Natural surfactants have significant advantages such as biodegradability, non-toxicity, and easy availability, making their extraction processes and technologies a focus of research. This study employed the high-gravity foam separation technology to extract saponins from Sapindus mukorossi, aiming to develop an efficient separation and purification process. The effects of different operating conditions on the separation efficiency were investigated. The results indicate that under the optimal conditions of high-gravity factor of 30, feed mass concentration of 0.1 g·L-1, gas flow rate of 150 L·h-1, liquid loading volume of 4 L, and liquid flow rate of 250 mL·min-1, the recovery rate of saponin from Sapindus mukorossi by high-gravity foam separation reaches 90%, the enrichment ratio reaches 6.38, and the purity is increased from 65% to 95% in a single pass. Compared with traditional foam separation methods, the recovery rate is increased by 36 percentage points, the enrichment ratio is improved by twofold, and the purity is increased by 30 percentage points. Furthermore, the structure and purity of commercially available saponins were compared with those of the self-prepared saponins. The results indicate that the structures of the two types of saponins are consistent, and the purity of the self-prepared saponins is higher than that of the commercially available ones. The high-efficiency separation of saponins achieved in this study using high-gravity foam separation technology is primarily attributed to the intensification of the interfacial adsorption process in foam separation by the high-gravity field. This process alters the morphology, size, and distribution of the foam, enhances the effective contact area between saponins and bubbles, and thereby enables the efficient separation and purification of saponins from Sapindus mukorossi. The high-gravity foam separation extraction process employed in this study offers significant advantages, including the absence of any new chemical additives, and environmental friendliness. This approach addresses the issues of low separation efficiency and environmental pollution associated with current extraction methods, providing new insights and techniques for the high-performance separation and purification of natural surfactants.
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