This model shows a high determination coefficient (R2 ¼ 0.97)
which indicates a statistically significant model. The ANOVA with
quadratic regression model demonstrates that the model is significant;
this is indicated by a low probability (P < 0.0001 and <
0.0001 for MYand biodegradability, respectively). The main factors
of S/X ratio, Ni concentration, and Co concentration all had individual
significant influences on the MY and biodegradability
(Table 3).