Experimental assessment of tio₂-poe nanolubricant stability and optimization process using one factor at a time (OFAT) based on response surface methodology

This paper aims to elaborate on the results of the experimental assessment of the stability of TiO2-Polyester (POE) nanolubricant. There are six samples in this investigation, with each concentration of 0.02 vol%. The TiO2 nanoparticles were dispersed into synthetic lubricant POE for 30 min using a magnetic stirrer. Then, the samples were sonicated for 0, 40, 60, 80, 100, and 120 min, respectively—the visual observation for 720 hours, UV visible spectrophotometry, and absolute zeta potential employed to investigate the samples. After data acquisition, optimization with one factor at a time (OFAT) is applied to determine the most optimum sample. The results show that the sample with sonication treatment for 120 min is the most optimum. This finding was confirmed by the absorbance ratio value of 0.95 with an -80.48mV zeta potential. The output of ANOVA analysis shows the regression coefficient is 0.9999, and the adjusted R2 value is 0.9998 with a p-value that is much smaller than 0.05, which is <0.0001. These results demonstrate that sonication duration has a significant effect on increasing the stability of TiO2-POE nanolubricant