Lignin-based formulations to prevent pesticides pollution.

The pesticides isoproturon, imidacloprid and cyromazine, identified as groundwater pollutants, were incorporated in lignin-based formulations to obtain controlled release (CR) properties. The formulations were prepared by mixing the pesticide with a commercially available pine kraft lignin under melting conditions. A high efficiency of the preparations was therefore reached; it oscillated between 93.36% and 98.20% for the cyromazine and the isoproturon formulations. Kinetic-release experiments carried out in water showed that the release rate of isoproturon, imidacloprid and cyromazine from CR granules diminished in all cases in relation to the technical products. From the analysis of the time taken for 50% of the active ingredient to be released into water (T(50)), it can be deduced that the release rates were much higher in cyromazine CR formulations than in those prepared with isoproturon. However, imidacloprid showed an intermediate release rate. The obtained linear regression between T(50) values and granule size can be suitable to select the most appropriate formulation to avoid the isoproturon, imidacloprid and ciromazine tendency to leach.