Metolachlor metal-organic framework nanoparticles for reducing leaching, ecotoxicity and improving bioactivity

BACKGROUND The adverse effects of pesticides has led to a series of ecological, environmental and public health issues. Amide herbicides are an important agrochemical, yet many are prone to leach and pollute the environment, which limits their further application. In this study, metolachlor (METO) was selected as a model pesticide and a controlled released nanoparticle (NP) system was constructed employing a zeolitic imidazolate framework-8 hybrid inorganic-organic porous material (METO@ZIF-8). RESULTS The synthesis parameters of METO@ZIF-8 were optimized, and the loading content of METO@ZIF-8 was maximized by a central composite design of response surface test. The NPs were regular dodecahedron with uniform size (mostly 54.3 nm diameter). METO@ZIF-8 had high specific surface area and good dispersal in water. Moreover, it endowed the active ingredient with a pH-responsive release property. The nanocarrier effectively improved the adsorption capacity of METO in soil and reduce the leaching by 10.3-21.7%. Pot experiments suggested that the control effect of METO@ZIF-8 was 16.6 and 48.4% higher than that of METO emulsifiable concentrate (EC) and METO technical concentration (TC) at the recommended dose. Based on the excellent controlled release profiles, METO@ZIF-8 did not affect corn plant growth and significantly reduced the risk of phytotoxicity induced by METO. METO@ZIF-8 effectively reduced acute toxicity in zebrafish compared with METO EC. CONCLUSION This study explored the fabrication of a nanocarrier for improving the efficacy and promoting the environmental safety of leachable amide herbicides. (c) 2022 Society of Chemical Industry.

Automated summary

This study successfully constructed a controlled released nanoparticle system using a zeolitic imidazolate framework-8 hybrid material for the model pesticide metolachlor. The nanocarrier showed high loading content, pH-responsive release property, and improved adsorption capacity of the pesticide in soil, effectively reducing leaching and achieving better control efficacy compared to traditional formulations.