Novel Technology for the Removal of Fe and Al from Spent Li-Ion Battery Leaching Solutions by a Precipitation–Complexation Process

The conventional neutralization method for removing impurities Fe(III) and Al(III) from spent Li-ion battery (LIB) leaching solutions has encountered problems of low impurity removal efficiency or high loss of valuable metals. In this study, highly selective and effective separation of Fe(III) and Al(III) from spent LIB leaching solutions was achieved by the precipitation–complexation technology. It was found that almost all Fe(III) together with most of the Al(III) could be removed by preferential precipitation using NaHCO3 neutralization under an equilibrium pH of 3.3 at 95 °C. Phytic acid, as a selectively complexing agent, was then introduced to completely remove the residual Al(III) from Fe-removed solutions with an Al/PA molar ratio of 3:1 at 60 °C. As a result, more than 99.5% Fe(III) and 97.08% Al(III) could be removed from the actual solutions, with a total loss of Ni, Co, Mn, and Li of only 1.1%. Furthermore, the obtained Al-phytates could be decomposed to form Al(PO3)3 products at 1000 °C. The whole process not only realized the efficient removal of Al(III) and Fe(III) at low pH with minimal loss of Ni, Co, Mn, and Li but also reduced the emission of wastes and utilized the Al resources

Polysaccharide-Based Composite Hydrogel with Hierarchical Microstructure for Enhanced Vascularization and Skull Regeneration

Critical-size skull defects caused by trauma, infection, and tumor resection raise great demands for efficient bone substitutes. Herein, a hybrid cross-linked hierarchical microporous hydrogel scaffold (PHCLS) was successfully assembled by a multistep procedure, which involved (i) the preparation of poly(lactic-co-glycolic)/nanohydroxyapatite (PLGA-HAP) porous microspheres, (ii) embedding the spheres in a solution of dopamine-modified hyaluronic acid and collagen I (Col I) and cross-linking via dopamine polyphenols binding to (i) Col I amino groups (via Michael addition) and (ii) PLGA-HAP (via calcium ion chelation). The introduction of PLGA-HAP not only improved the diversity of pore size and pore communication inside the matrix but also greatly enhanced the compressive strength (5.24-fold, 77.5 kPa) and degradation properties to construct a more stable mechanical structure. In particular, the PHCLS (200 mg, nHAP) promoted the proliferation, infiltration, and angiogenic differentiation of bone marrow mesenchymal stem cells in vitro, as well as significant ectopic angiogenesis and mineralization with a storage modulus enhancement of 2.5-fold after 30 days. Meanwhile, the appropriate matrix microenvironment initiated angiogenesis and early osteogenesis by accelerating endogenous stem cell recruitment in situ. Together, the PHCLS allowed substantial skull reconstruction in the rabbit cranial defect model, achieving 85.2% breaking load strength and 84.5% bone volume fractions in comparison to the natural cranium, 12 weeks after implantation. Overall, this study reveals that the hierarchical microporous hydrogel scaffold provides a promising strategy for skull defect treatment