Biodecolorization of Reactive Orange 16 using biochar produced from groundnut shell (Arachis hypogaea): batch, isotherm, kinetic, and regeneration studies

The present investigation explored the potential of biochar produced from groundnut shells in the removal of Reactive Orange 16 (RO16) in an aqueous solution. The characteristics of the biochar were evaluated using a thermogravimetric analyzer, scanning electron micrographs (SEM) with energy dispersive system (EDS), and Fourier transform infrared (FT-IR) spectra. The batch adsorption studies were conducted by determining the influencing parameters, namely, solution pH, sorbent dose, solution temperature, and initial RO16 concentration. Furthermore, adsorption isotherm models, namely, Freundlich, Langmuir, and Toth model were used to predict the sorption capacity of the model. Pseudo-first-order and pseudo-second-order kinetic models were developed to understand the sorption of the dye molecules at different time intervals. To evaluate the potential of the sorbent, regeneration studies were performed. A maximum removal efficiency of 73.67% and a sorption capacity of 11.05 mg/g were obtained.