Synthesis of Activated Coke via Co-carbonization of Mixed Atmospheric Residue and Polypropylene Waste and KOH-Activation for the Desulfurization of Model Fuel

The increasing need for environmentally friendly methods to reduce sulfur content in transportation fuels has motivated the search for efficient and low-cost adsorbents. This study aims to synthesize a novel activated coke (AC) from a combination of atmospheric residue (ATR) from the Al-Kasik refinery and polypropylene (PP) waste collected from a cement factory. The co-carbonization process was carried out at 400 °C for 1 hour, followed by chemical activation using potassium hydroxide (KOH). The resulting activated coke was characterized using X-ray diffraction (XRD), nitrogen adsorption–desorption at 77 K, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) to evaluate its crystallinity, surface area, pore structure, morphology, and elemental composition. The optimized AC exhibited a surface area of 220.96 m²/g and an average pore width of 2.95 nm, indicating a mesoporous structure. The adsorptive performance of the AC was tested using a model fuel containing dibenzothiophene (DBT) dissolved in hexane. A removal efficiency of 97.62% was achieved under optimal conditions (0.3 g of AC at 30 °C for 80 minutes). The adsorption process followed the Freundlich isotherm model and pseudo-second-order kinetics. Moreover, the AC demonstrated good reusability, retaining 88.13% removal efficiency after five regeneration cycles. The study demonstrates that the synthesized activated coke is a promising and efficient adsorbent for sulfur removal from transportation fuels, offering a sustainable solution utilizing industrial waste materials.