Tailoring electronic configurations in adsorptive sites for the enhancement of As(V) removal from groundwater

Abstract

Abstract In the past few decades, heavy metal pollution, such as As(V), has become an important issue for aqueous environment safety. For reasons of practical feasibility and cost-effectiveness, adsorption has been widely used in the water treatment and reuse community, with rapid development of adsorbents. However, the precise control of the electronic configuration of the adsorbents' sites to enhance adsorption performance is largely unexplored. In this study, to demonstrate the effect of electronic configuration on adsorption performance, we synthesized granular activated carbon (GAC) supported Fe-based hydroxides adsorbents by varying the valence state in transition metals. Furthermore, the adsorbents are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) to identify surface structure and morphological properties. Adsorptive performance studies show that the adsorption capacity and arsenic removal efficiency of Fe(II)-GAC are twice those of Fe(III)-GAC, as a matter of charge transfer between adsorbents and cationic pollution (such as Fe-O and As species). Finally, PO43− was selected as a control sample to confirm the rationality of the removal mechanism. Collectively, fine-tuning of the electronic configuration from charge transfer will not only benefit heavy metal removal channels, but also supply fundamental information for adsorbents design for organics removal.