Ml Of Ethylene Glycol Research Articles

Nest-like NiFe-LDH derived from the ethylene glycol-assisted hydrothermal route: A highly efficient electrocatalyst for water oxidation in neutral solutions

Water oxidation is an optimistic pathway for hydrogen generation with high quality. In this work, nest-like nickel iron-layered double hydroxide (NiFe-LDH) nanomaterials were successfully prepared using the ethylene glycol-assisted hydrothermal strategy. Morphological and structural studies showed that in the assistance of ethylene glycol (EG), morphologies of the NiFe-LDH nanomaterials were modified, and their surface areas were enhanced. The nano nest-like NiFe-LDH-EG3 derived with 3.0 mL of EG exhibited an excellent oxygen evolution reaction (OER) activity with a low overpotential of about 400 mV at a current density of 10 mA/cm2 and a Tafel slope of 79 mV/dec in neutral media, and such an outstanding OER activity was attributed to the modified morphology, good crystallinity, and high surface area of the nest-like NiFe-LDH-EG3.

Ultrafast 99% Polyethylene terephthalate depolymerization into value added monomers using sequential glycolysis-hydrolysis under microwave irradiation

Effective and efficient hybrid depolymerisation technologies are emerging as high potential sustainable routes with considerable benefits over conventional recycling methods for the achievement of circular economies for plastics. Herein, combined green and fast glycolysis-hydrolysis depolymerization of polyethylene terephthalate (PET) was carried out under microwave irradiation (MW) with excellent efficiencies. In MW assisted glycolysis of PET, the catalytic activity of two deep eutectic solvents (DES) based on (choline chloride-urea (DES 1)) and (choline chloride-thiourea (DES 2)) was evaluated and compared. Optimised glycolysis conditions were determined using Box Behnken Design (BBD) to attain maximum weight loss of PET, low crystallinity and increased carbonyl index of residual PET. DES volume of 4 mL, 5.5–6 mL of ethylene glycol, and 0.5 min MW irradiation time resulted in a prominent rise in PET weight loss and carbonyl index of residual PET. DES 2 showed an improved catalytic activity than that of DES 1 which is associated to its stronger interaction with EG and PET polymer chains during the course of the reaction. Residual PET obtained post glycolysis reaction was further depolymerized using MW assisted hydrolysis in the presence of weakly basic Na2CO3 and EG. Within 3-minute, the proposed sequential depolymerization technologies facilitated ≈99% conversion of PET to terephthalic acid (TPA), monohydroxyethyl terephthalate (MHET), and bis (2-hydroxyethyl) terephthalate (BHET) monomers produced at a yield of 62.79–80.66%, 17.22–34.79% and 0.54–0.59% respectively. Application on post-consumer PET sample also revealed very satisfactory results with 96.77–98.25% PET conversion and 60.98–78.10% yield of TPA.

Electrochemical synthesis of titanium dioxide nanostructures and its application in the in dye photocatalytic removal

By electrochemical anodization to titanium sheets, titanium dioxide nanostructures were sintered for 10 V and 20 V and times of 3 hours and 5 hours. For the electrolytic solution, 0.3 g of ammonium fluoride, 97 mL of ethylene glycol and 3 mL of distilled water were used. The sheets (51 mm × 21 mm × 0.4 mm) were treated using abrasive paper and cleaned with a 1:1 solution of ethanol water by means of ultrasound and dried using hot air. A stirring frequency of 300 rpm was used during anodizing. For the sintering of the titanium dioxide anatase phase, heat treatment was applied at 550 °C for 3 hours by means of an electric muffle, with heating speed of 10 °C/min. The crystallinity index, and the quantification of the sintered phases was carried out by means of X-ray diffraction, while the nanoporosities and their distribution were carried out using imageJ software to the images taken by means of scanning electron microscopy. For the photocatalytic treatment of the methylene blue dye in water, the titanium dioxide nanostructures that reported the highest anatase phase were used, where ultraviolet C radiation from a led lamp was applied for 4 direct hours. The efficiency in the removal of the dye was studied by UV-Vis spectrophotometry, finding the highest degradation of the dye for the wavelength of 644 nm.

High-performance Al separation and Zn recovery from a simulated hazardous sludge

Zn2+ is a heavy metal ion, and hazardous sludge from the electroplating and alloy industry is rich in Zn and impure Al and Ca. Such sludge is commonly recycled by dissolution in strong acid and then selective extraction to recycle Zn2+ by a special extraction reagent. In this process, impurity Al3+ is dissolved and then participates in the extraction of Zn2+, so Al3+ should be removed first. Here, a new strategy was reported for the effective removal of Al3+ and recovery of Zn2+ from a simulated Al/Zn-bearing sludge via an improved acid solution–precipitation route. The sludge was simulated by coagulating Zn-bearing waste water (290 mg/L Zn2+) with 600 mg/L polyaluminium chloride. The sludge was dissolved in sulphuric acid and nitric acid to form an acidic solution with Al3+ and Zn2+ concentrations of 3.2 g/L and 5.7 g/L, respectively. The solution was treated directly by hydrothermal method at 270 °C, in which 55% Al3+ was precipitated as boehmite and Al hydroxide. After the addition of 0.2 mL of ethylene glycol, the removal rate of Al3+ dramatically increased to 99.8%, with Zn2+ loss of 1.5%. The residual Zn2+ was 5620 mg/L in the treated solution and further directly precipitated by adjusting the pH of the solution to pH 7.5 with NaOH. The precipitated Zn2+ was in the form of simonkolleite with ZnO content of 63.1%, with Al content of only 0.8%. In the hydrothermal precipitation, the removal rate of Al3+ increased with the temperature and extension of reaction time. Al3+ was hydrolysed and precipitated as aluminium oxonium sulphate hydroxide and then recrystallised in boehmite form. Then, H+ was generated and consumed in the redox reaction of nitrate and ethylene glycol, accelerating the Al3+ precipitation. This method provides a way to efficiently separate Al3+ from a Zn-bearing solution and can be applied in the recycling of Al/Zn-bearing sludge.

Fabrication of titanium dioxide nanotubes by difference the anodization voltage and time

In this paper, Titanium dioxide nanotube arrays (TNAs) were obtained by electrochemical anodization in the electrolyte containing 0.3 wt% solution of ammonium fluoride in 90 ml of ethylene glycol and 10 ml of deionized water. Following this the different conditions of voltage (5–50 V) and time (30 min − 2 h) at room temperature. The morphology, composition, and crystalline phases of the TNAs were examined by Field Emission Electron Microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction technique (XRD), respectively. The results of the experiment show that anodizing time and anodizing potential affected the formation of TNAs. When anodizing potential increased anodizing time decreased but when anodizing potential decreased anodizing time increased. Moreover, the formation of titanium dioxide starts becoming tubes at 10 V. Also, the diameter of the TNAs were about 10–100 nm.

EFFECT OF POLYVINYLPYRROLIDONE ON THE SYNTHESIS AND CATALYTIC PROPERTIES OF PLATINUM-CONTAINING OXYGEN ELECTROREDUCTION CATALYSTS

Results of the work on the synthesis of highly effective nanocomposite platinum-containing oxygen reduction electrocatalysts for hydrogen-oxygen fuel cells are presented and ways of increasing their activity are considered. Fuel cells (FCs) represent the most promising renewable and environmentally friendly energy sources that can operate at low temperatures with high efficiency and with low or zero levels of hazardous waste. The main problem of fuel cells is that the oxygen reduction reaction is slowed down in relation to the hydrogen oxidation reaction, which leads to an increase in the overvoltage at the cathode and, as a result, to a decrease in the productivity of FCs. To solve this problem, the new methods are being developed for the synthesis of highly efficient platinum electrocatalysts, which currently have the best performance, since platinum has the highest specific catalytic activity among other materials used in low temperature FCs. The purpose of this work is to determine the optimal composition of reaction mixture and conditions for the preparation of a platinum based catalyst for oxygen electroreduction where Vulcan XC-72 nanodispersed carbon black is used as a carrier. We have worked out 6 methods for preparing Pt (40 %)/XC-72 catalysts. To evaluate the activity of the prepared catalysts and to determine the kinetic parameters of the oxygen reduction on them, cathodic stationary polarization curves were recorded in a 0.5 M H2SO4 solution on a floating gas diffusion electrode superficially modified by the catalysts. For preparation of all electrocatalysts we are used 3.6 ml of a hexachloroplatinic acid (H2PtCl6) solution, containing 18.8 mg Pt/ml, 100 ml of ethylene glycol or its mixture with deionized water (3 : 1) and 100 mg of Vulcan XC-72 carbon black, previously oxidized in HNO3 solution. 1 M NaOH or KOH solutions were used to create the necessary medium (pH = 11). Some Pt(40 %)/XC-72 electrocatalysts were prepared when additions of polyvinylpyrrolidone (PVP) (100 mg or 300 mg) and/or 60 ml of formaldehyde were introduced into reaction mixture. Temperature during syntheses was in the range 75 - 160 °C. It was shown that reducing the synthesis temperature from 160 to 75 °C and introduction of PVP together with formaldehyde into reaction mixture had a positive effect on the activity of obtained nanocomposite platinum-containing catalysts Pt(40 %)/XC-72 for oxygen electroreduction.The sizes of the obtained platinum clusters on the surface of carbon black nanoparticles were in the range of 1.7 - 5.7 nm, and under optimal synthesis conditions they were evenly and densely distributed on the surface of the carbon carrier. The obtained kinetic characteristics of oxygen electroreduction on the studied catalysts indicate that the mechanism of this process depended on both the current density and the method of catalyst synthesis.

Mono-Dispersed Pt/MWNTs: Growing Directly on Multiwall Carbon Nanotubes (MWNTs) Using NaBH4 as Reducing Agent for Component of Proton Exchange Membrane Fuel Cell (PEMFC)

Synthesis of mono-dispersed Pt/MWCNTs has been performed. Platinum nanoparticles (Pt NPs) were grown directly on multiwall carbon nanotubes (MWCNTs) through sol-gel method using NaBH4 as reducing agent.       120 mg of activated MWCNT were weighed and then incorporated into the mixture (1) and sonicated for 2 hours to form the mixture (2). H2PtCl6 was weighed as much as 90 mg and dissolved into 45 mL of ethylene glycol until formed mixture (3). Solution (3) was dropwise every 3 seconds into the mixture (2). After that the mixture was distilled for 12 hours at a rate of 450 rpm. Subsequently the mixture was sonicated for 3 hours, then checked its pH, adjusting the desired pH to 4, 7, or 13 using the mixture 2M NaOH-ethylene glycol. The tests include SEM, EDS, XRD, and TEM for the morphologies and microstructures of the mono-dispersed Pt/MWCNT. The result of SEM observation and the analysis of the element using EDS found that the composite sample looked homogenous and contained element of C (MWCNT) and Pt (platinum). From the XRD shows that the composite Pt/MWCNT of the product synthesized without the reducing agent consists of three phases, namely C (MWCNTs), Pt (platinum), and H2PtH4, while the product synthesized using NaBH4 reducing agent consist of two phases, namely C (MWCNTs) and Pt (platinum ). The TEM image shows that the Pt NPs are spherical in size ~ 5 nm. Pt NPs appear to be attached on MWCNTs, either agglomerated or dispersed on the surface of MWCNTs. This paper will be compared between Pt/MWCNTs synthesis results with and without using NaBH4 reducing agent, as well as dispersed Pt NPs on MWCNTs.

(Invited) Rapid Optical Tissue Clearing Using Polyelectrolyte Hydrogels for Three-Dimensional Fluorescence Imaging

Introduction: Optical tissue clearing methods have been attractive for three-dimensional fluorescence imaging of intact tissues and organs. Most tissues are optically opaque, because tissue components such as water, protein and lipids have different refractive indices. A CLARITY method using polyacrylamide gels was recently developed. There are four steps in this method to achieve the optical tissue clearing. (1) Tissues containing chemical reagents are prepared, (2) proteins are embedded in the hydrogel, (3) lipids are removed from the tissue, and (4) the refractive index of media is adjusted. Brains became easily transparent using this method, but extracellular matrix (ECM)-rich tumor tissues did not. The third step is a rate-limiting step. We attempted to apply polyelectrolyte hydrogels to the CLARITY method for rapid removal of lipid molecules. Polyelectrolyte hydrogels are highly swollen, as the polymer networks expand because of the electrostatic repulsion between charged groups on the polymer chains. Thus, it was expected that polyelectrolyte hydrogels would contribute to rapid optical clearing because of the rapid removal of lipid molecules. Experiments: Sodium styrenesulfonate (SS), sodium 2-acrylamido-2-methylpropane sulfonate (AMPS) and acrylic acid (AcA) were used as anionic monomers. Hydrogels were prepared by using acrylamide (AAm), anionic monomers, a water soluble azo initiator (VA-044), in the presence of bis-methyleneacrylamide (bisAA). Optical tissue clearing was performed, as follows. The tissues were immersed in 10 mL of phosphate buffer saline (PBS) solution (pH 7.4) containing monomers (5.6 mmol in total), bisAA (50 mg), VA-044 (125 mg) and paraformaldehyde (400 mg) at 4oC for 24 h. Then, the hydrogel was prepared at 37oC for 24 h. After removing the gel outside the tissue, tissues were immersed in 30 mL of 0.8 M boric acid buffer containing 4% sodium dodecyl sulfate (SDS) at 37oC and were shaken for 3 days. Photos of the tissues were taken before and after the SDS treatment. Then, the tissue was placed in 30 mL of 0.1% (vol/vol) of a Triton X-100 solution. After shaking at 37oC for 2 days, it was immersed in 20 mL of ethylene glycol for 1 h. Photos of the tissues were then taken. Results and Discussion: First, a poly(AAm-co- SS) hydrogel was designed as a polyelectrolyte hydrogel for the rapid optical tissue clearing. Although poly(sodium styrenesulfonate) hydrogels were not prepared, the poly(AAm-co-SS) hydrogels with not more than 80mol% of SS could be prepared. The swelling ratio of the poly(AAm-co-SS) hydrogels became higher with a higher SS content, as expected. The optical clearing of ECM-rich tumor tissues with 15 mm × 10 mm × 1 mm was performed. The optical tissue clearing proceeded more rapidly, by using poly(AAm-co-SS) hydrogel at higher SS content. It took 2 months to clear tumor tissues using the polyacrylamide hydrogel, but only 8 days using the poly(AAm-co-SS) hydrogel at a ratio of 25/75, as shown in the attached image. Next, polyelectrolyte hydrogels with AMPS and AcA were prepared to compare the physicochemical properties and the speed of optical tissue clearing of various tissues. These polyelectrolyte hydrogels were highly swollen, and the poly(AAm-co-AMPS) hydrogel became larger than the poly(AAm-co-SS) and poly(AAm-co-AcA) hydrogels even at the same mole content. It may be because AMPS is a hydrophilic and strong electrolyte. The tumor tissues embedded in these polyelectrolyte hydrogels became transparent more rapidly, compared with the conventional method using a polyacrylamide gel. However, the clearing speeds of brain were similar among these hydrogels with and without anionic monomers. The swelling behaviors of brain tissues were different. Brain tissues embedded in the poly(AAm-co-AMPS) and poly(AAm-co-SS) hydrogels were swollen, but not in the poly(AAm) and poly(AAm-co-AcA) hydrogels. The fluorescence imaging was performed by using green fluorescent protein (GFP)-expressing tissues. The fluorescence signals were observed from tissues embedded in the poly(AAm-co-AcA) hydrogel with a similar level to those in the polyacrylamide hydrogel. However, the fluorescence signals from tissues embedded in the poly(AAm-co-AMPS) and poly(AAm-co-SS) hydrogels were diminished, suggesting that GFP in tissues was denatured by these polymers. Conclusions: The poly(AAm-co-AcA) hydrogels were the best polyelectrolyte hydrogel in this study for optical tissue clearing and the subsequent fluorescence imaging, because the clearing speed was higher and the polymer did not affect the proteins very much. Figure 1

Ethylene glycol mediated facile and controlled growth of ultralong hexagonal silver molybdate microrods

A controlled growth of nano/micro rods with defined morphologies are of great interest due to its special and unique properties. Here we report ethylene glycol mediated facile and controlled synthesis of ultra-long (∼100 μm) perfect hexagon shaped microrods of silver molybdate by a cost effective method of hydrothermal. The exact conditions are optimized by varying the effective parameters. The synthesis involves the mixing of different concentration of silver nitrate solution (0.025, 0.075, 0.125 M) with ammonium molybdate in the presence of 10 ml of ethylene glycol and then post hydrothermal treatment at 150 °C for 12 hrs. Only 0.075 M conc. of silver nitrate results perfect hexagons whereas the lower and higher concentrations result the formation of distorted edge shaped and longer microrods of Ag6Mo10O33. The magnetic measurement shows the perfect diamagnetic behavior of these mircorods.

Preparation of Ptpb/TiO2/Cup-Stacked Carbon Nanotube Composite for Enhancement of Electrocatalytic Reaction of Oxygen Reduction Reaction

PtPb ordered intermetallic nanoparticles (NPs) was deposited on titanium oxide (TiO2)/cup-stacked carbon nanotube (CSCNT) for improvement of the activity of the electrochemical oxygen reduction reaction (ORR). Employment of CSCNT as a support material caused high loading of PtPb NPs/TiO2. The PtPb NPs/TiO2/CSCNT which was prepared by the step-by-step preparation method; annealing under inert gas atmosphere with Ti-alkoxide for TiO2, photodeposition for Pt NPs and microwave synthesis to prepare ordered intermetallic PtPb NPs on TiO2 via the reaction of Pb2+ with Pt/TiO2, exhibited the enhancement of ORR electrocatalytic activity. Scheme 1 shows a schematic depiction of the step-by-step preparation method of PtPb NPs/TiO2/CSCNT by annealing under inert gas atmosphere with Ti-alkoxide for TiO2, photodeposition for Pt NPs and microwave synthesis to prepare ordered intermetallic PtPb NPs on TiO2 via the reaction of Pb2+ with Pt/TiO2. A commercially available CSCNT (100 nmf, Sankei Giken Kogyo Co., Ltd., Japan) was treated with an acidic mixture solution of H2SO4 (6 M) and HNO3 (6 M) at 90 °C for 6 h to introduce a carboxylic acid functional group on the surfaces and then washed with water, followed by drying overnight at 110 °C. A Ti precursor solution was prepared by dissolving Titanium (IV) isopropoxide (TTIP, 0.2 g) in iso-propanol (100 mL). Functionalized carbon was added to the solution under vigorous stirring. De-ionized water (1.0 mL) was used to accelerate the reaction of TTIP. After further stirring for 6h, the resulting mixture was collected and dried overnight under vacuum condition, followed by heat-treatment at 450 °C for 1 h under Ar atmosphere to yield CSCNT-supported TiO2 (TiO2/CSCNT). Pt NPs were photochemically deposited on TiO2/CSCNT to prepared Pt NPs/TiO2/CSCNT. The Pt NPs/TiO2/CSCNT (0.030 g) and Pb(CH3COO)2 ¥3H2O (0.022 mmol) were dissolved in 50 mL of ethylene glycol. The mixture was then sonicated in a bath-type ultrasonicator and treated in the flask with a reflux set for 1 min under 300-W microwave radiation. The mixture in the flask was cooled to room temperature with water. The mixture was again treated under microwave (focused microwave instrument, CEM) radiation of 300 W for 9 min. After the mixture cooled, the PtPb NPs/TiO2/CSCNT was collected via centrifugation, washed sequentially with methanol and dried under vacuum. Figure 1 shows linear-sweep ORR voltammograms for (a) PtPb NPs/TiO2/CSCNT and (b) Pt NPs/CB in O2-saturated 0.1 M HClO4 solution. Here, CB-supported Pt NPs (b) was used as a control. The ORR curve (a) obtained with PtPb NPs/TiO2/CSCNT shifts to the positive direction, owing to the interaction between PtPb NPs and TiO2when compared with one of Pt/CB (b). Scheme 1. Schematic representation of the step-by-step methode to prepare ordered intermetallic PtPb NPs/TiO2/CSCNT Figure 1. Linear sweep voltammograms (LSV) for ORR on (a) PtPb/TiO2/CSCNT and (b) Pt/CB in O2-saturated 0.1 M HClO4 aqueous solution at 10 mVs-1. Inset: a TEM image of PtPb/TiO2/CSCNT used to obtain the LSV. Figure 1

Influence of Anodization Time and Voltage on the Parameters of TiO2 Nanotubes

A vertically aligned titania nanotube layer was obtained by electrochemical anodic oxidation in the electrolyte contained 0.4 wt% solution of NH4F in 54 ml of ethylene glycol and 5 ml of deionized water, after titanium was chemically cleaned/etched with a mixture of HCl, H2O and HNO3 solution for removing the natural oxide films. The morphology and composition of the titania nanotube layer were examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The anodization of TiO2 nanotubes was done using 60 V for 240 min and 30 min, and 30 V for 30 min. The diameter of the titania nanotubes was about 52-156 nm, the wall thickness about 32-53 nm and the height about 0.9-6.3 μm. The pore size of TiO2 nanotubes influences the dissolution rate of CaP thin films and Young's modulus, which is significantly lower than that of the Ti substrate. Our future challenge will be investigation of the microstructure and mechanical behavior of titania nanotubes with CaP film.

Electrochemical Simultaneous Detection of Dopamine, Ascorbic Acid and Uric Acid Using LaMnO3 Nanostructures

A facile hydrothermal approach was employed to prepare diverse morphologies of LaMnO3 nanostructures. These nanostructures were used to modify the electrode for electrochemical detection of dopamine (DA) in the presence of excess ascorbic acid (AA) and uric acid (UA). The morphology was tuned by changing the concentration of ethylene glycol (EG) and the size and roughness was controlled by urea. The electrochemical behavior of glassy carbon electrode (GCE) modified with different morphologies of prepared LaMnO3 nanostructures was investigated by using cyclic voltammetry (CV). The results confirm the LaMnO3 nanostructure prepared with 10 mL of EG has strong electrocatalytic activity than other concentrations of EG. This electrode was further used as an electroactive probe for the electrochemical simultaneous detection of DA, AA and UA. The final results clearly confirm the GCE modified with LaMnO3 nanostructure can be successfully employed for the electrochemical simultaneous detection of DA, AA and UA in real biological samples.

Rapid,Microwave-Assisted Synthesis of a Composite of Mesoporous MnCo2O4 and Reduced Graphene Oxide(RGO) As a High Perfomance Anode for Li- Ion Batteries

Over the last two decades Li-ion batteries (LIBs) have been investigated to improve their electrochemical properties. LIBs have ushered wireless technology and are now employed in large scale applications such as electric vehicles, solar and wind electricity generation systems. The performances of LIBs depend on properties of electrode materials. Since the first commercialization of LIBs by Sony in 1991, graphitic carbons have been used as anode materials. However graphite suffers from challenges like limited capacity, lithium plating at high current densities and formation solid electrolyte interface (SEI). This has motivated researchers to develop alternate anode materials which could deliver high energy and power densities. Cobalt oxide, iron oxide, manganese oxide and tin oxide are some among them. But most of these materials show rapid capacity fade due to low electronic conductivity. Binary metal oxides such as ZnFe2O4, CuCo2O4, ZnCo2O4, ZnMn2O4, NiCo2O4 and MnCo2O4 have shown good capacity upon cycling because of their better electronic conductivity. MnCo2O4, belongs to cubic spinel structure have attracted much attention due to its characteristics inherited from manganese and cobalt based metal oxides. One of the challenging issues in conversion reaction of a bulk electrode material is to maintain structural integrity during electrochemical cycling with associated issues such as volume changes, pulverization, etc., which affect the performance porous materials have been studied widely because of the easy percolation of electrolyte into core of particles which result in high rate capability and also by allowing volume expansion/contraction arising from intercalation/deintercalation of Li+ ions. Using templates become a general approach to synthesize these porous structures. However in most of the cases, the synthesis requires long duration and involves specially designed autoclaves. Here in we report a single step and rapid, microwave-assisted synthesis route to synthesize mesoporous microspheres of MnCo2O4 dispersed with low concentration (≤ 5 wt%) of reduced graphene oxide (RGO). In a typical synthesis, 0.02 g of graphite oxide (GtO) was added to 20 ml of ethylene glycol and sonicated for 20 minutes at room temperature to form graphene oxide (GO) dispersion. 0.5 mmol of Manganese (II)nitrate. tetra hydrate, 1.0 mmol of cobaltous(III)nitrate.hexahydrate and 15 mmol of ammonium bicarbonate were dissolved in 20 ml of ethylene glycol and stirred for 30 minutes to obtain a homogeneous solution. Then this solution was added drop wise to already prepared solution of graphite oxide under sonication. After sonication, solution was taken into 80 ml glass vessel, heated to 200 oC by microwave irradiation in a single mode microwave reactor (2.45 GHz, Discover, CEM, USA) equipped with a pressure sensor, and an optical fibre temperature sensor, and held at the same temperature for 30 minutes. The system was then cooled down to room temperature naturally. The dark grey coloured product was collected by centrifugation and washed several times with distilled water and ethanol, followed by drying at 60 oC overnight. As prepared dark grey powder was heated to 600 oC at an average heating rate 5 oC per minute in a tube furnace under the flow of nitrogen and held at the same temperature for 5 h to convert it into MnCo2O4 and RGO composite. The phase purity and morphology of the final product were studied by XRD, SEM and TEM analysis. The microscopic image (figure.1) shows that mesoporous MnCo2O4 microspheres were attached on to RGO sheets. The charge-discharge profile is shown in Fig. 2. The specific discharge capacities of 841, 801, 832 and 765 mAh g-1 were obtained for 1st, 2nd, 5th and 30th cycles, respectively, at a current density of 100 mA g-1 in the potential range of 0.01 and 3.0 V vs Li/Li+. These values are comparable with the values that were reported previously. Results pertaining to the aforementioned studies including both physical and electrochemical investigations would be presented. Figure 1

Facile Process and Electrochemical Characterizations of Carbon Nanotube-LiFePO4 Composite As a Cathode for High Rate Lithium Ion Batteries

: LiFePO4 nanoparticles were incorporated with multi-walled carbon nanotubes (CNTs) via a facile one-step at low temperature polyol process. The CNTs were fund to embed into the LiFePO4 particles that form a network to enhance the electrochemical performance of LiFePO4 electrode. Structural morphologies of these CNT-LiFePO4 composites were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The electrochemical properties were analyzed by charge/discharge testing and cyclic voltammetry. Primary results showed that the CNT-LiFePO4 composites exhibited enhanced electrochemical performance with a good reversibility and the electronic conductivity. Introduction: Lithium-ion batteries have been considered to play an important role in the electric vehicles (HEV) and plug-in HEV (PHEV) in the near future, which require high power density and high energy density. Thus, cathode materials with high rate capability are in demand [1, 2]. LiFePO4 shows promise as a cathode material for HEVs owing to its high specific capacity and excellent structural stability [3, 4]. However, its poor electronic conductivity and lithium diffusion significantly limit its performance at high rates [5-9]. Therefore, studies on LiFePO4 have focused on improving its rate capability. Coatings of conductive materials [5-10] has been reported to improve the electronic conductivity. Recent efforts have been made to improve rate performance of the LiFePO4 by the synthesized nanocomposites using carbon nanotubes (CNTs) [11]. These nano-carbons improve the high rate capability of LiFePO4, when they are uniformly dispersed in the composite. Herein we report the facile synthesis of CNT-LiFePO4composites with the CNT network providing a conduction path. Experimental: Multi-walled carbon nanotubes (5 wt.% ) were functionalized via the mixed acid method in order to remove the impurities and acquire excellent dispersion in the polyol medium. CNT-LiFePO4 nanocomposites were obtained by using a polyol process as follows: first, the CNTs were added into 100 ml of ethylene glycol and a homogeneous dispersion was achieved by an ultrasonic process. Then, pristine LiFePO4 particles (~50 nm) were directly dissolved into the dispersion by mechanical agitation in a three-neck round flask. Lastly, the mixed dispersion was heated to above its boiling point and maintained for 10 h under stirring and refluxing. After cooling down, the products were separated from the solvent via centrifugation. In order to remove the organic residue impurities, the products were washed with deionized water several times. Finally, the CNT-LiFePO4composite powders were dried at 100 °C for 24 h. Structural morphology were characterized by X-ray diffraction, scanning and transmission electron microscopy (SEM, TEM). Electrochemical performances were investigated by galvanostatic charge-discharge and cyclic voltammetry (CV) over the voltage between 2.0 and 4.0 V using coin cells (CR2032) at a LAND-CT2001A battery-testing system. Results: The morphology of the composites were investigated by scanning electron microscopy (SEM), as showed in Fig.1 that the LiFePO4 nanoparticles are dispersed uniformly with the CNT network. The electrochemical CVs tests were performed in the voltage of 2.0 and 4.0 V at the scanning rate of 0.1 mV s−1. A pair of redox peaks is clearly exhibited in the CNT-LiFePO4 composite cathode, which correspond to the two-phase charge-discharge reaction of the Fe2+/Fe3+ redox couple. The peak curves are very symmetric. The oxidation and reduction peaks appear at around 3.5 and 3.3 V with the potential gap of 0.2 V, which is less than the value of pristine LiFePO4 cathode as reported, and suggested that electrode reaction reversibility and the electronic conductivity of these composites are greatly enhanced owing to the incorporation of CNTs. Acknowledgements: Financial supports from University of Waterloo President’s Award, Natural Sciences and Engineering Research Council of Canada (NSERC) and Waterloo Institute for Nanotechnology (WIN) are greatly appreciated.

Thermal Characteristics of a Circular Finned Thermosyphon Using Different Working Fluids

The two-phase closed thermosyphon (TPCT), which is essentially a gravity-assisted wickless heat pipe, utilizes the evaporation and condensation of the working fluid inside the TPCT to transport heat. This experimental study was carried out to understand the thermal performance of circular finned thermosyphon using nanofluid with alcohol and was analyzed, compared with alcohol and base fluid DI water. The concentration of nanoparticle used in this setup was 110mg/lit of TiO2combined with 0.2 ml of ethylene glycol. The heat input (Q) were 10W, 12W, 14 W and 16 W and the orientation 30°, 45°, 60° and 90°.The results demonstrate that TiO2nanofluid with 0.2 ml of ethylene glycol improves the performance through reduction in thermal resistance by 85.86%.

Porous Flower-like α-Fe2O3 As a High Performance Anode for Lithium-Ion Batteries

Since commercializing of the first lithium-ion battery by Sony Corporation in 1991, graphitic carbons have been used as anode materials. Graphitic carbons owe to their favorable characteristics such as eco-friendly, stability upon cycling, low operating potential versus Li/Li+, etc. however, carbon materials also poses several challenges that include limited specific capacity (~ 372 mAh g-1), formation of a solid-electrolyte interphase (SEI), lithium plating or formation of a surface film at high current rates, etc. To overcome these difficulties, research has been focused on transition metal oxides as alternate anode materials. Various metal oxides (to mention a few Co3O4, MnO2, Fe3O4 and Fe2O3) have been reported to undergo conversion reactions while exhibiting lower voltages with high reversible capacities than the traditional graphitic carbon counterparts. This has motivated many researchers to study the conversion reaction of oxide materials.1 Among the transition metal oxides studied, hematite α-Fe2O3 has been intensively studied due to its low cost, excellent stability, environmental friendly properties and also providing high theoretical capacity 1007 mAh g-1 based on 6 Li+per formula unit.One of the challenging issues in conversion reaction of a bulk electrode material is to maintain structural integrity during electrochemical cycling with associated issues such as volume changes, pulverization, etc., which affect the performance.2Congruently, through nanostructured materials such as nanoparticles, nanocubes, nanorods, nanotubes and nanoflowers, we may facilitate an increase in the electrochemical performance due to short diffusion length for Li-ion and electronic transport. Among these, porous materials have been studied widely because of the easy percolation of electrolyte into core of particles which result in high rate capability. Porous materials can also sustain mechanical stress generated by volume expansion/contraction during the electrochemical cycling.In the present work, we report synthesis of iron alkoxide precursors using 4.4 mmol FeCl3.6H20, 90 mmol urea and 124 mmol tetra butyl ammonium bromide are added to 180 ml of ethylene glycol in 250 ml round bottomed flask, stirred for 10 min to get homogeneous solution and refluxed at 195 oC for 30 min. The obtained green precipitate of iron alkoxide is washed with ethanol and dried at 60 oC for 12 h. The resultant dried powder is calcined at a range of temperatures from 300 to 500 oC for 3 h in air.3 A porous flower-like nanostructured α-Fe2O3 is obtained by subsequent calcination of iron alkoxide precursor. The phase purity and morphology of the final product (α-Fe2O3) are studied by XRD, SEM and TEM analysis. The microscopic images show (Fig. 1) a flower-like morphology. The BET surface area and its pore size of the α-Fe2O3 are measured and they are 64 m2 g-1 and 6 nm, respectively. The α-Fe2O3 powder is subjected to galvanostatic charge/discharge experiments between 0.01 and 3.0 V versus Li/Li+. The charge-discharge profile is shown in Fig. 2. The discharge capacities obtained for 1st, 10th and 20th cycle are of 1058, 1044 and 917 mAh g-1 respectively for the sample prepared at 300 oC. These values are greater than the values reported so far on α-Fe2O3. Porous nature of α-Fe2O3 prepared in the present study is responsible for high discharge capacity and also high rate capability. Results of these studies including both physical and electrochemical investigations will be presented. Acknowledgements: SS and TRP acknowledge University Grants Commission (UGC), Government of India for Dr. D. S. Kothari fellowship and Senior Research Fellowship, respectively.

Statistical modelling studies on leachability of titania-rich slag obtained from plasma melt separation of metallized ilmenite

In the course of the present study optimization of leaching parameters by HCl was carried out using response surface method with central composite design. Effect of three parameters, viz. acid concentration, residence time and additive concentration on iron leaching (taken as response) were studied to obtain a statistical model. To determine factor response initial experiments were planned by factorial design and orthogonal central composite design methods. Factor level were estimated based on statistical analysis and optimum parameters obtained are at acid concentration of 6.71 M HCl with 94 min of residence time and 6.09 ml of ethylene glycol for 0.5 g of slag in a batch scale. Based on the model obtained by means of variance analysis, about 77.3% Fe could be leached out, which conforms to the model predictions, giving a residue containing about 94% TiO 2.

AGHCF GASEOUS-EFFLUENT TRITIUM SAMPLING SYSTEM: DESIGN CONSIDERATIONS AND PERFORMANCE TESTING RESULTS

Performance testing results involving the operation of a gaseous-effluent tritium sampling system are provided. A system description, including design improvements made over the course of several years of operation, is also presented. The sampling technique is based on using ethylene glycol bubblers for collecting tritiated water entrained as vapor in a nitrogen purge gas from a hot cell facility. Tritiated gas is converted to water vapor using a high temperature copper oxide bed; newly-formed water molecules are readily collected in a second set of ethylene glycol bubblers. For a single bubbler containing 20 mL of ethylene glycol, the tritium collection efficiency was determined to be 98.3%. To optimize performance and to minimize the volume of mixed waste generated, tests were performed to evaluate variations in the collection efficiency as a function of sorbent volume. For purposes of comparison the performance of water-filled bubblers was also evaluated. With two water bubblers connected in series the overall collection efficiency was quite satisfactory at 95.4%, although appreciable water losses were evident. The bed oxidation efficiency for tritiated gas was evaluated over a range of temperatures; at a catalyst bed temperature of 350 degrees C nearly all the gas was converted to water vapor. System memory effects were assessed by measuring the amount of residual contamination present in the bubblers after purging the sampling system for a week offline. Contamination problems arising from previous sampling periods were inconsequential. The overall uncertainty associated with the total quantity of tritium discharged to the environment based on the results of the performance testing was estimated to be +/-24% at the 95% confidence level.

Effects of dextran on five biuret-based procedures for total protein in serum.

We evaluated the effect of dextran on values for total protein in serum as measured by the biuret method with five widely used automated instruments: the American Monitor Parallel; the Du Pont aca II; the Roche Cobas-Bio; the Kodak Ektachem 400; and the Beckman Astra 8. Dextran concentrations as great as 25 or 30 g/L had relatively little or no influence on total protein measurements by the latter three instruments. Dextran concentrations exceeding 6 g/L caused falsely low results with the aca, whereas the Parallel gave falsely high results when the dextran concentration exceeded 2 g/L. The aca total protein procedure could be protected from the interference by dextran concentrations up to 30 g/L by injecting 0.4-0.8 mL of ethylene glycol directly into the reagent pack before sampling. However, we could not eliminate the interference with the Parallel procedure by any simple means; we thus recommend that it not be used for measuring total protein in serum samples from patients who are being treated with dextran.

Interface characteristics of Inp MOS capacitors

A new electrolyte based on a solution of 10 g of ammonium pentoborate in 100 ml of ethylene glycol buffered to a ph of 6.0 has been used to produce a dielectric layer on the surface of InP. The relative permittivity of the anodic oxide is 7.9 and its dielectric breakdown strength is 3×106v/cm. The electrical characteristics of the surface states at the anodic oxide–-type InP interface have been investigated using MOS capacitors. Capacitance–voltage data at 200 kHz indicate that the InP surface is already depleted at zero bias with a flat band voltage of 0.85 V. An inversion-type low frequency (1 Hz) response has been observed for the first time on an InP MOS structure using an anodic oxide. Our analysis of the admittance data yields a U-shaped surface state distribution having a minimum density of 4×1011 cm−2 eV−1 at mid-band gap. Many other fea ures of our results also resemble those previously obtained with InP/organic insulator structures.