Abstract: The photocatalytic degradation of a wisely used pesticidemethomyl was studied in this paper. The degradation was catalyzed by titanium dioxide. The products, kinetics and factors that affect the rate of degradation was discussed. Methymol can be photooxided into inorganic materials in 10 minutes under the catalysis of titanium dioxide. FTIRstudy shows that the products are NH₄⁺, SO₄^2- and CO₂. The degradation is first order reaction and the kinetic reaction curve was modeled. Some cations and anions can affect the reaction rate. Most ions retard the rate but Cu²⁺ and Cl^- at low concentrations stimulate the reaction.

Key words: Methymol, Photocatalytic degradation, Kinetic study