Large-scale comprehensive utilization of coal fly ash (CFA) has become an inevitable issue. In this study, one-step mixed alkali (KOH + CaO) hydrothermal extraction of alumina and synergistic preparation of soil amendment from CFA was developed. The Al 2 O 3 and SiO 2 in CFA were dissolved rapidly under the action of KOH, and the dissolved silicate was transformed into tobermorite under the action of CaO. This approach realized efficient separation of aluminum and silicon with simultaneous regeneration of KOH. The optimum leaching ratio of Al 2 O 3 was 56.44 %, while the leaching ratio of SiO 2 was 3.38 %. The dealuminated CFA (DACFA) was simultaneously transformed into porous aggregates intertwined with tobermorite fibers, which are rich in Si, Ca and K 2 O nutrients due to the excellent cation exchange of tobermorite or formation of tobermorite and leucite minerals. The effective Si, Ca, and K 2 O in F90 were 16.19 %, 20.45 % and 5.31 %, respectively, which met the primary standard of fertilizer. The pot experiment showed that DACFA effectively improved soil quality and immobilized soil heavy metals, thereby accelerating the growth of pakchoi. Through this technology, the high-value transformation from CFA to alumina and soil amendments is expected to facilitate large-scale utilization of CFA and enhance agricultural productivity.
Jiaxin Wu,Zhi Li,Xingliang Meng,Bo Cheng,Jing Yang,Binbin Li,Xinyu Wang
Promoting mechanical strength and osteoinductivity properties is crucial for dental implants materials. Herein, we synthesized silicocarnotite (CPS) powder via a hydrothermal method, and mixed it with zirconia to create a composite material for preparing four slurries: xCPS-(1−x)ZrO 2 (x = 0, 1/6, 1/3, and 1/2 vol%). The optimal printing parameters for each slurry were investigated. Following the printing of the slurries, debinding was performed on them in the temperature range of 25 °C–600 °C in nitrogen atmosphere and 600 °C–1000 °C in air atmosphere, respectively, followed by sintering at 1350 °C for 2 h. The graded zirconia-based composite ceramics prepared using stereolithography (SLA) exhibited excellent mechanical properties, including a flexural strength of 742.37 ± 22.52 MPa, Vickers hardness of 7.29 ± 0.15 GPa, fracture toughness of 5.34 ± 0.29 MPa m 1/2 , and a relative density of 96.3 %. Compared with zirconia ceramics, the graded composite ceramics displayed higher surface roughness. The graded composite ceramics degraded and released Ca, Si, and P ions, promoting MC3T3-E1 cells proliferation, adhesion, and osteogenic differentiation. These findings suggest that ZrO 2 -CPS/ZrO 2 graded composite ceramics synthesized via SLA holds great potential as dental implants with high osteoinductivity.
The treatment of infective or potentially infectious bone defects is a critical problem in the orthopedic clinic. Since bacterial activity and cytocompatibility are always contrary factors, it is hard to have them both in one material. The development of bioactive materials with a good bacterial character and without sacrificing biocompatibility and osteogenic activity, is an interesting and valuable research topic. In the present work, the antimicrobial characteristic of germanium, GeO2was used to enhance the antibacterial properties of silicocarnotite (Ca5(PO4)2SiO4, CPS). In addition, its cytocompatibility was also investigated. The results demonstrated that Ge–CPS can effectively inhibit the proliferation of bothEscherichia coli(E. coli) andStaphylococcus aureus(S. aureus), and it showed no cytotoxicity to rat bone marrow-derived mesenchymal stem cells (rBMSCs). In addition, as the bioceramic degraded, a sustainable release of germanium could be achieved, ensuring long-term antibacterial activity. The results indicated that Ge–CPS has excellent antibacterial activity compared with pure CPS, while no obvious cytotoxicity was observed, which could make it a promising candidate for the bone repair of infected bone defects.Keywords:implant material;silicocarnotite;germanium dioxide;antibacterial activity;cytocompatibility
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