New pH Correlations for Stainless Steel 316L, Alumina, and Copper(I) Oxide Nanofluids Fabricated at Controlled Sonication Temperatures

This research investigates the pH value of stainless steel (SS) 316L/ deionised water (DIW), alumina (Al2O3)/DIW, and copper(I) oxide (Cu2O)/DIW nanofluids prepared using a two-step controlled sonication temperature approach of 10 degrees C to 60 degrees C. The nanoparticles volumetric concentration of each family of as-prepared nanofluid ranged from 0.1 to 1.0 vol%, using as-received nanopowders, of 18 - 80 nm average particles size. Furthermore, the pH measuring apparatus and the measurement procedure were validated by determining the pH of commercially supplied calibration fluids, of pH 4, 7, and 10. Following the validation, pH correlations were obtained from the experimental measurements of the 0.1, 0.5, and 1.0 vol% nanofluids in terms of varied sonication bath temperatures and volumetric concentrations. Those correlations were then combined into one robust pH(nf) correlation and validated using the pH data of the 0.3 and 0.7 vol% nanofluids. The new proposed correlation was found to have a 2.18%, 0.92%, and 0.63%, average deviation from the experimental pH measurements of SS 316L, Al2O3, and Cu2O nanofluids, respectively, with an overall prediction accuracy of similar to 92%.