Key Engineering Materials Vol. 814

Abstract: Catalytically active cerium dioxide is used as light reflection materials for cosmetic applications. Therefore, cosmetics containing this pigment too much cause oxidation of the skin. Therefore, the substitute for cerium dioxide is required to prepare the cosmetics without catalytic activity. Herein, as novel white pigments for use in cosmetics, cerium phosphates were prepared from cerium oxalate under various conditions. The chemical composition, powder properties, catalytic activity, color phase, and smoothness of the cerium phosphates were evaluated. All samples had weak unknown peaks in XRD patterns. Samples prepared at high temperature and for long time indicated the peaks of phosphate in IR spectra. Samples prepared in this work had no photo and oxidation catalytic activities. Samples prepared at high temperature and for long time indicated enough high whiteness and high smoothness.

Abstract: With the use of nanotechnology, clay minerals, specifically montmorillonites, have been reengineered to be used in environmental remediation, especially in the treatment of mining wastewater containing hazardous heavy metal ions. The objective of this study is to assess the practicality of using iron-modified montmorillonite (Fe-MMT) nanomembranes in the removal of mercury using the adsorption process. The nanomembranes, which were synthesized via electrospinning, were subjected to mercury cyanide solutions during the batch adsorption set ups to determine the adsorption efficiency. During the subsequent elution tests, three factors– eluent type (CH₃COOH and C₆H₈0₇), eluent concentration (0.01 M and 0.05 M) and contact time (3 and 5 hours) – were tested. SEM images of the mats were acquired to study the structure of the adsorbent. HD XRF analysis was done to identify the ions present in the membrane, as well as the initial Hg concentrations, amount of remaining Hg in the wastewater after batch adsorption and amount of desorbed metal. Results showed that using the Fe-MMT nanomembrane as adsorbent material resulted to 61.74% removal of Hg in the mercury cyanide solutions with initial concentrations of 13.87 to 38.9 mg L^-1. Acetic acid exhibited better desorption results, with the highest efficiency of 31.36% (0.01 M, 5 h) compared to citric acid’s 7.40% (0.05M, 3 h).

Abstract: Ni_0.75Fe_0.25O_x-GDC cermet anode for intermediate temperature solid oxide fuel cell was prepared by hard template method and wet impregnation method. LSC-GDC cathode-supported single cell was fabricated by using Ni_0.75Fe_0.25 coated tubular GDC as anode for the performance test. The composite anode material with Ni-Fe alloy particles coated tubular GDC was analyzed by XRD and SEM. The maximum power density of the single cell in hydrogen and dry methane was 736 and 400 mW·cm^-2 at 800 °C, respectively. The SEM observation showed that the anode had a porous three-dimensional microstructure with high specific surface and rich gas channel, resulting a high power generation performance.

Abstract: This In this study, the Ca-Al layered double hydroxide was used as a potential adsorbent for the removal of Congo red from aqueous solutions. The effects of Initial concentration and contact time on the adsorption properties of Congo red by Ca-Al LDHs were studied. The removal rate of Conge red reached to 59.416 mg/g under room temperature with 0.2g of adsorbent, initial concentration of 50 ppm, adsorption time of 210 min, shaking speed of 90r/min. The experimental equilibrium data for the removal of Congo red were evaluated by various isotherm models. The pseudo-second-order kinetic models were found to fit the adsorption kinetics, and the equilibrium data were appropriately fitted to Langmuir and Freundlich model adsorption isotherm.

Abstract: The objective of this study was to determine the optimal value of factors affecting the extraction of compounds such as, polyphenols, flavonoids of Roselle. The investigated factors included extraction temperatures (30, 40, 50, 60, 70 and 80°C), extraction time (30, 60, 90, 120 and 150 minutes) and solid to solvent ratio (1:5, 1:10, 1:20, 1:40 and 1:50 g/mL). The efficiency of extraction was evaluated based on total phenolic content (TPC) and total flavonoid content (TFC). The results showed that temperature range of 60–80°C was the appropriate temperature for TFC while extraction temperature over 60°C was suitable for achieving highest TPC. Considering the effect of extraction time, duration of 90–150 minutes facilitated the extraction of both phenolics and flavonoids. Moreover, the solid to solvent 1:20 was chosen for extraction process based on the balance of antioxidant contents and their yield.

Abstract: Anthocyanins are naturally occurring compounds that are responsible for a wide variety of colors in many plants, fruits and vegetables. In this study, the extraction of natural anthocyanins from Vietnamese Carissa carandas L. beverage was optimized using response surface methodology (RSM). We applied a Box–Behnken design consisting of three levels and three factors. Examined factors are extraction temperature (ranging from 40 to 60°C), liquid to solid ratio (ranging from 2:1 to 4:1), extraction time (ranging from 30 to 60 min). Using 60% ethanol as solvent for the process, we determined the maximum yields of anthocyanin was 273.786 mg/L. This yield corresponds to extraction conditions of 3:1 (v/w) liquid to solid ratio, temperature of 48.10 °C with a 44.08 min extraction time. The experimental results also fit well with the proposed response model of anthocyanin yield (R² = 0.9992). Therefore, this study suggested optimization of different extraction methods for the defatted fruit parts.

Abstract: Microfluidic chip injection photocuring is a new method for microfluidic chip fabrication. The accuracy of microfluidic chip photocuring has an important impact on the reliability of microfluidic chip. The reaction rate of photocuring system directly affects the final quality and efficiency of microfluidic chip. The rapid reaction rate of photocuring system will lead to poor feeding effect of the reaction system. The forming accuracy is affected, and the reaction rate is too slow, which will increase the forming time and affect the forming efficiency. In this paper, the conversion rate and reaction rate of different active monomers and oligomers used in the formulation system of microfluidic chips were measured on-line. The photocuring reaction kinetics of microfluidic chips was studied, and the influence of the formulation system on the photocuring reaction was explored, which laid a foundation for optimizing the formulation of microfluidic chips.

Abstract: Using zinc acetate, glycerol alcohol and sodium hydroxide as principal raw materials, the ZnO microspheres were prepared by hydrothermal method at 200°C. The samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). Using methyl orange as the degradation object, the photocatalytic activities and recycling stability of ZnO were characterized. The results show that ZnO samples are spherical and the average diameter is approximately 3-4μm. Moreover, the bandgap width is 3.1eV. Under ultraviolet light irradiation, it is testified that ZnO shows a excellent photocatalytic activity for the degradation of methyl orange. From experience, we can draw a conclusion that the ZnO samples were in line with first-order kinetics, with an apparent rate constant of 0.016min^-1. At the same time, ZnO showed excellent recycling performance. Although the samples have been recycled three times, it still maintained high photocatalytic activity.

Abstract: Compared with inorganic phosphonates, organic phosphonates have better chemical stability in water treatment, and are not easy to hydrolyze in higher temperature and wider pH range. In this paper, a one-step synthesis method of ethylene diamine tetra (methylene phosphonic acid) sodium (EDTMPS) and methylene phosphonic acid (DTPMPA) were studied. A new phosphate scale inhibitor was prepared and its scale inhibition performance was evaluated. The results showed that the scale inhibition rate increased with the increase of the concentration of synthetic products (EDTMPS, DTPMPA). At the same concentration, compared with DTPMPA, EDTMPS has better scale inhibition performance, and the maximum scale inhibition rate can reach 96.85%. The scale inhibition performance of composite scale inhibitor is better than that of single scale inhibitor, and the scale inhibition rate of the synthesized products can reach more than 90% after compounding. And inhibitory mechanism has been proposed: Because phosphonates effectively control the rate of nucleation. In addition, polyphosphonates can chelate Ca²⁺, Mg²⁺ plasma to form monocyclic or bicyclic chelates. This will destroy the normal growth process of calcium carbonate and other crystals, thus preventing the formation of calcium carbonate scale.

Abstract: Ligustrum vulgare is an evergreen tree. The leaves are opposite, glossy dark green, 6–17 centimetres (2.4–6.7 in) long and 3–8 centimetres (1.2–3.1 in) broad. The ligustrum vulgare leaves contain two main components, one of which is oleanolic acid and the other is p-hydroxyphenylethanol which indicates its extracts suitable to be used as an effective corrosion inhibitor. Extracts of ligustrum vulgare leaves (PE) were modified with hydroxymethylation reaction (PM1) and Mannich reaction (PM2) to produce the relative stable green acidic corrosion inhibitors. The extracts of ligustrum vulgare leaves have been investigated on the corrosion inhibition of A₃ steel with weight loss. The results show that these inhibitors have good corrosion inhibition effect on A₃ steel. The PM2 are the most effective for corrosion inhibition, and the inhibition efficiency can reach 75.95%. When the temperature is 60°C, the corrosion inhibition rate of PE, PM1, PM2 is only 24.46%, 42.35% and 39.35% respectively which can not effectively prevent the corrosion of the metal. And the extracts inhibit corrosion mainly by adsorption mechanism. This adsorption accords with Langmuir adsorption isotherm.