Date of Award

12-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Chemical Engineering

First Advisor

Toufiq Reza

Second Advisor

Manolis Tomodakis

Third Advisor

Maria Pozo de Fernandez

Fourth Advisor

Spencer Fire

Abstract

Harmful Algal Bloom (HAB) events involve the proliferation of microalgae which discharge lethal toxins into fresh and brackish water bodies due to anthropogenic and climatic activities. Common examples of HABs include causative organisms such as Cyanobacteria, Pyrodinium bahamense and more. These genera are known to release potent toxins including Microcystins, and Saxitoxins, respectively, which can seriously endanger human and marine health. Ingestion of these toxins can result in several health problems, such as nausea, vomiting, gastroenteritis, skin irritation, liver damage, paralysis, and respiratory arrest. The Great Lakes, Gulf of Maine, Florida’s coasts, Lake Erie, and Lake Okeechobee have all been frightened by these outbreaks, negatively impacting fisheries, the economy, and marine ecosystems. Physical water treatment, such as adsorption using carbonderived adsorbents provides a low-cost, high effective solution to remove these pollutants. Thermochemical conversion processes, such as hydrothermal carbonization (HTC), and pyrolysis have significant potential in transforming biomass such as waste corn stover, loblolly pine and washed up sargassum into valuable adsorbent material known as biochar. Given that these techniques enhance the surface properties of biochar, it is necessary to examine how the synthesis iv parameters affect the material characteristics for toxin adsorption applications. Considering the importance of removing these toxins, it is imperative to study the various mechanisms involved in adsorption. This will provide valuable insights into the interactions between the different toxins and biochar. The main objectives of this dissertation are to (1) investigate the material characteristics of biochar procured using varying synthesis techniques; (2) examine the adsorption efficiency of biochar as well as the interactions between biochar and HAB toxins; and (3) determine the economic feasibility to produce industrial volume of biochar derived from waste corn stover. The following techniques to characterize biochar will be used: Ultimate analysis, Thermogravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) Analysis, Scanning Electron Microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), surface charge, and Boehm titration analysis. These findings supported the presence of active binding sites for adsorption such as high porosity, oxygen containing functional groups, and positive/negative surface charge which all varies depending on the synthesis conditions applied. The efficacy of the various modified biochar against Microcystin-LR (MCLR), and Saxitoxin (STX) will be examined using batch adsorption tests, with different parameters such as dosage amount, contact time, initial concentration, and pH. Enzyme-linked immunosorbent assay (ELISA) will be used to assess the examines toxins. Ultimately, a thorough technoeconomic assessment analysis will be conducted to investigate the commercial scale-up of biochar procured under differing pyrolysis temperature conditions.

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