文摘
The herbicide atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) was incorporatedin alginate-based granules to obtain controlled-release (CR) properties. The basic formulation [sodiumalginate (1.40%)-atrazine (0.60%)-water] was modified by the addition of sorbents. The effect onatrazine release rate caused by the incorporation of acid-treated bentonite (0.5 and 2.5 M H2SO4) inalginate formulation was studied by immersion of the granules in water under static conditions. Thewater uptake, sorption capacity of the sorbent, permeability, and time taken for 50% of the activeingredient to be released into water, t50, were calculated for the comparison of the preparations. t50values were longer for those formulations containing acid-treated bentonite (36.78 and 29.01 daysfor 0.5 and 2.5 M H2SO4 treatments, respectively) than for the preparation without bentonite (9.69days). On the basis of a parameter of an empirical equation used to fit the herbicide release data, itappears that the release of atrazine from the various formulations into water is controlled by diffusionmechanism. The sorption capacity of the sorbents and the permeability of the formulations (rangingfrom 4.99 to 20.83 mg day-1 mm-1) were the most important factors affecting herbicide release.Keywords: Atrazine; controlled release; activated bentonite; sorption