Study on adsorption and desorption of nitenpyram in tropical soil

In order to understand the environmental behavior of nitenpyram in acid soil with higher degree of weathering in tropical areas, according to experimental guideline for environmental safety evaluation of chemical pesticides, this paper analyzed the adsorption processes of Nitenpyram in three types of tropical soil by batch equilibration technique. Results showed that the adsorption isotherms of Nitenpyram in three types of tropical soil could be described well by Freundlich and Langmuir equations. Adsorption behavior of Nitenpyram varied in different types of tropical soil: adsorption coefficient (Kf) of nitenpyram in paddy soil, ferric-udic cambosols and udic ferralisols was 1.530, 93.153 and 2.724 L/kg, respectively. Nitenpyram was hard to be adsorbed in these soils but was easy to desorb. Adsorption free energy (G) of nitenpyram in three types of tropical soil was lower than 40 kJ/mol, showing that the partition was predominant and the adsorption process relied mainly on physical adsorption.