Comparative Evaluation of Polyester and Polyether Polyurethane Foams for <i>Escherichia coli</i> Adsorption in Water Disinfection

In 2022, an estimated 1.7 billion people globally lacked access to safe drinking water, with more than 100 million still relying on untreated surface water. Contamination of water with fecal bacteria can cause a variety of diseases. Many methods have been proposed and used to remove bacteria from drinking water. However, many of these methods still are not broadly used in remote areas, as they can be inefficient, require chemicals, or use complicated operational procedures. This study conducts an initial investigation of the potential of polyurethane foams for water disinfection. Specifically, we compared polyester polyurethane (PESPU) and polyether polyurethane (PU) foams with similar morphologies for <i>Escherichia coli</i> (<i>E. coli</i>) adsorption. The relationship between foam properties (surface charge, surface energy, and surface chemistry) and bacterial removal efficiency was investigated to identify the critical aspects for future adsorbent development. It was found that the PESPU foam achieved a bacterial log reduction of approximately 2.9 for<i>E. coli</i> when immersed in a solution with an initial concentration of 10⁴-10⁵ CFU/mL for 1 h, whereas the PU foam showed negligible effectiveness under the same conditions. It was discovered that the PESPU foam exhibited a larger surface charge and surface energy than the PU foam, which likely contributed positively to its superior performance. This study is a step toward improving new foams employing surface charge, surface energy, and surface chemistry to improve bacterial adsorption effectiveness and provide accessible water treatment for underserved locations.