This research reveals an innovative way of finding the ultimate time of ultrasonication that offers photothermal capability across carbon black (CB) water nanofluids, a great contribution to the field of solar energy absorption and nanofluid technology. The samples were generated using a two-step procedure with varying ultrasonication periods employed, ranging from 15 to 120 minutes, in concentrations of 0.005 wt% CB nanoparticles and 0.005 wt% sodium dodecyl sulfate (SDS) surfactant. Thirty days after preparation visible observation and UV spectroscopy, scanning electron microscopy (SEM) images, and particle size distribution were used to confirm the samples’ stability. The stability properties results demonstrated the beneficial effects of ultrasonication on the dispersion properties of nanofluids. Ultrasonication of less than 30 minutes resulted in the early sedimentation of nanoparticles. According to the …