Solar photooxidation of pesticides in dilute hydrogen peroxide

Photodegradation of 3-phenoxybenzoic acid in water and on solid surfaces

“…Photodegradation of I was slightly accelerated in the presence of hydrogen peroxide, which also showed the importance of indirect photolysis by a hydroxyl radical, as reported previously for some pesticides (Draper and Crosby, 1984). In contrast, the photodegradation of I was slightly retarded in the presence of humic acids.…”

“…The emission spectrum of a xenon lamp measured with a USR-2OB photometer (Ushio) is shown in Figure 1. Photolysis was conducted under air at pH 7 (0.067 M phosphate buffer), and the effect of hydrogen peroxide (100 pM) or humic acid (1 ppm) was examined according to the methods reported previously (Draper and Crosby, 1984;Takahashi et al, 1988). The pK.…”

Catalytic Strategy for Efficient Degradation of Nitroaromatic Pesticides by Using Gold Nanoflower

“…The pH value of pendimethalin aqueous solution was adjusted by 1 M HCl or 1 M NaOH aqueous solution and the final concentration was 2.34 mM. 500 μL of pendimethalin aqueous solution (2.34 mM) of different pH value (pH 1,4,7,11,14) were mixed with 500 μL 15 mM of NaBH 4 aqueous solution in 2.0 mL test tube respectively, and 100 μL Au nanoflower aqueous solution was added to make each solution 1.1 mL. Finally, these mixtures were detected by the UV−vis absorption spectrum at room temperature.…”

Reviews of Environmental Contamination and Toxicology

“…With thiobencarb, traces of H 2 0 2 significantly increased the photolysis rate but the effect was less striking than for molinate. A likely mechanism for the production of indirect photodegradation products, for instance compounds 112-114 of herbicide 107, involving the interactions of hydroxyl radicals photolytically generated from H 2 O 2 with 107 as well as subsequent reactions of dissolved oxygen with the resultant radical species, is shown in Scheme 7 (Draper and Crosby 1984a). In such phtoreaction, 4-chlorobenzoic acid was also detected.…”

“…Although the field photosensitizer was not identified, similarities between photoproducts could suggest that similar oxidants were involved. Knowing that the instability of hydrogen perioxide under sunlight may lead to the formation of reactive hydroxyl free radicals, Draper and Crosby (1984a) investigated the photoreactivity of aqueous solutions of thiobencarb (107) (10 mgjL) and molinate (l08) (20 mgjL) containing hydrogen peroxide (H 2 0 2 ) (5 and 100 J.lM) in mid-October sunlight. With thiobencarb, traces of H 2 0 2 significantly increased the photolysis rate but the effect was less striking than for molinate.…”