Extraction of saponins from soapnut and their application in controlling ammonia and particulate matter

Synthetic surfactants have been associated with environmental concerns, requiring their replacement with natural alternatives such as saponins. In this study, saponin extraction from soapnut was optimized using the reflux method through the Box–Behnken design and response surface methodology (RSM). Foams generated from the saponin solution were evaluated for effectiveness in ammonia and particulate matter (PM) removal, along with foam characteristic analysis. The optimized saponin extraction yielded 30.18% saponin, exceeding the yields achieved through conventional methods. The extracted saponin exhibited enhanced foamability with increasing concentrations, leading to an expanded surface area that facilitated the removal ammonia and PM removal through foam-based adsorption. Ammonia removal was further improved as the foamability and stability of surfactant foams increased at saponin concentrations above the critical micelle concentration (CMC) under neutral pH conditions. The comparable PM removal efficiency of saponin-based foams to that of synthetic surfactants underscores their potential as an effective and environmentally sustainable solution for air pollution control.