Tailoring Biowaste-Derived Activated Hydrochar With Multifunctionality Toward Antibiotic Adsorption, CO2 Capture, and Energy Storage.

This work investigates the potential of hydrochar (HC) produced from date seeds (DS) as a multifunctional material. Two adsorbents were synthesized by the hydrothermal route: HC and phosphoric acid-activated hydrochar (AHC). Their performances were assessed for levofloxacin (Lvx) removal, CO2 uptake, and as stabilizers in palmitic acid (PA)-based composite phase change materials (PCMs). The maximum adsorption capacity of HC and AHC for Lvx was found to be 18.05 and 41.94 mg/g, respectively, at 25 °C and an initial concentration of 10 mg/L, due to the larger surface area, increased active sites, and lower binding energy, supported by Brunauer-Emmett-Teller analysis (BET), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). Kinetic data were well described by Elovich and intraparticle diffusion models, while Langmuir and Temkin isotherms gave the best equilibrium fits. The adsorption showed a spontaneous and exothermic behavior. CO2 capture measurements demonstrated the superior efficiency of AHC (1.53 mmol/g) compared to HC (0.32 mmol/g). Both HC and AHC were utilized to obtain shape-stabilized PCMs, where PA/AHC exhibited higher latent heat storage and thermal stability relative to PA/HC. Overall, the findings highlight activated HC as a versatile material that can simultaneously address antibiotic pollution, CO2 mitigation, and energy storage challenges.