highly significantp < 0.0001
This approach allowed for the identification of the individual and interactive influence of each variable on the response, providing a predictive model to optimize the formulation, as shown: ST red = 31.291 + 0.134A − 0.519B + 0.154C + 3.409D − 1.149AB + 0.595AC + 1.810AD − 1.433BC − 1.981BD + 0.766CD − 0.316A 2 + 0.065B 2 + 0.102C 2 − 0.597D 2 , (7) The analysis of variance (ANOVA) for the quadratic model of surface tension reduction (ST red ) is presented in Table 3 and revealed that the model was highly significant, with an F-value of 14.78 and p < 0.0001, indicating a strong fit to the experimental data.