Abstract
A raw clay obtained from a clay deposit in Ikere-Ekiti, Ekiti State, South West
Nigeria was characterised, followed by the determination of its cation exchange
capacity (CEC). Five techniques were used: X-ray powder diffraction (XRD), X-ray
fluorescence (XRF), thermogravimetric analysis (TGA), attenuated total reflection
Fourier transform infrared (ATR-FTIR) and scanning electron microscopy (SEM). The
clay is composed mainly of kaolinite but also contains its polytypes dickite and
halloysite. It also contains other minerals: quartz, mica, K-feldspar, Ti-rich Fe-oxides
and traces of sulphides, but does not contain swelling clays. The clay is poorly
crystalline with abundant impurities, and Fe2O3 content is the most elevated impurity
up to 16.8 wt%. The CEC was determined without pH to be 2.60 cmol (+)/kg and to be
5.85 cmol (+)/kg for a pH of 3.26.
The kaolin clay was purified and modified via direct intercalation with an organic
anionic surfactant, sodium dodecyl sulphate (SDS). The purified kaolin clay (PKC) and
the modified clay (SDS-PKC) were characterised using seven techniques: XRD, XRF,
TGA, FTIR, CHNS - elemental analyzer, SEM and Brunauer-Emmett-Teller (BET)
analysis. The results indicated that the organic anionic surfactant were intercalated
both into the kaolinite layers and on the crystal of the clay mineral. Different types of
electrodes, namely: carbon paste electrode (CPE), unmodified clay-carbon paste
electrode (PKC-CPE) and modified clay carbon paste electrode (SDS-PKC-CPE)
were prepared. The bare CPE, PKC-CPE and SDS-PKC-CPE were electrochemically
investigated using cyclic voltammetry in 5mM [Fe(CN)63-/4-] redox probe. Results from
cyclic voltammetry shows that 0.16 g G : 0.1 mL oil composition has the highest signal
current for the CPE. This was due to a high electroactive area of 0.0382 cm2...
M.Sc. (Chemistry)