Premium
Mechanism and kinetics of H‐acid degradation in TiO 2 /O 3 /UV process
Author(s) -
Pan Zhenhua,
Cai Qizhou,
Luo Qiang,
Li Xinwei
Publication year - 2014
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.21901
Subject(s) - kinetics , photocatalysis , benzene , chemistry , degradation (telecommunications) , ozone , reaction mechanism , photochemistry , radical , ultraviolet , carboxylic acid , catalysis , nuclear chemistry , materials science , organic chemistry , telecommunications , physics , optoelectronics , quantum mechanics , computer science
Abstract The mechanism and kinetics of synergetic effect in TiO 2 /O 3 /UV process on H‐acid degradation were investigated. The experimental results showed that H‐acid removal rate of TiO 2 /O 3 /UV process was the highest among TiO 2 /UV, O 3 /UV and TiO 2 /O 3 /UV processes. The investigation of reactions with suitable active species scavengers confirmed that H‐acid was mainly oxidised by ozone and holes on TiO 2 in the TiO 2 /O 3 /UV process. The recombination between holes and electrons in TiO 2 reduced in the presence of ozone, as indicated by fluorescence emission spectra. Moreover, the intermediates generated during H‐acid oxidation in various processes were analysed by LC/MSD trap. It is proposed that H‐acid was oxidised to polyhydroxy aromatics, benzene carboxylic acids and quinoids in the first step. Then, saturated aliphatics carboxylic acids were formed and mineralised to inorganic compounds through the Photo‐Kolbe reaction. Finally, a kinetic study on TiO 2 /UV, O 3 /UV and TiO 2 /O 3 /UV processes was conducted and it was confirmed that both ozonation and photocatalytic activity were improved in TiO 2 /O 3 /UV process because of the synergetic effect.