Time-dependent sorption of norflurazon in four different soils: Use of β-cyclodextrin solutions for remediation of pesticide-contaminated soils

The change of the sorption parameter Kd as affected by the time, and desorption studies of NFL previously adsorbed on four different soils with different characteristics have been performed in the presence of 0.01 M BCD or 0.01 M Ca(NO3)2 acting as extractant solutions. NFL sorption increased with the residence time in soil, making it more resistant to be desorbed. Likewise, leaching experiments were performed in packed soil columns eluting initially with distilled water, with the aim to simulate the herbicide drainflow losses because of rainfall, approaching to a more realistic environment, and later with 0.01 M BCD solutions to extract the residual NFL bound. The results showed that removal efficiencies of the different flushing systems were significantly influenced by their affinity and selectivity for the contaminants in the soil matrix as well as BCD adsorption on soils, since this could act like a bridge between pesticide molecule and soil particles increasing the stay of NFL in soil. These results are further information to be in condition to predict the potential effect of the BCD solutions on soil chemical decontamination in the field situation assessing the likelihood for bioremediation of a pesticide contaminated-soil, since the increasing in hydrosolubility of the contaminants means the first step before microorganism uptaken.