Key Engineering Materials Vol. 897

Abstract: The application of piezoelectric polyvinylidene fluoride (PVDF) has become of a great interest. Due to its piezoelectric properties, PVDF is used in various applications, namely, microdevices and sensors. Electrospinning was found to be the most suitable and efficient method to synthesis PVDF nanofibers. It is used to obtain PVDF nanofibers without additional mechanical stretching and with high β phase content. For these reasons, it is considered to be an economic technique. In the present paper, the parameters affecting the synthesis of PVDF nanofibers such as solution concentration, flow rate, voltage and Tip to Collector Distance (TCD), have been investigated. The optimum conditions were found to be 18% concentration, 15 cm TCD, 1 mL/h flowrate and 19 kV voltages. The fabricated nanofiber has been characterized using SEM, FTIR, XRD and a conductivity test.

Abstract: Bi-Pb-Sr-Ca-Cu-O (BPSCCO) superconductors are recognized as a projectable high-temperature superconductor for high-efficiency electrical applications. The addition of Ti enhances the formation of the Bi-2223 phase from the BPSCCO superconductor. The process of producing BPSCCO superconducting materials with TiO₂ dopants is performed by the solid-state process and the production of wire rolling, consisting of bismuth (III) oxide powder (Bi₂O₃ = 99%), Strontium Carbonate powder (SrCO₃ = 99%), Calcium Carbonate powder (CaCO₃ = 99%), Copper Oxide powder (CuO₂ = 99%), Lead Oxide powder (PbO₂ = 98%) Bi: Pb: Sr: Ca: Cu ratio: 1.6: 0.4:2:2:3 doped by 1 %wt Titanium Oxide powder (TiO₂ = 98.5%). The variables used in this study were the comparison of the sintering method at 860°C for 24 hours and 820 °C calcination for 20 hours, and 850°C sintering for 20 hours. The superconductor characterization was tested through the X-Ray Diffraction (XRD) test, Scanning Electron Microscopy (SEM), and Resistivity test. XRD test results showed the formation of Bi₂Sr₂CuO₆ and Bi₂Sr₅Cu₃O₁₆ phase. SEM results showed an increase in grain size. The resistivity test results showed that all samples formed critical temperatures, 9.6 and 9.5K respectively.

Abstract: The efficiency of batteries, supercapacitors, and dye-sensitized solar cells for energy storage and harvesting processes depends on the relative energy levels and the charge transfer kinetics at the electrode/electrolyte interface. Owing to their distinctively tunable properties including non-volatility, low flammability, wide electrochemical stability, inherent conductivity, and high thermal stability, developing low viscosity ionic liquids (ILs) is vital for energy device fabrication. In this work, 1-methylimidazolium ILs were synthesized by a one-step sonochemical solventless reaction and were characterized using FT-IR, ¹H-NMR, and ¹³C-NMR spectroscopy to confirm their structure. Hybrid electrolytes based on the 1-methylimidazolium chloride ([MIM]Cl) infused with titanium dioxide (TiO₂) particles at varying concentrations were prepared, and the effect of solute concentration on their electrochemical and interfacial properties was investigated. Ionic conductivity results revealed that the as-prepared [MIM]Cl-TiO₂-0.5% hybrid electrolytes exhibited a higher conductivity in comparison with neat [MIM]Cl. Furthermore, cyclic voltammetry was used to determine their electrochemical stability window and revealed that a wide ESW of 3.56 ± 0.01 V was also obtained by [MIM]Cl-TiO₂-0.5% attributed to the enhanced surface tension of 35.92 ± 0.07 mN/m due to the addition of TiO₂ particles. This observation was validated by the generated pendant drop images showing the remarkable correlation of solute concentration with surface tension and ESW of the hybrid electrolytes. The utilization of these metal oxide-infused solvent-free IL as a substitute for aqueous-and organic-based electrolytes can address issues on electrochemical stability and provide insight in suppressing self-discharge processes, especially when used at higher potentials.

Abstract: The metal-air batteries, especially the Zinc-air batteries, are great solutions to the growing energy crisis with excellent rechargeable capacity. ORR is the key electro-chemical reaction in Zinc-air batteries, and the development of the ORR efficiency is being studied extensively. The doping of transition metal in Co₃O₄, with the basement of N-doped graphene have been confirmed to have catalytic activity which can be comparable to Pt/C. Herein, the Fe-doped Co₃O₄ supported by N-doped graphene is constructed as the catalyst of ORR, and that without Fe doping is also constructed as comparison. Through first-principle calculation, it shows that the adsorption energies to O₂ on the same site of each surface and on different sites on Fe-doped one. The partial density of state of the O₂ adsorption system shows the effects of electron transfer and orbital hybridization on catalysis, which provide evidence to the catalytic mechanism with Fe doping. The energy changes of each step in ORR on catalyst with Fe doping and without Fe doping show the shortcomings of the simulation, including the spin of Fe atoms. Thus the study confirms that the adding of Fe contributes to the catalystic capability compared to the pure Co₃O₄.

Abstract: Globally, the adverse environmental impact of waste plastics is of increasing concern. Most plastics are naturally non-degradable, thus imposes serious environmental threats, especially, to marine life. Upcycling such waste into valuable contents is an effective approach to managing waste plastics. In this study, graphene is synthesized from waste polystyrene (PS) by thermal decomposition at different temperatures (500, 600, 700, 800, 900 and 1000 °C) for two hours reaction time in a stainless steel autoclave. The synthesized materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-disperse X-ray analysis (EDS) and surface area by using Brunauer–Emmett–Teller (BET). The yield of the product materials was investigated and optimized against the temperature. The synthesized graphene is considered a promising material for many applications, especially in environmental applications.

Abstract: This review article presents the usage of various animal bones such as chicken bone, fish bone, pig bone, camel bone, and cow bone as reliable biosorbent materials to remove heavy metals contained in contaminated water and wastewater. The sources and toxicity effects of heavy metal ions are also discussed properly. Then specific insights related to adsorption process and its influential factors along with the proven potentiality of selected biosorbents especially derived from animal bone are also explained. As the biosorbents are rich in particular organic and inorganic compounds and functional groups in nature, they play an important role in heavy metal removal from contaminated solutions. Overall, after conducting study reports on the literature, a brief conclusion can be drawn that animal bone waste has satisfactory efficacy as effective, efficient, and environmentally friendly sorbent material.

Abstract: This research work presents an optimum setting at which the production of calcium citrate malate would have the highest yield. The factors that were varied are temperature and the concentrations of citric acid and malic acid. Duck eggshells were used as the source of calcium. The temperature settings were at room temperature (25°C) and at 80°C, the concentrations of citric acid at 1.5 M and 1.7 M and that of malic acid at 2.2 M and at 2.5 M. Using 2³ factorial design of experiment (8 settings), the main effects and the interaction effects were plotted to derive an empirical model to predict the yield of calcium citrate malate. Furthermore, a comparison of x-ray diffraction graphs was conducted to evaluate the final product.

Abstract: In this paper, we report that an effective and simple chemical method under the low temperature (60 °C) could synthesize zinc oxide (ZnO) nanoparticles and effectively control the crystal growth based on the hydrothermal method. X-ray diffraction, X-ray electron spectroscopy, high resolution transmission electron microscopy and ultra violet visible spectroscopy were used to characterize the structure and performance of the samples. It is shown that the ZnO nanoparticles synthesized under the optimal reaction conditions are strong ultraviolet absorption, high-uniformed sphere and high specific surface. In the photodegradation of rhodamine B (RhB) tests, ZnO nanoparticles thrived well during the reaction and degraded the material in 50 minutes. Since ZnO nanoparticles towards RhB degradation shows a good stability, it might provide an effective way to tackle environmental pollution.

Abstract: The Life Cycle Assessment (LCA) is one of the most important analytical tools available to provide the scientific basis of engineering solutions for sustainability. The focus of this study was a LCA (cradle to gate) of a product intended to be used in countertops. The functional unit chosen was 1 m² of finished panel (countertop) and the boundary system involved the study of raw materials and product packaging and the panel’s production process. The chosen method for impact assessment was EPD (2018) available in SimaPro PhD software and Acidification, Eutrophication, Global Warming, Photochemical Oxidation, Abiotic Depletion (elements), Abiotic Depletion (fossil fuels), Water Scarcity and Ozone Layer Depletion were the impact categories considered. Results showed that the panel’s manufacturing is the process that presented the highest influence in all categories analyzed ranging from 88% on Abiotic Depletion to approximately 101% on Water Scarcity. Polyvinylchloride (PVC) is the greatest contributors to all impact categories except to Photochemical Oxidation that is the Polyester.

Abstract: Ordinary Portland cement (OPC) is a material that is widely used in construction. The production of OPC creates large amounts of carbon dioxide. Mortar is one of the building materials that uses cement as the main ingredient, including the use of natural sand as a fine aggregate. Therefore, to reduce the use of cement and natural materials, flue-gas desulfurization (FGD) gypsum was used instead of OPC, and water treatment sludge (WTS) was used instead of fine sand to create cement mortar. This research used both materials as ingredients in the production of cement mortar and helped to reduce waste in the environment. The objective is to study the suitable ratios of FGD gypsum and WTS in the production of cement mortar. As for the binder, FGD gypsum was used instead of OPC at 0%, 10%, 20%, 30%, and 40%. Instead of fine sand, WTS was used at 0%, 5%, 10%, and 15%. The cement mortar was tested after 7 days for compressive strength. It was found that the cement mortar made with increased ratios of FGD gypsum and WTS decreased in compressive strength.