Hagenia abyssinica-Biomediated Synthesis of a Magnetic Fe3O4/NiO Nanoadsorbent for Adsorption of Lead from Wastewater

Magnetic nanocomposite adsorbents are cost-effective, environmentally friendly, easy to use, and highly efficient at removing metals from large volumes of wastewater in a short time by using an external magnetic field. In this study, an Fe3O4/NiO composite nanoadsorbent was prepared by varying the mass percent ratios of NiO (50, 40, 30, 20%), which are denoted Fe3O4/50%NiO, Fe3O4/40%NiO, Fe3O4/30%NiO, and Fe3O4/20%NiO, respectively, using Hagenia abyssinica plant extract as the template/capping agent and a simple mechanical grinding technique. The nanocomposites were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, nitrogen adsorption, and ζ-potential measurements. The adsorption performance of the nanoadsorbent was assessed for the removal of lead (Pb2+) ions from aqueous solutions. Among the composite adsorbents, Fe3O4/50%NiO demonstrated the best Pb(II) removal efficiency (96.65%) from aqueous solutions within 80 min at pH 8, at a 100 mg/L lead concentration and 0.09 g of adsorbent dose. However, with the same parameter, only 62.8% of Pb(II) was removed using Fe3O4 nanoparticles (NPs). The adsorptive performance indicated that the optimum amount of porous material (NiO) in the preparation of the Fe3O4/NiO composite nanoadsorbent, with the aid of H. abyssinica plant extract, enhances the removal of toxic heavy metals from aqueous solutions. Multiple isotherm and kinetic models were used to analyze the equilibrium data. Adsorption isotherm and kinetic studies were found to follow the Freundlich isotherm and pseudo-second-order kinetics, respectively.

Annealing Effect on Mechanical and Tribological Behaviors of Nanoscale Mechanics of Zr60Cu25Al5Ag5Ni5 Thin-Layer Metallic Glasses for Engineering Materials Applications

A new and unique alloy formulation design strategy has been developed in order to fabricate thin-layered metallic glasses (TLMGs) with superior fracture resistance and low coefficient of friction (COF) during the nanoscratching test. Due to the outstanding properties, TFMG could be applied for different uses, such as for surface coating, biomedical, bioimprinting, electronic devices, spacecraft, and railway, all of which need surface fracture resistance. The fabricated Zr-based metallic glass was prepared from Zr, Al, Cu, Ni, and Ag above 99.9 Wt % in purity by arch melting techniques. TFMGs were coated on silicon wafer by sputtering the vapor deposition method from bulk metallic glass then annealed below glass transition temperature Tg ∼ 450 °C for 10, 30, and 60 min. Nanoindentation and nanoscratch tests were used to investigate nanomechanical and nanotribological properties, and atomic force microscopy (AFM) was used to examine the surface morphology and microstructures of TLMG. The nanoindentation data indicated that the average hardness of metallic glasses increased from 9.75 (as-cast MG) to 13.4 GPa (annealed for 60 min). Coefficients of friction for the cast sample, annealed for unannealed, 10, 30, and 60 min, were 0.062, 0.049, 0.039, and 0.03, respectively, as well as the wear depths were 201.56, 148.43, 37.32, and 25.27 nm, respectively. These studies show that the coefficient of friction and wear rate decreases when the annealing time increases as a result of atomic reordering and structural relaxation that occurred at longer annealing times. Furthermore, continuous wear process, wear depth, wear track volume, and contact area decrease with increasing annealing time. This study can be used to design protocols to prepare novel TLMGs, which have outstanding mechanical and tribological properties for engineering materials applications.

Healable supramolecular micelle/nano-encapsulated metal composite phase change material for thermal energy storage

Phase change materials (PCMs) have emerged as promising materials for latent heat storage due to their characteristic solid-liquid phase transition behavior during the melting and cooling process. Among them, organic phase change materials are commonly used in latent heat storage. Herein, new phase change self-assembled micelles (PCSM) demonstrated thermal-based phase transition properties. Silver nanoparticles were employed as an additive to improve the thermal properties of the shape-stabilized composite PCSM. The surface morphology and microstructure, general thermal properties and heat adsorption and release behaviors of the samples were characterized with the aid of TEM, SEM, OM, DSC, TGA and DLS techniques. The DSC curve showed that the latent heat adsorption and temperature, heat capacity and thermal reliability of the composite PCSM improved upon the addition of Ag NPs. The TGA curves demonstrated that the presence of Ag NPs increased the onset decomposition temperature and the peak weight loss temperature. PCSM demonstrated low thermal conductivity, whereas the composite PCSM showed better thermal conductivity. This study provides new insight into the promising preparation of healable composite PCMs and their application in thermal energy storage.

Dual stimuli-responsive supramolecular boron nitride with tunable physical properties for controlled drug delivery

The new concept of modifying and tailoring the properties of existing two-dimensional (2D) nanomaterials by invoking the assembly of supramolecular networks upon association with a adenine-functionalized macromer (A-PPG) has significant potential to facilitate the development of highly water-dispersible few-layered 2D nanosheets. In this study, we propose that water-soluble A-PPG directly self-assembles into a long-period stacking-ordered lamellar structure over the surface of hexagonal boron nitride (BN) in aqueous solution, due to the efficient non-covalent interactions between A-PPG and BN nanosheets. The layer number of BN nanosheets can be easily tuned by altering the mass ratio of the A-PPG and BN blend, and the resulting exfoliated nanosheets also exhibit excellent temperature/pH-responsive behavior, biocompatibility and extremely high drug-loading capacity (up to 36.2%), features that are highly desirable yet exceedingly rare in traditional 2D nanomaterials. Importantly, in vitro drug release studies showed the drug-loaded nanosheets function as a stable nanocarrier with excellent stability and drug entrapment under normal physiological conditions. Increasing the environmental temperature to 40 °C or decreasing the pH to 5.5 triggered rapid release of the encapsulated drug from the drug-loaded nanosheets, suggesting this newly developed material has potential as a novel multi-responsive 2D nanocarrier to safely deliver drugs and effectively facilitate controlled drug release under specific microenvironmental conditions. This study provides new insight towards the promising application of this system in controlled release drug delivery systems.

Dynamic tungsten diselenide nanomaterials: supramolecular assembly-induced structural transition over exfoliated two-dimensional nanosheets

Supramolecular polymers can easily control the lamellar microstructures on exfoliated tungsten diselenide nanosheets.

A simple and effective method for direct exfoliation of tungsten diselenide (WSe₂) into few-layered nanosheets has been successfully developed by employing a low molecular weight adenine-functionalized supramolecular polymer (A-PPG). In this study, we discover A-PPG can self-assemble into a long-range, ordered lamellar microstructure on the surface of WSe₂ due to the efficient non-covalent interactions between A-PPG and WSe₂. Morphological and light scattering studies confirmed the dynamic self-assembly behavior of A-PPG has the capacity to efficiently manipulate the transition between contractile and extended lamellar microstructures on the surface of metallic 1T-phase and semiconducting 2H-phase WSe₂ nanosheets, respectively. The extent of WSe₂ exfoliation can be easily controlled by systematically adjusting the amount of A-PPG in the composites, to obtain nanocomposites with the desired functional characteristics. In addition, the resulting composites possess unique liquid–solid phase transition behavior and excellent thermoreversible properties, revealing the self-assembled lamellar structure of A-PPG functions as a critical factor to manipulate and tailor the physical properties of exfoliated WSe₂. This newly developed method of producing exfoliated WSe₂ provides a useful conceptual and potential framework for developing WSe₂-based multifunctional nanocomposites to extend their application in solution-processed semiconductor devices.