Application of visible radiation for 2 chlorophenol degradation in aqueous environment

W artykule przedstawiono wyniki badań nad możliwością wykorzystania promieniowania widzialnego do degradacji 2-chlorofenolu (2-CP) poprzez fotosensybilizowane utlenianie. 2-CP stanowi składnik wielu popularnych środków ochrony roślin. Badano szybkość zaniku 2-CP w roztworach wodnych w zależności od różnych parametrów doświadczalnych: mocy promieniowania świetlnego, stężenia tlenu i sensybilizatora oraz pH środowiska reakcyjnego. W doświadczeniach źródło światła stanowiły łukowe lampy ksenonowe, o widmie emisyjnym zbliżonym do widma promieniowania słonecznego. Wykonano również serię eksperymentów z wykorzystaniem światła słonecznego. Uzyskane wyniki wskazują, że 2-CP może być skutecznie degradowany na drodze sensybilizowanego fotoutleniania, również z immobilizowanym sensybilizatorem. Potwierdzono też możliwość zastosowania do degradacji 2-CP w środowisku wodnym najtańszego źródła światła, a mianowicie promieniowania słonecznego, skutecznego również przy naszych szerokościach geograficznych.In the article the results of studies on the 2-chlorophenol (2-CP) degradation possibility through photosensitized oxidation, using visible radiation, are presented. 2-CP constitutes the major ingredient of many popular crop protection products. The rate of 2-CP decay in aqueous solution was investigated with respect to experimental parameters such as radiant power, oxygen and sensitizer concentration and pH of reaction medium. The arc xenon lamps simulating solar radiation were used in the experiments. Field experiments involving direct and scattered solar radiation were performed as well. The obtained results indicate the possibility of the application of solar radiation - the cheapest source of light - for the 2-CP degradation via photosensitized oxidation, especially in the middle latitude

Efficiency of xenoestrogen 4-tert-octylphenol degradation by photochemical method

W pracy przestawiono wyniki badań nad fotodegradacją 4-tert-oktylofenolu (OP). Celem przeprowadzonych eksperymentów było porównanie efektywności metod unieszkodliwiania tego związku w homogenicznym roztworze wodnym. Degradację OP zbadano przy użyciu następujących metod: fotolizy bezpośredniej przy wykorzystaniu trzech różnych źródeł światła, fotosenybilizowanego utleniania oraz układu H2O2/UV.Results of the study on photodegradation of 4-tert-octylphenol (OP) are presented with the aim to compare its removal efficiency from aqueous solution. Various methods of OP degradation were tested: direct photolysis with the use of three different radiation sources, H2O2 UV advanced oxidation process and photosensitized oxidation

Photodegradation of atrazine and ametryn with visible light using water soluble porphyrins as sensitizers

Abstract The photodegradation of the herbicides atrazine and ametryn with visible light in aerated neutral aqueous solutions and 5, 10, 15, 20-tetrakis (2,6-dichloro-3-sulfophenyl) porphyrin or 5, 10, 15, 20-tetrakis (4-sulfophenyl) porphyrin as sensitizers are reported for the first time. Our findings show that the degradation percentage reached 30% for atrazine and 63% for ametryn. The final photoproducts were characterized as dealkylated s-triazines. Photolysis of the pesticides in the presence of a singlet oxygen quencher showed only a minor contribution of this type of mechanism, while a bimolecular quenching reaction between the triplet state of the sensitizer and the pesticides is excluded by flash photolysis studies. It is proposed that the mechanism may involve the formation of a superoxide radical anion from the triplet state of the sensitizer and molecular oxygen, followed by a radical decomposition pathway

Removal of Emerging Contaminants by Fenton and UV-Driven Advanced Oxidation Processes

This paper is closed access.The removal efficiencies of four different parabens (methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP)) using Fenton reagent, UV irradiation, UV/H2O2, and UV/ H2O2/Fe2+ were evaluated to assess the level of paraben degradation achieved using different advanced oxidation processes (AOPs). UV irradiation by itself provided paraben conversions between 27 and 38 % after a reaction time of 180 min. The UV/ H2O2 system increased the paraben conversion to values between 62 and 92 %, and the Fenton process was revealed as inefficient in paraben degradation within the experimental conditions used. Photo- Fenton presented similar removal rates to the UV/ H2O2 process. Among the four parabens studied, butylparaben was the most easily removed, and it was possible to attain degradations higher than 90 %. In the UV/H2O2 and photo-Fenton processes, the overall kinetic constant could be split into two main components: direct oxidation by UV radiation (photolysis) and oxidation by free radicals (mainly HO•) generated from the photodecomposition of H2O2. This work reveals that UV-driven oxidation processes can be widely used to remove parabens from contaminated aqueous solution