Abstract—Water, soil and sediment contaminated with metolachlor poses a threat to the environment and human health. We determined the effectiveness of nano-zerovalent iron (NZVI) to dechlorinate metolachlor [2-chloro-n-(2-ethyl-6-methyl-phenyl)-n- (1-methoxypropan-2-yl)acetamide] in pH solution and the presence of aluminium salt. The optimum dosage of degradation of 100 mlL -1 metolachlor was 1% (w/v) NZVI. The degradation kinetic rate (k obs ) was 0.218×10 -3 min -1 and specific first-order rates (k SA ) was 8.72×10 -7 L m -2 min -1 . By treating aqueous solutions of metolachlor with NZVI, metolachlor destruction rate were increased as the pH decrease from 10 to 4. Lowering solution pH removes Fe (III) passivating layers from the NZVI and makes it free for reductive transformations. Destruction kinetic rates were 20.8×10 -3 min -1 for pH4, 18.9×10 -3 min -1 for pH7, 13.8×10 -3 min -1 for pH10. In addition, destruction kinetic of metolachlor by NZVI was enhanced when aluminium sulfate was added. The destruction kinetic rate were 20.4×10 -3 min -1 for 0.05% Al(SO 4 ) 3 and 60×10 -3 min -1 for 0.1% Al(SO 4 ) 3 . Keywords— destruction, kinetic rate, metolachlor, nano-zerovalent iron I. INTRODUCTION rganic pollutants which are important contaminants in soil water and groundwater, threat ecology system and environment. These pollutants are emitted from various sources such as pesticides from agricultural land or chemical from production process. Metolachlor [2-chloro-n-(2-ethyl-6-methyl-phenyl)-n-(2- methoxy-1-methyl ethyl) acetamide] is one of the more popular chloroacetanilide and is used a variety of commercial blends to control annual grasses and small-seeds broadleaf weeds. A national well wall water survey involving more than 6 million private and commercial was indicated a 1% detection of metolachlor (approximately 60,000 wells) at concentrations of ≥0.03 μL -1 [1]. Surface water have also been affected by metolachlor in at least 14 states, with maximum S. Suntornchot is with in the Department of Environmental Science, Faculty of Science, Kasetsart University, P.O. Box 1072, Phahon Yothin Rd, Chatuchak, Bangkok 10903, Thailand. (email: g5164246@ku.ac.th). T. Satapanajaru is with in the Department of Environmental Science, Faculty of Science, Kasetsart University, P.O. Box 1072, Phahon Yothin Rd, Chatuchak, Bangkok 10903, Thailand. (corresponding author to provide phone: +66(2)-942-8036 Fax: +66(2)-942-8715; e-mail: fscitus@ku.ac.th). S.D. Comfort is with the School of Natural Resource Institute of Agriculture and Natural Resource, University of Nebraska Lincoln, 68503, USA. concentration of 138 μgL -1 (USEPA, 1987). While attention to agrichemical use and the environment has centered on mitigating nitrate contamination, this focus may shift, or at least broaden as more state and federal regulators became attuned to problems associated with pesticide use and can recommend or endorse reliable remediation treatments for pesticide-contaminated soil and water. Metolachlor is a health hazard, thus it is necessary to remove from environmental [2]. There are several methods for treating it such as incineration, fenton-oxidation and biodegradation [3]. Although these methods are easy but they are expensive. In recently, nanotechnology represents a new generation of environmental technology that provides high effectiveness solutions to environmental cleanup and remediation by using nano- zerovalent iron (NZVI) (particle size 1-100 nm) as chemical reductant [4]. The high effectiveness of NZVI is due to its high surface area and surface reactivity which higher than microscale zerovalent iron (ZVI) about 10 – 10,000 times. Therefore, the objectives of this study were to determine the effectiveness of nano-zerovalent iron (NZVI) to destruction metolachor and to investigate the effects of the iron dosage, solution pH and aluminum sulfate (Al 2 (SO 4 ) 3 ). II. MATHERIALS AND METHODS A. Materials Nano-zerovalent iron (Nanofer 25S) was obtained from NANOIRON,s.r.o.(Czech Republic). Metolachlor was prepared from the commercial product Dual 8E (Syngenta, Greenboro, NC). The chemical structure of metolachlor was shown in fig. 1. Commercial grade-aluminium sulfate (Al 2 (SO 4 ) 3 ) were purchase from Aldrich chemical Co. (Milwaukee,WI). Sulfuric acid (H 2 SO 4 ) and sodium hydroxide (NaOH) were purchased from Fisher Scientific Co Ltd. HPLC grade- acetonitrile was purchase from EMD. Fig. 1 chemical structure of metolachlor Application of Nano-Zero Valent Iron for Treating Metolachlor in Aqueous Solution P. Suntornchot, T. Satapanajaru, and S.D. Comfort 0 World Academy of Science, Engineering and Technology International Journal of Environmental and Ecological Engineering Vol:4, No:12, 2010 657 International Scholarly and Scientific Research & Innovation 4(12) 2010 ISNI:0000000091950263 Open Science Index, Environmental and Ecological Engineering Vol:4, No:12, 2010 publications.waset.org/6632/pdf