A Hybrid Mesoporous Sulphur-doped CoMn Oxide @ Cobalt Alginate-derived Carbon Spongy-like Beads for Methylene Blue Decolorization: Isotherm, Kinetic, and Machine Learning Modeling

This study presents the synthesis of hybrid mesoporous sulphur-doped CoMn oxide @
cobalt alginate-derived carbon spongy-like beads (M-CoACBs) to remove methylene blue
(MB) dye from aqueous solutions. The M-CoACBs were synthesized through a two-step
process, followed by extensive characterization using SEM, EDX-mapping, XPS, XRD,
and N
2 adsorption-desorption isotherms. The characterization revealed that the sulphurdoped CoMn oxide significantly enhanced the cobalt alginate-derived carbon beads’ structural integrity and surface properties, leading to increased adsorption capacity. The decolorization performance of the M-CoACBs was systematically evaluated and compared to
untreated CoACBs. Results showed a remarkable 35% increase in MB removal efficiency
with the M-CoACBs, demonstrating the effectiveness of sulphur-doping in improving adsorption capacity. Batch adsorption experiments were conducted to optimize key parameters such as pH, sorbent dose, and initial dye concentration. The optimal conditions were
found at pH 7, where the maximum dye removal efficiency was achieved. The adsorption
data best fit the Langmuir isotherm (R² = 0.98) and pseudo-second-order kinetic model
(R² = 0.99), indicating high capacity and chemisorption. Machine learning (ML) techniques, specifically the Extra Trees algorithm, were employed to predict the adsorption
capacity, achieving an R² of 0.999, with error metrics of MSE =0.263, RMSE= 0.513, and
MAE=0.334. The ML model highlighted the importance of key variables such as initial
MB concentration and stirring time. The M-CoACBs exhibited high adsorption capacity
and rapid adsorption kinetics, making them a promising material for removing MB dye
in wastewater treatment applications. The study highlights the potential of sulphur-doped
CoMn oxide as a powerful modification for enhancing the adsorptive properties of carbonbased materials, providing an efficient and sustainable solution to the growing issue of dye
pollution in water systems