ABSTRACT
Predicting the fate and transport of pesticides in soil environment is an important issue especially in understanding and modelling of the environmental behaviour of pesticides. Classical batch sorption method often has been identified as insufficient to derive the actual extent of sorption. In this study, the batch equilibrium method was compared to the centrifugation method, which can permit measurement of sorption under more natural conditions. The results of the comparison of the batch with the centrifugation method for imidacloprid and carbofuran pesticides indicate that the batch method overestimates sorption in comparison to the centrifugation method. These results are in agreement with others, which use high soil:solution ratios with batch and those that used the centrifugation method.
Subject(s)
Carbofuran/analysis , Imidazoles/analysis , Pesticides/analysis , Soil Pollutants/analysis , Soil/analysis , Adsorption , Carbofuran/chemistry , Centrifugation/methods , Chromatography, High Pressure Liquid/methods , Imidazoles/chemistry , Neonicotinoids , Nitro Compounds , Pesticides/chemistry , ThermodynamicsABSTRACT
Beta-endosulfan solutions were ozonated in a lab scale semi-batch reactor in various experimental conditions. Ozonation kinetics of beta-endosulfan and effects of some parameters such as pH, temperature, partial pressure and ozone dosage on oxidation were investigated. Increasing ozone dosage and decreasing of temperature and pH increased the oxidation rate of beta-endosulfan. Maximum 97% of beta-endosulfan could be removed at both 16-mg/min ozone dosages and pH = 4 for 60 minutes of ozonation. The order of the reaction is determined as pseudo first order. Although the rate of reaction was lower than other pesticide oxidation rates cited in the literature, beta-endosulfan reaction to ozonation was achieved with almost 90% removal rate. The temperature dependent rate constant for beta-endosulfan oxidation was determined as kd = 0.947 exp(-2.16 x 10(-3)/T).
