Efficient Adsorptive Removal of Methyl Violet Dye from Wastewater Using Functionalized Groundnut Shell Biochar: Application, Mechanism, Modeling, and Optimization Study.

This investigation focuses on the abatement of methyl violet (MV) dye from industrial effluents using the deployment of functionalized biochar prepared from methanol-extracted groundnut shell residue. The biochar was functionalized by 30% tartaric acid(C4H4O6) to boost the surface functionality and adsorption performance. It was determined by conducting SEM, FTIR, XRD, and ZP analysis that a porous structure was developed with high concentrations of oxygen-carrying functional groups and favorable surface charge qualities. Batch adsorption studies were designed to evaluate the effect of influential parameters on the removal performance. The equilibrium behavior was successfully interpreted using several mathematical models. The maximum adsorption capacity was found ∼88.57 mg/g. The kinetic and thermodynamic evaluation revealed that both pseudo-first-order and pseudo-second-order models closely represent the experimental data, suggesting that the adsorption behavior arises from multiple interacting synergistic pathways rather than a single dominant mechanism, and the adsorption proceeds spontaneously, followed by an endothermic process. Additionally, the Box-Behnken and experimental designs were used to show that the system is highly sensitive to the relationship between operational parameters. The results, when combined, reveal that the FGNB biochar derived from secondary waste biomass provides a possible solution to dye-contaminated wastewater treatment that is economically feasible and eco-friendly.