Characteristics and mechanism of effectively capturing arsenate by sulfate intercalated and self-doping layered double hydroxide derived from field acid mine drainage.

[Display omitted] • A novel sulfate intercalated and self-doping LDHs was derived from the field AMD. • Effects of Mg2+/Fe3+ molar ratios and coexisting ions on the characteristics of LDHs synthesized from AMD were evaluated. • The LDHs exhibit superior capacity for immobilization As(V) under a wide range of pH values. • Anion exchange and complexation play crucial roles in As(V) removal. • The quality of AMD was improved after being utilized as a source of metal and sulfate precursors for the formation of LDHs. A novel approach was investigated for the synthesis of sulfate intercalated iron based layered double hydroxides (LDHs) from field acid mine drainage (AMD) by co-precipitating Fe3+, Mg2+ and SO 4 2− ions. By strategically controlling the Mg2+/Fe3+ molar ratios in AMD, the structural and interfacial properties of LDHs were effectively regulated. Compared to LDHs synthesized from chemical reagents, which had charge density of 3.99 e/nm2 and basal spacing of 0.816 nm, the AMD-synthesized LDHs exhibited higher charge density of 5.34 e/nm2 and larger interlayer d-spacing (0.872 nm) due to the incorporation of co-existing Al3+ and Ca2+ in AMD. The LDHs synthesized from AMD displayed a higher adsorption capacity of 80.16 mg/g and demonstrated strong anti-interference ability, with the removal efficiency of As(V) being maintained at approximately 96% across a pH range of 2.0 to 9.0. The effective capture of arsenate was attributed to the anion exchange of arsenate ions with interlayer sulfate, as well as the strong metalloid binding affinities between the -OH active sites and arsenate. This study revealed that the self-doping LDHs derived from AMD were superior for As(V) removal and the adverse impacts of AMD were alleviated. [ABSTRACT FROM AUTHOR]