Enhanced metal bioleaching mechanisms of extracellular polymeric substance for obsolete LiNixCoyMn1-x-yO2 at high pulp density.

Harmful chemicals present in electric vehicle Li-ion batteries (EV LIBs) can limit the pulp density of bioleaching processes using Acidithiobacillus sp. to 1.0% (w/v) or lower. The strong enhancing mechanisms of extracellular polymeric substances (EPS) on the bioleaching of metals from spent EV LIBs at high pulp density (4% w/v) were studied using bio-chemical, spectroscopic, surface structure imaging and bioleaching kinetic methods. Results demonstrated that the added EPS significantly improved bioleaching efficiency of Ni, Co and Mn improved by 42%, 40% and 44%, respectively. EPS addition boosted the growth of cells under adverse conditions to produce more biogenic H+ while Fe3+ and Fe2+ were adsorbed by the biopolymer. This increased Li extraction by acid dissolution and concentrated the Fe3+/Fe2+ cycle via non-contact mechanisms for the subsequent contact bioleaching of Ni, CO and Mn at the EV LIB-bacteria interface. During the leaching process, added EPS improved adhesion of the bacterial cells to the EV LIBs, and the resultant strong interfacial reactions promoted bioleaching of the target metals. Hence, a combination of non-contact and contact mechanisms initiated by the addition of EPS enhanced the bioleaching of spent EV LIBs at high pulp density.

Novel Electrodeposition Method for Cu-In-Cd-Ga Sequential Separation from Waste Solar Cell: Mechanism, Application, and Environmental Impact Assessment.

While CIGS solar cell has been experiencing an expanded photovoltaic market and increasing research interest in cell design, its treatment after obsoletion remains an upcoming issue. The heavy metals involved, such as Cd, can threat the environment, while strategic resources, such as rare metals In and Ga, offer a great recycling oppotunity. However, due to its multimetal feature, traditional recycling methodology shows poor separation-extraction efficiency and additional environmental burdens with intense reagent consumption and waste generation. Here, we report a sequential electrodeposition method for pure metal recycling from this Cu-In-Cd-Ga quaternary system in a more environmentally friendly and efficient manner. Stability constant-corrected redox potential supplemented with metal electroreduction tests predicts well the potential window for sequential electrodeposition. Cu and In electrodeposition shows 100% separation with high Coulombic efficiency (>80%), whereas Ga electrodeposition presents slower kinetics and performs better at a pH of 2.5. Environmental impact assessment indicates that the proposed recycling route allows remarkable reduction of global warming and toxicity impacts compared with metal production from virgin mining and reference processes. We further unveiled the applicability of the electrodeposition technique in the context of anthropogenic mineral recycling, emphasizing resource sustainability and cleaner production.

Unlikely lead-bearing phases in river and estuary sediments near an ancient mine (Huelgoat, Brittany, France).

Anthropocene mineral diversity is the result of the purification of metals naturally combined with other chemical elements in natural environment. Moreover, the advent of human mining and manufacturing mineral-like compounds has experienced a punctuation event in diversity and distribution owing to the pervasive impact of human activities. In this context, the wastes of an abandoned historical mine, Huelgoat mine (Brittany, France), famous during the eighteenth and the nineteenth century contain significant amounts of chemical elements potentially dangerous to the environment. Lead concentration and Pb-bearing phases were quantified in 7 sediments samples located from mine upstream to the Aulne estuary (100 km downstream to the mine). Results show very high concentrations of lead in the stations located upstream and downstream of the Huelgoat mine, using X-ray fluorescence spectroscopy, ranging from 7000 mg/kg downstream of the mine to a natural concentration of about 80 mg/kg upstream. At the same time, Pb-bearing phases were identified depending on the particle sizes, fine (< 50 µm) and coarse (> 50 µm), using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), total organic carbon (TOC), and pH analyses. For the first time, evidence of anthropogenic mineral "iodoplumbate" formation has been described in a natural environment.