Competitive and non-competitive adsorption of atrazine and diuron on alluvial soil

The competitive and non-competitive adsorption of herbicides atrazine and diuron individual and in binary combination on alluvial soil depends upon the batch equilibration technique were evaluated. The results indicated that the optimum wavelengths obtained from spectral curves were 222 nm and 289 nm and the k values obtained from calibration curves were 0.1327 and 0.0061 for atrazine and diuron, respectively. The equilibrium time for atrazine and diuron in clay loam soil is 3 hours. The adsorption of atrazine and diuron individually in clay loam soil is fitted with Freundlich model. The isotherms of either atrazine and diuron alone or in the binary mixture are S-type. The adsorption capacity of tested clay loam soil is more for atrazine neither individual nor in binary combination than that for diuron individual and in binary combination. The adsorption capacity of tested clay loam soil is lower for individual atrazine compared to that in binary combination with diuron. While, the adsorption capacity of tested clay loam soil is higher for individual diuron compared to that in the binary combination. In general, the relatively weak sorbing diuron in competitive system might depend on the available binding sites which influenced by atrazine. However, the sorption of the relatively stronger adsorbing atrazine was less affected by diuron at the same concentration range.