RAPID:Novel Foam formulations for decontamination of surfaces with minimum wastewater generation

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The broader impact of this RAPID project is to advance the understanding of a new disinfectant composition. A common approach to contain the spread of infectious diseases involves spraying decontaminating disinfectants onto the floors in hospitals, apartments, parks, airports, footpaths, and other surfaces. The disinfectants commonly used are bleach, hydrogen peroxide, phenols and iodophors. Sprays of such solutions on surfaces do not stick to surfaces of protective clothing and hence have to be applied multiple times a day for decontamination results. Furthermore, such operations can result in seepage of the solutions into the ground. Considering the pandemic nature of infectious diseases such as COVID-19, decontamination practices can often span for months, causing prolonged exposure to disinfectant fumes that may be harmful to the lungs and irritating for the respiratory tract. The proposed project aims to overcome these issues by developing and applying disinfectant formulations as a foam allowing sufficient exposure. A foam with super spreaders can penetrate cracks and crevices, sticking to surfaces long enough to decontaminate. The formulation will be designed for decontamination of floors and windows in houses, vehicles, hospitals, and large areas such as airports. In order to further minimize the use of disinfectants such as bleach, an antimicrobial reagent serving as the foaming agent will be used. This will benefit communities experiencing contagious diseases. The objective of this RAPID project is to prepare a set of innovative foam formulations that differ in disinfectant and surfactant type, and test them for their foamability and deployment using a sprayer. A biosurfactant surfactin that also exhibits anti-microbial properties will be used as a foam stabilizer. This project will: Determine the air/water interfacial tension as a function of surfactant concentration; study parameters, including the rates of foam formation (foamability) and breaking (stability), as well as bubble size; determine and correlate storage and rigidity modulus values for the foams with foam texture for different air/water ratios; study deployment with a variety of delivery equipment, such as household and backpack sprayer and foam lancer; characterize the time-dependent texture of foam formed on a tile surface and relate it to the foamability, the foam-stability parameters, and the storage and elastic modulus values. The tile surfaces after foam completely breaks down will be analyzed using an electron microscope to assess if disinfectant is deposited uniformly or in the form of patches. This assessment will be verified using the Raman spectroscopic mapping of the tile surface; the interfacial tension data at different ratios of surfactant types provide an estimate of their adsorption density at the air/water interface in the presence of hypochlorite ions in the aqueous phase, while the foam stability parameters provide insights into their intermolecular interactions at the interface and the possibility of synergistic effects among different types of surfactants that govern the stability of a foam.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.