Synthesis of Activated Carbon from PET (Polyethylene Terephthalate) Plastic Waste with Fe3O4 Composite as Adsorbent for Methylene Blue

The purpose of this research is to produce an activated carbon composite from PET (Polyethylene Terephthalate) plastic waste combined with Fe₃O₄ for methylene blue dye wastewater treatment. Activated carbon was produced by carbonizing PET plastic, followed by physical activation at 850°C for 25 minutes and chemical activation by soaking in 4M KOH for 2 hours. Activated carbon–Fe₃O₄ composite ware was synthesized by coprecipitation with mass ratios of 1:1 (composite 1), 3:2 (composite 2), and 2:1 (composite 3). XRD and SEM were used to analyze the activated carbon, and the best-performing composite was further characterized by XRD and SEM-EDX mapping. The composite contains a crystalline phase, likely originating from Fe₃O₄. The composite's morphology consists of fine, high-surface-area particles. The detection of Fe and O peaks in the elemental analysis verified the existence of Fe₃O₄ within the sample. The highest adsorption capacity was achieved by composite 2, reaching 3.244 mg/g under optimum conditions at pH 7 for 30 minutes, and was best fit by the pseudo-second-order adsorption kinetic model. The synthesis of the activated carbon–Fe₃O₄ composite enhances the adsorption capacity for methylene blue and facilitates separation using an external magnet.