Nanospherical inorganic α-Fe core-organic shell necklaces for the removal of arsenic(V) and chromium(VI) from aqueous solution

Mesoporous nanospherical necklaces (NSN) of inorganic α-Fe core-organic shell and ethylenediaminetetraacetic acid (EDTA) were fabricated. The necklaces were 1 μm in length and 50 nm in thickness, with massive nanospherical particles connecting and overlapping in a neat micro-/nano-necklace archery cage for capturing/trapping of As(V) and Cr(VI) species from water sources. The α-Fe core and the dressing shell of EDTA provided numerous active sites for adsorption, which led to 100% adsorption uptake of these toxic ions. The adsorption isotherms revealed that NSN adsorbent with mesoporous caves and organic-decorated surfaces was promising and effective for the spontaneous and endothermic removal of both ions from contaminated water. The NSN structure exhibited long-term stability. The adsorption efficiency and uptake of the deleterious arsenic and chromium species were achieved after multi-particulate processing of reuse cycles. The pH-dependent removal of As(V) and Cr(VI) species is an emerging topic in selective adsorption assays among competitive ions. Furthermore, the ion-selective conditions at pH 5 for As(V) and pH 7 for Cr(VI) significantly affected the adsorption capacity and affinity of 306.7 and 406.5 mg g⁻¹ into NSN cages, respectively. The obtained results could be used as a basis to provide effective and low-cost products for the purification of wastewater resources from toxic metals.