Interfacial-active green surfactants from sugarcane bagasse and its biochar for enhanced oil recovery.

Sugarcane bagasse (SCB), a primary agricultural waste from sugar production, poses significant environmental challenges due to its accumulation. This study introduces the direct application of SCB and its biochar (SCB-B) as cost-effective and eco-friendly agents for Enhanced Oil Recovery (EOR). We systematically investigated their efficacy in reducing oil-water interfacial tension (IFT) and altering the wettability of carbonate rocks. Both materials significantly reduced IFT by up to 70% and shifted strongly oil-wet surfaces towards neutral-wet conditions by up to 47% at very low concentrations. A pivotal finding was the shift in governing mechanisms at the Critical Micelle Concentration (CMC), which increased from 16 ppm in distilled water to 70 ppm in saline environments. Interestingly, a reversal in the performance trends of SCB and SCB-B for wettability alteration was observed precisely at the CMC, attributed to a concentration-dependent agglomeration behavior of surface functional groups. While the ultimate IFT reduction is less pronounced than that of pure chemical surfactants or saponins, the key advantage of our approach lies in utilizing unprocessed agricultural waste directly, bypassing the need for costly and complex extraction procedures. This work establishes a dual-value proposition by offering a sustainable strategy for waste management and presenting an economically viable, green alternative to conventional chemical EOR agents.