Vanadium (V) concentrations in organisms are usually very low. To date, among animals, only some urochordate and annelid species contain very high levels of V in their tissues. A new case of hyper-accumulation of V in a distinct animal phylum (Porifera), namely, the two homoscleromorph sponge species Oscarella lobularis and O. tuberculata is reported. The measured concentrations (up to 30 g/kg dry weight) exceed those reported previously and are not found in all sponge classes. In both Oscarella species, V is mainly accumulated in the surface tissues, and in mesohylar cells, as V(IV), before being partly reduced to V(III) in the deeper tissues. Candidate genes from Bacteria and sponges have been identified as possibly being involved in the metabolism of V. This finding provides clues for the development of bioremediation strategies in marine ecosystems and/or bioinspired processes to recycle this critical metal.

Adult corals are among the most sensitive marine organisms to dissolved manganese and experience tissue sloughing without bleaching (i.e., no loss of Symbiodinium spp.) but there are no chronic toxicity data for this sensitive endpoint. We exposed adult Acropora millepora to manganese in 2-d acute and 14-d chronic experiments using tissue sloughing as the toxicity endpoint. The acute tissue sloughing median effect concentration (EC50) was 2560 μg Mn/L. There was no chronic toxicity to A. millepora at concentrations up to and including the highest concentration of 1090 μg Mn/L i.e., the chronic no observed effect concentration (NOEC). A coral-specific acute-to-chronic ratio (ACR) (EC50/NOEC) of 2.3 was derived. These data were combined with chronic toxicity data for other marine organisms in a species sensitivity distribution (SSD). Marine manganese guidelines were 190, 300, 390 and 570 μg Mn/L to provide long-term protection of 99, 95, 90, and 80 % of marine species, respectively.

We propose a novel integrated model for the recovery of tantalum from tantalum-rich waste using a combination of hydrometallurgical and bio-metallurgical processes. To this end, leaching experiments with heterotrophs (Pseudomonas putida, Bacillus subtilis and Penicillium simplicissimum) were carried out. The heterotrophic fungal strain leached manganese with an efficiency of 98%; however, no tantalum was detected in the leachate. An unidentified species did mobilise 16% tantalum in 28 days in an experiment with non-sterile tantalum capacitor scrap. Attempts to cultivate isolate and identify these species failed. The results of a range of leaching trials resulted in an effective strategy for Ta recovery. A bulk sample of homogenised Ta capacitor scrap was first subjected to microbial leaching using Penicillium simplicissimum, which solubilised manganese and base metals. The residue was subjected to the second leach using 4 M HNO3. This effectively solubilised silver and other impurities. The residue collected after the second leach was pure tantalum in concentrated form. The hybrid model produced derives from observations from previous independent studies and shows that we can effectively recover tantalum along with silver and manganese in an efficient and environmentally friendly manner from tantalum capacitor scrap.

The essence behind metal solvent extraction is the interaction between metal species and organic extractants. Aqueous metal species tuning at the molecular level is critical to improve the extraction efficiency and selectivity of the target metal. Herein, we demonstrate a quantitative metal species tuning strategy which is capable of extracting the most critical metals (e.g., V, W, and Mo) in extraction systems constructed by amines. We reveal the superior activities of V4 and V10 species among various V and Cr species by calculations and experiments. In addition, the contribution of various Vn species was quantitatively evaluated via Ion Species Contribution Evaluation (ISCE). Our tuning strategy is rationally designed by bridging species characteristics and routine aqueous conditions with extraction activities. Consequently, a three-dimensional model of V and Cr solvent extraction is established for the prediction of reaction regions, and the reactivities of nearly 20 kinds of typical metal species are compared and predicted. Our strategy serves for industrial solvent extraction, and may provide inspiration for the traditional hydrometallurgical revolutionary.

In a circular economy context, there is a growing need for more sustainable waste management options to recover elements from end-of-life materials. These \"secondary ores\" represent a source of critical elements that are often present in higher concentration compared to their primary ore. In this work, the recovery of lanthanum (La) from waste nickel metal hydride battery (NiMH) leachate is investigated using an aqueous biphasic system (ABS) process based on a pluronic triblock copolymer (L35). An initial screening is performed to determine the influence of the ABS phase forming salt anion and alizarin red extractant on the La extraction efficiency and selectivity. From these results, a three-step ABS process is developed, varying only the nature of the salt and requiring no additional extractant. In a first step, the ABS composed of L35 + thiocyanate ammoniun + H2O efficiently extracts iron, manganese, and cobalt leaving La, cerium, and Ni in solution. Nickel is subsequently recovered by precipitation using dimethylglyoxime. Finally, La is separated from cerium using the L35 + ammonium nitrate + H2O ABS, recovering 62 g of La with 94% purity per kilogram of black mass of NiMH battery. This work highlights the applicability of ABS for the treatment of raw and complex matrices, potentially allowing for a greener hydrometallurgical treatment of wastes.