Uranium extraction through the in situ leaching method stands as a pivotal approach in uranium mining. In an effort to comprehensively assess the repercussions of in situ uranium leaching on groundwater quality, this study collected 12 representative groundwater samples within the Bayan-Uul mining area. The basic statistical characteristics of the water samples showed that the concentrations of SO₄²⁻ and total dissolved solids (TDS) were relatively high. Through the use of cluster analysis, the water samples were categorized into two distinct clusters. Seven samples from wells W-d, W-u, N01, W10-2, W08-1, W10-1, and W13-1, situated at a considerable distance from the mining area, were grouped together. Conversely, five samples from wells W08-2, W13-2, W01-1, W02-2, and the pumping well located in closer proximity to the mining area, formed a separate cluster. A decision tree-based machine learning approach was employed to discern the influence of various hydrochemical indicators in forming these clusters, with results indicating that SO₄²⁻ exerts the most substantial influence, followed by Ca²⁺. The mineral saturation indices from geochemical modeling indicated that, as the distance from the mining area increased, the trend of calcium minerals changed from dissolution to precipitation; iron minerals were in a precipitation state, and the precipitation trend was gradually weakening. In light of these findings, it is clear that in situ uranium leaching significantly impacted the groundwater in the vicinity of the mining area. The prolonged consumption of groundwater sourced near the study area, or its use for animal husbandry, poses potential health risks that demand heightened attention.

Photoreduction of CO₂ into the chemical feedstocks of fuels provides a green way to help solve both the energy crisis and carbon emission issues. Nevertheless, undesirable charge separation and migration, as well as rapid reverse charge recombination results in the unsatisfactory photocatalytic activity of most conjugated microporous polymers (CMPs). Herein, a pair of donor–acceptor (D-A) CMPs for CO₂ photoconversion was developed through position isomerism by altering linkage sites. The results show that Py-D₂₇F with 2,7-site linkage exhibits a completely conjugated structure and a large molecular dipole moment, thus significantly accelerating charge separation and transfer. As a result, Py-D₂₇F achieves a higher yield of 320.9 μmol g⁻¹ h⁻¹ for CO₂-to-CO photoreduction (without the addition of any photosensitizers and precious metals), which is about three-fold greater than that of Py-D₃₆F (3,6-site linkage). This study provides a valuable idea for exploring outstanding CMP photocatalysts for the efficient processing of photocatalysis.

Bioleaching of heavy metals from sludge from acid-leached waste lithium batteries is limited by the restricted maximum acid-producing ability of a single bacterium. Compatibility of acidophilic autotrophic bacteria in bioleaching is desirable. Herein, five microorganisms, including Acidithiobacillus ferrooxidans (Af), Leptospirillum ferriphilum (Lf), Thiobacillus thiooxidans (Tt), Acidithiobacillus caldus (Ac), Sulfobacillus thermotolerans (St) and their mixed microbial consortia (MC), were applied to leach Ni and Co from sludge from acid-leached waste lithium batteries. Bioleaching kinetics were investigated as functions of single bacterium species, MC species, Ac and St ratios in MC, and solid/liquid ratio. Compared with the single bacterium, the bioleaching ratios of MC with 20% of Ac and 20% of St (45 °C and a solid/liquid ratio of 10%) were 1.17 times higher for Ni (bioleaching ratio of 88.4% and equilibrium time of 8 days), and MC with 25% of St (40 °C and solid/liquid ratio of 10%) presented 1.18 times higher bioleaching efficiency for Co (bioleaching ratio of 75.4% and equilibrium time of 6 days). The quantitative ratios of Ni and Co species, including acid-soluble, reducible, oxidizable, and residual states in the remaining bioleached sludge, were determined. MC presented optimal bioleaching efficiency with 90.3% for the leached fraction and 5.9% for the residual fraction for Ni, and 82.9% for the leached fraction and 11.8% for the residual fraction for Co. This study provides a valuable reference for efficiently bioleaching waste lithium batteries.

Various porous polymer materials have been prepared for the separation of CO₂ from mixed gases. However, complex processes, expensive monomers, and costly catalysts are commonly used for their synthesis, making the adsorbents difficult to achieve in industrial applications. Herein, we developed a strategy to fabricate a series of benzene rings containing porous polymer materials (B-PPMs) via a facile condensation reaction of two inexpensive monomers, namely tetraphenylsilane and 1,4-bis(bromomethyl)benzene. The B-PPMs are verified to have accessible surface areas, large pore volumes, and appreciate pore sizes via a series of characterizations. The B-PPM-2 exhibits the best CO₂ adsorption amount of 67 cm³·g⁻¹ at 273 K and 1 bar, while the CO₂/N₂ selectivity can reach 64.5 and 51.9 at 273 K and 298 K, respectively. Furthermore, the adsorbent B-PPM-2 can be completely regenerated after five cycles of breakthrough experiments under mild conditions, which may provide promising candidates for selective capture of CO₂ from mixtures.