Synthesis of ZrO2 nanoparticles and effect of surfactant on dispersion and stability

This work investigates the stability of dispersions of zirconium oxide nanoparticles, synthesized by the sol-gel method, with zirconium isopropoxide precursors. Nanofluids at concentrations of 0.1 wt% were prepared by dispersing the synthesized nanoparticles in deionized water. Anionic sodium dodecylbenzene sulfonate (SDBS), cationic cetyltrimethylammonium bromide (CTAB), and non-ionic polyvinyl pyrrolidone (PVP) at concentrations of 0.01 wt%, 0.03 wt%, and 0.05 wt% were used for nanoparticle dispersion. Stability was analyzed by means of dynamic light scattering (DLS), zeta potential, pH, visual inspection, and UV–vis. Transmission electron microcopy (TEM) images revealed particles with a size of 59.9 ± 13.5 nm, and x-ray diffraction (XRD) showed crystalline materials. The results of sedimentation, hydrodynamic radius, and absorbance indicate that the presence of surfactants reduces agglomeration and improves the stability of nanofluids over time. The non-ionic surfactant, PVP, produced a better effect on the hydrodynamic radius than its ionic counterparts (SDBS and CTAB). In addition, the type of surfactant was found to have a significant effect on the pH, zeta potential, and isoelectric point of the ZrO₂ nanoparticles. Finally, the stability analysis revealed that stable nanofluids with a final concentration of 0.01 wt% of particles can be obtained after 20 days, demonstrating the potential of such nanofluids for heat transfer applications.