Dissertation > Excellent graduate degree dissertation topics show

Study on Degradation of Perfluorooctanoic Acid by UV-Fenton

Author: LeiMin
Tutor: ZhuLiHua
School: Huazhong University of Science and Technology
Course: Analytical Chemistry
Keywords: UV-Fenton system Perfluorooctanoic acid Degradation Hydroxyl radical
CLC: X703
Type: Master's thesis
Year: 2011
Downloads: 167
Quote: 1
Read: Download Dissertation

Abstract


Perfluorinated compounds （PFCs） have many excellent characteristics such as high surface-active effect, high thermal and chemical stability and high light transparency. Thus they have been widely used as surface treatment agents in emulsion, fire retardants, paper coatings and carpet cleaners. These compounds have caused serious health concerns such as potential toxicity on human organs, reproductive and immune systems because of its persistence and bioaccumulation. Perfluorooctane sulfonates （PFOS） and its salts and perfluorooctane sulfonyl chloride are classified as persistent organic pollunants （POPs） on the fourth conference of the Stockholm Convention. Perfluorooctanoic acid （PFOA） and PFOS are produced when most of these perfluorinated precursor degradation.Hydroxyl radical （·OH） oxidation as one of the advanced oxidation technologies is commonly used in the treatment of organic pollutants. But many researchers consider that·OH cannot oxidize PFCs on account of its abstract hydrogen process hindered. So they think that·OH has no affinity to these compounds. This work aimed at solving this problem. We used UV irradiation enhanced the Fenton’s oxidation capacity in order to degradation PFCs.In this work, we used Fenton’s reagents which combined with UV irradiation of 254 nm to degrade PFOA. The optimized conditions were as follows: the initial Fe2+ concentration 2.0 mM, the initial H2O2 concentration 20.0 mM and the initial solution pH 3.0. It was found that defluorination ratio of PFOA at the initial period of the reaction increased rapidly. The defluorination and degradation ratio reached more than 40% and 90% within the first two hours, respectively. The degradation products were short-chain perfluorinated carboxylic acids and F- as determined by IC and LC-MS, and there was no HCOOH formed.In addition, this work discussed the PFOA degradation mechanism by UV-Fenton system. Through the experimental results of the role of hydrogen peroxide （H2O2）, identification of active radicals and the molar ratio of Fe2+/Fe （total） in the reaction solution, we propose the possible mechanisms as below: when there is H2O2 in the system,·OH accelerate decarboxylation process of PFOA, and if H2O2 completely consumed, the ferric ion in the system receive one electron from PFOA which leading to decarboxylation. The subsequent degradation processes are similar of the two ways decarboxylation.

Related Dissertations

  1. Study on the Degradation of Unsaturated Polyester Resin and Fiber Reinforced Polymer in Hot Compressed Water,TQ320.1
  2. Study on the Degradation of 2-MIB in Aqueous Solution by ZnOOH Catalized Ozonation,X703
  3. Process Optimization and Degradation Kinetics for Microwave Vacuum Drying of Different Traditional Chinese Medicine Extract,TQ461
  4. Study on the Preparation of the Low Molecular Weight Fuciodan from Sargassum Henslowianum (C.Agardh) and Anti-tumor Activity,TS254.9
  5. Study on Activated Carbon Supported Cerium Catalytic Ozone Oxidation of Chloramphenicol,X703
  6. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  7. Process and Mechanism of Eucalyptus Pulp Bleaching Catalysed by Cu2+/Co2+,TS745
  8. The Research on Sulfate Leaching Properties of Cation-exchange Resin Used in Power Plants,TQ425.23
  9. Study of Nitrobenzene Wastewater’s Treatment by Combination of Immobile Phanerochaete Chrysosporium and Activated Sludge,X703
  10. Study on the Breeding of High Efficient Detoxification Strains and Suggestion Parameters of Solid Fermentation on Cottonseed Meal,S816.6
  11. Detection of Exogenous Recombinan DNA of Transgenic Rice and Its Rice Product,S511
  12. Effects of Nitrogen Management Practices on Expression and Degradation of Bt-protein in Transgenic Cotton,S562
  13. The Biodegradation Behavior of Silk Fibroin Materials,R318.08
  14. Preparation and Properties of Silk Fibroin Porous Scaffolds with Nanofibrous-like Component,R318.08
  15. The Study on Catalyzed Ozonation of p-CNB in Water by Si-FeOOH,X703
  16. Heterogeneous Catalytic Ozone Oxidation for Pharmaceutical Wastewater Treatment,X787
  17. Synthesis of FeTiO3 Mineral and Characteristic of Photocatalysis,X703
  18. Preparation of Heterogeneous Metal Phthalocyanine Catalysts and Photodegradation of Toxic Organic Pollutants,X52
  19. Suppressing food hydrazine used in rice safety evaluation,S481.8
  20. Study on Detection of Transgenic Ingredients in Genetically Modified Cottonseed Meal and Its Degradation during Feed Processing,S816

CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
© 2012 www.DissertationTopic.Net  Mobile