With the rapid development of the electronics industry, efficient gold recovery from electronic waste bears substantial economic benefits and carries profound ecological importance. In this study, by means of 3D printed technology, a polyethylenimine/graphene oxide/calcium alginate (3D PGC) composite adsorbent with millimeter-to-micrometer multilevel macroporous morphology has been successfully constructed. Excellent hydrophilicity and gold adsorption capacity have been confirmed, with values of 1120 mg g-1 (298.15 K), 1406 mg g-1 (308.15 K), and 1598 mg g-1 (318.15 K) being achieved for Au3+ adsorption under a pH of 2.5, respectively. This remarkable adsorption performance is attributed to its multi-scale structural optimization and abundant surface-active functional groups (nitrogen and oxygen-containing groups). Characterization suggests that the adsorption of Au3+ on the 3D PGC surface is attributed to the synergistic effects of electrostatic interactions and redox reactions. Furthermore, 3D PGC displays a highly efficient selective adsorption capability for Au3+, maintaining a high adsorption capacity even after 8 cycles of repeated adsorption-desorption. In practical applications, without pH adjustment, the specific selectivity of 3D PGC for Au3+ in real acidic gold-containing aqueous solution reaches up to 96%. Furthermore, the gold adsorbed on the 3D PGC can be desorbed through acid washing, and subsequently reduced using oxalic acid to obtain foam gold. After calcination, elemental gold can be obtained, thereby achieving gold recovery. Therefore, owing to its exceptional multi-level macroporous structure and modified active functional groups, 3D PGC presents efficient selective adsorption capability for Au3+ in acidic aqueous solutions, indicating substantial potential to be applied in the efficient gold recovery from electronic waste.
With the rapid development of the electronics industry, efficient gold recovery from electronic waste bears substantial economic benefits and carries profound ecological importance. In this study, by means of 3D printed technology, a polyethylenimine/graphene oxide/calcium alginate (3D PGC) composite adsorbent with millimeter-to-micrometer multilevel macroporous morphology has been successfully constructed. Excellent hydrophilicity and gold adsorption capacity have been confirmed, with values of 1120 mg g-1 (300.15 K), 1406 mg g-1 (310.15 K), and 1598 mg g-1 (320.15 K) being achieved for Au3+ adsorption under a pH of 2.5, respectively. This remarkable adsorption performance is attributed to its multi-scale structural optimization and abundant surface-active functional groups (nitrogen and oxygen-containing groups), surpassing the reported capacities of similar adsorbents in the literature. Characterization suggests that the adsorption of Au3+ on the 3D PGC surface is attributed to the synergistic effects of electrostatic interactions and redox reactions. Furthermore, 3D PGC displays a highly efficient selective adsorption capability for Au3+, maintaining a high adsorption capacity even after 8 cycles of repeated adsorption-desorption. In practical applications, without pH adjustment, the specific selectivity of 3D PGC for Au3+ in real acidic gold-containing aqueous solution reaches up to 96%. Furthermore, the gold adsorbed on the 3D PGC can be desorbed through acid washing, and subsequently reduced using oxalic acid to obtain foam gold. After calcination, elemental gold can be obtained, thereby achieving gold recovery. Therefore, owing to its exceptional multi-level macroporous structure and modified active functional groups, 3D PGC presents efficient selective adsorption capability for Au3+ in acidic aqueous solutions, indicating substantial potential to be applied in the efficient gold recovery from electronic waste.
Abstract Artificial bone is the alternative candidate for the bone defect treatment under the circumstance that there exits enormous challenge to remedy the bone defect caused by attributes like trauma and tumors. However, the impact of pore size discrepancy for regulating new bone generation is still ambiguous. Using direct 3D printing technology, customized 3D polycaprolactone/ β -tricalcium phosphate (PCL/ β -TCP) artificial bones with different structural pore sizes (1.8, 2.0, 2.3, 2.5, and 2.8 mm) were successfully prepared, abbreviated as the 3D PCL/ β -TCP. 3D PCL/ β -TCP exhibited a 3D porous structure morphology similar to natural bone and possessed outstanding mechanical properties. Computational fluid dynamics analysis indicated that as the structural pore size increased from 1.8 to 2.8 mm, both velocity difference (from 4.64 × 10 −5 to 7.23 × 10 −6 m s −1 ) and depressurization (from 7.17 × 10 −2 to 2.25 × 10 −2 Pa) decreased as the medium passed through. In vitro biomimetic mineralization experiments confirmed that 3D PCL/ β -TCP artificial bones could induce calcium–phosphate complex generation within 4 weeks. Moreover, CCK-8 and Calcein AM live cell staining experiments demonstrated that 3D PCL/ β -TCP artificial bones with different structural pore sizes exhibited advantageous cell compatibility, promoting MC3T3-E1 cell proliferation and adhesion. In vivo experiments in rats further indicated that 3D PCL/ β -TCP artificial bones with different structural pore sizes promoted new bone formation, with the 2.5 mm group showing the most significant effect. In conclusion, 3D PCL/ β -TCP artificial bone with different structural pore sizes could promote new bone formation and 2.5 mm group was the recommended for the bone defect repair.
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