Synthesis of nanosized mixed metal oxides heat and corrosion resistant pigments: CaMnO3, Ca2Cr2O5 and CaSb2O6

2015 ◽  
Vol 44 (6) ◽  
pp. 379-385 ◽  
Author(s):  
Osama A. G. Wahba ◽  
Ali M. Hassan ◽  
H. Abd El-wahab ◽  
A. Mohy-Eldin ◽  
A.M. Naser ◽  
...  
Keyword(s):  
Low Cost ◽  
Chemical Properties ◽  
Mixed Metal Oxide ◽  
Corrosion Resistant ◽  
Content Type ◽  
Mixed Metal ◽  
Nanosized Materials ◽  
Physico Chemical ◽  
And Performance ◽  
Co Precipitation

Purpose – The purpose of this paper is to investigate the synthesis of calcium-based group of mixed metal oxide (MMO) pigments. The evaluation of these pigments as heat and corrosion resistant was also explored. Design/methodology/approach – Two simple synthesis techniques, namely, co-precipitation and solid-state calcination method, were used to synthesise nanosized MMO pigments. And then the physico-chemical requirements according to standards for the synthesised pigments are investigated. Findings – The prepared MMO pigments were mainly in the single phase double oxide forms. The prepared oxides exhibited good heat (up to 600°C) and corrosion resistance properties (in 5 per cent NaCl for 500 h). Research limitations/implications – This paper investigates the physico-chemical properties of synthesised calcium-based group of MMO pigments. And then evaluate it as heat and corrosion resistant paints. The simple techniques used for synthesis of nanosized MMO pigments will significantly improve the research and development of pigments’ structure and performance. Practical implications – Calcium-based MMO pigments can be used as heat and corrosion resistant pigments. The easy synthesis of the mixed oxide pigments will open the door for further vital special industrial uses and applications. Originality/value – Low cost, simple techniques and using naturally abundant material can be used for mass production of some other low-cost nanosized materials.

scholarly journals Mixed Oxide Catalyst for the Oxidation of Glycerol to Lactic Acid: Influence of the Preparation Method and Calcination Temperature

2020 ◽  
Vol 20 (3) ◽  
pp. 608
Author(s):  
Noraini Razali ◽  
Ahmad Zuhairi Abdullah
Keyword(s):  
Lactic Acid ◽  
Oxidation Reaction ◽  
Chemical Properties ◽  
Catalytic Performance ◽  
Mixed Metal Oxide ◽  
Acid Yield ◽  
Glycerol Conversion ◽  
Mixed Metal ◽  
High Temperature Reaction ◽  
Co Precipitation

The selective oxidation reaction of glycerol to produce lactic acid is a high-temperature reaction, and requiring a catalyst with high thermal stability. The mixed metal oxide is one of the potential catalysts to be explored. In this study, prepared CaCe supported on ZrO2 catalyst with two preparation methods (co-precipitation and impregnation), and calcination temperatures (800 and 600 °C) were investigated. The oxidation reaction of glycerol to lactic acid was carried out at 250 °C for 2 h in a base-free condition using pure glycerol as a reactant. The catalysts were characterized using XRD, TGA, XPS, SEM and basicity test to evaluate and correlate the physical and chemical properties with their catalytic performance. It was found that the catalyst prepared by co-precipitation and calcined at 800 °C exhibited the highest catalytic performance. The high lactic acid yield of 38.8 and 95% glycerol conversion were achieved. The catalyst was successfully developed with sufficient porosity and high intensity of mixed metal structure that contributed to the desired high performance. Improvement in the basicity and formation of surface oxygen vacancies was attributed to cationic Ce4+/Ce3+ elements leading to the promotion of lactic acid yield and high glycerol conversion.

Design of symmetrical half-bridge converter with a series coupling capacitor

2020 ◽  
Vol 17 (5) ◽  
pp. 609-620
Author(s):  
Ruchi Rashmi ◽  
Shweta Jagtap
Keyword(s):  
Low Cost ◽  
Control Mode ◽  
Variable Load ◽  
Content Type ◽  
Symmetrical Mode ◽  
Coupling Capacitor ◽  
Switched Mode Power Supply ◽  
And Performance ◽  
Asymmetrical Mode ◽  
Voltage Control Mode

Purpose With the advancement of technology, size, cost, and losses of the switched mode power supply (SMPS) have been decreasing. However, due to the high frequency switching, design of magnetic drives and isolation circuits are becoming a crucial factor in SMPS. This paper presents design criteria, procedure and implementation of AC-DC half bridge (HB) converter with lower cost, smaller size and lower voltage stress on the power switch. Design/Methodology/approach The HB converter is designed in a symmetrical mode with a series coupling capacitor. Isolated power supplies are used for the converter and control circuit. Further, a transformer based isolated gate driver is used to drive both MOSFETs. The control IC works in voltage control mode to regulate voltage by controlling the duty cycle of the MOSFETs. Findings Control characteristics and performance of the HB converter is simulated using the MATLAB software and prototype of 170 W HB converter is built to validate the analytical results under variable load current and source voltage. The power quality and variation of load voltage at 2 A, 5 A, 7 A are reported. Originality/value This paper presents the design of a low-cost HB converter in a symmetrical mode which saves the additional cost of symmetric correction circuit normally required in asymmetrical mode design. This paper also focuses on the selection of primary and secondary side switch, series coupling capacitor, commuting diode, isolated drive and charge equalizer resistor.

scholarly journals The Simultaneous Removal of Zinc and Cadmium from Multicomponent Aqueous Solutions by Their Sorption onto Selected Natural and Synthetic Zeolites

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 343 ◽  
Author(s):  
Bożena Kozera-Sucharda ◽  
Barbara Gworek ◽  
Igor Kondzielski
Keyword(s):  
Aqueous Solutions ◽  
Low Cost ◽  
Environmental Pollutants ◽  
Chemical Properties ◽  
Simultaneous Removal ◽  
Physico Chemical ◽  
Synthetic Zeolites ◽  
Sorption Mechanisms ◽  
Synthetic Aluminosilicate ◽  
Natural And Synthetic

Natural and synthetic aluminosilicate minerals, in particular zeolites, are considered to be very useful in remediation processes, such as purification of waters polluted with heavy metals. That is due to their unique and outstanding physico-chemical properties, rendering them highly efficient, low-cost, and environmentally friendly sorbents of various environmental pollutants. The aim of this study was to examine the sorption capacity of four selected zeolites: A natural zeolite and three synthetic zeolites (3A, 10A, and 13X), towards zinc and cadmium present in multicomponent aqueous solutions, in relation to identified sorption mechanisms. It was stated that synthetic zeolites 3A and 10A were the most efficient in simultaneous removal of zinc and cadmium from aqueous solutions. Additionally, zeolite 10A was demonstrated to be the mineral best coping with prolonged pollution of water with those elements. The mechanism of sorption identified for tested minerals was physisorption.

The Retrospects and Prospects of Pure Water Hydraulic Technology

2012 ◽  
Vol 201-202 ◽  
pp. 979-982 ◽  
Author(s):  
Feng Xu ◽  
Li Xiang Zhang
Keyword(s):  
Hydraulic System ◽  
Low Cost ◽  
Pure Water ◽  
Chemical Properties ◽  
Simple System ◽  
Hydraulic Oil ◽  
Physico Chemical ◽  
Water Hydraulic ◽  
Research Situation ◽  
The Ideal

Pure water hydraulic technology attracts more and more attention of people due to no pollution, low cost, simple system, and many other advantages. This paper compares physico-chemical properties between pure water and hydraulic oil, concludes that pure water is the ideal medium for hydraulic system. Then it discusses the development of pure water hydraulic technology, introduces the present research situation and development of pure water hydraulic components from home to abroad in the future.

scholarly journals Impact of mission requirements on the design of low observable UCAV configurations

2019 ◽  
Vol 91 (10) ◽  
pp. 1295-1307
Author(s):  
Eduardo Sepulveda Palacios ◽  
Howard Smith
Keyword(s):  
Low Cost ◽  
Leading Edge ◽  
Aircraft Design ◽  
Considerable Proportion ◽  
Design Environment ◽  
Sweep Angle ◽  
Content Type ◽  
Aerial Warfare ◽  
And Performance ◽  
Excess Power

Purpose The purpose of this paper is to characterise the effects of mission and performance parameters on the design space of low observable subsonic unmanned combat aerial vehicles (UCAVs) operating in typical Hi-Lo-Hi ground strike missions. Design/methodology/approach Conceptual design methodologies appropriate to low observable, tailless UCAVs have been integrated into a multidisciplinary aircraft design environment, GENUS, developed at Cranfield University’s aircraft design group. A basic Hi-Lo-Hi mission is designed and a baseline configuration is established through the GENUS framework. Subsequently, an evolutionary optimiser and a robust gradient-based optimiser are used to obtain convergent design solutions for various leading edge sweep angles, mission ranges, cruise Mach numbers and other operational constraints. Findings The results indicate that performance constraints, specifically in the form of specific excess power (SEP), have a large influence on the overall sizing of subsonic tailless UCAVs. This requirement drives the engine sizing, which represents a considerable proportion of the empty and gross mass of the vehicle. Cruise Mach number studies show that no significant advantages exist for operating at low speeds while maintaining performance requirements consistent with combat missions. There is a drastic increase in the vehicle’s mass and thrust requirements for flight speeds above Mach 0.8, with low sweep configurations showing a more pronounced effect. Increases in the range are not overly dependent on the leading edge sweep angle. Top-level radar cross section (RCS) results also favour configurations with higher leading edge sweep angles, especially from the nose-on aspect. Finally, research and development costs are shown to be directly linked to engine size. Originality/value This research shows the use of an integrated aircraft design environment that incorporates aerodynamics, performance, packaging and low observability aspects into the optimisation loop. Through this methodology, this study supports the efforts towards characterising and establishing alternate visions of the future of aerial warfare through the use of low cost, survivable unmanned platforms in network-centric cooperative tasks.

scholarly journals New Activated Carbon from Mine Coal for Adsorption of Dye in Simulated Water or Multiple Heavy Metals in Real Wastewater

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2498 ◽  
Author(s):  
Marwa Elkady ◽  
Hassan Shokry ◽  
Hesham Hamad
Keyword(s):  
Activated Carbon ◽  
Nitric Acid ◽  
Metal Ions ◽  
Low Cost ◽  
Dye Adsorption ◽  
Chemical Properties ◽  
Batch Adsorption ◽  
Maximum Adsorption Capacity ◽  
Physico Chemical ◽  
Multiple Heavy Metals

Nano-activated carbon (NAC) prepared from El-Maghara mine coal were modified with nitric acid solution. Their physico-chemical properties were investigated in terms of methylene blue (MB) adsorption, FTIR, and metal adsorption. Upon oxidation of the ACS with nitric acid, surface oxide groups were observed in the FTIR spectra by absorption peaks at 1750–1250 cm−1. The optimum processes parameters include HNO3/AC ratio (wt./wt.) of 20, oxidation time of 2 h, and the concentration of HNO3 of 10% reaching the maximum adsorption capacity of MB dye. Also, the prepared NAC was characterized by SEM, EDX, TEM, Raman Spectroscopy, and BET analyses. The batch adsorption of MB dye from solution was used for monitoring the behavior of the most proper produced NAC. Equilibrium isotherms of MB dye adsorption on NAC materials were acquired and the results discussed in relation to their surface chemistry. Langmuir model recorded the best interpretation of the dye adsorption data. Also, NAC was evaluated for simultaneous adsorption of six different metal ions (Fe2+, Ni2+, Mn2+, Pb2+, Cu2+, and Zn2+) that represented contaminates in petrochemical industrial wastewater. The results indicated that the extracted NAC from El-Maghara mine coal is considered as an efficient low-cost adsorbent material for remediation in both basic dyes and metal ions from the polluted solutions.

scholarly journals The Influence of the Preparation Method on the Physico-Chemical Properties and Catalytic Activities of Ce-Modified LDH Structures Used as Catalysts in Condensation Reactions

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6191
Author(s):  
Alexandra-Elisabeta Stamate ◽  
Rodica Zăvoianu ◽  
Octavian Dumitru Pavel ◽  
Ruxandra Birjega ◽  
Andreea Matei ◽  
...  
Keyword(s):  
Preparation Method ◽  
Mixed Oxides ◽  
Condensation Reaction ◽  
Chemical Properties ◽  
Precipitation Method ◽  
Synthesis Methods ◽  
Molar Ratios ◽  
Base Catalysts ◽  
Physico Chemical ◽  
Co Precipitation

Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3Al0.75Ce0.25(OH)8(CO3)0.5·2H2O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs.

scholarly journals Mg-Al-Cr2O7 Hydrotalcite-Like Catalysts Synthesized at Different pH Values for Styrene Oxidation

2020 ◽  
pp. 13-21
Author(s):  
Le Huy Tran ◽  
Thi Ngoc Mai Tran ◽  
Tuan Vu Anh ◽  
Pham Quoc Khanh ◽  
Thi Minh Thu Nguyen ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Styrene Oxidation ◽  
Preparation Conditions ◽  
Physico Chemical ◽  
Ph Conditions ◽  
Dichromate Anions ◽  
Co Precipitation ◽  
Styrene Conversion

Dichromate anions were intercalated between two consecutive hydroxide layers of [Mg0.6Al0.4(OH)2]0.40+ via co-precipitation at different pH conditions. The physico-chemical properties of the obtained solids were examined by physical methods such as X-ray diffraction (XRD), Infrared (IR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) and Energy-Dispersive Spectroscopy (EDS). The experimental results indicated that the amount of dichromate anions in the catalysts varies with the pH media. Also, the morphology, structure and chemical composition of the materials depends strongly on the preparation conditions. The Mg-Al-Cr2O7 hydrotalcite-like compounds are used as heterogeneous catalysts for the styrene oxidation with H2O2 at mild conditions. The styrene conversion is about 20-50% while styrene selectivity remains rather high.

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