SYNTHESIS AND CHARACTERIZATION OF BENTONITE CLAYS MODIFIED WITH CETYLTRIMETHYLAMMONIUM BROMIDE FOR THE TREATMENT OF CRUDE OIL POLLUTION IN WATER
SYNTHESIS AND CHARACTERIZATION OF BENTONITE CLAYS MODIFIED WITH CETYLTRIMETHYLAMMONIUM BROMIDE FOR THE TREATMENT OF CRUDE OIL POLLUTION IN WATER
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Date
2015-04
Authors
NWANKWERE, EMEKA THOMPSON
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Abstract
Three types of Nigerian bentonite based nanoclays – Potassium (sample A), Calcium (Sample B) and Sodium (Sample C) bentonites– were investigated for their potential as oil spill sorbents after modification with Cetyltrimethylammonium Bromide (CTAB). The nanoclay samples were purified and subjected to hydrothermal ion exchange reaction to synthesize organoclays under mild reaction conditions. Changes in the microstructural, morphological and physicochemical properties of the modified clays caused by the intercalation of CTA+ cations before and after the synthesis procedure were investigated. The changes in the chemical profile of the clays were studied by X-Ray Flouresence (XRF) and Neutron Activation Analysis (NAA). Crystallographic studies by X-Ray Diffraction (XRD), show higher intercalation time and surfactant loading, produce organoclays with higher basal spacing and more efficient oils sorption capacities. These observations were further explained by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Thermal Gravimetric Analysis (TGA). The presence of new (organic) groups in the characteristic bentonite structure of the nanoclays is prime evidence of successful synthesis. The organoclays were further tested in a simulated oil spill situation to assess their potential as oil sorbents and sorbed about 5 times their weight in water. To understand the manner and mechanism of the sorption procedure, batch kinetic and equilibrium studies were carried out using kinetic and equilibrium isotherm models. The kinetic data was best described by the Pseudo-second-order rate model (R2 = 0.999, 0.990 and 0.9975 for the organoclay Samples 2, 5 and 15 respectively) demonstrating that the sorption procedure and mechanism was by chemisorption and that more than one process may have occurred during the procedure. The Langmuir isotherm model best described the manner of crude oil sorption (R2 = 0.9968, 0.997 and 0.9936 for samples 2, 5 and 15 respectively) as predominantly monolayer. The results showed that these natural clays can be modified and used for the treatment of oil spillage. The organoclays present a cost effective and a suitably environmentally friendly alternative for the remediation of oil spill polluted lands in the Niger Delta region of Nigeria.
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A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY IN CHEMISTRY
DEPARTMENT OF CHEMISTRY,
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
SYNTHESIS,, CHARACTERIZATION,, BENTONITE CLAYS MODIFIED,, CETYLTRIMETHYLAMMONIUM BROMIDE,, TREATMENT,, CRUDE OIL POLLUTION,, WATER,