Silica-Bacterial Cellulose Composite Aerogel Fibers with Excellent Mechanical Properties from Sodium Silicate Precursor

Forming fibers for fabric insulation is difficult using aerogels, which have excellent thermal insulation performance but poor mechanical properties. A previous study proposed a novel method that could effectively improve the mechanical properties of aerogels and make them into fibers for use in fabric insulation. In this study, composite aerogel fibers (CAFs) with excellent mechanical properties and thermal insulation performance were prepared using a streamlined method. The wet bacterial cellulose (BC) matrix without freeze-drying directly was immersed in an inorganic precursor (silicate) solution, followed by initiating in situ sol-gel reaction under the action of acidic catalyst after secondary shaping. Finally, after surface modification and ambient drying of the wet composite gel, CAFs were obtained. The CAFs prepared by the simplified method still had favorable mechanical properties (tensile strength of 4.5 MPa) and excellent thermal insulation properties under extreme conditions (220 °C and −60 °C). In particular, compared with previous work, the presented CAFs preparation process is simpler and more environmentally friendly. In addition, the experimental costs were reduced. Furthermore, the obtained CAFs had high specific surface area (671.3 m²/g), excellent hydrophobicity, and low density (≤0.154 g/cm3). This streamlined method was proposed to prepare aerogel fibers with excellent performance to meet the requirements of wearable applications.

Removal of Zn(II) By Magnetic Composite Adsorbent: Synthesis, Performance, And Mechanism

In this study, L-methionine and nano-Fe3O4 were encapsulated and cured on sodium alginate by the ionic cross-linking method to form magnetic composite gel spheres (SML). The influence of adsorbent dosages, pH, reaction time, and initial ion concentration on the ability of the gel spheres to adsorb Zn(II) was investigated. The experimental results indicated that under the optimum conditions, the maximum amount of Zn(II) adsorbed by the adsorbent gel spheres reached 86.84 mgˑg-1. The experimental results of adsorption indicate that the reaction process of this adsorbent fits well with the Langmuir and pseudo-second-order kinetic models and is a heat absorption reaction. The results of the adsorption investigation of the coexistence system showed that the adsorbent would preferentially adsorb Pb(II), and the adsorption efficiency of Zn(II) decreased when the concentration of interfering ions increased. The structure of this adsorbent and the adsorption mechanism were investigated by Fourier transform infrared spectrometer, thermal gravimetric analyzer, vibrating sample magnetometer, scanning electron microscope, Brunner-Emmet-Teller measurements, and X-ray photoelectron spectroscopy. The results show that this magnetic composite adsorbent is a mesoporous material with superior adsorption performance, and the amino and carboxyl groups on it react with Zn(II) via ligand chelation; the ion exchange effect of Ca(II) also plays a role. The desorption-adsorption experiments of the adsorbent indicated that the adsorption amount of Zn(II) was maintained at a higher level after several cycles, and the loss of Fe was approximately 0.2%. In summary, SML is an ideal adsorbent for environmental protection.

Development of Injectable Hydroxyapatite/2-(dimethylamino)Ethyl Methacrylate/Polyvinylpyrrolidone Aqua-Hydrogel System to Repair of the Shoulder Joint Head for Hemiarthroplasty

This study aimed to develop osteogenic structure assembly for modular bone treatment presentations, effect of 2-(dimethylamino)ethyl methacrylate and polyvinyl pyrrolidone combination as cell adhesive molecule with hydroxyapatite-based composite as osteoconductive constituent was inspected on bone fracture repair. The prepared injectable composite hydrogel showed significantly improved mechanical stability. The ternary composite gel was characterized for functional group modifications and chemical interactions using Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Moreover, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses were performed to observe surface appearances of the hydrogel. The hydroxyapatite/2-(dimethylamino)ethyl methacrylate/poly-N-vinyl-2-pyrrolidone hydrogel played key role in supporting osteoblastic cell spread due to their bioactivity and strength abilities. The present findings revealed the significance of hydroxyapatite concentration on proliferation and osteogenic purpose of the cells. The developed performances of hydrogel have been improved cell proliferation and functions to repair bone fracture.