Contamination by heavy metals is a pressing issue due to its numerous hazardous effects on human health. One of the main challenges associated with this type of contamination is the resistance of heavy metals to degradation and their accumulation in living organisms. However, a wide variety of methods, including ion exchange, membrane filtration, flotation, electrolytic methods, and adsorption, can be employed to eliminate heavy metals from water. To achieve the efficient removal of heavy metals from water, a high-surface-area absorbent is necessary. This enhances contact and interaction with heavy metal ions, and the use of nanoparticles significantly improves this aspect. This study investigates the preparation of Fe₃O₄ nanoparticles using a solvothermal method. This method allows to produce ultrafine magnetite powders with homogeneous particles, a narrow size distribution, and consistent morphology, free from other crystalline phases that could hinder heavy metal ion absorption. The experiments involved varying temperatures (180-220 °C) and reaction times (4-12 h) and utilized FeCl₃ as the iron ion precursor. Following the solvothermal treatments, the precipitated particles were magnetically separated from the hydrothermal solution. The magnetic particles were then analyzed using XRD, SEM, and FTIR. Structural characterization via SEM confirmed that the obtained particles were magnetite in the form of homogeneous spherical particles with an average size of 450 nm, composed of smaller agglomerated nanoparticles with an average size of 8.4 nm. Microstructural characterization using the XRD and FTIR techniques also confirmed the magnetite structure, exhibiting defined reflections without any secondary crystalline phases. Kinetic and isotherm data from a preliminary study fit well with established models, indicating efficient fluoride capture. Additionally, the maximum adsorption capacity reached 39.44 mg/g F^- within 30 minutes, remaining stable thereafter. These findings suggest that the synthesized magnetite nanoparticles are ideal candidates for heavy metal and fluoride removal from water.