Co-sorption of arsenic and fluoride using the hierarchical Mg-La-Fe nanosheets derived from layered double oxides

Abstract

Considering the prevalent natural occurrence of arsenic and fluoride with a higher concentration gradient in groundwater, in this study, a novel MgLaFe layered double oxide material in the form of highly dispersed curly nanosheets (MLF-NS) was prepared using an urea hydrothermal method and low-temperature hydrogen peroxide exfoliation, applying to purity the contaminants of arsenic and fluoride. The prepared MLF-NS possesses exceptional co-sorption properties for As(III), As(V), and F− and the maximum co-sorption capacities (Qm) of As(III), As(V), and F− reach 36.95 mg g−1, 98.70 mg g−1, and 387.68 mg g−1, respectively, which is superior to those of most similar adsorbents. MLF-NS also exhibits excellent stability and reusability which can effectively regenerate and preserve their high adsorption capacity after four adsorption–desorption cycles. The mechanism investigation reveals the expansion of the interlayers due to the adsorbed arsenic ions, combining with the synergistic effect of motherboard cation coordination and exchanging with anions in the interlayer, plays a crucial role in enhancing the adsorption for both arsenic and fluoride. Meanwhile, the well-dispersed MLF-NS overcome the aggregation disadvantage, and thus exposes more adsorption sites to improve the co-removal efficiency of As(III), As(V), and F−. The collaborative analysis of mean adsorption free energy, FT-IR, AFM, XPS, adsorption energy, and CDD support the findings. Overall, the unique properties of MLF-NS make it a promising solution for effective removal of As(III), As(V), and F− in wastewater treatment.