High-efficiency removal of Rhodamine B using modified biochar from agricultural waste pine nut shell: investigation of kinetics, isotherms, and artificial neural network modeling

This study investigated the efficacy of modified biochar derived from pine nut shells (MPNBC) in removing Rhodamine B (RhB) through adsorption. The objective was to eliminate RhB from aqueous systems by employing agricultural wastes as an adsorbent. MPNBC was characterized using SEM, TGA, XRD, BET, and FTIR analyses, revealing a significant BET surface area favorable for RhB adsorption. The study unveiled an average RhB adsorption capacity of 110.68 mg/g and an average BET surface area of 1280.189 m²/g. The adsorbent exhibited the capacity to remove RhB dye with high efficiency; almost 100% elimination is achieved in experiments performed under optimal conditions with an initial dye concentration of 10 mg/L at pH 3.0 with an adsorbent dosage of 0.5 g/L. Kinetic modeling revealed good fits to pseudo-first-order, pseudo-second-order, and Elovich models. Equilibrium isotherms were also well described by Freundlich, Langmuir, Temkin, Redlich-Peterson, and Khan models, with high correlation coefficients. Additionally, an artificial neural network (ANN) model effectively optimized the adsorption parameters, with predicted values closely matching the experimental data. The ANN model yielded excellent statistical performance, with a root-mean-square error (RMSE) of 0.9985 and a coefficient of determination (R²) of 0.983. Overall, the adsorbent exhibited excellent adsorption capabilities for the azo dye under study.