Publisher: Chemical Society of Nigeria

Studies of The Thermal Stability of Cetyltrimethylammoniumbromide Modified Kaolinite Clay

T. O. Egbuchunam, G. Obi,, F. E. Okieimen, F. Tihminlioglu
KEYWORDS: Thermal stability, activation energy, kaolinite clay, degradation kinetics


The thermal properties and degradation kinetics using two sensitive integral methods – Broido and Coats- Redfern, for unmodified and modified kaolinite clay synthesized through the intercalation of cetyltrimethylammoniumbromide (CTAB) have been studied by thermogravimetric (TG) analysis to investigate the effect of surfactant concentration on the thermal stability of modified organokaolinite clay. The clay samples were decomposed in the TG furnace at 10oC min-1 heating rate under nitrogen atmosphere of 40 mL min-1. The TG curves showed three thermal transitions between the temperature ranges of 60 – 200oC, 195 – 320oC and 420 – 570oC. The degradation kinetic parameters were obtained using the integral methods of Broido and Coats-Redfern. The values of activation energies for degradation, Ea, tended to increase with increase in the extent of organophilization. The Broido model provided a better fix for the experimental data with values of activation energy ranging from 18.82 kJ mol-1 for the raw (unmodified clay) to 27.68 kJmol-1 for the organoclay (50% CEC). The incorporation of surfactant molecules into the clay structure led to a slight increase in basal spacing indicating the intercalation of organic moiety between the layers of kaolinite clay.    

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