| Summary: | The aim of this study was to apply the central composite design technique to study the interaction of the amount of formic acid (6-12 mL), amount of hydrogen peroxide (6-10 mL), temperature (54-58°C) and reaction time (40-60 min) during the oxidative desulphurisation (ODS) of tyre-derived oil (TDO). The TDO was oxidised at various parametric interactions before being subjected to solvent extraction using acetonitrile. The acetonitrile to oil ratios used during the extraction were 1:1 and 1:2. The content of sulphur before and after desulphurisation was analysed using ICP-AES. The maximum sulphur removal achieved using a 1:1 acetonitrile to oxidised oil ratio was 86.05%, and this was achieved at formic acid amount, hydrogen peroxide amount, temperature and a reaction time of 9 mL, 8 mL, 54°C and 50 min respectively. Analysis of variance (ANOVA) indicated that the reduced cubic model could best predict the sulphur removal for the ODS process. Coefficient of determination (R2 = 0.9776), adjusted R2 = 0.9254, predicted R2 = 0.8356 all indicated that the model was significant. In addition, the p-value of lack of fit (LOF) was 0.8926, an indication of its insignificance relative to pure error.
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