Biosorption of Methylene Blue Dye from Textile-Industry Wastewater onto Sugarcane Bagasse: Response Surface Modeling, Isotherms, Kinetic and Thermodynamic Modeling

Abstract This research focuses on the viability of removing basic dye methylene blue (MB) from water solutions by the application of sugarcane bagasse (SCB), an economic natural biosorbent. Batch experiments were conducted based on solution pH, contact period, initial adsorbate dye concentration, biosorbent amount, and temperature as independent variables by employing a central composite design approach of response surface methodology (RSM). With the use of RSM, the optimization of the MB biosorption process was carried out for maximum MB removal. The biosorption equilibrium of the dye solution was achieved after a contact time of 90 min and explained by the Langmuir and Freundlich isotherms. The biosorption data is employed for the kinetic modeling, from pseudo-first- and pseudo-second-order kinetic equation. Thermodynamic parameters (Enthalpy change ΔH, entropy change ΔS, and Gibbs free energy ΔG) were studied, which showed that biosorption is natural and endothermic in nature by reducing color randomness at the liquid and solid interface. Biosorbent characterization explained in this analysis is performed through Fourier-transform infrared spectroscopy before and after MB biosorption. Characteristic tests and separation factor proved that SCB was able to be used as an option to commercial biosorbents for the aqueous solution and removal of MB from wastewater.