STABILITY OF PARATHION ON ATTAPULGITE AS AFFECTED BY STRUCTURAL AND HYDRATION CHANGES

The structure and hydration status of attapulgite clay after heating at elevated temperatures and the stability of parathion on these clays was studied. It was found that the bound water was lost in two steps, at 250 degree and 450 degree C, with the first step being largely reversible. At 650 degree C the structure began to dissolve releasing significant amounts of Mg, and a decrease in aggregate porosity was noted. At 850 degree C an amorphous phase was formed bearing little resemblance to the original attapulgite. Parathion was stable on all of the preheated clays when kept at 25 degree C for 190 days. The reactions of parathion on the preheated clays was studied at 110 degree C. Hydrolysis of parathion was found to be minimal. Isomerization was the main reaction occurring on the Ca-attapulgite, whereas on an organo-clay no isomerization was observed. Refs.