Kinetics of Sorption of Pendimethalin on Soil Samples Obtained from the Banks of Rivers Katsina-Ala and Benue, Central Nigeria

摘要

Kineticsof the sorption of the herbicide, pendimethalin (3,4-Dimethyl-2,6-dinitro-N-pentan-3-yl-aniline) on four soilsamples obtained from the banks of Rivers Benue and Katsina-Ala, in CentralNigeria was studied by contacting 5.0 g soil samples with 100 mL 7 × 10-6 M herbicide solution. The sorption was monitored by following the herbicideconcentration in the aqueous phase spectrophotometrically at one hour intervalsfor 5 hours (at 25°C, 35°C, 45°C, 55°C and 65°C, respectively). Pseudo-firstorder kinetics treatment of the data showed that sorption rates as well as theaccompanying activation energies were low, indicating that physical adsorption isthe operative mechanism for its retention in the soils and that the herbicidetended to reside more in the aqueous phase, which raised its potential tocontaminate natural water systems, when applied on the field.