Montmorillonite-Phenyltrimethylammonium Yields Environmentally Improved Formulations of Hydrophobic Herbicides

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• 作者：Yasser El-Nahhal ; Shlomo Nir ; Carina Serban ; Onn Rabinovitch ; and Baruch Rubin
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2000
• 出版时间：October 2000
• 年：2000
• 卷：48
• 期：10
• 页码：4791 - 4801
• 全文大小：132K
• 年卷期：v.48,no.10(October 2000)
• ISSN：1520-5118

文摘

This study aimed to design formulations of hydrophobic herbicides, alachlor and metolachlor, byadsorbing them on the clay mineral montmorillonite preadsorbed by the small organic cationphenyltrimethylammonium (PTMA). An adsorption model that considers electrostatics and specificbinding and the possibility of cation adsorption above the cation exchange capacity (CEC) couldexplain and yield predictions for PTMA adsorption in the presence of NaCl concentrations from 0to 500 mM. Adsorption of alachlor and metolachlor from aqueous solution on a clay mineralpreadsorbed by PTMA was determined by GC and modeled by Langmuir equation. Herbicideinteractions with the organoclay were studied by Fourier transform infrared spectroscopy. Leachingof herbicides was determined by a bioassay using a column technique and Setaria viridis as a testplant. The adsorbed amounts of alachlor and metolachlor on montmorillonite preadsorbed by PTMAat a loading of 0.5 mol/kg (Mont-PTMA0.5) were higher than at a loading up to the CEC, that is,0.8 mol/kg, and were higher than those obtained by using several other organic cations. Herbicideformulations based on Mont-PTMA0.5 yielded the largest shifts of the infrared peaks of theherbicides. These formulations based on Mont-PTMA0.5 gave slower release and showed improvedweed control in comparison with formulations based on other organoclays. These formulationsmaintained herbicidal activity in the topsoil and yielded the most significant reduction in herbicideleaching.Keywords: Alachlor; metolachlor; montmorillonite; organoclays; phenyltrimethylammonium;release; leaching; herbicidal activity