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Surfactants and Detergents

Poster

Session:: Surfactants and Detergents Poster Session

Synergistic effects of surfactant and chelating agent on stubborn bathtub keratin grime

Monday, May 1, 2023
4:30 PM – 6:00 PM MDT
Abstract: Modern lifestyles are diversifying, and people need to simplify their household chores to free up more time. Since long ago, Japan has had a unique bathing culture, and people in Japan bathe frequently for various purposes and share bathwater with their families, which results in bathtubs becoming easily soiled. While there is a strong need to keep bathtubs clean, cleaning the bathroom is viewed as the most troublesome household chore. We previously reported that the main component of bathtub grime is keratin-Ca, a compound formed when keratin protein binds to calcium ions found in tap water. We also reported that there is a high correlation between keratin-Ca’s removal ratio and its swelling ratio. However, the phenomenon of keratin-Ca swelling was not fully understood. In this study, we investigated the effect of the individual components of detergent on keratin-Ca removal in order to elucidate the mechanism of swelling.

We achieved a result of rapid and easy removal of keratin-Ca when rinsing with low mechanical force by applying an aqueous solution containing the chelating agent ethylenediaminetetraacetic acid (EDTA), which has the ability to easily capture calcium ions, and the anionic surfactant alpha-olefin sulfonate (AOS), the combination of which synergistically improved the swelling ratio of keratin-Ca (Fig. 1). Focusing on the wettability of the solution on the surface of keratin-Ca and its permeability, we were able to clarify that improved solution permeation attributable to the anionic surfactant contributes to keratin-Ca swelling. A detailed analysis of structural changes in keratin-Ca during the swelling process by time-domain NMR suggests that the combination of AOS and EDTA increases the molecular mobility of not only the amorphous part of keratin-Ca but also the crystal part and loosens the structure, thereby changing it to a state that allows for rapid removal with low mechanical force.