Effect of addition of HPBCD on diuron adsorption-desorption, transport and mineralization in soils with different properties

The influence of different soil properties on diuron adsorption and the effect of hydroxypropyl-β-cyclodextrin (HPBCD) on its desorption, leaching, and mineralization have been investigated. The significant variables on adsorption were organic matter (OM) content, aluminum oxides, and clay fraction. Diuron desorption from soils presents negative hysteresis when HPBCD solutions were used as an extractant, in comparison to the positive hysteresis when using Ca(NO3)2 solutions. Therefore, higher amounts of diuron were desorbed by HPBCD due to the formation of an inclusion complex that causes an increase in its solubility. However, the application of HPBCD in columns of selected soils did not cause increased leaching of the herbicide. Finally, the presence of HPBCD shows clearly an increase in the rate of mineralization of diuron in contaminated soils and a drastic reduction of DT50 values due to its increasing bioavailability. HPBCD is proposed as an efficient tool for diuron soil bioremediation.