Doctor of Philosophy (PhD)
The land produces more than 95% of the global food supply, and with a continuously growing population, we need to optimize the use of the available agricultural land. Soil organic matter (SOM) is an essential component of soils, especially concerning their fertility and sorption behavior. The chemical composition of the SOM consists of lipids, lignin, and cellulose. However, the heterogeneous and complex nature of SOM, and real soils, makes their study challenging and introduces uncontrollable factors.
Therefore, structural mimics of natural soils with increasing complexity representing the real soil functionality were synthesized and evaluated for bulk properties related to their structural composition. These soil mimics are referred to as engineered soil surrogates (ESSs). The ESSs are composed of silica particles that model mineral particles, different sized aliphatic chains to represent the lipid fraction of real soils, and phenolic oligomers to mimic the lignin fraction hydrophilic oligomers to represent the polar fraction of SOM. The technique of atom transfer radical polymerization was used to synthesize ESSs. This technique is simple, easy to set up, and allows precise control over the final polymer molecular weight. We started with a grafting-from approach, which had some drawbacks due to the mesoporous silica's presence in the reaction. Subsequently, we shifted to a more prosperous and controllable alternative approach, which is grafting-onto. The ESSs were characterized using thermo-gravimetric analysis and nuclear magnetic resonance. Norflurazon sorption to the ESSs was investigated using batch equilibration experiments, and the Freundlich isotherm modeled the data. This provided insights into the sorption capacity (Kd) and whether a partitioning or non- partitioning mechanism was at play.
Abdalla, Ghada Yehia, "Development of Engineered Soil Surrogates for Modeling Natural Soil Sorption Behavior" (2021). LSU Doctoral Dissertations. 5448.
Available for download on Wednesday, January 17, 2024