Exploring the influence of heat treatment duration and temperature on the properties and adsorption performance of Sn0.5Ni0.3Mn0.2Fe2O4 nanoparticles

Various pollutants like microplastics, oil spills, and chemical wastes contributing to water pollution are a global issue that has not yet found an end. Chemical dyes, which are widely used as food coloring and textiles, can be toxic and may include mild and potentially carcinogenic effects. One of the most promising solutions is the use of an adsorption process for these dyes using magnetic nanoparticles, which enables easy removal of the adsorbent and allows for reuse. In this work, tri-metal spinel ferrite magnetic nanoparticles based on the stoichiometry SnNiMnFeO were synthesized for different heat treatment temperatures and times. Analysis (XRD) demonstrated that the heating time increase causes the unit cell contraction while higher temperature lattice parameter expands. From the transmission electron microscope (TEM) images, it can be observed that the particle size increased with heating duration and temperature. The purity and successful formation of the desired nanoparticles were confirmed by energy dispersive X-ray (EDX) analysis, with the obtained atomic percentages aligning with the theoretical values. Photoluminescence (PL) spectra indicated that the highest electron-hole recombination rate was observed at the highest heat treatment temperature and duration. The optimal conditions for synthesizing SnNiMnFeO nanoparticles, which demonstrated enhanced adsorption efficiency for trypan blue (TB) removal, were heat treated at 600 °C for 2 h. Notably, 83.4% of the TB dye was adsorbed after a contact time of 240 min. The optimal sample was confirmed to have the largest surface area and pore volume via the Brunauer-Emmett-Teller (BET) analysis and the Barrett-Joyner-Halenda (BJH) model. This study also examined the adsorption of a TB and Congo red (CR) dye mixture to simulate industrial effluents discharged into water.