APPLICATION OF ZEOLITE 4A – METAKAOLIN MATRIX FOR THE REMOVAL OF SOME HEAVY METALS FROM CRUDE OIL TANK FARM WASTEWATER
APPLICATION OF ZEOLITE 4A – METAKAOLIN MATRIX FOR THE REMOVAL OF SOME HEAVY METALS FROM CRUDE OIL TANK FARM WASTEWATER
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Date
2014-08
Authors
NWAFULUGO, FRANCISCA UNOMA
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Abstract
Pollution of water, especially in communities close to crude oil deposits and refineries,
has created worldwide concerns because of the associated heavy metals, inter-alia,
released to the environment which have adverse effects on the environment - human and
aquatic life. Despite all the efforts of the refineries to curtail this, the inorganic
pollutants were not sufficiently catered for. Analysis of the pollution loading of
wastewater samples collected from the dewatering tanks in the tank farm of Kaduna
Refining and Petrochemicals Company (KRPC) and at the point of discharge to the
receiving river indicated concentrations of 0.04 mg/l of Ni, 0.225 mg/l Pb, 0.022 mg/l
Cd and 1.823 mg/l Mn as against 0.01 mg/l, 0.01 mg/l, 0.003 mg/l and 0.2 mg/l
standards, respectively, set by the National Environmental standard Regulatory and
Enforcement Agency (NESREA). There was a consideration to use commercial Zeolite
4A, deriving from its high pore volume and adsorptive sites, but in order to reduce the
cost of importation of the Zeolite 4A, a cheap and available local kaolin from Kankara
village in Katsina State was used as a blend. The kaolin was processed to sodium base
metakaolin using ion exchange techniques to insert sodium ion in the metakaolin
structure. The sodium based metakaolin was blended in various proportions with
Zeolite 4A to form matrices of Zeolites 4A and metakaolin. The mineralogical and
chemical compositions of Zeolites 4A, metakaolin and Zeolites 4A–metakaolin matrices
were investigated and analysed using X-ray Florescence (XRF), X-ray Diffraction
(XRD), Scanning Electron Microscopy (SEM)-Energy Dispersive X - ray (EDX) and
Brunauer, Emmett and Teller (BET). The metakaolinization was achieved under
controlled calcination at the temperature of 750 oC for 3 hours and the blend of Zeolites
4A and metakaolin in the ratio of 25 to 75 % respectively gave a unique matrix. The
batch adsorption process was used to investigate the effect of variables such as contact
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time, matrix dose and pH, on the response. The aggregate removal of the specified
heavy metals (nickel, lead, cadmium and manganese) from crude oil tank farm
wastewater was achieved in one batch process. This could be attributed to the
adsorbent’s high surface area per unit mass, numerous ionic sites per unit mass and their
corresponding affinity to the metals. Isotherm and Kinetic studies were carried out. The
correlation coefficient (R2) for the adsorption isotherm models showed that the
experimental data fitted well with the Freundlich, Langmuir, Temkin, and pseudo –
second – order models. A statistical analysis was also carried out for factorial and
Response Surface methodology (RSM). The results indicated that the main effects and
the 2-way-interactions of the three variables has the highest effect on the response and
should be more carefully controlled during routine experiment. The RSM results
indicated that at optimum condition of 1.28 g/50 ml of Matrix 4 dose, 20 minutes
contact time and pH of 10.35, that the adsorption of 97.991 % nickel, 94.234 % lead,
99.239 % cadmium and 99.919 % manganese could be achieved which is commensurate
to the one factor at a time laboratory result of 1 g/50 ml, contact time of 10 minutes and
pH range of 8 - 10. The crude oil tank farm wastewater treated at this condition was
compared to the untreated sample and it showed a marked decrease in the concentration
of the specified metals far below the standard limits set by NESREA.
Description
A PROJECT DISSERTATION SUBMITTED TO THE SCHOOL OF
POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILlMENT OF THE REQUIREMENTS FOR THE AWARD
OF DOCTOR OF PHILOSOPHY DEGREE IN CHEMICAL ENGINEERING
DEPARTMENT OF CHEMICAL ENGINEERING,
FACULTY OF ENGINEERING
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
AUGUST, 2014
Keywords
APPLICATION,, ZEOLITE,, 4A – METAKAOLIN,, MATRIX,, REMOVAL,, HEAVY,, METALS,, CRUDE OIL,, TANK FARM,, WASTEWATER.