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Sorption and desorption of flumioxazin to soil, clay minerals and ion‐exchange resin
Author(s) -
Ferrell Jason A,
Vencill William K,
Xia Kang,
Grey Timothy L
Publication year - 2005
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.956
Subject(s) - sorption , chemistry , adsorption , desorption , freundlich equation , loam , kaolinite , clay minerals , cation exchange capacity , ion exchange , soil water , partition coefficient , environmental chemistry , mineralogy , chromatography , organic chemistry , soil science , geology , ion
Flumioxazin adsorption kinetics were described using a Greenville sandy clay loam soil. Adsorption kinetics experiments showed that 72% of total herbicide was absorbed after 1 h of continuous shaking and continued to increase to 78% after 72 h. Flumioxazin adsorption was then tested on seven agriculturally important soils throughout the southern USA. Adsorption isotherms for all soils had K f (Freundlich distribution coefficient) values that ranged from 8.8 to 0.4, with many near 1.5. Soil organic matter content was the parameter most highly correlated with flumioxazin adsorption ( r 2 = 0.95, P < 0.001). Sorption to clay minerals had K f values ranging from 50 for bentonite to 4.7 for kaolinite. However, normalizing K f for sorbent surface area revealed that aluminum hydroxide (gibbsite) possessed the greatest flumioxazin sorption per unit area. Sorption to anionic exchange resin ( K f 676) was greater than cationic exchange resin ( K f 42). Molecular model calculations were performed to elucidate why sorption was greater to anionic exchangers. These calculations indicated that a region of dense electronegativity exists on the 3‐dione moiety of the molecule. This would lead to greater flumioxazin sorption by positively charged surface sites. Desorption isotherms from soil exhibited no effect of hysteresis. Desorption from clay minerals was very rapid and flumioxazin in solution was undetectable after three desorption steps. From these data it was concluded that flumioxazin can become readily available in soil solution with increase in soil water content. Copyright © 2004 Society of Chemical Industry