Particulate suspensions of TiO2 irradiated with natural solar tight in a large experimental plant catalyse the oxidation of organic contaminants. The problem in using TiO2 as a photocatalyst is electron/hole recombination. One strategy for inhibiting e−/h+ recombination is to add other (irreversible) electron acceptors to the reaction. In many highly toxic waste waters where degradation of organic pollutants is the major concern, the addition of an inorganic anion to enhance the organic degradation rate may be justified. For better results, these additives should fulfil the following criteria: dissociate into harmless by-products and lead to the formation of ·OH or other oxidising agents. In this paper, we attempt to demonstrate the optimum conditions for the treatment of commercial pesticide rinsates found in the wastewater produced by a pesticide container recycling plant. The experiments were performed in one of the pilot plants of the largest solar photocatalytic system in Europe, the Detoxification Plants of the Plataforma Solar de Almería (PSA), in Spain. After testing ten different commercial pesticides, results show that peroxydisulphate enhances the photocatalytic miniralization of all of them. This study is part of an extensive project focused on the design of a solar photocatalytic plant for decontamination of agricultural rinsates in Almería (Spain).
Subpicosecond electron-hole recombination time and terahertz-bandwidth photoresponse in freestanding GaAs epitaxial mesoscopic structures
