Triadimefon Interactions with Organoclays and Organohydrotalcites

We determined the ability of several organoclays (octadecylammonium‐ and hexadecyltrimethylammonium‐exchanged montmorillonite) and organohydrotalcites (dodecylsulfate‐ and dodecylbenzenesulfonate‐exchanged hydrotalcite) to sorb the uncharged pesticide triadimefon [1‐(4‐chlorophenoxy)‐3,3‐dimethyl‐1‐(1H‐1,2,4‐triazol‐1‐yl)‐2‐butanone] to test the potential use of these sorbents for decontamination purposes and as slow release formulations of the pesticide. Interlayered organoclays and organohydrotalcites were at least six times more sorptive than the untreated minerals. Triadimefon sorption was higher on paraffin‐like sorbents (organohydrotalcites and organoclays prepared from high‐charge Arizona montmorillonite) than on bilayered sorbents (organoclays prepared from low‐charge Wyoming montmorillonite). The nature and amount of organic ion in the interlayer also influenced triadimefon desorption from the different sorbents. Desorption and spectroscopic studies suggested, in general, weak hydrophobic interactions between triadimefon and the interlayer organic phase of the organoclays and organohydrotalcites. However, hydrogen bonding between the carbonyl group of triadimefon and the monosubstituted amino group of octadecylammonium‐exchanged organoclays reinforced the strength of the interaction and resulted in reduced desorption from these sorbents. Selecting the interlayer ion appeared, therefore, as a good strategy to control the sorptivity and desorption of the sorbed pesticide for organoclays and organohydrotalcites. The results showed that organoclays and organohydrotalcites may find application as sorbents of pesticides similar to triadimefon.