Three-dimensional surfaces and contour plots are graphical representation of regression equation for the optimization of reaction Status. The results of the interactions between four independent variables and dependent variable are indicated in Figs. 6 and 7.
Fig 6 Contour and 3-D plots showing Interactive effect of: (a) TC concentration (mg/L) and PS concentration (mM); (b) TC concentration (mg/L) and sonication time (min)