title: Reduction of Hexavalent Chromium by Green Tea Polyphenols and Green Tea Nano Zero-Valent Iron (GT-nZVI).
abstract: This study reports on the direct reduction of hexavalent chromium [Cr(VI)] by green tea polyphenols, including a green tea solution and pure epigallocatechin gallate (EGCG) solution. A linear trend was observed between the amount of reduced Cr(VI) and the amount of added polyphenols. The green tea solution showed a continued decrease in the observed stoichiometry with increasing pH, from a maximum of 1.4 mol per gallic acid equivalent (GAE) of green tea at pH 2.5, to 0.2 mol/GAE at pH 8.8. The EGCG solution exhibited different behavior, with a maximum stoichiometry of 2 at pH 7 and minimum of 1.6 at pH 4.4 and 8.9. When green tea was used to first react with Fe3+and form GT-nZVI, the amount of Cr(VI) reduced by a certain volume of GT-nZVI was double compared to green tea, and 6 times as high considering that GT-nZVI only contains 33 % green tea.
authors: Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Road Unit 3037, Storrs, CT, 06269, USA. maria.chrysochoou@uconn.edu.
authors: M
authors: M
authors: Chrysochoou
authors: Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Road Unit 3037, Storrs, CT, 06269, USA.
authors: K
authors: K
authors: Reeves
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification*; D052918:Environmental Restoration and Remediation / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D059808:Polyphenols / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013662:Tea / Q000737:chemistry*; D014874:Water Pollutants, Chemical
chemical_list: D059808:Polyphenols; D012996:Solutions; D013662:Tea; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D002392:Catechin; C045651:epigallocatechin gallate; D007501:Iron
keywords: EGCG; Green tea; Hexavalent chromium; Nano zero-valent iron; Polyphenols