Natural Ceramic Membrane Filter for Water Purification Eileen Freres, Marcia Silva* *corresponding author: msilva@uwm.edu Water Technology Accelerator (WaTA), UW-Milwaukee

Background Reverse osmosis systems Require high energy to force water through filters. Resulting in excessive waste: up to 20 gallons of wasted fluid per gallon of purified water (1). Extended filtration time of 3-4 hours per gallon of purified water produced (1). Unnecessarily remove most of the minerals from the water, leaving it with an acidic pH (1). The proposed ceramic filter will allow for selective filtration of water by utilizing the chemical- altering properties of the subject material (3). The material used will reduce costs of filtration because it is naturally accessible, inexpensive, and replaces the need for additional, chemical water treatments. Figure 1: Purtec Industrial Water, “What is Reverse Osmosis?”

Approach Develop a ceramic membrane filter for water purification that: Is efficient, accessible, and durable. Utilizes ion exchange Natural, sandy material will filter by: Mechanical filtration Ion exchange Desirable Properties: Durability Permeability Fabrication Dry Press material (Current Stage) Controlled Variables For Optimized Properties: Force, Volume, Grain Size Heat treatment Chemical functionalization Figure 2: (a) First mold design. (b) Second mold design.

Results Mold 1 limits the volume of subject material (Figure 3a). Mold 2 has a limiting compressive strength (Figure 3b, 3c). Ceramic specimen was fabricated (Figure 3b, 3c). Diameter: 47 mm Grain size: powder-0.7 mm Mass: 5 g Pressure: 300 MPa (b) (c) Figure 4: (a) Powder material after pressing in Mold 1. (b) Medium material after pressing in Mold 2. (c) Fractured specimen from Figure 4b.

Conclusion and Next Steps Material can be formed into cylindrical, ceramic filter wafer at 300 MPa using 0.7 mm grain size. If parameters are optimized, the material may be strong enough to withstand pressure from fluid flow. Next Steps: Create a new mold of hardened steel to withstand a higher applied load. Continue fabricating filters with large, medium, and small grain sizes. Heat treat filters at various temperature ranges and duration. Chemically functionalize material using in situ technique. Measure effective filtration by specimens to find optimal grain size, pressure, heat treatment, and functionalization parameters.