Another relevant factor is the rate of molecular diffusion, which is directly correlated with temperature . With greater mobility of the molecules in the solution, the reactants interact more quickly, increasing the rate of product formation. Finally, it is crucial to consider the organic compounds present in yerba mate, such as polyphenols and alkaloids, which can act as reducing, dispersion, or stabilizing agents in the formation of copper oxide . The effectiveness of these compounds can be enhanced at higher temperatures, favoring the complete conversion of the precursors into copper oxide Finally, the experimental design proposed a polynomial model that statistically describes the CuO NPs synthesis process Eq. ( ). The model represented by Eq. ( ) has coded variables X1 and X2 corresponding to the reaction temperature and mass of copper nitrate trihydrate respectively.