Date of Award
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Civil Engineering
Committee Chair
Tingting Wu
Committee Member
Ashraf Z. Al-Hamdan
Committee Member
Jie Ling
Committee Member
Jason Kirby
Committee Member
Michael Anderson
Research Advisor
Tingting Wu
Subject(s)
Inorganic polymers--Absorption and adsorption, Eutrophication, Nutrient pollution of water, Agricultural pollution--Purification
Abstract
With the rise of population placing strain on food supplies and the failure of current prevention strategies to mitigate effects of agricultural pollution, research is needed to develop new technologies for the removal and recovery of nutrients from agricultural runoff and drainage. Geopolymer, an alkali-silicate material polymerized within an acidic or alkaline medium, is promising as an adsorptive substrate due to its multifaceted customizability, cost effectiveness, and adsorptive properties. Hence, the objective of this research was to develop porous metakaolin (MK) geopolymer based adsorptive materials with high affinities for phosphate and ammonium/ammonia to act as nutrient control within agricultural runoff and drainage. I first conducted a literature review to evaluated the most frequently proposed adsorbents, biochars and polymers, as phosphate adsorbents and slow-release fertilizer after exhaustion. In general, this information assisted in creating the MK-geopolymer, which has high nutrient selectivity and economic feasibility. In the third chapter, the MK-geopolymer was explored for phosphate adsorption by adhering lanthanum (La) to the adsorbent’s surface. The ratio of Na2SiO3: NaOH within the geopolymer slurry was manipulated to evaluate its effect on phosphate adsorption capacity, and was eventually determined considering the performance, structural strength of the material, safety, and economic cost for preparation. The La-loaded geopolymer was also evaluated using a synthetic agricultural solution, which yielded a Type III adsorption isotherm, demonstrating unrestricted multilayer phosphate adsorption. In the fourth chapter, the MK-geopolymer was optimized for ammonia/ammonium (NH3/NH4+) adsorption by hydrochloric acid (HCl) treatment. The HCl-treated geopolymer was evaluated in both ammonium solutions to examine the influence of various water chemistry and operating parameters and in synthetic agricultural runoff. To access possible nutrient recovery, adsorbent regeneration was performed for 3 cycles, in which subsequent adsorption capacity improved due to the geopolymer’s interaction with the NaCl in the regeneration solution. Results from this Ph.D. research showed that geopolymer-based materials can be promising adsorbents for nutrients removal and recovery from agricultural runoff.
Recommended Citation
Savoir, Gabrielle Jacquelle, "Developing geopolymer-based adsorptive materials for nutrient removal from agricultural runoff and drainage" (2024). Dissertations. 425.
https://louis.uah.edu/uah-dissertations/425
Comments
Submitted...in the joint Civil Engineering Program.