Enhanced removal of Sb(V) from aqueous solutions using layered double hydroxide modified with sodium dodecyl sulfate

In this study, surfactant-modified layered double hydroxides (LDHs) were prepared via a hydrothermal method using sodium dodecyl sulfate (SDS). The synthesized sorbent (DS-LDH) was utilized for the removal of Sb(V) from aqueous solutions. The results demonstrated that DS4-LDH with a SDS/(Mg2++Al3+) molar ratio of 0.35 exhibited excellent Sb(V) sorption ability (136 mg g−1), which was 11 times that of pure LDH (12 mg g−1), for an initial Sb(V) concentration of 40 mg L−1. Acidic and alkalescent aqueous solutions and ionic strength hardly affected Sb(V) sorption by DS4-LDH, whereas strong alkalinity inhibited Sb(V) sorption. Under neutral conditions, coexisting anions, including sulfate and phosphate, exhibited a significant influence on Sb(V) removal, whereas chloride, acetate, and carbonate had negligible effects. Ion exchange and the formation of brandholzite-like structures primarily contributed to the Sb(V) sorption by DS4-LDH. The intercalation of dodecyl sulfate ions in LDH increased the interlayer spacing, which enhanced anion exchange between the original interlayer ions of LDH and Sb(OH)6-, and facilitated contact between the interlayer functional sites and Sb(OH)6-, leading to an improved removal of Sb(V). This study proposes a new concept for the development of high-performance LDH sorbents modified by organic surfactants, which could be promising remediating substances for the efficient removal of Sb(V).