The photolytic and photocatalytic activity of TiO2 doped Zn₄O(BDC)₃ nano MOF for removing cyprodinil fungicide residues from hard water

The TiO₂-doped Zn₄O(BDC)₃ MOF (Metal-organic framework) revealed an exceptional capacity to decompose cyprodinil fungicide residues in water under simulated sunlight conditions. It was synthesized using autoclave methods. A solution containing 0.2 mmol of zinc nitrate (Zn (NO₃)₂), 0.2 mmol of titanium isopropoxide (TTIP), and 0.2 mmol of terephthalic acid (H₂BDC) was prepared in 25 mL of N, N-dimethylformamide (DMF) at room temperature. The study's goal was to observe the dissipation of cyprodinil in Standard D water by introducing uniform concentrations: T0 - Untreated Control, T1 - Cyprodinil 50% WP at 1.0 µg/mL, and T2 - at 2.0 µg/mL. The spiked samples were exposed to sunlight, and water samples were collected at different intervals (0, 6, 12, 24, and 48 h). All samples were analyzed until the residues were below detectable levels. The effectiveness of the process was demonstrated with a catalyst concentration of 0.03% for complete degradation. High-performance liquid chromatography with a Photodiode Array detector (HPLC-PDA) was employed to analyze cyprodinil residues, allowing for the accurate determination of the rate constant and DT50. The DT50 (Half-Life) for Cyprodinil was determined through regression analysis of the dissipation data, resulting in DT50 values of 13.87 h for the T1 dose and 13.95 h for the T2 dose with catalyst, as well as DT50 values of 10.36 days for the T1 dose and 10.53 days for the T2 dose without catalyst. The TiO₂-doped Zn₄O(BDC)₃ MOF serves as a potent photocatalyst for pesticide degradation, combining the MOF's porous framework for pesticide adsorption with TiO₂ nanoparticles that yield electron-hole pairs when subjected to UV light. This combination enhances light absorption into the visible spectrum and improves charge separation, thereby augmenting the generation of reactive oxygen species (ROS). The mechanism involves light absorption, charge transfer to TiO₂, and the creation of radicals that convert pesticides into less harmful substances. This composite outperforms both pure TiO₂ and Zn₄O(BDC)₃, underscoring its potential for environmental applications and the need for further exploration of its stability and specificity towards pollutants.