TITLE:
Effects of Advanced Oxidation Processes on the Decomposition Properties of Organic Compounds with Different Molecular Structures in Water
AUTHORS:
Harufumi Suzuki, Shoichi Yamagiwa, Sadao Araki, Hideki Yamamoto
KEYWORDS:
Advanced Oxidation Process, Ozone, Hydroxyl Radical, Decomposition Efficiency, Water Treatment
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.8 No.9,
July
27,
2016
ABSTRACT: Studies
to decompose persistent organic pollutants in wastewater from chemical
factories by using Advanced Oxidation Processes (AOPs) have recently been
performed. Oxidation reactions involving ozone and •OH radicals and cleavage
caused by UV are the main decomposition reactions that occur in AOPs using
ozone and UV. The mechanisms through which organic compounds are decomposed in
AOPs are complicated and difficult to understand because various decomposition
reactions occur simultaneously. The Total Organic Carbon (TOC) removal
efficiencies achieved in several different AOPs were evaluated in this study.
The TOC removal efficiencies were different for organic compounds with
different chemical structures. The TOC was more effectively removed when
aromatic compounds were treated using the O3-UV-TiO2 process than when using the other AOPs, and the TOC was removed more
effectively by the O3-UV process than by the UV-TiO2 process. However, the TOC was removed more effectively when open-chain
compounds were treated using the UV-TiO2 process than using the O3-UV
process, and the UV-TiO2 and O3-UV-TiO2 processes resulted in similar TOC removal efficiencies. Therefore, it is
necessary to use the O3-UV-TiO2 process to decompose aromatic
compounds as quickly as possible. On the other hand, the UV-TiO2 process degraded the open-chain compounds most effectively, and the O3-UV-TiO2 process did not need to decompose open-chain compounds. Moreover, the TOC of
aromatic compounds was removed more slowly than that of open-chain compounds.
The TOC removal efficiency increased with decreasing the number of carbon atoms
in the molecule. The TOC removal efficiencies increased in order of the organic
compounds containing methyl groups, aldehyde groups and carboxyl groups. The
removal of the TOC when organic compounds were treated using the O3-UV-TiO2 process followed pseudo-zero-order kinetics.