Adsorption and desorption of carbendazim and cadmium in typical soils in northeastern China as affected by temperature

The adsorption and desorption of carbendazim and cadmium (Cd) in soils (burozem and phaeozem) typically distributed in northeastern China were investigated at two different temperatures, 25 and 40 degrees C. The effects of interaction between carbendazim and Cd on their adsorption and desorption were also discussed. The results showed that the adsorption of carbendazim was exothermic with Delta H-circle minus values of -5.3 kJ/mol for burozem and -33.6 kJ/mol for phaeozem, while the adsorption of Cd was endothermic with Delta H-circle minus values of 43.2 and 37.4 kJ/mol, respectively. Increasing the temperature from 25 degrees C to 40 degrees C could promote the desorption hysteresis of carbendazim, but decreased the desorption hysteresis of Cd. The coexistence of carbendazim and Cd promoted the adsorption of carbendazim but suppressed the adsorption of Cd and the effect was amplified as the temperature increased to 40 degrees C. The adsorption amount of carbendazim at 25 degrees C increased 11% for burozem and 4% for phaeozem respectively when the concentration of Cd was 50 mg/L This increased to 56% and 20% respectively when the temperature was increased to 40 degrees C. When the concentration of carbendazim was 30 mg/L, the amount of Cd adsorption decreased 13% for burozem and 5% for phaeozem at 25 degrees C, and 33% and 14% at 40 degrees C, respectively. (c) 2010 Elsevier B.V. All rights reserved.