A novel AQDS–rGO composite to enhance the bioreduction of As(v)/Fe(iii) from the flooded arsenic-rich soil

Abstract

Anthraquinone-2,6-disulphonate (AQDS) and reduced Graphene Oxide (rGO) were selected to prepare the AQDS–rGO composites for investigating the bioreduction performance of As(V)/Fe(III) from the flooded arsenic-rich soil. The addition of AQDS–rGO composites coupled with acetate helped release more 849.87 ± 97.05 μg L⁻¹ of As(III) and 144.02 ± 10.02 mg L⁻¹ of Fe(II) from soil, compared to acetate control at 208.17 ± 35.97 μg L⁻¹ of As(III) and 85.75 ± 4.80 mg L⁻¹ of Fe(II). Meanwhile, the performance was also perceived to be better than the amendments with the mixture of gradient AQDS and acetate, as well as the incorporation of gradient AQDS, rGO and acetate (identified by the maximal levels of Fe(II) and As(III), less than 130.74 ± 22.01 mg L⁻¹ and 675.15 ± 67.06 μg L⁻¹, respectively). Because metal-reducing or metal-oxidizing bacteria in the soil are susceptible to the soluble AQDS level, it would in turn influence the bioreduction performance of As(V)/Fe(III). The mediated strategies of AQDS-composites positively correlated with the loaded contents of AQDS, electrical conductivity and increasing abundance of metal-reducing bacteria (e.g., Desulfitobacterium, Clostridium, Pseudomonas, Geobacter, and Anaeromyxobacter) derived from the AQDS–rGO composites amendments, favor the bioreductive dissolution of As(V)/Fe(III) from the soil. This insight will encourage the application of a promising tool as an alternative technology for remediating arsenic-polluted soil.