Removal of herbicides mixture of atrazine, metribuzin, metolachlor and alachlor from water using granular carbon

Removal of atrazine, metribuzin, metolachlor and alachlor in mixture at 5 μg mL-1 fortification level on granular carbon has been studied using batch method. Metribuzin is found to be the most adsorbed herbicide and adsorption followed the order: metribuzin> atrazine> alachlor> metolachlor. Desorption results suggest that atrazine and metribuzin are bound irreversibly while metolachlor and alachlor are desorbed and percent desorption of alachlor (1.28%) is more than metolachlor (1.14%). Column studies using granular carbon have been carried out at fortification level of 5, 1 and 0.1 μg mL-1. At higher concentration (1 and 5 μg mL-1), metolachlor is least sorbed and sorption followed order: metolachlor>alachlor> atrazine>metribuzin but, at lower concentration (0.1 μg mL-1), alachlor is the least adsorbed herbicide. The performance of horizontal column is found better than the vertical column