Enhanced Solubility, Stability, and Herbicidal Activity of the Herbicide Diuron by Complex Formation with β-Cyclodextrin

The herbicide diuron is hardly soluble in water and most organic solvents and is usually made into a wettable powder or mixed with soil when used, which causes environmental risk and a reduction in herbicidal efficacy. In this study, the physicochemical properties were changed by using beta-cyclodextrin (beta-CD) to encapsulate diuron to form an inclusion complex. Some key technologies, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and nuclear magnetic resonance (H-1 NMR), were used to characterize the inclusion complex. The stoichiometry of the inclusion complex was determined by recording the H-1 NMR spectrum or by using a diagram of inclusion ratios. A phase solubility study proved that the formed inclusion complex exhibited higher water solubility. Thermogravimetric analysis (TGA) demonstrated that the formed inclusion complex exhibited better thermal stability. Biological activity studies indicated that the herbicidal activity, in terms of herbicide removal, of the formed inclusion complex was higher than that of the original diuron. In general, the formation of the inclusion complex could reduce the environmental damage caused by diuron and enhance its herbicidal activity, providing an environmentally friendly method for using diuron.