From Marine Waste to Synergistic Adsorbents: A Comparative Study of Polyaniline, Posidonia oceanica-Derived Carbon, and Their Composite for Murexide Capture

Developing sustainable and high-performance adsorbents for dye-contaminated wastewater remains a pressing environmental challenge. Herein, we report the formation and comparative evaluation of polyaniline (PANI), activated carbon obtained from Posidonia oceanica (ACPO), along with their hybrid PANI/ACPO compound, for the efficient uptake of the anionic organic dye murexide from aqueous solutions. This strategy leverages the valorization of abundant marine biomass together with a nitrogen-rich conducting polymer to create environmentally friendly adsorbents with enhanced functionality. Comprehensive physicochemical characterization confirmed the successful transformation of Posidonia biomass into hierarchically porous activated carbon and the uniform incorporation of PANI in its doped emeraldine form within the composite structure. Adsorption tests revealed that PANI exhibited the highest capacity (333.33 mg·g-1), followed closely by the PANI/ACPO composite (322.58 mg·g-1), while ACPO showed a moderate capacity (149.25 mg·g-1), illustrating the synergistic potential of the hybrid material that combines efficiency with sustainability. The findings demonstrate that all three materials efficiently remove Murexide, and the PANI/ACPO composite in particular stands out as a sustainable, high-performance, and competitive adsorbent, offering a robust and practical strategy for wastewater remediation. Detailed adsorption mechanisms and extended kinetic analyses are discussed in the full manuscript submitted to a peer-reviewed journal.