Abstract:
Clopyralid is a hormone-type heterocyclic herbicide that has been widely used to control broad-leaved weeds in crops such as rapeseed, corn, and wheat. However, clopyralid is water soluble and mobile, and it has been recognized as a new type of pollutant in agricultural wastewater. The preparation of sustained-release formulations of clopyralid can effectively reduce its negative impact on the environment. This study prepared a clopyralid loading system using zeolitic imidazolate frameworks-8 (ZIF-8) as a carrier and optimized the loading method. The morphology, size distribution, chemical functional groups, crystal structure, thermal stability and other indicators were characterized by transmission electron microscopy, dynamic light scattering, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and N
2 adsorption desorption. The release mechanism and herbicidal activity were also studied. The results showed that clopyralid could be successfully loaded into the ZIF-8 carrier, with the particle size being approximately 219.3 nm after loading with clopyralid. The drug loading rate reached a maximum of 43.6%, and its release mode was most consistent with the Weibull model (
R2=0.9999). Additionally, the results of bioactivity experiment against
Echinochloa crus-galli showed that the herbicidal activity of clopyralid was not reduced after loading into ZIF-8, and even at a high concentration, ZIF-8 could play a certain synergistic effect. This study provided a reference for the preparation of herbicide loading systems based on ZIF-8 carrier.