Liam Brodie, “Synthesis of Polyeurothane Foam with Iron Oxide Nanoparticles for Arsenic Filtration”
Mentor: Krishna Pillai, Mechanical Engineering

Groundwater arsenic contamination is a global issue that affects developing countries significantly. 50 parts per billion (ppb) or greater in concentration of arsenic has been linked to adverse health effects including respiratory disease and neurological malformity. The maximum contaminant level for arsenic by the Environmental Protection Agency is 10 ppb. By synthesizing polyeurothane filters with readily accessible nanoparticle additives, a low cost, efficient filter might be built for increased availability and greater understanding of arsenic removal. Based on previous studies with positive correlation of arsenic removal and polyeurothane foam, this experiment will vary the ratios of constituents to determine the most effective nanoparticle distribution. Nanoparticles will be iron oxide primarily due to previous research results. By manipulating the media while it forms, the pore space might be altered to maximize surface area contact with nanoparticles responsible for removal of arsenic. To test varying arsenic removal efficiencies, aqueous arsenic will be passed through filters synthesized and run independently then attempt to replicate this formula for additive manufacturing. To simulate household flow, a pump test system must be developed. Polyeurothane foam will be made using 2,4-toluene diisocyanate (TDI) and polypropylene glycol (PPG). Hydroxyl functional groups on the PPG react with TDI to create polyeurothane, a process that requires time and heat. A previous study by Arundhati Pillai suggest a molar ratio of two to one of TDI to PPG, which will be replicated. The TDI must first be heated to 70 degrees Celsius for maximum reactivity, done in a vacuum furnace. Using a bath of mineral oil to ensure consistent heating, a flask will be heated with the two to one ratio of TDI to PPG and injected with nitrogen gas to ensure an inert atmosphere. Previous work suggests a four to five hour reaction time, which will be done using a hot plate and magnetic stirrer. Upon completion of this time, a polysiloxane surfactant and metal nanoparticles will be added. The surfactant lowers surface tension to allow bubbles to form and create the filter lattice. Previously 10% by mass of nanoparticles were used. For this experiment, iron oxide with 8 nm sizes will be used, substantially smaller than the 15-20 nm used before and enhancing removal as suggested by Dr. Y.F. Shen and Dr. J. Tang. Roughly 7 mL of deionized water are added in this step, with thorough mixing. The flask is left in a stable environment to allow for the release of carbon dioxide for bubble formation to promote microstructure channels. After 24 hours of settling, the foam is rinsed gently with deionized water and the remaining product is iron oxide loaded polyeurothane foam. To test the efficacy of these filters, the system will be housed in clear PVC pipe to be the size of standard market filters and run through the filtration test system. The automated system includes flow, pH, and pressure sensors to accurately measure breakthrough on this new filter set and compare breakthrough times and removal efficiency against current market filters.