Nanocomposites for Phosphate Recovery: Investigating the Effects of Competing Contaminants and pH

Student’s name: Tobi Onasanya Home Institution: University of North Carolina at Chapel Hill NNCI Site: SHyNE @ Northwestern University REU Principal Investigator: Professor Vinayak Dravid, Materials Science and Engineering, Northwestern University REU Mentor: Kelly Matuszewski, Materials Science and Engineering, Northwestern University Abstract: Nutrient pollution in natural water systems, such as nitrogen and phosphorus introduced into bodies of water primarily from agricultural runoff, can lead to harmful algal blooms, oxygen depletion, and severe impacts on aquatic ecosystems and water quality. Eutrophication, excessive nutrients, contribute to disruptions of the nitrogen and phosphorus cycles and the growth of algal bloom creating dead zones in aquatic environments. Current water treatment technologies are timely and lack versatility to remove different contaminants. Conversely, interest in the use of nanomaterials is increasing due to their availability and ability to be tailored to containments. Here we aim to investigate the remediation of phosphates and metals typically found in storm and wastewater using a nanocomposite that consists of iron oxide nanoparticles coated cellulose sponge. Previous studies have shown success, with high-performing adsorption rates of phosphorus in lower pH systems and subsequent recovery of the phosphorus occurs at a pH near 11. In exploring the impact of pH levels, we also investigate how much water is required for successful recovery of phosphorus off the nanocomposite, testing recovery in volumes of 15 mL, 100 mL, and 500 mL of pH 11 water. Kinetics trials were run to examine how the system's contents affect the capture and recovery rates by comparing phosphorus and multi-ion kinetics. Finally, a flow-through system was used to mimic real water systems and study how flow rate influences performance. Scanning electron microscopy (SEM) is also used to observe how the nanoparticle coating is affected by these variables. This study will give more insight into how nanoparticle coatings can selectively remove pollution from flowing and stagnant water; creating a solution for large-scale pollution that is cost-effective and sustainable for the environment allowing us to recover and reuse these nutrients.