Photocatalytic Degradation of Pesticides in Natural Water: Effect of Hydrogen Peroxide

Abstract

The aim of this paper is to evaluate the effectiveness of photocatalytic treatment with titanium dioxide in the degradation of 44 organic pesticides analyzed systematically in the Ebro river basin (Spain). The effect of the addition of hydrogen peroxide in this treatment is studied, and a monitoring of effectiveness of photocatalytic processes is carried out by measurements of physical-chemical parameters of water. The application of photocatalytic treatment with 1 g L−1of TiO2during 30 minutes achieves an average degradation of the studied pesticides of 48%. Chlorine demand, toxicity, and dissolved organic carbon (DOC) concentration of water are reduced. If hydrogen peroxide is added with a concentration of 10 mM, the average degradation of pesticides increases up to 57%, although chlorine demand and toxicity of water increase while DOC concentration remains unchanged with this treatment. The application of either photocatalytic treatments does not produce variations in the physical-chemical parameters of water, such as pH, conductivity, colour, dissolved oxygen, and hardness. The pesticides which are best degraded by photocatalytic treatments are parathion methyl, chlorpyrifos, α-endosulphan, 3,4-dichloroaniline, 4-isopropylaniline, and dicofol while the worst degraded are HCHs, endosulphan-sulphate, heptachlors epoxide, and 4,4′-dichlorobenzophenone.

Photocatalytic discolouration of Reactive Black 5 by UV-A LEDs and solar radiation

“…Some authors have reported that the addition of hydrogen peroxide to photocatalytic treatment enhances the yield of the treatments, either through the inactivation of microorganisms [37,38] or through the removal of persistent organic micropollutants [39]. However, an excess of H 2 O 2 is detrimental to the final discolouration rate, and other studies confirm the results obtained from the TiO 2 /H 2 O 2 treatments performed in this research work.…”

Escherichia coli Inactivation in Fresh Water Through Photocatalysis with TiO2‐Effect of H2O2 on Disinfection Kinetics

“…The photocatalysis/H 2 O 2 treatment remains inferior to the photocatalytic treatment. In contrast, some authors have reported that the addition of hydrogen peroxide to photocatalytic treatment enhances the yield of the treatment, either in the inactivation of microorganisms or in the removal of organic persistent micropollutants . However, other studies confirm the results obtained in the photocatalysis and photocatalysis/H 2 O 2 treatments performed in this work.…”

Heterogeneous Photo-Fenton Reaction Catalyzed by Nanosized Iron Oxides for Water Treatment

“…The Fenton reaction is frequently investigated as a physicochemical technology because it involves highly oxidative activity of hydroxyl radicals ( • OH) with respect to the substrates [1]. The • OH is the second most powerful oxidizing species after fluorine in aqueous media, and it is believed to destroy or even mineralize most organic substrates nonselectively in advanced oxidation processes [2][3][4][5].…”