Exploring biosorption properties of Litchi chinensis peel for a cationic dye Rhodamine 6G in Liquid/Solid phase system: Kinetics and equilibrium studies

The Rhodamine 6G (Rh6G), a cationic dye is actively being used as a potentially tracing dye in the field of biotechnology for immunological studies. The peel powder of Litchi Chinensis was employed in native condition to explore the sorption properties at different experimental conditions like initial dye concentration, contact time, dosage of biosorbent, temperature and pH. The detailed characteristics of Litchi chinensis peel before and after adsorption were performed by using sophisticated instruments like SEM-EDX, FTIR, BET and XRD. From the adsorption studies it was observed that the equilibrium data followed Pseudo-second order rate kinetics and Freundlich isotherm. The Langmuir adsorption capacity (Q_o) was found to be 6.66 mg/g, and the adsorption process was spontaneous and exothermic in nature (based on ΔG, ΔH and ΔS values). All the laboratory experiments proven to be an evident for the Litchi chinensis peel as an efficient biosorbent for the removal of Rhodamine 6G in the liquid/solid phase system.