Selective recovery of lithium and ammonium from spent lithium-ion batteries using intercalation electrodes.

Recycling lithium-ion batteries has recently become a major concern. Ammonia leaching is commonly employed in such battery recycling methods since it has various advantages such as low toxicity and excellent selectivity toward precious metals. In this study, an electrochemical system with intercalation-type electrodes was used to investigate the selective recovery of lithium and ammonium from ammonia battery leachate. Using an activated carbon electrode as a counter electrode, the selectivity of lithium from the lithium manganese oxide (LMO) electrode and the selectivity of ammonium from the nickel hexacyanoferrate (NiHCF) electrode were examined within the system. The LMO//NiHCF system was next evaluated for lithium and ammonium recovery using a synthetic solution as well as real ammonia battery leachate. When compared to previous ammonium recovery methods, the results revealed good selectivity of lithium and ammonium from each LMO and NiHCF electrode with relatively low energy consumption for ammonium recovery (2.43 Wh g-N-1). The average recovery capacity of lithium was 1.39 mmol g-1 with a purity of up to 96.8% and the recovery capacity of ammonium was 1.09 mmol g-1 with 97.8% purity from the pre-treated leachate. This electrochemical method together with ammonia leaching can be a promising method for selective resource recovery from spent lithium-ion batteries.

Cation selectivity of activated carbon and nickel hexacyanoferrate electrode materials in capacitive deionization: A comparison study.

In this study, the electrosorption selectivity of porous activated carbon (AC) and nickel hexacyanoferrate (NiHCF), which represent two working mechanisms of capacitive electrosorption and redox intercalation, was investigated to separate cations in capacitive deionization (CDI). The cyclic voltammetry diagrams of AC showed the rectangular shape of double-layer charging, while that of NiHCF showed separated peaks associated with redox reactions. The specific capacitance of NiHCF was 143.6 F/g in 1 M NaCl, which was almost two times higher than that of AC. Cation selectivity experiments were conducted in single-pass CDI for a multi-cation solution. The electrosorption preference of the AC cathode was determined by a counterbalance between the ionic charge and hydrated size, reflecting the selectivity coefficient of different cations over Na+ in the range of 0.86-2.63. For the NiHCF cathode, the cation selectivity was mainly dominated by the hydrated radius and redox activity. Notably, high selectivities of K+/Na+ ≈ 3.57, Na+/Ca2+ ≈ 9.97, and Na+/Mg2+ ≈ 18.92 were obtained. A significant improvement in the electrosorption capacity and monovalent ion selectivity can be achieved by utilizing the NiHCF electrode. The study demonstrates the fundamental aspects and promising opportunities of CDI in regard to ion selectivity.

Lithium adsorptive properties of H2TiO3 adsorbent from shale gas produced water containing organic compounds.

Shale gas produced water is a by-product from shale gas production which causes environmental issues and needs for a wastewater treatment process. Lithium is one of the valuable metals that exists in the shale gas produced water, and it can be recovered during the water treatment process. However, the concentration of organic carbon in the produced water is significantly high, and these organic compounds may affect the lithium recovery efficiency. Therefore, the lithium adsorption from shale gas produced water containing organic compounds was carried out in this study to observe the influence of organic compounds on lithium adsorption using H2TiO3 adsorbent. The equilibrium time from the kinetic study and the maximum adsorption capacity calculated from the Langmuir isotherm equation decreased with the addition of organic compounds to the produced water. Overall, lithium was selectively recovered from the pH buffered shale gas produced water with or without organic compounds. However, the results indicate the addition of organic compounds, especially the smaller-molecular-weight organic compound, to the produced water inhibits the lithium adsorption significantly.