As a solid waste, kaolinite-type pyrite flotation tailings (KPFT) are a type of low-quality kaolin that contain impurities, such as iron and titanium. In this study, KPFT were calcined at 800 °C for two hours. The calcined production (CKPFT), which is mainly metakaolin, was used as the silicon and aluminum source to synthesize 4A zeolite (Na12[(AlO2)12(SiO2)12]·27H2O) via hydrothermal synthesis. The optimal hydrothermal synthesis conditions were determined from X-ray diffraction phase analysis, relative crystallinity (RC), and cation ion exchange capacity (CEC). The optimal hydrothermal synthesis conditions were determined to be a ratio of 5 g CKPFT, 6.5 g NaOH, 65 mL H2O, crystallization temperature 110 °C, and crystallization time of three hours. Under the optimal hydrothermal synthesis conditions, the RC and CEC of the synthesized 4A zeolite were 40.77% and 210.32 mg CaCO3·g−1, respectively. Further characterizations including pore size distribution, scanning electron microscopy, energy dispersive X-ray, thermogravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy were performed. The results revealed that impurities in KPFT do not affect the synthesis of 4A zeolite. The surface morphology of the synthesized 4A zeolite was composed of chamfered-edged cubes with a particle size of one to three μm that was thermally stable up to approximately 890 °C.

Effective bone tissue engineering is important to overcome the unmet clinical challenges of periodontal tissue regeneration. Successful bone tissue engineering comprises three key factors: stem cells, growth factors, and scaffolds. 6-Bromoindirubin-3′-oxime (BIO) is an inhibitor of glycogen synthase kinase-3 (GSK-3) that can activate the Wnt signaling pathway by enhancing β-catenin activity. In this study, the effects of BIO on the proliferation, migration, and osteogenic differentiation of periodontal ligament stem cells (PDLSCs) were investigated. Poly­(lactic-co-glycolic acid) (PLGA) and hyaluronic acid (HA) emerged as promising biomaterials; thus, we developed a novel HA hydrogel embedded with BIO-encapsulated PLGA microspheres and injected the formulation into the gingival sulcus of mice with experimental periodontitis. The release speed of this system was fast in the first week and followed a sustained release phase until week 4. In vivo experiments showed that this PLGA-BIO–HA hydrogel system can inhibit periodontal inflammation, promote bone regeneration, and induce the expression of bone-forming markers alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), and osteocalcin (OCN) in a mouse periodontitis model. Therefore, this PLGA-BIO–HA hydrogel system provides a promising therapeutic strategy for periodontal bone regeneration.

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The activation mechanism of lead ions (Pb 2+ ) in perovskite flotation with an octyl hydroxamic acid collector was systematically investigated using microflotation experiments, zeta-potential measurements, adsorption tests, Fourier transform infrared (FT-IR) analysis, and X-ray photoelectron spectroscopy (XPS) analysis. The results of microflotation experiments and adsorption tests indicate that the presence of Pb 2+ can promote the adsorption of octyl hydroxamic acid (OHA) on the perovskite surface and enhance the flotability of perovskite under weakly acidic conditions. The maximum recovery of 79.62% was obtained at pH 6.5 in the presence of Pb 2+ , and the maximum recovery of 57.93% was obtained at pH 5.7 without Pb 2+ . At pHs below 7, lead species are mainly present as Pb 2+ and PbOH + in the solution; besides this, the relative content of titanium increases on the perovskite surface. The adsorption of Pb 2+ and PbOH + on the perovskite surface makes the zeta-potential of perovskite shift positively, and increases the number of activated sites on the perovskite surface. FT-IR and XPS analyses confirm that OHA chemisorbs on the surface of Pb 2+ -activated perovskite and forms hydrophobic Pb-OHA complexes, which improve the flotability of perovskite.