Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Polyvinyl Alcohol and Graphite as Methylene Blue Adsorbents

Methylene blue (MB) is one of the toxic synthetic dyes that are being discharged heavily into water supplies. Hence, MB removal is one of the most important tasks for a cleaner water supply. By using inexpensive, abundant, and easy-to-synthesize materials, superparamagnetic iron oxide nanoparticles, which were synthesized using the co-precipitation method with polyvinyl alcohol and graphite (SPION/PVA/GR), can be used to adsorb MB. The adsorbent was characterized using FE-SEM, FTIR, XRD, VSM, and BJH. The entrapment efficiency of MB on SPION/PVA/GR after 12 days was 33.96 ± 0.37–42.55 ± 0.39%, at 333.15, 310.15, and 298.15 K, and the initial concentration of MB was 0.017–0.020 mg/mL. The adsorption process can be considered spontaneous, endothermic, chemisorption, heterogeneous, or multilayer adsorption. When releasing MB at 298.15 K and a pH of 3.85 after 7 days, the release percentage ranged from 11.56 ± 0.33 to 22.93 ± 5.06 depending on the initial loading conditions and mainly the releasing temperature following the Higuchi kinetic model. Since this is a novel SPION-based MB adsorbent, optimization, and different forms of adsorbent (i.e., thin film composite) should be further researched.