectively.

Keywords

lignin; bioplastics; chemical engineering; material science

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