Zero-valent iron/TiO₂ supported on MOF aerogel for photo-Fenton degradation of trichloroacetic acid

To transcend the limitations of conventional remediation techniques and fully leverage the synergistic potential of advanced oxidation processes (AOPs), this study developed a novel photocatalytic system, TiO₂/MOF-808@SiO₂@Fe(0), for the highly efficient degradation of trichloroacetic acid (TCA) under UV irradiation. The composite catalyst was synthesized via a multi-step preparation procedure: (1) synthesis of a hierarchically porous SiO₂ aerogel support by the sol-gel method; (2) in-situ growth of MOF-808 nanocrystals within the aerogel matrix; (3) deposition of UV-responsive TiO₂ nanoparticles; and (4) immobilization of zero-valent iron (Fe(0)) to activate the photo-Fenton reaction pathway.This composite architecture integrates the high specific surface area and structural stability of SiO₂ aerogel, the adsorptive porosity of MOF-808, the photocatalytic efficiency of TiO₂, and the reductive capability of zero-valent iron. Experimental results demonstrate that under conditions of pH = 6, 45 ℃, and 50 mL of 10 mg/L TCA solution, the system achieved a remarkable TCA degradation rate of approximately 94.2%. This high performance is attributed to the synergistic interactions among Fe²⁺, Fe(0), and TiO₂, which collectively enable excellent TCA mineralization efficiency. The system thus presents a novel and promising technological platform for the removal of recalcitrant organochlorine compounds in water treatment applications.