Synthesis of metal organic framework mesostructured UIO-66 with defections in frameworks for enhancing photocatalytic degradation of residues pesticides

Abstract

Novel photocatalysts, based on modified mesostructured UiO-66-Zr composites with defects sites in framewwork arrays were prepared by solvothermal synthesis method using CTABr as ionic surfactant template, acetic acid and benzoic acid as modulators.  Modified UiO-66-Zr with defects sites in framewworks by using ionic surfactants CTABr, benzoic acid (UiO-66-M) and acetic acid (UiO-66-A) as modulators were synthesized, characterized by BET, XRD, FTIR, TEM, EDX techniques. The photocatalytic performances over material samples were tested in photodegradation of chlopyrifos ethyl in aqueous solution under simulated solar light irradiation and evaluated by UV-Vis spectra commbied with HPLC analysis. These modified UiO66 showed a highly effective photodegradation and mineralization of chlopyrifos ethyl (peesticide/insecticide) in aqueous solution. The photocatalytic activities of the modified UiO66-Zr were considerably greater than unmodified UiO66-Zr composites were explained by the roles of defected sites created in material framewworks. The presence of the defects not only resulted in the dramatically enhanced porosity (pore size), but also induced the creation of Zr-OH groups which served as the main active adsorption sites for efficient ROS sequestration.The photo-degradation rate of chlopyrifos ethyl was ranked in the order of samples UiO66-Zr-M > UiO66-Zr-A > UiO66-Zr with reaction constant rate of k₃ = 1.23×10^-2 (min^-1) > k₂ = 9.1×10^-3 (min^-1) > k₁ = 2×10^-4 (min^-1), respectively. The obtained results showed potential application of modified UiO66-Zr composites for photocatalytic treament of hydrophobic pesticide residues in water without any toxic secondary pollution in agriculture.