Arsenic removal from water by magnetite/reduced graphene oxide nanocomposite: From material synthesis to engineering applications

Date

2026-2-27

Author

Çelebi, Sarp

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Arsenic that is a highly toxic semi-metal with proven carcinogeity, is removed from water by magnetite-reduced graphene oxide (MrGO), a graphene-based nanocomposite with demonstrated capacity for its adsorption. The objective of this study is to investigate and demonstrate the potential of MrGO nanocomposite for As removal from water. For this purpose, first MrGO is synthesized, and then its material characterizations and coating on sand grains are accomplished to demonstrate the synthesized product is suitable for As removal using fixed bed-continuous flow reactors of common engineering applications. Improvements in the synthesis and mass production of MrGO are achived through clarifications, modifications and new findings regarding the existing procedures reported in the literature. For arsenic speacitation analysis in water, a practical, single sample matrix hydride generation flow injection atomic absorption spectromety method is developed. In batch adsorption kinetics, pseudo-second order prevailed (R2 ≥ 0.95 for all cases), and consistently, Fruendlich isotherm model fit better in equilibrium tests (R2 ≥ 0.95), both of which imply abundant and heterogenous adsorption sites. A single coating procedure at 450°C with overnight gradual cooling was developed to coat sand with MrGO, to be used in column experiments. Column runs confirm complex adsorption kinetics observed in batch, therefore a three-step adsorption mechanism is proposed. MrGO coated sand showed 5 times better performance than ZVI, a more commercially available adsorbent, yet their combination showed a synergistic, dual effect and multiplied removal performance further to at least 5 times compared to MrGO alone, a point that can be considered for cost-effectiveness in engineering applications. A unit volume of 1 m3 of water contaminated with 100 µg/L of As(III) was taken as a concrete example to demonstrate application of the nanocomposite material for arsenic treatment from water. To produce 1 m3 of treated water, a column with 10 L of empty bed volume packed with 9.25 kg MrGO coated sand having 5.2 mg/g MrGO dosage subject to 37 L/hr flowrate seemed sufficient.

Subject Keywords

Nanomaterials, Arsenic, Adsorption, Magnetite Reduced Graphene Oxide, Column Studies

URI

https://hdl.handle.net/11511/119075

Collections

Graduate School of Natural and Applied Sciences, Thesis