Kinetic aspects of the photodegradation of phenolic and lactonic biocides under natural and artificial conditions

JUAN P. ESCALADA; ADRIANA PAJARES; MABEL BREGLIANI; ALICIA BIASUTTI; SUSANA CRIADO; PATRICIA MOLINA; WALTER MASSAD; NORMAN A. GARCÍA

Engineering, Water & Earth Sciences. Advanced Oxidation Technologies ? Sustainable solutions for environmental treatments

CRC Press. Balkema

Año: 2014; p. 59 - 80

The continuous and exponential growth of world population is concurrent with higher demands for more and better food and fiber products. In modern agriculture, application of biocides has been introduced as one of the tools that favor the achievement of the vital increases and quality improvement of productions, which are basic necessities for human life and development. Initially, these chemicals were thought to be only harmful for a target group such as insects, fungi, nematodes or weed species, but innocuous for humans; however this statement is not always true. Biocides have proved to be beneficial to control plagues and diseases, but their residues contaminate soils and natural water reservoirs. For that reason, they constitute a serious risk for human health and environmental quality. Significant amounts of agricultural pesticides are usual contaminants of surface waters and soils (Tomlin, 1994) and their use in crop protection must be conditioned by their persistence in the environment. Consequently, their thermal, microbiological and photochemical pathways of degradation are topics of particular research interest. a This article is dedicated to the memory of our friend and colleague, Prof. Dr. Francisco Amat-Guerri, whose life was an example of integrity and dedication to science.   Within the context of environmentally friendly methods for the elimination of surface water pollutants, photochemical reactions become a major degradation pathway.In the environment, photodegradation can take place in two ways: direct, in which a pollutant absorbs energy from the sunlight (<300 nm); or indirect, in which the substance itself does not absorb the radiation, the energy is absorbed by an intermediary compound and afterwards transmitted to the target that is intended to be photodegraded. Here we present a comparative kinetic study between naturally and artificially promoted photodegradation of known phenolic and lactonic biocides mainly based on published data from our group (García, 1994; Escalada et al.,2008; Escalada et al.,2011) and interrelated to findings from other researchers (Konachy et al.,1990; Feely et al., 1992; Mansfield and Richard, 1996; Mushtaq et al. 1998; Mártire and González, 2000; Kolar et al.,2003).