Date of Award

Spring 2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil & Environmental Engineering

Committee Director

Sandeep Kumar

Committee Member

Mujde Erten-Unal

Committee Member

Bijandra Kumar

Committee Member

James Lee

Committee Member

Jaewan Yoon

Abstract

This study establishes a technical and theoretical foundation for the efficient conversion of organic waste into biocrude and high-value carbon materials, aiming to facilitate the industrialization of hydrothermal and solvothermal liquefaction. The dissertation research is structured as follows:

Chapter 2 developed a novel chemical kinetic model for the HTL of corn stover based on elemental balances (C, H, N, and O). By incorporating temperature, residence time, solid loading as an independent variable, the model successfully predicted product yields and properties, revealing that there was non-pseudo-first-order reaction pathways in the conversion of water soluble organics in aqueous phase (AP) to hydrochar.

Chapter 3 focused on statistical optimization using Principal Component Analysis (PCA) and regression analysis. Predictive models for light bio-oil (LBO) yields, AP solution weight, and the biodegradability index IC50 of HTL wastewater were established. By integrating these findings with the kinetic models from Chapter 2, this study expanded the predictable domain of the HTL process, demonstrating an effective approach to balancing biocrude production with environmental impact assessment.

Chapter 4 investigated the specific influence of heating rates on product distribution. Using microcrystalline cellulose (MCC) as a model compound, this phase clarified how rapid heating conditions independently affect chemical pathways and product characteristics, contrasting these effects with maximum temperature and severity factor, which is an index frequently prioritized in the field of HTL.

Chapter 5 explored the synthesis of advanced functional materials through solvothermal liquefaction (STL). Biocrude derived from model food waste (pasta) was converted into hard carbon for supercapacitor electrodes. The resulting material achieved an exceptional specific surface area of 2,754 m2·g-1 and a specific capacitance of 530 F·g-1, demonstrating the potential of organic waste for high-performance energy storage.

In conclusion, this dissertation demonstrates that integrating kinetic modeling, heating rate analysis provides a robust engineering framework for the social implementation of biomass conversion technologies.

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DOI

https://doi.org/10.25777/vj5q-5n11

ISBN

9798197813725

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