Recovery of Iridium by Solvent Extraction and Direct Electrodeposition Using Phosphonium-Based Ionic Liquids

Abstract

The extraction behavior of Ir(IV) in a phosphonium-based ionic liquid (IL) system, triethyl-n-pentyl phosphonium bis(trifluoromethyl-sulfonyl)amide ([P2225][NTf2]), was investigated using an amine extractant. In addition, the electrochemical behavior of the extracted Ir(IV) species in [P2225][NTf2] during electrodeposition was studied. Voltammetry-based electrochemical analysis revealed that the reduction of Ir(IV) proceeded via an intermediate Ir(III) species in two steps, namely, Ir(IV) + e− → Ir(III) and Ir(III) + 3e− → Ir(0). Diffusion coefficients of the extracted Ir(IV) species in the IL were determined over the temperature range of 298–373 K using semi-integral and semi-differential analyses, and values obtained from the two analyses were consistent with each other. Furthermore, consecutive solvent extraction and electrodeposition of Ir metal in the IL bath were performed for 10 cycles. The entire Ir electrodeposit was in the metallic state, as is evident from the 4f 7/2 spectrum obtained by XPS.

Recovery of Palladium by Extraction-electrodeposition Using N, N, N’, N’, N”, N”- Hexaoctyl-nitrilotriacetamide

“…Hence, the development of extraction-electrodeposition processes to reduce the volume of secondary waste is very important. We have also demonstrated the recovery of Pd [13] , ruthenium (Ru) [14] , iridium (Ir) [15] , and platinum (Pt) [16] from the loaded organic phase by consecutive extraction-electrodeposition processes in our previous studies.…”

Modulating Electronic Structure of Iridium Single‐Atom Anchored on 3D Fe‐Doped β‐Ni(OH)2 Catalyst with Nanopyramid Array Structure for Enhanced Oxygen Evolution Reaction

“…[27] The Ir 4f spectrum (Figure 2b) shows that the binding energy of Ir 4f 5/2 for the SAs Ir/Fe-𝛽-Ni(OH) 2 /NF appears at 65.25 eV, which is higher than those of Ir with zero valence while lower than that of Ir with trivalent valence, which is because Ir atoms obtain more electrons through Ir─O─Ni bonds, resulting in Ir atoms carrying more electrons than Ir 3+ in the raw material. [28,29] activity and the turnover frequency (TOF) of the SAs Ir/Fe-𝛽-Ni(OH) 2 /NF were also calculated to investigate the electrocatalytic intrinsic activity of SAs Ir/Fe-𝛽-Ni(OH) 2 . [31,32] As shown in Figure S4 (Supporting Information), LSV curves normalize with the mass of Ir shows that 0.6-SAs Ir/Fe-𝛽-Ni(OH) 2 exhibits the best OER performance, and the TOF result shows that the values of 0.6-SAs Ir/Fe-𝛽-Ni(OH) 2 are significantly higher than that of the other as-prepared electrode materials (Table S2, Supporting Information), suggesting that the electrode of intrinsic activity mostly depend on the mass of Ir.…”

Recovery of Gold by Solvent Extraction and Direct Electrodeposition Using Phosphonium-Based Ionic Liquids

“…Silver recovery from acidic solution using SX, followed by the electrochemical stripping of the extracted Ag(I)-calixarene complex is one of the methods reported [5]. Furthermore, we could show that SX and electrodeposition (ED) can recover Ru [6], Ir [7], and Pt [8] metals from phosphonium-based ILs. This novel SX-ED process using an IL has several advantages, including the elimination of numerous complex processing steps, reduced secondary waste generation, reduced environmental risk, a significant volume reduction, and easy handling of the electrodeposits.…”