Liquid Phase Oxidation of Phenols in Industrial Wastewater Using an Adsorbent – Catalyst Matrix
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Date
2015-05-22
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Abstract
Phenols constitute an important class of toxic organic compounds found in most refinery
waste water streams. Due to its refractory nature towards conventional waste water
treatment methods it requires a much more severe conditions to effect meaningful
oxidation. Catalytic Wet Air Oxidation (CWAO), the most promising treatment method for
phenol abatement currently has a high operation cost due largely to the absence of a
suitable cost effective catalyst. The current study has investigated the use of the spent
Fluidized Catalytic Cracking (FCC) catalyst as a suitable cost effective catalyst for the
CWAO process and identified the appropriate operating conditions for its usage in this
regard.
The spent FCC catalyst has been proven to be a good adsorbent of phenol, a property not
found in the fresh catalyst. Its performance as phenol adsorbent compared with activated
carbon has been found to be about 16.62% that of activated carbon. It was found out that
particles were agglomerated with a d25 for the fresh and spent catalyst being 48 μm and 68
μm respectively against a d50 of 68 μm and 88 μm respectively. The pore volume had also
increased from 0.4 cm3/g to 0.9 cm3/g. The spent FCC unlike the fresh catalyst was found
to contain Ni, V, Cu, Fe and Sr which are potential catalyst.
The spent catalyst was impregnated with varying amounts of CuO, Fe2O3 and MnO2 and
tested for phenol oxidation using various amounts of H2O2 as radical initiator. It was
however found out that the spent catalyst impregnated with 0.97% Fe2O3 was a very
effective catalyst for the catalytic wet air oxidation of phenol using 1 vol. % H2O2 as a
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radical initiator and a relatively low air pressure of 0.4 cm Hg (533 Pa) gauge and
temperature of 50oC. The results were then tested with refinery stripped sour water with
about 100% mineralization.
Description
Thesis submitted to the
School of Graduate Studies, Kwame Nkrumah University of Science and Technology
in partial fulfillment of the requirement for the degree of
DOCTOR OF PHILOSOPHY