Visible-light-driven chlorophyll-sensitized TiO2@HEC-CA biophotocatalyst film for efficient photocatalytic degradation of emerging organic contaminants

In this work, a cellulose-based biophotocatalyst film, (Ch–TiO 2 @HEC-CA), was successfully synthesized using a melt-mixing method. The structural characteristics of the fabricated film were verified through ATR-FTIR vibrational spectroscopy and X-ray diffraction (XRD). while its surface morphology and thermal behavior were further investigated by scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDX) and thermal analysis (TGA-DTA), respectively. Optical properties revealed a drastic drop in the optical band gap from 4.75 eV for (HEC-CA) and 3.18 eV for (TiO 2 @HEC-CA) to 1.83 eV for Ch–TiO 2 @HEC-CA. Furthermore, Tauc plot γ values close to 2 suggested that the material undergoes indirect electronic transitions. Concurrently, a surprising increase in photocatalytic activity, following pseudo-first-order kinetics (Langmuir-Hinshelwood, k ap ≈ 0.0776 min −1 ), was observed ranging from 70 % for TiO 2 -HEC-AC to 99 % for Ch–TiO 2 @HEC-CA. Monte Carlo simulations demonstrated a negative adsorption energy (E ads ), confirming the spontaneous and exothermic nature of the adsorption process.