Reductive Dechlorination of Chloroacetanilide Herbicide (Alachlor) Using Zero-Valent Iron Nanoparticles

Abstract

Nanoscale zero-valent iron (NZVI) was used for the first time to reductively degrade the chloroacetanilide herbicide, alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide], in laboratory studies. NZVI was synthesized by the borohydride reduction method and characterized using transmission electron microscopy and Brunauer–Emmett–Teller surface area analysis. Resulting particles had an average diameter of 35 nm and a Brunauer–Emmett–Teller surface area of 25 m2 g−1. Alachlor degradation in the presence of NZVI was rapid and complete. Parallel comparison trials with commercial microscale zero-valent iron (surface area = 1–2 m2/g−1) were also conducted. Surface area-normalized rate constants (kSA) for NZVI and microscale zero-valent iron were found to be 38.5 × 10−5 and 3.8–7.7 × 10−5 L h−1/m−2, respectively. A reaction product was identified as dechlorinated alachlor [N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide]. Based on results obtained in the research, the authors stipulate that NZVI may be a viable option for both site remediation and treatment of low-volume, high-concentration pesticide waste generated during pesticide application operations and in storage.