Influence of clay minerals on the hydrolysis of carbamate pesticides

Using batch experiments, we investigated the influence of clay minerals (mo ntmorillonite, beidellite, illite, and vermiculite) on the hydrolysis of fi ve carbamate pesticides: carbosulfan, carbofuran, aldicarb, pirimicarb, and chlorpropham. Compared to the other minerals, montmorillonite had the stro ngest influence on the hydrolysis of these carbamates. Montmorillonite enha nced the hydrolysis of carbosulfan and aldicarb. In contrast, the hydrolysi s of chlorpropham was inhibited by montmorillonite, probably because of its strong adsorption on montmorillonite. The hydrolysis of pirimicarb was not affected by montmorillonite. The presence of organic substances, phosphate , and fluoride in suspensions decreased the catalytic activity of montmoril lonite. Surface acidity of montmorillonite and/or formation of surface chel ates are probably the key factors of surface catalysis in the case of the h ydrolysis of carbosulfan.