Arsenic removal from water using magnetite/reduced graphene oxide nanocomposites: A comparative study with zero-valent iron and their combinations

Date

2026-1

Author

Elkawefi, Omar Ashraf Ibrahim Mohammed

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Arsenic contamination, particularly by mobile and toxic trivalent arsenite (As(III)), presents a significant environmental challenge. This thesis evaluates Magnetite reduced Graphene Oxide (MrGO), its thermally-treated derivative (HMrGO), and Zero Valent Iron (ZVI) as standalone adsorbents and in dual-mode combined (HMrGO-ZVI) systems to remove As(III) and As(V) from water. This approach aims to leverage synergy to overcome ZVI surface passivation and slow kinetics, while also addressing the limited capacity of the nanocomposites. Equilibrium studies showed ZVI had a high Langmuir capacity of 1037.29 mg/g, compared to 580.22 mg/g for MrGO and 232.45 mg/g for HMrGO. Nanocomposites followed Pseudo-Second-Order kinetics, while ZVI followed First-Order kinetics, under As(III) loading. Under As(V), both the nanocomposites and ZVI followed Pseudo-Second-Order kinetics. HMrGO demonstrated the fastest kinetics, removing 80.8% As(III) at 100 µg/L As(III) within two hours. Notably, the HMrGO-ZVI combination (0.02 mg/mL HMrGO with 0.2 mg/mL ZVI) achieved a superior capacity of 1203.25 mg/g. This performance is driven by galvanic coupling, where the MrGO backbone catalyzes As(III) oxidation and prevents ZVI passivation. Validation in synthetic real groundwater from Balçova and Çitgöl, Türkiye, showed efficiencies of 71.3% and 67.6% for HMrGO, and 77.1% and 87.7% for the combination, respectively, confirming the system's potential for remediation in complex aqueous environments.

Subject Keywords

Zero-Valent Iron (ZVI), Magnetite-Reduced Graphene Oxide (MrGO), Groundwater treatment, Combined nanocomposites, Arsenic remediation

URI

https://hdl.handle.net/11511/118490

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Graduate School of Natural and Applied Sciences, Thesis