Removal and detoxification of iprodione in water using didodecyldimethylammonium bromide-montmorillonite organoclay and manganese dioxide.

Abstract

Combination of organoclay sorption with manganese(IV) oxide (MnO2) catalyzed catechol oxidation was studied for the removal of a dicarboximide fungicide, iprodione, from water. Iprodion in water was sorbed on didodecyldimethylammonium bromide (DDAB)-modified montmorillonite (MT) organoclay and converted into the degraded product, 3,5-dichloroaniline (DCA). The degree of sorption increased by the modification with DDAB, because of the formation of a hydrophobic region for the incorporation of iprodione and negligibly interfered by coexisting MnO2. The half-life for the degradation of irodione in water at 25°C was 7 days, whreas it reduced to 15min in the organoclay. The activation energy, 65.4 ± 4.8kJmol-1, for the first-order reaction in the aqueous solution (pH 7.0) decreased to 43.9 ± 1.8kJmol-1 in the organoclay, indicating the catalytic activity of the organoclay that accelerates the hydrolysis reaction of iprodione. In the coexistence of appropriate amounts of MnO2 and catechol, the degraded product, DCA, reacted with oxidized products of catechol to form a water-insoluble precipitate and was successfully eliminated from water. The results obtained in the present study strongly suggest the applicability of the combined method of organoclay sorption method and MnO2-catalyzed oxidation for the diffusion control of toxic agrochemicals.