Eco-friendly Biowaste-based natural surfactant for lyotropic assemblies and Bio-adsorbent for dye removal

Abstract

Aggregation behavior of biowaste Litchi Chinensis (LC) seed in three different solvents of varying polarity [water (80), formamide (108), and glycerol (37)] has been studied. Nematic liquid crystalline phase has been obtained for studied systems as confirmed by a polarizing optical microscope (POM). Potential of the LC seeds has been checked to remove the Rhodamine B (RhB) dye from the wastewater. Effect of dye varying concentration (1 mg/L, 3 mg/L, 5 mg/L, 7 mg/L and 10 mg/L) varying pH (3,6 and 9), and contact time (0 to120 sec) on adsorption process have been evaluated. About 52% of dye removal efficiency is achieved with bare 50 mg adsorbent at pH≈ 6. Pseudo-first-order kinetics is found best fitted for the adsorption process (R2~0.98). Freundlich isotherm is found best fitted to the adsorption data which is also vindicated by a greater value of R2~0.95. Hydrogen bonding, electrostatic interactions, and pi-pi interaction between RhB and LC seeds (saponin) could be responsible for the adsorption process. These results indicate that LC seed can act as a perfect surfactant for lyotropic assemblies and also an effectual natural adsorbent for the dye adsorption and cleaning of aquatic systems.