Adsorption and desorption of atrazine on a melamine-based soil amendment

Abstract

Adsorption kinetics and adsorption-desorption of atrazine on organoclay composites prepared with the surfactant 6-piperazin-1-yl-N,N'-bis-(1,1,3,3-tetramethyl-butyl)-(1,3,5)triazine-2,4-diamine and Houston Black clay were studied using the indirect batch equilibration procedure. The organoclay composites sorbed significantly more atrazine than the Houston Black clay. Adsorption equilibrium was reached after 72 h for the organoclay composites. Atrazine adsorption isotherms were described by linear partitioning. The Koc values ranged from 605 to 5271 L kg-1 for the organoclay composites compared to a value of 41 L kg-1 for the Houston Black clay. The organoclay composite containing 20% surfactant on a total weight basis provided the most efficient adsorption of atrazine, although organoclay composites containing much lower amounts of surfactant also adsorbed significant amounts of atrazine. An average of 11% of sorbed atrazine was released during desorption. Characterization of desorption products showed only atrazine molecules being released from the organoclay composites.