Characterization of Saponin Extracted from Acacia concinna (Shikakai or Soap Pod) and Thermodynamic Studies of Its Interaction with Organic Dye Rhodamine B

The complete study is comprised with three important investigations on the plant based natural surfactant saponin (NS). The primary extraction of the NS was done from Acacia Concinna (native name shikakai or soap-pod) fruit-pericarp. After isolation and purification, characterization of the saponin (NS) was performed by employing HR-ESI-TOF–MS (ES +), ¹H-NMR, ¹³C-NMR, FT-IR, HR-TEM, HR-SEM and UV–Vis spectroscopic methods. The CMC of the extracted saponin was determined by conductometric and UV–Vis Spectro-photometric methods, the CMC values of the NS were recorded to be 4.67 × 10^–4 M and 5.7 × 10^–4 M respectively, which indeed are much lower in value with respect to most of the commercially available surfactants. The thermodynamics of dye-surfactant interaction studies among selective cationic dye Rhodamine-B (RhB) with the isolated saponin were studied. Two other synthetic surfactants CPC (cationic) and SDS (anionic) were also used to have an inclusive comparative understanding of the dye-surfactant interaction. The presence of a replaceable ‘–H’ in the natural surfactant moiety is the reason behind its ability to interact with the selected cationic dye. The self-degradation of the NS in normal temperature and in aerobic and anaerobic condition was also kept in record. The NS is definitely a proven alternate for the synthetic surfactants that best suits with the sustainable goals of UNSDGs.