Search results for: metal nanoparticles

Authors: Aboul-Nasr Amal, Sabry Soraya, Sabra Mayada

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The effects of phosphorus amendments and arbuscular mycorrhizal (AM) fungi Glomus intraradices on the sweet basil (Ocimum basilicum L.), chemical composition and percent of volatile oil, and metal accumulation in plants and its availability in soil were investigated in field experiment at two seasons 2012 and 2013 under contaminated soil with Pb and Cu. The content of essential oil and shoot and root dry weights of sweet basil was increased by the application of mineral phosphorus as compared to control. Inoculation with AM fungi reduced the metal concentration in shoot, recording a lowest value of (33.24, 18.60 mg/kg) compared to the control (46.49, 23.46 mg/kg) for Pb and Cu, respectively. Availability of Pb and Cu in soil were decreased after cultivation in all treatments compared to control. However, metal root concentration increased with the inoculation, with highest values of (30.15, 39.25 mg/kg)compared to control (22.01, 33.57mg/kg) for Pb and Cu, respectively. The content of linalool and methyl chavicol in basil oil was significantly increased in all treatments compared to control. We can thus conclude that the AM-sweet basil symbiosis could be employed as an approach to bioremediate polluted soils and enhance the yield and maintain the quality of volatile oil of sweet basil plants.

Keywords: arbuscular mycorrhizal fungus, heavy metals, sweet basil, oil composition

Procedia PDF Downloads 244

Authors: Javaid Butt, Habtom Mebrahtu, Hassan Shirvani

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The paper presents a new additive manufacturing process for the production of metal and composite parts. It is termed as composite metal foil manufacturing and is a combination of laminated object manufacturing and brazing techniques. The process has been described in detail and is being used to produce dissimilar aluminum to copper foil single lap joints. A three dimensional finite element model has been developed to study the thermo-mechanical characteristics of the dissimilar Al/Cu single lap joint. The effects of thermal stress and strain have been analyzed by carrying out transient thermal analysis on the heated plates used to join the two 0.1mm thin metal foils. Tensile test has been carried out on the foils before joining and after the single Al/Cu lap joints are made, they are subjected to tensile lap-shear test to analyze the effect of heat on the foils. The analyses are designed to assess the mechanical integrity of the foils after the brazing process and understand whether or not the heat treatment has an effect on the fracture modes of the produced specimens.

Keywords: brazing, laminated object manufacturing, tensile lap-shear test, thermo-mechanical analysis

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Authors: Srinivas Nerella

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A series of new heterodentate N, O-donor ligands derived from condensing 3-amino Coumarins with hydroxy benzaldehydes and acetophenones were used to afford new mononuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) coordination compounds. All the complexes were characterized by IR, 1H-NMR, 13C-NMR, Mass, ESR, Electronic spectra, Conductance, Magnetic and Thermal studies. The ligands show hexa coordination in Mn(II), Co(II), Ni(II), and Pd(II) complexes resulting octahedral geometries, while the ligands in Zn(II) and Cu(II) complexes show tetra coordination resulting tetrahedral and square planar geometries respectively. These mononuclear complexes were investigated as catalysts in the hydrothiolation of aromatic and aliphatic alkynes with thiols. These metal complexes were acted as versatile catalysts and gave good yields.

Keywords: schiff bases, divalent metal complexes of schiff bases, Catalytic activity, hydrothiolation

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Authors: Yusuf Emirov, Abdullatif Hakami, Prasanta K Biswas, Elias K Stefanakos, Sesha S Srinivasan

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This study is aimed to develop microencapsulated thermochromic materials and the analysis of core-shell formation using high resolution electron microscopy. The candidate metal oxides (e.g., titanium oxide and silicon oxide) used for the microencapsulation of thermochromic materials are based on the microemulsion route that involves the micelle formation using different surfactants. The effectiveness of the core-shell microstructure formationrevealed the influence of surfactants and the metal oxide precursor concentrations. Additionally, a detailed thermal and color chromic behavior of these core-shell microcapsules are evaluated with the pristine thermochromic dye particles.

Keywords: core-shell thermochromic materials, core-shell microstructure formation, thermal and color chromic behavior of core-shell microcapsules, development micro-capsulated thermochromic materials

Procedia PDF Downloads 151

Authors: Reza Eslami-Farsani, Hamed Khosravi, Saba Fayazzadeh

Abstract:

Lightweight and efficient structures have the aim to enhance the efficiency of the components in various industries. Toward this end, composites are one of the most widely used materials because of durability, high strength and modulus, and low weight. One type of the advanced composites is grid-stiffened composite (GSC) structures which have been extensively considered in aerospace, automotive, and aircraft industries. They are one of the top candidates for replacing some of the traditional components which are used here. Although there are a good number of published surveys on the design aspects and fabrication of GSC structures, little systematic work has been reported on their material modification to improve their properties, to our knowledge. Matrix modification using nanoparticles is an effective method to enhance the flexural properties of the fibrous composites. In the present study, a silane coupling agent (3-glycidoxypropyltrimethoxysilane/3-GPTS) was introduced onto the silica (SiO2) nanoparticle surface and its effects on the three-point flexural response of isogrid E-glass/epoxy composites were assessed. Based on the fourier transform infrared spectrometer (FTIR) spectra, it was inferred that the 3-GPTS coupling agent was successfully grafted onto the surface of SiO2 nanoparticles after modification. Flexural test revealed an improvement of 16%, 14%, and 36% in stiffness, maximum load and energy absorption of the isogrid specimen filled with 3 wt.% 3-GPTS/SiO2 compared to the neat one. It would be worth mentioning that in these structures, a considerable energy absorption was observed after the primary failure related to the load peak. Also, 3-GPTMS functionalization had a positive effect on the flexural behavior of the multiscale isogrid composites. In conclusion, this study suggests that the addition of modified silica nanoparticles is a promising method to improve the flexural properties of the grid-stiffened fibrous composite structures.

Keywords: isogrid-stiffened composite panels, silica nanoparticles, surface modification, flexural properties, energy absorption

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Authors: Qingtao Yu, Guojia Ma

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Approaches to microwave absorption and low infrared emissivity are often conflicting, as the low-emissivity layer, usually consisting of metals, increases the reflection of microwaves, especially in high frequency. In this study, an infrared-radar compatible stealth surface was fabricated by first depositing a layer of low-emissivity metal film on the surface of a layer of radar-absorbing material. Then, ultrafast laser was used to generate patterns on the metal film, forming a frequency selective surface. With proper pattern design, while the majority of the frequency selective surface is covered by the metal film, it has relatively little influence on the reflection of microwaves between 2 to 18 GHz. At last, structures on the radar-absorbing layer were fabricated by ultra-fast laser to further improve the absorbing bandwidth of the microwave. This study demonstrates that the compatibility between microwave absorption and low infrared emissivity can be achieved by properly designing patterns and structures on the metal film and the radar-absorbing layer accordingly.

Keywords: frequency selective surface, infrared-radar compatible, low infrared emissivity, radar-absorbing material, patterns, structures

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Authors: A. Fernandez Zuvich, I. Gana Watkins, H. Zolotucho, H. Troiani, A. Caneiro, M. Prado, A. L. Soldati

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The study of actinide nanoparticles (NPs) has attracted the attention of the scientific community not only because the lack of information about their ecotoxicological effects but also because the use of NPs could open a new way in the production of nuclear energy. Indeed, it was recently demonstrated that UO2 NPs sintered pellets exhibit closed porosity with improved fission gas retention and radiation-tolerance , ameliorated mechanical properties, and less detriment of the thermal conductivity upon use, making them an interesting option for new nuclear fuels. In this work, we used a combination of diffraction and microscopy tools to characterize the morphology, the crystalline structure and the composition of UO2 nanoparticles doped with 10%wt Gd2O3. The particles were synthesized by a modified sol-gel method at low temperatures. X-ray Diffraction (XRD) studies determined the presence of a unique phase with the cubic structure and Fm3m spatial group, supporting that Gd atoms substitute U atoms in the fluorite structure of UO2. In addition, Field Emission Gun Scanning (FEG-SEM) and Transmission (FEG-TEM) Electron Microscopy images revealed the presence of micrometric agglomerates of nanoparticles, with rounded morphology and an average crystallite size < 50 nm. Energy Dispersive Spectroscopy (EDS) coupled to TEM determined the presence of Gd in all the analyzed crystallites. Besides, FEG-SEM-EDS showed a homogeneous concentration distribution at the micrometer scale indicating that the small size of the crystallites compensates the variation in composition by averaging a large number of crystallites. These techniques, as combined tools resulted thus essential to find out details of morphology and composition distribution at the sub-micrometer scale, and set a standard for developing and analyzing nanoparticulated nuclear fuels.

Keywords: actinide nanoparticles, burnable poison, nuclear fuel, sol-gel

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Authors: K. Sivasubramanin, S. Mahimairaja, S. Pavithrapriya

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Heavy metal pollution originating from industrial wastes is becoming a serious problem in many urban environments. These heavy metals, if not properly managed, could enter into the food chain and cause a serious health hazards in animals and humans. Industrial wastes, sewage sludge, and automobile emissions also contribute to heavy metal like Pb pollution in the urban environment. However, information is scarce on the heavy metal pollution in Coimbatore urban environment. Therefore, the current study was carried out to examine the extent of lead pollution in Coimbatore urban environment the maximum Pb concentration in Coimbatore urban environment was found in ukkadam, whose concentration in soils 352 mg kg-1. In many places, the Pb concentration was found exceeded the permissible limit of 100 mg kg-1. In laboratory, closed incubation experiment showed that the concentration of different species of Pb viz., water soluble Pb(H2O-Pb), exchangeable Pb(KNO3-Pb), organic-Pb(NaOH-Pb), and organic plus metal (Fe & Al) oxides bound-Pb(Na2 EDTA-Pb) was found significantly increased during the 15 days incubation, mainly due to biotransformation processes. Both the moisture content of soil and ambient temperature exerted a profound influence on the transformation of Pb. The results of a batch experiment has shown that the sorption data was adequately described by the Freundlich equation as indicated by the high correlation coefficients (R2= 0.64) than the Langmuir equation (R2 = 0.33). A maximum of 86 mg of Pb was found adsorbed per kilogram of soil. Consistently, a soil column experiment result had shown that only a small amount of Pb( < 1.0 µg g-1 soil) alone was found leached from the soil. This might be due to greater potential of the soil towards Pb adsorption.

Keywords: lead pollution, adsorption, transformation, heavy metal pollution

Procedia PDF Downloads 319

Authors: Reza Eslami-Farsani, Hamed Khosravi, Saba Fayazzadeh

Abstract:

Lightweight and efficient structures have the aim to enhance the efficiency of the components in various industries. Toward this end, composites are one of the most widely used materials because of durability, high strength and modulus, and low weight. One type of the advanced composites is grid-stiffened composite (GSC) structures, which have been extensively considered in aerospace, automotive, and aircraft industries. They are one of the top candidates for replacing some of the traditional components, which are used here. Although there are a good number of published surveys on the design aspects and fabrication of GSC structures, little systematic work has been reported on their material modification to improve their properties, to our knowledge. Matrix modification using nanoparticles is an effective method to enhance the flexural properties of the fibrous composites. In the present study, a silane-coupling agent (3-glycidoxypropyltrimethoxysilane/3-GPTS) was introduced onto the silica (SiO2) nanoparticle surface and its effects on the three-point flexural response of isogrid E-glass/epoxy composites were assessed. Based on the fourier transform infrared spectrometer (FTIR) spectra, it was inferred that the 3-GPTS coupling agent was successfully grafted onto the surface of SiO2 nanoparticles after modification. Flexural test revealed an improvement of 16%, 14%, and 36% in stiffness, maximum load and energy absorption of the isogrid specimen filled with 3 wt.% 3-GPTS/SiO2 compared to the neat one. It would be worth mentioning that in these structures, considerable energy absorption was observed after the primary failure related to the load peak. In addition, 3-GPTMS functionalization had a positive effect on the flexural behavior of the multiscale isogrid composites. In conclusion, this study suggests that the addition of modified silica nanoparticles is a promising method to improve the flexural properties of the grid-stiffened fibrous composite structures.

Keywords: isogrid-stiffened composite panels, silica nanoparticles, surface modification, flexural properties

Procedia PDF Downloads 228

Authors: Neeraj Kumar Verma

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Lanthanum hydroxide and manganese oxide nanocomposite are synthesized by chemical routes. Physical characterization is done by TEM to look at the size and dispersion of the nanoparticles in the composite. Chemical characterization is done by X-ray diffraction technique and FTIR to ascertain the attachment of the functionalities and bond stretching. Further thermal analysis is done by thermogravimetric analysis to find the tendency of the thermal decomposition in the elevated temperature range of 0-1000°C. Proper analysis and correlation of the various results obtained suggested the controlled growth of crystalline without agglomeration and good stability in the various temperature ranges of the composite.

Keywords: nanoparticles, XRD, TEM, lanthanum hydroxide, manganese oxide

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Authors: Thi Lan Huong Nguyen, Motohei Kanayama, Takahiro Higashi, Van Chinh Le, Thu Ha Doan, Anh Daochu

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Waste from industrial sources, serves as sources of water for irrigating farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals in the soils. Soil samples were collected from the different locations from upstream to downstream of the Nhue River to evaluate heavy metal pollution. The results showed that the concentrations of all heavy metals in the soil samples in the farmland area were much higher than the background level in that area (1.2-2.6 mg/kg for Cd, 42-60 mg/kg for Cr, 22-62mg/kg for Cu, 30-86 mg/kg for Pb, 119-245 mg/kg for Zn, and 26-57 mg/kg for Ni), and exceeded the level of Vietnamese standard for agricultural soil for all heavy metals Cd, Cu, Pb, and Zn except soil samples at upstream and downstream of the Nhue River.

Keywords: heavy metal, soil, Nhue River, wastewater irrigation

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Authors: Sang Koo Jeon, Seung Hoon Nahm, Oh Heon Kwon

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The unit cell of solid oxide fuel cell (SOFC) must be stacked as several layers type to obtain the high power. The most of researcher have concerned about the performance of stacked SOFC rather than the structural stability of stacked SOFC and especially interested how to design for reducing the electrical loss and improving the high efficiency. Consequently, the stacked SOFC able to produce the electrical high power and related parts like as manifold, gas seal, bipolar plate were developed to optimize the stack design. However, the unit cell of SOFC was just layered on the interconnector without the adhesion and the hydrogen and oxygen were injected to the interfacial layer in the high temperature. On the operating condition, the interfacial layer can be the one of the weak point in the stacked SOFC. Therefore the evaluation of the structural safety for the failure is essentially needed. In this study, interfacial adhesion between SOFC and metal adhesive was estimated in the high temperature environment. The metal adhesive was used to strongly connect the unit cell of SOFC with interconnector and provide the electrical conductivity between them. The four point bending test was performed to measure the interfacial adhesion. The unit cell of SOFC and SiO2 wafer were diced and then attached by metal adhesive. The SiO2 wafer had the center notch to initiate a crack from the tip of the notch. The modified stereomicroscope combined with the CCD camera and system for measuring the length was used to observe the fracture behavior. Additionally, the interfacial adhesion was evaluated in the high temperature condition because the metal adhesive was affected by high temperature. Also the specimen was exposed in the furnace during several hours and then the interfacial adhesion was evaluated. Finally, the interfacial adhesion energy was quantitatively determined and compared in the each condition.

Keywords: solid oxide fuel cell (SOFC), metal adhesive, adhesion, high temperature

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Authors: Claudiu Marcu, Cristina Paul, Adelina Andelescu, Corneliu Mircea Davidescu, Francisc Péter

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Heavy metal pollution has become a more serious environmental problem in the last several decades as a result of its toxicity and insusceptibility to the environment. Methods for removing metal ions from aqueous solution mainly consist of physical, chemical and biochemical procedures. Biosorption is defined as the removal of metal or metalloid species, compounds and particulates from solution by a biological material. Biosorption represents a very attractive method for the removal of toxic metal ions from aqueous effluents because it uses the ability of various biomass to bind the metal ions without the risk of releasing other toxic chemical compounds into the environment. The problem with using biomass or living cells as biosorbents is that their regeneration/reuse is often either impossible or very laborious. One of the most common chelating group found in biosorbents is the thiol group in cysteine. Therefore, we immobilized cysteine using covalent binding using glutaraldehyde as a linker on a synthetic sol-gel support obtained using 3-amino-propyl-trimetoxysilane and trimetoxysilane as precursors. The obtained adsorbents were used for removal of cadmium from aqueous solutions and the removal capacity was investigated in relation to the composition of the sol-gel hybrid composite, the loading of the biomolecule and the physical parameters of the biosorption process. In the same conditions, the bare sol-gel support without cysteine had no Cd removal effect, while the adsorbent with cysteine had an adsorption capacity up to 25.8 mg Cd/g adsorbent at pH 2.0 and 119 mg Cd/g adsorbent at pH 6.6, depending on cadmium concentration and adsorption conditions. We used atomic adsorption spectrometry to assess the cadmium concentration in the samples after the biosorbtion process. The parameters for the Freundlich and Langmuir adsorption isotherms where calculated from plotting the results of the adsorption experiments. The results for cysteine immobilization show a good loading capacity of the sol-gel support which indicates it could be used to immobilize metal binding proteins and by doing so boosting the heavy metal adsorption capacity of the biosorbent.

Keywords: biosorbtion, cadmium, cysteine covalent binding, sol-gel

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Authors: M. E. Turan, H. Zengin, E. Cevik, Y. Sun, Y. Turen, H. Ahlatci

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In this study, the effects of B₄C and SiC particle reinforcements on wear properties of magnesium matrix metal composites produced by pressure infiltration method were investigated. AZ91 (9%Al-1%Zn) magnesium alloy was used as a matrix. AZ91 magnesium alloy was melted under an argon atmosphere. The melt was infiltrated to the particles with an appropriate pressure. Wear tests, hardness tests were performed respectively. Microstructure characterizations were examined by light optical (LOM) and scanning electron microscope (SEM). The results showed that uniform particle distributions were achieved in both B₄C and SiC reinforced composites. Wear behaviors of magnesium matrix metal composites changed as a function of type of particles. SiC reinforced composite has better wear performance and higher hardness than B₄C reinforced composite.

Keywords: magnesium matrix composite, pressure infiltration, SEM, wear

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Authors: Aneek Kuila, Yaron Paz

Abstract:

MIP 177 LT and HT are two-phase transformable metal organic frameworks consisting of a Ti12O15 oxocluster and a tetracarboxylate ligand that exhibits robust chemical stability and improved photoactivity. LT to HT only shows the changes in dimensionality from 0D to 1D without any change in the overall chemical structure. In terms of chemical and photoactivity MIP 177 LT is found to perform better than the MIP 177HT. Step-scan Fourier transform absorption difference time-resolved spectroscopy has been used to collect mid-IR time-resolved infrared spectra of the transient electronic excited states of a nano-porous metal–organic framework MIP 177-LT and HT with 2.5 ns time resolution. Analyzing the time-resolved vibrational data after 355nm LASER excitation reveals the presence of the temporal changes of ν (O-Ti-O) of Ti-O metal cluster and ν (-COO) of the ligand concluding the fact that these moieties are the ultimate acceptors of the excited charges which are localized over those regions on the nanosecond timescale. A direct negative correlation between the differential absorbance (Δ Absorbance) reveals the charge transfer relation among these two moieties. A longer-lived transient signal up to 180ns for MIP 177 LT compared to the 100 ns of MIP 177 HT shows the extended lifetime of the reactive charges over the surface that exerts in their effectivity. An ultrafast change of bidentate to monodentate bridging in the -COO-Ti-O ligand-metal coordination environment was observed after the photoexcitation of MIP 177 LT which remains and lives with for seconds after photoexcitation is halted. This phenomenon is very unique to MIP 177 LT but not observed with HT. This in-situ change in the coordination denticity during the photoexcitation was not observed previously which can rationalize the reason behind the ability of MIP 177 LT to accumulate electrons during continuous photoexcitation leading to a superior photocatalytic activity.

Keywords: time resolved FTIR, metal organic framework, denticity, photoacatalysis

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Authors: Jaemin Kim, Ilsun Pang, Yongrae Cho, Kwanghun Kim, Sungsun Baik

Abstract:

Manufacturing cost reduction is becoming more important due to excessive oversupply of Single crystalline ingot in recent solar market. Many companies are carrying out extensive research to grow more than one Single crystalline ingot in one batch to reduce manufacturing cost. However what most companies are finding difficult in this process is the effect on ingot due to increasing levels of impurities. Every ingot leaves a certain amount of melt after it is fully grown. This is the impurity that lowers the ingot quality. This impurity increase in the batch after second, third and more are grown subsequently in one batch. In order to solve this problem, the experiment to remove the residual melt in high temperature of hot zone was performed and succeeded. Theoretical average metal concentration of second ingot by new method was calculated and compared to it by conventional method.

Keywords: single crystal, solar cell, metal impurity, Ingot

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Authors: Okpaneje Onyinye Theresa, Ugwu Laeticia Udodiri, Okereke Ngozi Agatha, Okoli Nonso Livinus

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This work is on the synthesis and study of the optical characterization of polyaniline/nickel sulphide nanocomposite. Polyaniline (PANI) and nickel sulphide (NiS) nanoparticles were synthesized by oxidative chemical polymerization and sol-gel method. The polyaniline nickel sulphide nanocomposites with various concentrations of NiS were synthesized by in-situ polymerization of aniline monomer. In each case, the nickel sulphide nanoparticles were uniformly dispersed in the aniline hydrochloride before the initiation of oxidative chemical polymerization using ammonium persulphate. The samples formed were subjected to optical characterization using an ultraviolet (UV)-visible light (VIS) spectrophotometer (model: 756S UV – VIS). Optical analysis of the synthesized nanoparticles and nanocomposites showed absorption of radiation within VIS regions. The Tauc model was used to obtain the optical band gap. Energy band gap values of PANI and NiS were found to be 2.50 eV and 1.95 eV, respectively. PANI/NiSnanocomposites has an energy band gap that decreased from 2.25 eV to 1.90 eV as the amount of NiS increased (from 0.5g to 2.0g). These optical results showed that these nanocomposites are potential materials to be considered in solar cells and optoelectronics devices. The structural analysis confirmed the formation of polyaniline and hexagonal nickel sulphide with an average crystallite size of 25.521 nm, while average crystallite sizes of PANI/NiSnanocomposites ranged from 19.458 nm to 25.108 nm. Average particle sizes obtained from the SEM images ranged from 23.24 nm to 51.88 nm. Compositional results confirmed the presence of desired elements that made up the nanoparticles and nanocomposites.

Keywords: polyaniline, nickel sulphide, polyaniline-nickel sulphide nanocomposite, optical characterization, structural analysis, morphological properties, compositional properties

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Authors: Khushalini N. Ulman, Samane Maroufi, Veena H. Sahajwalla

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Globally, electronic waste (e-waste) continues to grow at an alarming rate. Several technologies have been developed to recover valuable materials from e-waste, however, their efficiency can be increased with a better knowledge of the e-waste components. Random access memory cards (RAMs) are considered as high value scrap for the e-waste recyclers. Despite their high precious metal content, RAMs are still recycled in a conventional manner resulting in huge loss of resources. Our research work highlights the precious metal rich components of a RAM. Inductively coupled plasma (ICP) analysis of RAMs of six different generations have been carried out and the trends in their metal content have been investigated. Over the past decade, the copper content of RAMs has halved and their tin content has increased by 70 %. The stricter environmental laws have facilitated ~96 % drop in the lead content of RAMs. To comprehend the fundamentals of thermal transformation of RAMs, our research provides their detailed kinetic study. This can assist the e-waste recyclers in optimising their metal recovery processes. Thus, understanding the chemical and thermal behaviour of RAMs can open new avenues for efficient e-waste recycling.

Keywords: electronic waste, kinetic study, recycling, thermal transformation

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Authors: R. F. Louh, Cathy Chou, Victor Wang, Howard Yan

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The aim of this study is to manufacture titania and reduced graphene oxide (TiO2/rGO) composite nanofibers via electrospinning (ESP) of precursor fluid consisted of titania sol containing polyvinylpyrrolidone (PVP) and titanium isopropoxide (TTIP) and GO solution. The GO nanoparticles were derived from Hummers’ method. A metal grid ring was used to provide the bias voltage to reach higher ESP yield and nonwoven fabric with dense network of TiO2/GO composite nanofibers. The ESP product was heat treated at 500°C for 2 h in nitrogen atmosphere to acquire TiO2/rGO nanofibers by thermal reduction of GO and phase transformation into anatase TiO2. The TiO2/rGO nanofibers made from various volume fractions of GO solution by ESP were analyzed by FE-SEM, TEM, XRD, EDS, BET and FTIR. Such TiO2/rGO fibers having photocatalytic property, high specific surface area and electrical conductivity can be used for photovoltaics and chemical sensing applications.

Keywords: electrospinning process, titanium oxide, thermally reduced graphene oxide, composite nanofibers

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Authors: Marc Evenst Jn Jacques, Sophie Bernard

Abstract:

Electrical and electronic applications, as well as rechargeable batteries, are common in any economy. They also contain a number of important and valuable metals. It is critical to investigate the impact of these new materials or volume sources on the metal market dynamics. This paper investigates the impact of responsible recycling within the European region on metal price volatility. As far as we know, no empirical studies have been conducted to assess the role of metal recycling in metal market price volatility. The goal of this paper is to test the claim that metal recycling helps to cushion price volatility. A set of circular economy indicators/variables, namely, 1) annual total trade values of recycled metals, 2) annual volume of scrap traded and 3) circular material use rate, and 4) information about recycling, are used to estimate the volatility of monthly spot prices of regular metals. A combination of the GARCH-MIDAS model for mixed frequency data sampling and a simple GARCH (1,1) model for the same frequency variables was adopted to examine the potential links between each variable and price volatility. We discovered that from 2010 to 2019, except for Nickel, scrap consumption (Millions of tons), Scrap Trade Values, and Recycled Material use rate had no significant impact on the price volatility of standard metals (Aluminum, Lead) and precious metals (Gold and Platinum). Worldwide interest in recycling has no impact on returns or volatility. Specific interest in metal recycling did have a link to the mean return equation for Aluminum, Gold and to the volatility equation for lead and Nickel.

Keywords: recycling, circular economy, price volatility, GARCH, mixed data sampling

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Authors: V. P. Muhamed Shajudheen, K. Viswanathan, K. Anitha Rani, A. Uma Maheswari, S. Saravana Kumar

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In this paper, a simple chemical precipitation route for the preparation of titanium dioxide nanoparticles, synthesized by using titanium tetra isopropoxide as a precursor and polyvinyl pyrrolidone (PVP) as a capping agent, is reported. The Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) of the samples were recorded and the phase transformation temperature of titanium hydroxide, Ti(OH)₄ to titanium oxide, TiO₂ was investigated. The as-prepared Ti(OH)₄ precipitate was annealed at 800°C to obtain TiO₂ nanoparticles. The thermal, structural, morphological and textural characterizations of the TiO₂ nanoparticle samples were carried out by different techniques such as DSC-TGA, X-Ray Diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), Micro Raman spectroscopy, UV-Visible absorption spectroscopy (UV-Vis), Photoluminescence spectroscopy (PL) and Field Effect Scanning Electron Microscopy (FESEM) techniques. The as-prepared precipitate was characterized using DSC-TGA and confirmed the mass loss of around 30%. XRD results exhibited no diffraction peaks attributable to anatase phase, for the reaction products, after the solvent removal. The results indicate that the product is purely rutile. The vibrational frequencies of two main absorption bands of prepared samples are discussed from the results of the FTIR analysis. The formation of nanosphere of diameter of the order of 10 nm, has been confirmed by FESEM. The optical band gap was found by using UV-Visible spectrum. From photoluminescence spectra, a strong emission was observed. The obtained results suggest that this method provides a simple, efficient and versatile technique for preparing TiO₂ nanoparticles and it has the potential to be applied to other systems for photocatalytic activity.

Keywords: TiO2 nanoparticles, chemical precipitation route, phase transition, Fourier Transform Infra-Red spectroscopy (FTIR), micro-Raman spectroscopy, UV-Visible absorption spectroscopy (UV-Vis), Photoluminescence Spectroscopy (PL) and Field Effect Scanning electron microscopy (FESEM)

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Authors: A. Threepanich, S. Youngme, P. Praipipat

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Although ground egg shells had the ability to eliminate lead in water, their efficiency may decrease in a case of contaminating of other cations such as Na⁺, Ca²⁺ in the water. The development of ground egg shells may solve this problem in which metal oxides are a good choice for this case since they have the ability to remove any heavy metals including lead in the water. Therefore, this study attempts to use this advantage for improving ground egg shells for the specific lead removal efficiency in the water. X-ray fluorescence (XRF) technique was used for the chemical element contents analysis of ground egg shells (GES) and ground egg shells with metal oxide (GESM), and Transmission electron microscope (TEM) technique was used to examine the material sizes. The batch test studies were designed to investigate the factor effects on dose (5, 10, 15 grams), pH (5, 7, 9), and settling time (1, 3, 5 hours) for the lead removal efficiency in the water. The XRF analysis results showed GES contained calcium (Ca) 91.41% and Silicon (Si) 4.03% and GESM contained calcium (Ca) 91.41%, Silicon (Si) 4.03%, and Iron (Fe) 3.05%. TEM results confirmed the sizes of GES and GESM in the range of 1-20 nm. The batch test studies showed the best optimum conditions for the lead removal in the water of GES and GESM in dose, pH, and settling time were 10 grams, pH 9, 5 hours and 5 grams, pH 9, 3 hours, respectively. The competing ions (Na⁺ and Ca²⁺) study reported GESM had the higher % lead removal efficiency than GES at 90% and 60%, respectively. Therefore, this result can confirm that adding of metal oxide to ground egg shells helps to improve the lead removal efficiency in the water.

Keywords: nano material, ground egg shells, metal oxide, lead

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Authors: H. V. Jayaprakash, P. V. Krupakara

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This paper deals with the high corrosion resistance developed by the metal matrix composites when compared with that of matrix alloy by open circuit potential test. Matrix selected is ZA-27 and reinforcement selected is red mud particulates, which is a ceramic material. The composites are prepared using liquid melt metallurgy technique using vortex method. Preheated but uncoated red mud particulates are added to the melt. Metal matrix composites containing 2, 4 and 6 weight percentage of red mud are casted. Matrix was also casted in the same way for comparison. Specimen are fabricated according to ASTM standards. The corrodents used for the tests were 0.025, 0.05 and 0.1 molar sodium hydroxide solutions. They are subjected to Open Circuit Potential studies and weight loss corrosion tests. Corrosion rate was found to be decreased with increase in exposure time in both experiments. Effect of exposure time and presence of increased percentage of reinforcement red mud is discussed in detail.

Keywords: composites, vortex, particulates, red mud

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Authors: Goban Kumar Panneer Selvam

Abstract:

In past years, there is lots of death caused due to harmful gases. So its very important to monitor harmful gases for human safety, and semiconductor material play important role in producing effective gas sensors.A novel solvothermal synthesis method based on sol-gel processing was prepared to deposit tin oxide thin films on glass substrate at high temperature for gas sensing application. The structure and morphology of tin oxide were analyzed by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM analysis of how spheres shape in tin oxide nanoparticles. The structure characterization of tin oxide studied by X-ray diffraction shows 8.95 nm (calculated by sheers equation). The UV visible spectroscopy indicated a maximum absorption band shown at 390 nm. Further dope tin oxide with selected metals to attain maximum sensitivity using dip coating technique with different immersion and sensing characterization are measured.

Keywords: tin oxide, gas sensor, chlorine free, sensitivity, crystalline size

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Authors: Ines Kovacic, Dijana Pavicic-Hamer, Petra Buric, Maja Levak Zorinc, Daniel M. Lyons

Abstract:

Silver nanoparticles (AgNPs), owing to their unique physical and chemical properties, have become one of the most widely used nanoparticles in consumer products. Despite the increased use of AgNPs in science and industry over the past twenty years, only relatively recently has concern been raised over their entering brackish and marine environments. However, data on their potential impact on marine organisms, especially invertebrates are very limited. This study aimed to examine the effects of 60 nm AgNPs (10, 100, 500 and 1000 µg/l) and silver ions (100, 1000 µg/l) on the Mediterranean green crab Carcinus aestuarii Nardo, 1847. The crab mortality was assessed during seven days of exposure. After the exposure, total haemocytes (THC) and differential haemocytes number (DHC) were counted (immune response), in addition to histological examination of gills stained with haematoxylin and eosin. The effect of AgNPs and silver ions resulted in a dose dependent mortality and destruction of gills epithelium with haemocytes infiltration in the gills lacuna. Total haemocyte count was greater with increasing concentration of AgNPs, at concentrations from 10 to 500 µg/l. Hyalinocytes were the most common immunological cells noted in the crab hemolymph, while granulocytes and semigranulocytes were suppressed with increasing concentration of AgNPs (500 and 1000 µg/l). Thus, as crabs are filter feeders, they are susceptible to uptake of AgNPs by direct accumulation in gills mucus or indirectly via circulation of haemocytes in their open vascular system. Results of this study on crabs add to knowledge of the effects of AgNPs in the marine environment.

Keywords: crab, immune response, histological alteration, silver nanoparticles

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Authors: Kalthoum Riahi, Max T. Rietberg, Javier Perez y Perez, Corné Dijkstra, Bennie ten Haken, Lejla Alic

Abstract:

Magnetic nanoparticles (MNPs) are widely used to facilitate magnetic particle imaging (MPI) which has the potential to become the leading diagnostic instrument for biomedical imaging. This comparative study assesses the effects of changing iron content and excitation frequency on point-spread function (PSF) representing the effect of magnetization reversal. PSF is quantified by features of interest for MPI: i.e., drive field amplitude and full-width-at-half-maximum (FWHM). A superparamagnetic quantifier (SPaQ) is used to assess differential magnetic susceptibility of two commercially available MNPs: Synomag®-D50 and Synomag®-D70. For both MNPs, the signal output depends on increase in drive field frequency and amount of iron-oxide, which might be hampering the sensitivity of MPI systems that perform on higher frequencies. Nevertheless, there is a clear potential of Synomag®-D for a stable MPI resolution, especially in case of 70 nm version, that is independent of either drive field frequency or amount of iron-oxide.

Keywords: magnetic nanoparticles, MNPs, differential magnetic susceptibility, DMS, magnetic particle imaging, MPI, magnetic relaxation, Synomag®-D

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Authors: J. C. Riaño-Rojas, J. D. Alzate-Cardona, E. Restrepo-Parra

Abstract:

In this work, a study of generic magnetic nanoparticles varying the metric space is presented. As the metric space is changed, the nanoparticle form and the inner product are also varied, since the energetic scale is not conserved. This study is carried out using Monte Carlo simulations combined with the Wolff embedding and Metropolis algorithms. The Metropolis algorithm is used at high temperature regions to reach the equilibrium quickly. The Wolff embedding algorithm is used at low and critical temperature regions in order to reduce the critical slowing down phenomenon. The ions number is kept constant for the different forms and the critical temperatures using finite size scaling are found. We observed that critical temperatures don't exhibit significant changes when the metric space was varied. Additionally, the effective dimension according the metric space was determined. A study of static behavior for reaching the static critical exponents was developed. The objective of this work is to observe the behavior of the thermodynamic quantities as energy, magnetization, specific heat, susceptibility and Binder's cumulants at the critical region, in order to demonstrate if the magnetic nanoparticles describe their magnetic interactions in the Euclidean space or if there is any correspondence in other metric spaces.

Keywords: nanoparticles, metric, Monte Carlo, critical behaviour

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Authors: Van Tran Thi Thuy, Dukjoon Kim

Abstract:

A series of pH- and thermosensitive poly(N-isopropyl acrylamide-co-acrylic acid) were synthesized by radical polymerization and grafted on poly succinimide backbones. The poly succinimide derivatives synthesized were coated on iron oxide magnetic nanoparticles for potential applications in drug delivery systems with theranostic and molecular imaging. The structure of polymer shell was confirmed by FT-IR, H-NMR spectroscopies. Its thermal behavior was tested by UV-Vis spectroscopy. The particle size and its distribution are measured by dynamic light scattering (DLS) and transmission electron microscope (TEM). The mean diameter of the core-shell structure is from 20 to 80 nm.

Keywords: magnetic, nano, PNIPAM, polysuccinimide

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Authors: M. Kheirandish, S. Borhani

Abstract:

In this experiment Polystyrene/Zinc-oxide (PS/ZnO) nanocomposite fibers were produced by electrospinning technique using limonene as a green solvent. First, the morphology of electrospun pure polystyrene (PS) and PS/ZnO nanocomposite fibers investigated by SEM. Results showed the PS fiber diameter decreased by increasing concentration of Zinc Oxide nanoparticles (ZnO NPs). Thermo Gravimetric Analysis (TGA) results showed thermal stability of nanocomposites increased by increasing ZnO NPs in PS electrospun fibers. Considering Differential Scanning Calorimeter (DSC) thermograms for electrospun PS fibers indicated that introduction of ZnO NPs into fibers affects the glass transition temperature (Tg) by reducing it. Also, UV protection properties of nanocomposite fibers were increased by increasing ZnO concentration. Evaluating the effect of metal oxide NPs amount on mechanical properties of electrospun layer showed that tensile strength and elasticity modulus of the electrospun layer of PS increased by addition of ZnO NPs. X-ray diffraction (XRD) pattern of nanopcomposite fibers confirmed the presence of NPs in the samples.

Keywords: electrospininng, nanoparticle, polystyrene, ZnO

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Authors: C. A. C. Castro, D. C. Urashima, E. P. Silva, P. M. L. Silva

Abstract:

Since 1920, the industry has almost completely changed the rivets production techniques for the manufacture of permanent welding join production of structures and manufacture of other products. The welding arc is the process more widely used in industries. This is accomplished by the heat of an electric arc which melts the base metal while the molten metal droplets are transferred through the arc to the welding pool, protected from the atmosphere by a gas curtain. The GMAW (Gas metal arc welding) process is influenced by variables such as: Current, polarity, welding speed, electrode, extension, position, moving direction; type of joint, welder's ability, among others. It is remarkable that the knowledge and control of these variables are essential for obtaining satisfactory quality welds, knowing that are interconnected so that changes in one of them requiring changes in one or more of the other to produce the desired results. The optimum values are affected by the type of base metal, the electrode composition, the welding position and the quality requirements. Thus, this paper proposes a new methodology, adding the variable vibration through a mechanism developed for GMAW welding, in order to improve the mechanical and metallurgical properties which does not affect the ability of the welder and enables repeatability of the welds made. For confirmation metallographic analysis and mechanical tests were made.

Keywords: vibration, joining, weldability, GMAW

Procedia PDF Downloads 415