Evaluation of conditions favorable for the enhanced stability of magnetite suspensions using visible spectroscopy

Abstract In this study, the conditions favorable for enhanced stability of magnetite nanoparticles synthesized via the coprecipitation of iron salts were evaluated for enhancing their effectiveness in various applications and ensuring homogeneous nanoparticle dispersion over time. The impact of various factors such as sonication power and time, use of pH modifiers, and surface preparation on the temporal evolution of transmittance of nanofluids was investigated by analyzing the Euclidian distances of 350- and 650-nm spectra for each time. Nanofluids were prepared by dispersing magnetite nanoparticles in deionized water using an ultrasonic homogenizer in line with the factorial experimental design that generated 32 runs. The stability of nanofluid was evaluated via direct observation, visible spectroscopy, and Zeta potential measurement. Results indicated that the combination of unwashed nanoparticles, pH-modified nanoparticles using NaOH, and those sonicated at 400 W for 60 min enhanced the stability of nanofluids, resulting in a homogeneous and stable dispersion. These findings offer valuable insights into optimize the synthesis conditions of magnetite nanofluids with potential applications in fields such as magnetic hyperthermia and controlled drug delivery. Graphical Abstract