STP1146

    Use of Deactivators in Granular Clay Formulations

    Published: Jan 1993


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    Abstract

    Clay-based granules find widespread use in pesticide formulations. Clays are absorptive, hard, easily handled and virtually dust-free. Formulation toxicity is often lessened and broadcast distribution less prone to drift than liquid spray formulations. Occasionally, though, a catalyzed pesticide degradation occurs. Presumably a clay has “active sites” that catalyze this degradation, particularly with phosphate ester insecticides. Clay suppliers have made great strides in lessening the catalytic activity of granules, but a deactivator is still often required in the formulation. These active sites are presumably Lewis acids, i.e., electron pair acceptors. Flooding the clay surfaces with an electron-rich compound covers the active sites and degradation no longer occurs. for this reason, oxygen and nitrogen containing compounds are often used. Historically, urea has been used with the chlorinated hydrocarbons. Today, glycols and their ethers are most often used. Data will be presented on the use of a variety of deactivators. Low molecular weight nitrogen-containing compounds such as ethanolamine are sometimes effective, also. Generally, propylene glycol is superior to ethylene glycol and their dimers are even more effective. Increasing polymer length, however, does little to improve observed pesticide stability over the dimers.

    Keywords:

    Pesticide, insecticide, granular formulation, deactivator, granules, clay


    Author Information:

    Kallay, WB
    Research scientist, technical director, research scientist, Oil-Dri Corporation of America, Vernon Hills, IL

    Goss, GR
    Research scientist, technical director, research scientist, Oil-Dri Corporation of America, Vernon Hills, IL

    Stein, JA
    Research scientist, technical director, research scientist, Oil-Dri Corporation of America, Vernon Hills, IL


    Paper ID: STP20195S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP20195S


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