Photoremediation of Carbamate Residues in Water

Abstract

Pesticides are extensively world wide used for agriculture and for non-agricultural purposes. The major environmental concern of used pesticides is their ability to leach down to subsoil and contaminate the ground water, or, if they immobile, they could persist on the top soil and become harmful to microorganisms, plants, animal and people (Jha & Mishra 2005; Radivojevic et al., 2008). Harmfull pesticide residues can contaminate the environment and accumulate in ecosystems than entering the human food chain (Đurovic et al., 2010; Gasic et al., 2002a; Gevao et al., 2000). Pesticides have various characteristics that determine how act once in soil where it could accumulate to toxic level. Generally, soil and groundwater pollution are the major consequences environmental effects of pesticides application. Pesticides can reach water through surface runoff from treated plants and soil. Pesticide sprays usually directly hit non-target vegetation or can drift or volatilize from the treated areas that contaminate air, soil, and non-target plants. Finally, using of pesticides has resulted in acute and chronic ecological damage either by direct injury such as birds and fish or by indirect. Carbamates are large group of pesticides which have been extensively used in almost sixty years. In this chapter an attempt is made to give the available data of the carbamates used as pesticides, their physico-chemical and toxicological characteristics, behaviour and fate in the environment, types of formulations which exist on the market as well as photochemical degradation for the certain members. Owing to widespread use in agriculture and relatively good solubility in water carbamate compounds can contaminate surface and ground waters and therefore carries a risk to various consumers, as well as the environment. In this chapter we will also discuss some very important photocatalytic methods for remediation of water containing carbamate residues: direct photodegradation (photolysis), photosensitized degradation and photocatalytic degradation (including heterogeneous TiO2 and ZnO processes and photo-Fenton and Fenton-like processes).