Sunlight-driven degradation of chlorpyrifos and imidacloprid using TiO₂/PHEMA nanocomposite: Synthesis, characterization, and photocatalytic performance

The environmental persistence and toxicity of chlorpyrifos (CPF) and imidacloprid (IMD) necessitate the development of efficient, solar-driven remediation strategies. This study reports the synthesis of a TiO₂/poly(2-hydroxyethyl methacrylate) nanocomposite (TiO₂/PHEMA NC) via in situ radical polymerization and evaluates its photocatalytic performance under natural sunlight. Comprehensive characterization (ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA)) confirms the successful incorporation of TiO₂ into the polymer matrix, resulting in a narrowed band gap (∼2.6 eV), improved dispersion, and enhanced interfacial charge transfer. Photocatalytic tests demonstrate significantly higher degradation efficiencies of CPF (95.6%) and IMD (97.3%) by TiO₂/PHEMA compared to pristine TiO₂, with superior reaction kinetics (k ≈ 0.019 min⁻ 1 ) and recyclability over five cycles. The enhanced activity is attributed to synergistic effects, including bandgap modulation, reduced recombination, and improved surface accessibility. This work provides the first evidence of TiO₂/PHEMA application for dual pesticide degradation under solar irradiation, highlighting its promise as a scalable and sustainable photocatalyst for environmental purification. GRAPHICAL ABSTRACT