A Comparative Evaluation of Magnetite Reduced Graphene Oxide Composite and Zero-Valent Iron for Arsenic Removal from Water

Arsenic is one of the most common toxic heavy metals that is found in groundwater, and it is a common contaminant encountered in water resources. Conventionally, Zero-Valent Iron (ZVI) is utilized by various mechanisms for the treatment of arsenic. ZVI is a material characterized as having a high adsorption capacity and availability; characteristics that make it an efficient reactive reagent. In comparison, the rising alternative media based on graphene and its derivative nanomaterials, such as magnetite-reduced graphene oxide (MrGO), are less conventionally utilized.  In this study, a comparative evaluation of arsenic treatment from water having different arsenic species and concentrations is carried out using both ZVI and synthesized MrGO to evaluate arsenic removal efficiencies and adsorption capacities. Selected media’s interaction with the contaminant and removal performance of the inorganic arsenic species (As(III) and As(V)) are analyzed in detail, with a focus on the preference and species interaction with the media. Kinetic and equilibrium batch studies of synthesized MRGO and ZVI reactive media are being conducted separately, as well as using several combinations of MrGO and ZVI at differing ratios. Speciation characteristics and adsorption preference of the synthesized nanocomposite media will provide insight into the effective removal of total arsenic and its individual forms for process optimization. This study will also give a broader view of the adsorption mechanism and inorganic arsenic chemistry in the presence of different forms of iron and iron oxides, amongst other environmental factors. Comparative and combinational studies are expected to demonstrate the potential of MrGO for arsenic adsorption as a supporting material that can easily be implemented in existing conventional infrastructure in order to achieve more efficient and higher arsenic removal rates.

Acknowledgement: This study is supported by TUBITAK (The Scientific and Technological Research Council of Turkey) 1001 Project with Grant Number 123Y025 and Research Fund of the Middle East Technical University, Research Universities Support Program (ADEP) with Grant Number ADEP-311-2022-11172