Green synthesis of a magnetite/graphitic carbon nitride 2D nanocomposite for efficient Hg2+ remediation

Abstract

Novel nanoadsorbents demonstrate the potential to efficiently eliminate harmful substances, such as Hg²⁺, from the environment while preserving ecological balance. However, the search for environmentally-friendly nanomaterials as ideal adsorbents, as well as the development of suitable synthesis protocols, remains a challenge. This study presents an effective thermal-sonication technique for producing unique de novo tris-s-triazine carbon nitride nanosheets decorated with magnetite nanoparticles (M-g-CN). The structural integrity and chemical properties of the M-g-CN nanocomposite were extensively characterized using a battery of analytical instruments, including FTIR, SEM, TEM, XRD, XPS, AFM, Raman, and NMR. The obtained data, along with the analysis results, are discussed in detail. The novel synthesis method yields a high percentage (97.7%) of stable, highly selective, and reusable M-g-CN (40 mg mL⁻¹). The resulting M-g-CN effectively binds Hg²⁺, with binding efficiencies of 96.0%, 97.5%, 98.2%, and 99.4% for Hg²⁺ concentrations of 50 pg mL⁻¹ in marine, stream, precipitation, and ultra-pure matrices, respectively. Also, the magnetite-decorated particles can be easily retrieved using an applied magnetic field. This greener and scalable synthesis method does not require harsh chemicals, making it cost-effective, eco-friendly, and non-toxic compared to other technologies such as carbon filters, ion exchange resins, chemical precipitation, membrane filtration, electrochemical methods, and biological remediation. Overall, the synthesized M-g-CN exhibits wide-ranging potential applications, particularly as a green adsorbent in passive samplers or materials for remediation purposes.