Process improvement approach to the saponification reaction by using statistical experimental design

The purpose of this study was to determine the effective operating parameters and the optimum operating conditions of a batch saponification process in the frame of the process improvement. Full two-level factorial and face-centered central composite (FCCC) statistical experimental design methods were used successively. Examined parameters were the main and interaction effects of temperature, agitation rate, initial sodium hydroxide (NaOH) and ethyl acetate (EtOAc, CH3COOC2H5) concentrations. Selected process response was the fractional conversion rate of NaOH (XA). Temperature and agitation rate were found to have no effect on the response at the 10% selected significance level (α = 0.1). The dependence of response on the NaOH and EtOAc concentrations was illustrated by a linear second-order polynomial model. Examination of the residuals served as a diagnostic check of the model and it was found that the model was good enough to fit the experimental data. Optimum operating conditions at which maximum XA was obtained about 100% were found to be 0.01 mol L−1 NaOH and 0.1 mol L−1 EtOAc by applying response surface method (RSM). With the use of residual analysis and statistical techniques, more reliable and proper results were obtained at the process improvement stage of the saponification process.