Separation of Rare-Earth Ions from Mine Wastewater Using B₁₂S Nanoflakes as a Capacitive Deionization Electrode...

In this study, nanoflakes of B₁₂S were fabricated by plasma-assisted reaction of sulfur dichloride in an ionic liquid at room temperature using europium boride as a hard template. The nanoflakes had an average width and thickness of about 3 ₁urn and 9.6 nm, respectively, and a large specific surface area of 1197.2 m² g ¹. They behaved like typical electric double-layer capacitors with a capacitance of 201.2 F g ¹ at 0.2 mA cm ² During capacitive deionization to recover rare-earth ions, the nanoflakes had higher adsorption selectivity for Sm³⁺ than for other competing ions present in real mine waste water. This is due to the strong interaction of the electron-concentered S-groups (S''') of the nanoflakes with S m³⁺. This provides an alternative to construct efficient systems to specifically remove Sm³⁺ from aqueous solution using B₁₂S nanoflakes. This process demonstrates that other boron sulfide compounds can be used to recover valuable ions by capacitive deionization.