Fotodegradação catalítica do herbicida hexazinona utilizando o TiO2 em argissolo e latossolo

Abstract

The hexazinone is a pre-emergent herbicide applied on sugar cane culture, chemical group triazine, rated as quite toxic to humans. When used in large quantities affects the organisms living in the soil because of their bioaccumulation and more persistence, if leachate can cause soil and water contamination. A strategy to prevent the risk of contamination, or an alternative for the remediation of contaminated areas is the TiO2-P25 photocatalyst application, which accelerates pollutant degradation process and intermediates in less toxic products or until full mineralization. To evaluate the photocatalytic degradation of hexazinone under UV light were selected two representative soils of the micro-region of Brejo Paraibano in Northest Brazil, from the Areia and Alagoa Nova cities. These soils were rated according to the requirements of the Brazilian System of Soil Classification (SiBCS) by physical (particle size, density and porosity), chemical (fertility and exchange complex; fractionation of organic matter, and elemental composition by XRF) and mineralogical (determination and quantification of crystalline phases by XRD) analyzes that also served to support evaluation of catalytic photodegradation experiments. Classified as Argissolo Vermelho Amarelo Distrófico úmbrico, textura argilosa, A proeminente, epi-e endoalítico e epi-endodistrófica, Tm e Latossolo Vermelho Distrófico típico, textura argilosa, B latossólico, epi-e endoalítico, epi-endodistrófica, Tmoa; these showed good physical characteristics and low fertility, with OM above the common and consistent with an forest area. Quartz, kaolinite, muscovite, feldspar-K and Na, muscovite, hematite and gibbsite minerals were predominant, with illite and goethite only in Latossolo. The photocatalytic degradation of hexazinone was differently influenced by OM and clays naturally occurring, with pronounced effect of TiO2 at 2%.