Tuning ZnO morphology for enhanced UV photodegradation of ofloxacin

ZnO photocatalysts with tunable morphologies, ZnO-nanosheets, ZnO-nanoflowers, ZnO-nanoneedles, ZnO-rice-like, ZnO-peanut-like, and ZnO-nanorods, were synthesized via a homogeneous precipitation method. Their structural, morphological, and optical properties were characterized by XRD, SEM, TEM, XPS, PL, ζ-potential, N2 adsorption-desorption analysis, and UV–Vis diffuse reflectance spectroscopy. All ZnO samples crystallized in the wurtzite type structure with hexagonal symmetry, exhibited negative surface charge, and showed band gaps in range of 3.16–3.22 eV.The photocatalytic degradation of ofloxacin under UV light followed pseudo-first-order kinetics. Ofloxacin removal up to 100% was achieved after 90, 150, 180, 210, 210, and 240 min for ZnO-nanosheets, ZnO-nanorods, ZnO-nanoneedles, ZnO-rice-like, ZnO-nanoflowers, and ZnO-peanut-like, respectively. ZnO-nanosheets showed the highest activity (k = 0.0574 min−1, R2 = 0.9996) due to their smallest crystallite size, narrowest band gap, and lowest PL intensity, enabling efficient charge separation and suppressed electron-hole recombination.ZnO-rice-like showed high stability and reusability, maintaining 90% and 84% ofloxacin removal after the second and third cycles. Radical-trapping experiments confirmed that photogenerated holes and hydroxyl radicals dominated the degradation process. HPLC-MS analysis identified major intermediates, and plausible degradation pathways were proposed.This study highlights morphology-controlled ZnO as an efficient and reusable photocatalyst for antibiotic removal.