Rapid reductive dechlorination of atrazine by zero-valent iron under acidic conditions

The dechlorination of atrazine (2-chloro-4-ethylaulino-6-isopropylamino-1,3,5-triazine) via reaction with metallic iron under low-oxygen conditions was studied using reaction mixture pH values of 2.0. 3.0, and 3.8. The pH control was achieved through addition of sulfuric acid throughout the duration of the reaction. The lower the pH of the reaction mixture, the faster the degradation of atrazine. The surface area of the sulfuric acid-treated iron particles was 0.31 (+/- 0.01) m(2) g(-1) and the surface area normalized initial pseudo-first order rate constants (k(SA), where rate = k(SA)x(surface area/l)x[Atrazine]) at pH values of 2.0, 3.0, and 3.8 were equal to, respectively, 3.0 (+/- 0.4)x 10(-3) min(-1) m(-2) 1, 5 (+/- 3)x 10(-4) min(-1) m(-2) 1, and 1 (+/- 1)x 10(-4) min(-1) m(-2) 1. The observed products of the degradation reaction were dechlorinated atrazine (2-ethylamino-4-isopropylamino-1,3,5-triazine) and possibly hydroxyatrazine (2-ethylamino-4-isopropylamino-6-hydroxy-s-triazine). Triazine ring protonation may account, at least in part, for the observed effect of pH on atrazine dechlorination via metallic iron. (C) 2000 Elsevier Science Ltd. All rights reserved.