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Degradation of phenol and trichlorophenol by heterogeneous photo-Fenton process using Granular Ferric Hydroxide: comparison with homogeneous system
Kavitha, V. & Palanivelu, K.
Abstract
The decomposition of phenol and
trichlorophenol (TCP) by using granular ferric hydroxide
(GFH) as a photo-Fenton catalyst was investigated and
compared with homogeneous photo-Fenton process.
Experiments were conducted in a batch mode, duplicate for
the degradation of phenol and TCP in the presence of solar
light for both the processes. The effect of operating variables
for heterogeneous photo-Fenton process like pH,
peroxide concentration and GFH concentration on the
degradation of the model compounds was optimized by
univariate approach. The optimum conditions for the
degradation of phenol and TCP were pH 3.0 ± 0.2, peroxide
concentration 29.4 mM for phenol and 14.7 mM for
TCP at GFH concentration of 0.5 g/500 mL. At optimum
conditions, the mineralization efficiency of phenol and
TCP by heterogeneous process was compared with
homogeneous process. The mineralization efficiency for
phenol and TCP was 96 and 86 %, respectively, for
heterogeneous photo-Fenton process, while almost complete
mineralization ( ~ 96 %) was observed for homogeneous
process. In heterogeneous photo-Fenton process,
longer reaction time was witnessed for complete mineralization
of the compounds studied. Low molecular weight
aliphatic acids like oxalic acid, acetic acid and inorganic
chloride ion (in case of TCP) were observed during both
the processes. In these processes, the reaction proceeds by
hydroxyl radical (·OH) abstraction of the model compound
studied. The mineralization of phenol and TCP obeys
pseudo-first-order kinetics irrespective of the processes
studied. The results indicate that GFH can be an effective
heterogeneous photo-Fenton catalyst for the degradation of
phenol and TCP.
Keywords
Granular ferric hydroxide (GFH); Heterogeneous photo-Fenton process; Homogeneous photo-Fenton process; Hydroxyl radical; Intermediates; Mineralization
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