Integrated adsorption–electrocoagulation for dyes removal using solid petcoke-derived activated carbon coupled with predictive machine learning models

Toxic dyes in wastewater pose significant threats to water quality and aquatic ecosystems. In this study, activated carbons (ACs) were synthesized from petroleum by-products (asphaltenes and asphalt) via potassium hydroxide (KOH) activation and evaluated as sustainable adsorbents for dye removal. The ACs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), confirming a porous structure with various surface functional groups. Adsorption performance was assessed for three dyes, Congo Red (CR), Methylene Blue (MB), and Rhodamine B (RhB), under varying initial dye concentrations and contact times. Adsorption kinetics and isotherm models were analyzed to elucidate the dye uptake mechanism. The ACs exhibited an adsorption efficiency of over 97% for all tested dyes, demonstrating their strong potential for efficient dye removal in wastewater treatment. For high-concentration dye solutions (100 ppm), a combined adsorption–electrocoagulation approach was tested to further enhance removal efficiency up to about 100 %. Dye removal was also evaluated in single-dye and binary-dye systems to determine individual and combined effects of operational variables. Furthermore, machine learning models were employed to capture complex parameter interactions and predict dye removal performance with R²of 0.979. Overall, these findings highlight the promise of converting petroleum by-products into effective adsorbents for dye removal from wastewater.