Tailoring Biowaste‐Derived Activated Hydrochar With Multifunctionality Toward Antibiotic Adsorption, CO ₂ 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, CO ₂ 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. CO ₂ 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, CO ₂ mitigation, and energy storage challenges.