Extractives-free sugarcane bagasse as adsorbent for the removal of Rhodamine B (Basic Violet 10) with high capacity and reusability

The use of extractives-free SCB (eSCB) as a renewable adsorbent for removing rhodamine B (RhB) in water was explored to contribute to strategies for conserving the environment and better use of natural resources. Different initial pH (3–9) and RhB concentrations (10–1100 mg/L) at various temperatures (303–333 K) during adsorption were carried out to assess the uptake kinetics and equilibrium uptake. The Elovich and the multi-mechanistic models best describe the adsorption kinetics. The adsorption of RhB on eSCB is primarily physisorption but may also involve chemisorption under certain conditions. The adsorption process co-occurs within and on the surface of the eSCB matrix. The adsorption capacity of eSCB for RhB is 88.71 mg/g at 318 K, and the Brouers-Sotologo model best describes the equilibrium uptake isotherm. The adsorption of RhB on eSCB is a spontaneous and exothermic process. This study is the first to report on the regeneration and reuse of eSCB as an adsorbent for RhB. Extractives-free SCB can be reused for at least 7 cycles, using 95% ethanol to remove the adsorbed dyes between cycles. The reused eSCB adsorbent retains 80 % of its adsorption capacity even after its 7th reuse.