The Production of Hydroxyl Radicals in Fenton Process by Decolourisation of AO7

• Main Authors: Che-Min Lin, 林哲民
• Other Authors: Jao-Jia Horng
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/82497595331645529793

碩士 === 國立雲林科技大學 === 環境與安全衛生工程系碩士班 === 100 === Fenton reaction (Fe2+/H2O2), Fenton-like (Cu2+/H2O2 or Co2+/H2O2) and so on that could generate highly reactive hydroxyl radicals (‧OH) to oxidize various compounds in wastewater. In this study, Fenton process and Fenton-like process were used to produce hydroxyl radicals to decolourize azo dye Acid Orange 7 (AO7) and to break the N=N bonding of auxochrome. It was Advanced oxidation process (AOPs). Fenton-like reaction was used the 3d orbitals ions which was copper or cobalt. Fenton-like was liked Fenton,the 3d orbitals ions generate hydroxyl radicals with hydrogen peroxide. This study also analyzed the deatoves and final prodents by Fenton and Fenton-like process. The hydroxyl radicals (‧OH) are formed DMPO-OH adducts with 5,5-dimethyl-l-pyrroline-N- oxide (DMPO) and characterized by Electron Paramagnetic Resonance (EPR). The production of ‧OH was analyzed by High-Performance Liquid Chromatography /Ultraviolet with salicylic acid as a scavenger and measured the reaction products. (2,3-Dihydroxybenzoic acid, 2,3-DHBA and 2,5-Dihydr -oxybenzoic acid, 2,5-DHBA) The optimal conditions of decolourization of Fenton process were 10 x10-4 M of Fe2+, 10x10-4 M of H2O2 and at pH 4 which could generate 1.97 x10-4 M of ‧OH. The optimal conditions of Fenton–like process of Cu2+/H2O2 were 10 x10-4 M of Cu2+, 600 x10-4 M of H2O2 and at pH 4 which could generate 192 x10-4 M of ‧OH. However, the conditions of Co2+/H2O2 Fenton–like process were 10 x10-4 M of Co2+, 10 x10-4 M of H2O2 and at pH 5 which was difficult to observe the reaction products. The DMPO-OH adducts were detected through Fenton (Fe2+/H2O2) and Fenton-like (Cu2+/H2O2 or Co2+/H2O2) processes. However, when the dosage of [H2O2] of Fe2+/H2O2 is high than 50 x10-4 M, the DMPO-OH will over-oxidized to form 5,5-dimethyl-2-pyrrolidone-N-oxyl (DMPOX). We also investigated the mechanism of the Fenton and Fenton-like and the used Kinetics'' Simulator ™ of IBM (IBM-CKS).