High-Performance Recovery of Vanadium(V) in Leaching/Aqueous Solution by a Reusable Reagent-Primary Amine N1519

Efficient extraction and stripping for recovering vanadium­(V) from the leaching/aqueous solution of chromium-bearing vanadium slag (V–Cr slag) are essential to the reuse of heavy metals. The performance characteristics of a new reagent, primary amine N1519, were first reported for extracting vanadium. With a phase ratio of organic to aqueous up to 1:1, 99.7% of vanadium­(V) can be effectively extracted from the leaching/aqueous solution, and powder of NH₄VO₃ was obtained through the stripping with ammonia. The new reagent can be recyclable in use for sustainable reuse after stripping. Different extraction conditions, e.g., the initial pH of the leaching/aqueous solution and the molar quantity of N1519 were investigated. The powder of vanadium-organic compounds (VOC) with N1519 formed in the process of extraction was obtained and purified through three-steps of solvent-out crystallizations. The hydrogen bond association mechanism of extraction was illustrated with the structure of VOC and the enthalpy change in extraction process. The fast extraction process and slow stripping procedure for recovering vanadium­(V) are suitable for use in annular centrifugal contactors with very short contact/resident times and mixed-settler extractors with very good mass transfer, respectively. The results offer significant advantages over conventional processes

Open-Framework Metal Oxides for Fast and Reversible Hydrated Zinc-Ion Intercalation

The development of high capacity and stable cathodes is the key to the successful commercialization of aqueous zinc-ion batteries. However, significant solvation penalties limit the choice of available positive electrodes. Herein, hydrated intercalation is proposed to promote reversible (de)­intercalation within host materials by rationally designing a matching electrode. In contrast to previously reported works, the as-prepared electrode (NHVO@CC) can achieve fast and reversible intercalation of hydrated zinc ions in the interlayer gap, leading to a high capacity of 517 mAh g–1 at 0.1 A g–1 and excellent electrode stability for long-term cycling. Besides, as a consequence of the flexibility of the NHVO@CC electrode, a quasi-solid-state battery was achieved with equally advantageous electrochemical behavior under various bending states. The proposed hydrated cation direct insertion/extraction sets up an efficient way of developing high-performance positive electrodes for aqueous batteries

Recovery of High-Purity Vanadium from Aqueous Solutions by Reusable Primary Amines N1923 Associated with Semiquantitative Understanding of Vanadium Species

The recovery of high-purity vanadium has attracted significant attention regarding both sustainability and environmental protection necessities. However, insufficient understanding of vanadium species in aqueous solution constrains further optimization of the vanadium recovery process. Here, a closed-loop technical route (extraction and stripping) was realized to recover high-purity vanadium products by in situ monitoring/controlling vanadium species. The evolution of vanadium species in the extraction reaction was semiquantitatively visualized by the system combined with annular centrifugal contactors (ACCs) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), while the active (V4 and V10 species) and nonactive (H2VO4–) vanadium species were identified. In the stripping process, the behaviors of vanadium species have been described, which affected the morphology of recycled NH4VO3 products. As a result, the transformation pathway of vanadium species in the whole recovery process was performed. Under deep studies of vanadium speciation, pilot-scale experiments have been carried out using actual leaching solution, and high-purity V2O5 products (99.9%) were obtained

Sustainable Preparation of LiNi_1/3Co_1/3Mn_1/3O₂–V₂O₅ Cathode Materials by Recycling Waste Materials of Spent Lithium-Ion Battery and Vanadium-Bearing Slag

Waste streams containing heavy metals are always of concern from both environmental and resource-depleting points of view. The challenges are in most cases related to the effectiveness for high-value-added materials recovery from such waste, with which the environmental impacts during recycling shall be low. In this research, two typical heavy-metal-containing waste streams, i.e., spent lithium-ion batteries and vanadium-bearing slag, were simultaneously treated, and this enables regeneration of the LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials which was considered difficult because of the dislocation of nickel and lithium ions during electrochemical performance. By using the intermediate product during vanadium-bearing slag treatment, the vanadium-embedded cathode material can be prepared which delivers excellent electrochemical performances with a specific capacity of 156.3 mA h g^–1 after 100 cycles at 0.1C with the capacity retention of 90.6%; even the additive amount is only 5%. A thin layer of vanadium oxide is found to be effective to promote electrochemical performance of the cathode material. Using the principles of green chemistry, this process enables high-performance cathode material regeneration without introducing extraction chemicals and with much lower environmental impacts as compared to traditional metallurgical technologies

Encapsulated Ni Nanoparticles within Silicalite‑1 Crystals for Upgrading Phenolic Compounds to Arenes

About 3–5 nm Ni nanoparticles were significantly encapsulated within different crystal sizes of a silicalite-1 matrix through tailoring the hydrothermal synthesis conditions and ratios of feeding materials, which were applied in the upgrading of phenolic compounds to arenes via the hydrogenolysis route. The smaller the sizes of Ni@silicalite-1 crystals with similar Ni contents and nanoparticles, the more obvious the active centers could be characterized. The enhancement in both phenol/m-cresol conversion and benzene/toluene selectivity was obtained with the decrease in crystal sizes of Ni@silicalite-1, which originated from the selective elimination of the hydroxyl group, hindrance of further hydrogenation of aromatics, and the formation of methane. Furthermore, Ni@silicalite-1 was first reported for its superior stability for more than 300 h during m-cresol conversion, which maintained a high conversion from 78.4% at 8 h to 76.2% at 334 h and aromatics yield from 73.1% at 8 h to 72.6% at 334 h. Therefore, Ni@silicalite-1 provided an alternative methodology for terminal priority to achieve selectivity control different from hydrogenation on phenyl rings via a thermodynamically favorable flat mode. Ni nanoparticles encapsulated within zeolites provided a new method to regulate the adsorption mode of reactants to modify aromatic selectivity steric effects originating from shape selectivity of the silicalite-1 matrix, which also contributed to much better stability of Ni nanoparticles

Inhibition Role of Solvation on the Selective Extraction of Co(II): Toward Eco-Friendly Separation of Ni and Co

Ternary cathodes account for more than half of the market share for lithium-ion battery cathodes, and recycling draws considerable attention. The traditional extraction process used to separate and recover Co and Ni from spent ternary cathode leachates produces a large amount of saline wastewater; thus, a green method is urgently needed. In this work, we underscore the crucial role played by metal solvation during extraction, and this provides a new perspective for achieving green separation. The extraction mechanism can be described as follows: metal cations M2+ (M–Ni and Co) generate stable hydrated ions M­(H2O)62+ upon solvation. However, Ni­(H2O)62+ and Co­(H2O)62+ exhibit different activities in reactions with acidic extractants (HA) and form different complexes, NiA2·2H2O and CoA2, respectively. Correspondingly, the coordinated water increases the electron density and steric hindrance of the center metal ions and thus inhibits the subsequent extraction. Therefore, a means of reducing solvation (adding lactic acid) was developed, and this approach exhibited good performance. The separation factor was improved by a factor of 192. These results open a new avenue for high-performance selective extraction of Co, which features a green recovery process and is suitable for future use in industrial production

Optimal Design of Solvent Blend and Its Application in Coking Wastewater Treatment Process

One of the key steps of coking wastewater treatment is phenolic and tar removal via extraction. However, the high loss of the extractant, i.e., methyl isobutyl ketone (MIBK), leads to the high cost of the process. The adoption of a novel solvent or solvent blend is considered as an efficient way to address this problem. In this paper, seven solvents (benzene, toluene, m-xylene, ethylbenzene, 1, 3, 5-trimethylbenze, cyclohexane, and octanol), selected as candidate diluters for MIBK according to operating requirements, are studied with a nonlinear programming (NLP) model based on ideal counter-current extraction. The results, verified with experiments, suggest toluene is the most promising candidate. Further investigation of this solvent blend reveals that both <i>D</i>_blend (the distribution coefficient of phenol between solvent blend and water) and <i>m</i>_MIBK (the MIBK concentration in raffinate) increase with <i>x</i>_MIBK (the molar fraction of MIBK in blend). The trade-off between the extraction performance and MIBK loss recommends the blend with <i>x</i>_MIBK = 0.05 as extractant for coking wastewater treatment. An industrial process consisting of extraction, back stripping, distillation, and mixer is presented. A corresponding NLP model is established for its operating optimization. To improve the accuracy, the representatives of typical phenolics and tar in wastewater (2,4 dimethyl phenol, m-xylene, and quinolone) are also considered in addition to phenol. The case study indicates that the blend exhibits economic advantage over pure MIBK with a makeup cost of 11.15 ¥/t, much less than the 185.15 ¥/t in the case of MIBK

Highly Stable and Selective Catalysts for <i>m</i>‑Cresol Hydrogenolysis to Aromatics

Deoxygenation is an essential link for upgrading bio-based low-value phenolics to aromatics, which is achieved through the catalytic hydrogenation way. Herein, we designed and synthesized kinds of Ni-confined catalysts via tailoring the preparation procedures. The highest hydroxyl hydrogenolysis performance (r[garomatics·gNi–1·h–1] = 103.5 at 290 °C) in vapor m-cresol conversion so far was obtained over Ni@Silicalite-1 prepared via the in situ encapsulation method due to the average 2.5 nm Ni nanoparticles uniformly encapsulated within silicalite-1 crystals for improving the shape selectivity with the vertical adsorption mode of phenolics. The appropriate porosities are proven to play a crucial role in shape-selective catalysis for hydroxyl hydrogenolysis of m-cresol. In addition, Ni@Silicalite-1 showed outstanding stability in 200 h long run with 95.5% conversion and 74.2% aromatics yield without obvious deactivation. This work provided a novel insight into tuning hydroxyl hydrogenolysis of phenolics by designing metal@zeolite catalysts with different microenvironments and ultrasmall metal nanoparticles