Heterogeneous photodegradation of methylene blue with iron and tea or coffee polyphenols in aqueous solutions.
Recently, we developed two new Fenton catalysts using iron (Fe) and spent tea leaves or coffee grounds as raw material. In this study, Fe-to-tea or Fe-to-coffee polyphenol complexes were successfully tested as heterogeneous photo-Fenton catalysts. The photodegradation efficiency of methylene blue solutions with Fe-to-polyphenol complexes was higher than that of homogeneous iron salts in the photo-Fenton process. Furthermore, the tested Fe-to-polyphenol complexes could be reused by simply adding H2O2 to the solutions. After three sequential additions of H2O2, the conventional catalysts FeCl2·4H2O and FeCl3 removed only 16.6% and 53.6% of the dye, while the catalysts made using spent coffee grounds and tea leaves removed 94.4% and 96.0% of the dye, respectively. These results showed that the complexes formed between Fe and chlorogenic acid, caffeic acid, gallic acid and catechin, which are the main polyphenols in tea and coffee, can be used to improve the photo-Fenton process.
National Agriculture and Food Research Organization, Postal 514-2392 Mie, Tsu, Ano, Kussawa 360, Japan E-mail: ckm@affrc.go.jp.
Claudio Kendi
CK
Morikawa
National Agriculture and Food Research Organization, Postal 514-2392 Mie, Tsu, Ano, Kussawa 360, Japan E-mail: ckm@affrc.go.jp.
Makoto
M
Shinohara
D028241:Camellia sinensis / Q000737:chemistry*; D002384:Catalysis; D040503:Coffea / Q000737:chemistry*; D005707:Gallic Acid; D006861:Hydrogen Peroxide; D007501:Iron / Q000737:chemistry*; D008751:Methylene Blue / Q000737:chemistry*; D010782:Photolysis; D059808:Polyphenols / Q000737:chemistry*; D014865:Waste Disposal, Fluid; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical
D059808:Polyphenols; D014874:Water Pollutants, Chemical; D014867:Water; D005707:Gallic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D008751:Methylene Blue