Search results for: amorphous metal

Authors: Anton Trník, Lenka Scheinherrová, Robert Černý

Abstract:

Silica fume is a by-product of the ferro-silicon and silicon metal industries. It is mainly in the form of amorphous silica. Silica fume belongs to pozzolanic active materials which can be used in concrete to improve its final properties. In this paper, the influence of silica fume on hydration of cement pastes is studied using differential scanning calorimetry (DSC) and thermogravimetry (TG) at various curing times (2, 7, 28, and 90 days) in the temperature range from 25 to 1000 °C in an argon atmosphere. Samples are prepared from Portland cement CEM I 42.5 R which is partially replaced with the silica fume of 4, 8, and 12 wt.%. The water/binder ratio is chosen as 0.5. It is identified and described the liberation of physically bound water, calcium–silicate–hydrates dehydration, portlandite and calcite decomposition in studied samples. Also, it is found out that an exothermic peak at 950 °C is observed without a significant mass change for samples with 12 wt.% of silica fume after two days of hydration. This peak is probably caused by the pozzolanic reaction between silica fume and Portland cement. Its size corresponds to the degree of crystallization between Ca and Si. The portlandite content is lower for the samples with a higher amount of silica fume.

Keywords: differential scanning calorimetry, hydration, silica fume, thermogravimetry

Procedia PDF Downloads 219

Authors: Aliyu Usman, Muhaammed Bello Ibrahim, Yusuf D. Amartey, Jibrin M. Kaura

Abstract:

This research is aimed at investigating the effect of using amorphous silica ash (ASA) obtained from rice husk as a partial replacement of ordinary Portland cement (OPC) on the mechanical and microstructure properties of cement paste and mortar. ASA was used in partial replacement of ordinary Portland cement in the following percentages 3 percent, 5 percent, 8 percent and 10 percent. These partial replacements were used to produce Cement-ASA paste and Cement-ASA mortar. ASA was found to contain all the major chemical compounds found in cement with the exception of alumina, which are SiO2 (91.5%), CaO (2.84%), Fe2O3 (1.96%), and loss on ignition (LOI) was found to be 9.18%. It also contains other minor oxides found in cement. Consistency of Cement-ASA paste was found to increase with increase in ASA replacement. Likewise, the setting time and soundness of the Cement-ASA paste also increases with increase in ASA replacements. The test on hardened mortar were destructive in nature which include flexural strength test on prismatic beam (40mm x 40mm x 160mm) at 2, 7, 14 and 28 days curing and compressive strength test on the cube size (40mm x 40mm, by using the auxiliary steel platens) at 2,7,14 and 28 days curing. The Cement-ASA mortar flexural and compressive strengths were found to be increasing with curing time and decreases with cement replacement by ASA. It was observed that 5 percent replacement of cement with ASA attained the highest strength for all the curing ages and all the percentage replacements attained the targeted compressive strength of 6N/mm2 for 28 days. There is an increase in the drying shrinkage of Cement-ASA mortar with curing time, it was also observed that the drying shrinkages for all the curing ages were greater than the control specimen all of which were greater than the code recommendation of less than 0.03%. The scanning electron microscope (SEM) was used to study the Cement-ASA mortar microstructure and to also look for hydration product and morphology.

Keywords: amorphous silica ash, cement mortar, cement paste, scanning electron microscope

Procedia PDF Downloads 408

Authors: S. Cheragh Dar, M. Saljooghi, A. Babrgir

Abstract:

In the last couple of decades researchers' attitudes were focused on developing and enhancing heat transfer processes by using new components or cellular solids that divide into stochastic structures and periodic structures. Open-cell metal foams are part of stochastic structures families that they can be considered as an avant-garde technology and they have unique properties, this porous media can have tremendous achievements in thermal processes. This paper argues and surveys postulating possible in industrial thermal issues which include: compact electronic cooling, heat exchanger, aerospace, fines, turbo machinery, automobiles, crygen tanks, biomechanics, high temperature filters and etc. Recently, by surveying exponential rate of publications in thermal open-cell metal foams, all can be demonstrated in a holistic view which can lead researchers to a new level of understanding in different industrial thermal sections.

Keywords: heat transfer, industrial thermal, cellular solids, open cell metal foam

Procedia PDF Downloads 275

Authors: Roman Marsalek

Abstract:

In this paper, snow samples containing dust particles from several sampling points around the city of Ostrava were analyzed. The pH values of sampled snow were measured and solid particles analyzed. Particle size, zeta potential and content of selected heavy metals were determined in solid particles. The pH values of most samples lay in the slightly acid region. Mean values of particle size ranged from 290.5 to 620.5 nm. Zeta potential values varied between -5 and -26.5 mV. The following heavy metal concentration ranges were found: copper 0.08-0.75 mg/g, lead 0.05-0.9 mg/g, manganese 0.45-5.9 mg/g and iron 25.7-280.46 mg/g. The highest values of copper and lead were found in the vicinity of busy crossroads, and on the contrary, the highest levels of manganese and iron were detected close to a large steelworks. The proportion between pH values, zeta potentials, particle sizes and heavy metal contents was established. Zeta potential decreased with rising pH values and, simultaneously, heavy metal content in solid particles increased. At the same time, higher metal content corresponded to lower particle size.

Keywords: dust, snow, zeta potential, particles size distribution, heavy metals

Procedia PDF Downloads 345

Authors: S. Hosseini, M. Ahmadi Najafabadi, M. Akhlaghi

Abstract:

The health of the journal bearings is very important in preventing unforeseen breakdowns in rotary machines, and poor lubrication is one of the most important factors for producing the bearing failures. Hydrodynamic lubrication (HL), mixed lubrication (ML), and boundary lubrication (BL) are three regimes of a journal bearing lubrication. This paper uses acoustic emission (AE) measurement technique to correlate features of the AE signals to the three lubrication regimes. The transitions from HL to ML based on operating factors such as rotating speed, load, inlet oil pressure by time domain and time-frequency domain signal analysis techniques are detected, and then metal-to-metal contacts between sliding surfaces of the journal and bearing are identified. It is found that there is a significant difference between theoretical and experimental operating values that are obtained for defining the lubrication regions.

Keywords: acoustic emission technique, pressure fed journal bearing, time and frequency signal analysis, metal-to-metal contact

Procedia PDF Downloads 131

Authors: Meimei Wen, Chang Nyung Kim

Abstract:

In the current study, three-dimensional liquid metal (LM) magneto-hydrodynamic (MHD) flows in a manifold with three sub-channels under a uniform magnetic field are numerically investigated. In the manifold, the electrical current can cross channel walls, thus having influence on the flow distribution in each sub-channel. A case with various arrangements of electric conductivity for different parts of channel walls is considered, yielding different current distributions as well as flow distributions in each sub-channel. Here, the imbalance of mass flow rates in the three sub-channels is addressed. Meanwhile, predicted are detailed behaviors of the flow velocity, pressure, current and electric potential of LM MHD flows with three sub-channels. Commercial software CFX is used for the numerical simulation of LM MHD flows.

Keywords: CFX, liquid metal, manifold, MHD flow

Procedia PDF Downloads 328

Authors: Yang Luo, Chang Nyung Kim

Abstract:

This study numerically analyzes a steady-state, three-dimensional liquid-metal magnetohydrodynamic flows in a conduit with multiple channels under a uniform magnetic field. The geometry of the conduit is of a four-parallel-channels system including one inflow channel and three outflow channels. The liquid-metal flows in the inflow channel, then turns 1800 in the transition segment, finally flows into three different outflow channels simultaneously. This kind of channel system can induce counter flow and co-flow, which is rarely investigated before. The axial velocity in the side layer near the first partitioning wall, which is located between the inflow channel and the first outflow channel, is the highest. ‘M-shaped’ velocity profiles are obtained in the side layers of the inflow and outflow channels. The interdependency of the current, fluid velocity, pressure, electric potential is examined in order to describe the electromagnetic characteristics of the liquid-metal flows.

Keywords: liquid-metal, multiple channels, magnetic field, magnetohydrodynamic

Procedia PDF Downloads 262

Authors: S. Meziane, H. I. Faraoun, C. Esling

Abstract:

Transition metal dichalcogenides have potential applications in power generation devices that convert waste heat into electric current by the so-called Seebeck and Hall effects thus providing an alternative energy technology to reduce the dependence on traditional fossil fuels. In this study, the thermoelectric properties of 1T and 2HTaX2 (X= S or Se) dichalcogenide superconductors have been computed using the semi-classical Boltzmann theory. Technologically, the task is to fabricate suitable materials with high efficiency. It is found that 2HTaS2 possesses the largest value of figure of merit ZT= 1.27 at 175 K. From a scientific point of view, we aim to model the underlying materials properties and in particular the transport phenomena as mediated by electrons and lattice vibrations responsible for superconductivity, Charge Density Waves (CDW) and metal/insulator transitions as function of temperature. The goal of the present work is to develop an understanding of the superconductivity of these selected materials using the transport properties at the fundamental level.

Keywords: Ab initio, High efficiency, Power generation devices, Transition metal dichalcogenides

Procedia PDF Downloads 172

Authors: Yogendar Singh, Parasmani Rajput, Pawan Kumar Kulriya

Abstract:

Understanding the radiation response of the pyrochlore structured ceramics in the nuclear reactor core-like environment is of quite an interest for their utilization as host matrices. Electronic excitation (100 MeV I7+) induced crystalline to amorphous phase transition in Nd2Zr2O7 pyrochlore synthesized through three steps solid-state sintering method was investigated. The x-ray diffraction, along with Raman spectroscopy and x-ray absorption spectroscopy experiments conducted on pristine and irradiated pyrochlore, showed an increase in the rate of amorphization with ion fluence. XRD results indicate that specimen is completely amorphized on irradiation at the highest fluence of 5×1013 ions/cm2. The EXAFS spectra of the K-Zr edge and the Nd LIII edge confirmed a significant change in the chemical environment of Nd upon swift heavy ion irradiation. Observation of a large change in the intensity of K-Zr pre-edge spectra is also a good indicator of the phase transition from pyrochlore to the amorphous phase, which is supported by the FT modulus of the LIII-Nd edge. However, the chemical environment of Zr is less affected by irradiation, but it clearly exhibits an increase in the degree of disorder.

Keywords: nuclear host matrices, swift heavy ion irradiation, x-ray absorption spectroscopy, pyrochlore oxides

Procedia PDF Downloads 73

Authors: R. Ravisankar, Tholkappian A. Chandrasekaran, Y. Raghu, K. K. Satapathy, M. V. R. Prasad, K. V. Kanagasabapathy

Abstract:

The coastal areas of Tamilnadu are assuming greater importance owing to increasing human population, urbanization and accelerated industrial activities. sIn the present study, sediment samples are collected along the east coast of Tamilnadu for assessment of heavy metal pollution. The concentration of 13 selected heavy metals such as Mg, Al, Si, K, Ca, Ti, Fe, V, Cr, Mn, Co, Ni and Zn determined by Energy dispersive X-ray fluorescence (EDXRF) technique. In order to describe the pollution status, Contamination factor and pollution load index are calculated and reported. This result suggests that sources of metal contamination were mainly attributed to natural inputs from surrounding environments.

Keywords: sediments, heavy metals, EDXRF, pollution contamination factors

Procedia PDF Downloads 315

Authors: S. U. Khan, T. Ayub, N. Shafiq

Abstract:

The properties of locally produced metakaolin (MK) as cement replacing material and the comparison of reactivity with commercially available micro-silica have been investigated. Compressive strength, splitting tensile strength, and load-deflection behaviour under bending are the properties that have been studied. The amorphous phase of MK with micro-silica was compared through X-ray diffraction (XRD) pattern. Further, interfacial transition zone of concrete with micro-silica and MK was observed through Field Emission Scanning Electron Microscopy (FESEM). Three mixes of concrete were prepared. One of the mix is without cement replacement as control mix, and the remaining two mixes are 10% cement replacement with micro-silica and MK. It has been found that MK, due to its irregular structure and amorphous phase, has high reactivity with portlandite in concrete. The compressive strength at early age is higher with MK as compared to micro-silica. MK concrete showed higher splitting tensile strength and higher load carrying capacity as compared to control and micro-silica concrete at all ages respectively.

Keywords: metakaolin, compressive strength, splitting tensile strength, load deflection, interfacial transition zone

Procedia PDF Downloads 184

Authors: Farzan Gity, Lida Ansari, Ian M. Povey, Roger E. Nagle, James C. Greer

Abstract:

Titanium nitride (TiN) films have been widely used in variety of fields, due to its unique electrical, chemical, physical and mechanical properties, including low electrical resistivity, chemical stability, and high thermal conductivity. In microelectronic devices, thin continuous TiN films are commonly used as diffusion barrier and metal gate material. However, as the film thickness decreases below a few nanometers, electrical properties of the film alter considerably. In this study, the physical and electrical characteristics of 1.5nm to 22nm thin films deposited by Plasma-Enhanced Atomic Layer Deposition (PE-ALD) using Tetrakis(dimethylamino)titanium(IV), (TDMAT) chemistry and Ar/N2 plasma on 80nm SiO2 capped in-situ by 2nm Al2O3 are investigated. ALD technique allows uniformly-thick films at monolayer level in a highly controlled manner. The chemistry incorporates low level of oxygen into the TiN films forming titanium oxynitride (TiON). Thickness of the films is characterized by Transmission Electron Microscopy (TEM) which confirms the uniformity of the films. Surface morphology of the films is investigated by Atomic Force Microscopy (AFM) indicating sub-nanometer surface roughness. Hall measurements are performed to determine the parameters such as carrier mobility, type and concentration, as well as resistivity. The >5nm-thick films exhibit metallic behavior; however, we have observed that thin film resistivity is modulated significantly by film thickness such that there are more than 5 orders of magnitude increment in the sheet resistance at room temperature when comparing 5nm and 1.5nm films. Scattering effects at interfaces and grain boundaries could play a role in thickness-dependent resistivity in addition to quantum confinement effect that could occur at ultra-thin films: based on our measurements the carrier concentration is decreased from 1.5E22 1/cm3 to 5.5E17 1/cm3, while the mobility is increased from < 0.1 cm2/V.s to ~4 cm2/V.s for the 5nm and 1.5nm films, respectively. Also, measurements at different temperatures indicate that the resistivity is relatively constant for the 5nm film, while for the 1.5nm film more than 2 orders of magnitude reduction has been observed over the range of 220K to 400K. The activation energy of the 2.5nm and 1.5nm films is 30meV and 125meV, respectively, indicating that the TiON ultra-thin films are exhibiting semiconducting behaviour attributing this effect to a metal-semiconductor transition. By the same token, the contact is no longer Ohmic for the thinnest film (i.e., 1.5nm-thick film); hence, a modified lift-off process was developed to selectively deposit thicker films allowing us to perform electrical measurements with low contact resistance on the raised contact regions. Our atomic scale simulations based on molecular dynamic-generated amorphous TiON structures with low oxygen content confirm our experimental observations indicating highly n-type thin films.

Keywords: activation energy, ALD, metal-semiconductor transition, resistivity, titanium oxynitride, ultra-thin film

Procedia PDF Downloads 268

Authors: Orish E. Orisakwe, Chinna N. Orish, Anthonet N. Ezejiofor

Abstract:

African mesquite has been recognized for its antimicrobial, anti-inflammatory, and potential anticarcinogenic activities. However, its neuroprotective benefits against heavy metal-induced neurotoxicity remain largely unexplored. Therefore, the objective of this study was to investigate the neuroprotective properties of African mesquite in the hippocampus and olfactory bulb against common environmental pollutants, including Cd, As, Hg, and Pb. Thirty-five albino Sprague Dawley rats were divided into five groups for the experiment. Group 1 served as the control and did not receive either the heavy metal mixture (HMM) or African mesquite. Group 2 was orally administered HMM, consisting of PbCl2 (20 mg/kg), CdCl2 (1.61 mg/kg), HgCl2 (0.40 mg/kg), and NaAsO3 (10 mg/kg), for 960 days. Meanwhile, groups 3, 4, and 5 were treated with HMM along with African mesquite at doses of 500 mg/kg, 1000 mg/kg, and 1500 mg/kg, respectively. African mesquite reduced heavy metal accumulation in the hippocampus and olfactory bulb. Additionally, Sprague Dawley rats exhibited improved performance in the Passive avoidance and Cincinnati Maze tests. Furthermore, treatment with African mesquite significantly alleviated inflammation macromolecules peroxidation. It also restored the concentrations of SOD, CAT, GSH, GPx, Hmox-1, and reduced the activity of AChE, NRF2 and NFkB and improved histopathological findings. African mesquite exhibits a multifaceted neuroprotective effect with the potential to mitigate various aspects of heavy metal-induced neurotoxicity.

Keywords: African mesquite, heavy metal mixture;, neurotoxicity;, chemoprevention

Procedia PDF Downloads 48

Authors: Ashish Mahalle, Kishore Borakhade

Abstract:

High porosity metal foams are excellent for heat dissipation. There use has been widened to include heat removal from high density microelectronics circuits. Other important applications have been found in compact heat exchangers for airborne equipment, regenerative and dissipative air cooled condenser towers, and compact heat sinks for power electronic. The low relative density, open porosity and high thermal conductivity of the cell edges, large accessible surface area per unit volume, and the ability to mix the cooling fluid make metal foam heat exchangers efficient, compact and light weight. This paper reports the thermal performance of metal foam for high heat dissipation. In experimentation metal foam samples of different pore diameters i.e. 35 µ, 20 µ, 12 µ, are analyzed for varying velocities and heat inputs. The study investigate the effect of various dimensionless no. like Re,Nu, Pr and heat transfer characteristics of basic flow configuration.

Keywords: pores, foam, effective thermal conductivity, permeability

Procedia PDF Downloads 283

Authors: Gulnur Arabaci

Abstract:

Heavy metals are one of the major groups of contaminants in the environment and many of them are toxic even at very low concentration in plants and animals. However, some metals play important roles in the biological function of many enzymes in living organisms. Metals such as zinc, iron, and cooper are important for survival and activity of enzymes in plants, however heavy metals can inhibit enzyme which is responsible for defense system of plants. Polyphenol oxidase (PPO) is a copper-containing metalloenzyme which is responsible for enzymatic browning reaction of plants. Enzymatic browning is a major problem for the handling of vegetables and fruits in food industry. It can be increased and effected with many different futures such as metals in the nature and ground. In the present work, PPO was isolated and characterized from green leaves of red poppy plant (Papaver rhoeas). Then, the effect of some known antibrowning agents which can form complexes with metals and metals were investigated on the red poppy PPO activity. The results showed that glutathione was the most potent inhibitory effect on PPO activity. Cu(II) and Fe(II) metals increased the enzyme activities however, Sn(II) had the maximum inhibitory effect and Zn(II) and Pb(II) had no significant effect on the enzyme activity. In order to reduce the effect of heavy metals, the effects of metal-antibrowning agent complexes on the PPO activity were determined. EDTA and metal complexes had no significant effect on the enzyme. L-ascorbic acid and metal complexes decreased but L-ascorbic acid-Cu(II)-complex had no effect. Glutathione–metal complexes had the best inhibitory effect on Red poppy leaf PPO activity.

Keywords: inhibition, metal, red poppy, poly phenol oxidase (PPO)

Procedia PDF Downloads 297

Authors: Shabnam, Jagdeep Kumar

Abstract:

Because of the impact of their greater surface area and smaller quantum sizes in comparison with other metal atoms or bulk metals, metal nanoparticles, such as those formed of gold, exhibit a variety of unusual chemical and physical properties. The size- and shape-dependent properties of gold nanoparticles (GNPs) are particularly notable. Metal nanoparticles have received a lot of attention due to their unique properties and exciting prospective uses in photonics, electronics, biological sensing, and imaging. The latest developments in GNP synthesis are discussed in this review. Green chemistry measures were used to assess the production of gold nanoparticles, with a focus on Process Mass Intensity (PMI). Based on these measurements, opportunities for improving synthetic approaches were found. With PMIs that were often in the thousands, solvent usage was found to be the main obstacle for nanoparticle synthesis, even ones that were otherwise considered to be environmentally friendly. Since ligated metal nanoparticles are the most industrially relevant but least environmentally friendly, their synthesis by arrested precipitation was chosen as the best chance for significant advances. Gold nanoparticles of small sizes and bio-stability are produced biochemically, and they are used in many biological applications.

Keywords: gold, nanoparticles, green synthesis, AuNP

Procedia PDF Downloads 58

Authors: Sarabjeet Singh Sidhu, Ajay Batish, Sanjeev Kumar

Abstract:

This paper reports the optimal process conditions for machining of three different types of metal matrix composites (MMCs): 65vol%SiC/A356.2; 10vol%SiC-5vol%quartz/Al and 30vol%SiC/A359 using PMEDM process. Metal removal rate (MRR), tool wear rate (TWR), surface roughness (SR) and surface integrity (SI) were evaluated after each trial and contributing process parameters were identified. The four responses were then collectively optimized using the technique for order preference by similarity to ideal solution (TOPSIS) and optimal process conditions were identified for each type of MMCS. The density of reinforced particles shields the matrix material from spark energy hence the high MRR and SR was observed with lowest reinforced particle. TWR was highest with Cu-Gr electrode due to disintegration of the weakly bonded particles in the composite electrode. Each workpiece was examined for surface integrity and ranked as per severity of surface defects observed and their rankings were used for arriving at the most optimal process settings for each workpiece.

Keywords: metal matrix composites (MMCS), metal removal rate (MRR), surface roughness (SR), surface integrity (SI), tool wear rate (TWR), technique for order preference by similarity to ideal solution (TOPSIS)

Procedia PDF Downloads 265

Authors: Kalyani Mer

Abstract:

Hydrogen peroxide (H₂O₂) is one of the most efficient and commonly used oxidants in in-situ chemical oxidation (ISCO) of organic contaminants. In the present study, we investigated the activation of H₂O₂ by heavy metal (nickel and lead metal ions) loaded biochar for phenol degradation in an aqueous solution (concentration = 100 mg/L). It was found that H₂O₂ can be effectively activated by biochar, which produces hydroxyl (•OH) radicals owing to an increase in the formation of persistent free radicals (PFRs) on biochar surface. Ultrasound treated (30s duration) biochar, chemically activated by 30% phosphoric acid and functionalized by diethanolamine (DEA) was used for the adsorption of heavy metal ions from aqueous solutions. It was found that modified biochar could remove almost 60% of nickel in eight hours; however, for lead, the removal efficiency reached up to 95% for the same time duration. The heavy metal loaded biochar was further used for the degradation of phenol in the absence and presence of H₂O₂ (20 mM), within 4 hours of reaction time. The removal efficiency values for phenol in the presence of H₂O₂ were 80.3% and 61.9%, respectively, by modified biochar loaded with nickel and lead metal ions. These results suggested that the biochar loaded with nickel exhibits a better removal capacity towards phenol than the lead loaded biochar when used in H₂O₂ based oxidation systems. Meanwhile, control experiments were set in the absence of any activating biochar, and the removal efficiency was found to be 19.1% when only H₂O₂ was added in the reaction solution. Overall, the proposed approach serves a dual purpose of using biochar for heavy metal ion removal and treatment of organic contaminants by further using the metal loaded biochar for H₂O₂ activation in ISCO processes.

Keywords: biochar, ultrasound, heavy metals, in-situ chemical oxidation, chemical activation

Procedia PDF Downloads 108

Authors: Kevlin Govender, Anthony Walker, Glen Bright

Abstract:

Mass customization is an area of increased importance and the development of rapid tooling applications is pivotal to the success of mass customization. This paper presents a laminated object manufacturing (LOM) process for rapid tooling. The process is termed 3D metal laminate printing and utilizes domestic-grade aluminum foil and epoxy for layered manufacturing. A detailed explanation of the process is presented to produce complex metal laminated composite parts. Aluminum-epoxy composite specimens were manufactured from 0.016mm aluminum and subjected to tensile tests to determine the mechanical properties of the manufactured composite in relation to solid metal specimens. The fracture zone of the specimens was analyzed under scanning electron microscopy (SEM) in order to characterize the fracture mode and study the interfacial bonding of the manufactured laminate specimens.

Keywords: 3D metal laminate printer, aluminum-epoxy composite, laminated object manufacturing, rapid tooling

Procedia PDF Downloads 260

Authors: Adetunji Olusegun Aderigibigbe

Abstract:

Shales, especially black shales, are of great geological significance, in the study of heavy/trace metal contamination. This is due to their abundance in occurrence and high concentration of heavy metals embedded which are released during their weathering. Heavy metals constitute one of the most dangerous pollution known to human because they are toxic (i.e., carcinogenic), non-biodegradable and can enter the global eco-biological circle. In the past, heavy metal contamination in aquatic environment and agricultural top soil has been attributed to industrial wastes, mining extractions and pollution from traffic vehicles; only a few studies have focused on weathering of shale as possible source of heavy metal contamination. Based on the above background, this study attempts to establish weathering of shale as possible source of trace/heavy metal contaminations. This was done by carefully selecting fresh and their corresponding weathered shale samples from selected localities in Bida and Anambra Basins. The samples were analysed in Activation Laboratories Ltd; Ontario, Canada for trace/heavy metal. It was observed that some major and trace metals were released during weathering, i.e., some were depleted and some enriched. By this contamination of water zones and agricultural top soils are not only traceable to biogenic processes but geogenic inputs (weathering of shale) as well.

Keywords: contamination, fresh samples, heavy metals, pollution, shales, trace metals, weathered samples

Procedia PDF Downloads 106

Authors: P. M. Fonseca Alfonso, E. A. Murillo Ruiz, M. Diaz Lagos

Abstract:

Understanding the physicochemical properties and mineralogy of fly ash from a particular source is essential for to protect the environment and considering its possible applications, specifically, in the production of geopolymeric materials that solidify/stabilize heavy metals ions. The results of the characterization of three fly ash samples are shown in this paper. The samples were produced in the TERMOPAIPA IV thermal power plant in the State of Boyaca, Colombia. The particle size distribution, chemical composition, mineralogy, and molecular structure of three samples were analyzed using laser diffraction, X-ray fluorescence, inductively coupled plasma mass spectrometry, X-ray diffraction, and infrared spectroscopy respectively. The particle size distribution of the three samples probably ranges from 0.128 to 211 μm. Approximately 59 elements have been identified in the three samples. It is noticeable that the ashes are made up of aluminum and silicon compounds. Besides, the iron phase in low content was also found. According to the results found in this study, the fly ash samples type F has a great potential to be used as raw material for the manufacture of geopolymers with potential use in the stabilization/solidification of heavy metals; mainly due to the presence of amorphous aluminosilicates typical of this type of ash, which react effectively with alkali-activator.

Keywords: fly ash, geopolymers, molecular structure, physicochemical properties.

Procedia PDF Downloads 98

Authors: Noura Kichou, Manel Tafergguenit, Nabila Ghechtouli, Zakia Hank

Abstract:

The aim of this work is to synthesize, characterize and evaluate the biological activity of two Ligands : glyoxime and dimethylglyoxime, and their metal Ni(II) chelates. The newly chelates were characterized by elemental analysis, IR, EPR, nuclear magnetic resonances (1H and 13C), and biological activity. The antibacterial and antifungal activities of the ligands and its metal complexes were screened against bacterial species (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungi (Candida albicans). Ampicillin and amphotericin were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with parent free ligand against bacterial and fungal species. A structural, energetic, and electronic theoretical study was carried out using the DFT method, with the functional B3LYP and the gaussian program 09. A complete optimization of geometries was made, followed by a calculation of the frequencies of the normal modes of vibration. The UV spectrum was also interpreted. The theoretical results were compared with the experimental data.

Keywords: glyoxime, dimetylglyoxime, nickel, antibacterial activity

Procedia PDF Downloads 76

Authors: Noura Kichou, Manel Tafergguenit, Nabila Ghechtouli, Zakia Hank

Abstract:

The aim of this work is to synthesize, characterize and evaluate the biological activity of two Ligands: glyoxime and dimethylglyoxime, and their metal Ni(II) chelates. The newly chelates were characterized by elemental analysis, IR, EPR, nuclear magnetic resonances (1H and 13C), and biological activity. The antibacterial and antifungal activities of the ligands and its metal complexes were screened against bacterial species (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungi (Candida albicans). Ampicillin and amphotericin were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with parent free ligand against bacterial and fungal species. A structural, energetic, and electronic theoretical study was carried out using the DFT method, with the functional B3LYP and the gaussian program 09. A complete optimization of geometries was made, followed by a calculation of the frequencies of the normal modes of vibration. The UV spectrum was also interpreted. The theoretical results were compared with the experimental data.

Keywords: glyoxime, dimetylglyoxime, nickel, antibacterial activity

Procedia PDF Downloads 86

Authors: Ertuğ Yıldırım, Dile Kara, Salih Zeki Yıldız

Abstract:

Metal containing polymers (MCPs) are macro molecules usually containing metal-ligand coordination units and are a multidisciplinary research field mainly based at the interface between coordination chemistry and polymer science. The progress of this area has also been reinforced by the growth of several other closely related disciplines including macro molecular engineering, crystal engineering, organic synthesis, supra molecular chemistry and colloidal and material science. Schiff base ligands are very effective in constructing supra molecular architectures such as coordination polymers, double helical and triple helical complexes. In addition, Schiff base derivatives incorporating a fluorescent moiety are appealing tools for optical sensing of metal ions. MCPs are well-known systems in which the combinations of local parameters are possible by means of fluoro metric techniques. Generally, without incorporation of the fluorescent groups with polymers is unspecific, and it is not useful to analyze their fluorescent properties. Therefore, it is necessary to prepare a new type epoxy polymers with fluorescent groups in terms of metal sensing prop and the other photo chemical applications. In the present study metal containing polymers were prepared via poly functional monomeric Schiff base metal chelate complexes in the presence of dis functional monomers such as diglycidyl ether Bisphenol A (DGEBA). The synthesized complexes and polymers were characterized by FTIR, UV-VIS and mass spectroscopies. The preparations of epoxy polymers have been carried out at 185 °C. The prepared composites having sharp and narrow excitation/emission properties are expected to be applicable in various systems such as heat-resistant polymers and photo voltaic devices. The prepared composite is also ideal for various applications, easily prepared, safe, and maintain good fluorescence properties.

Keywords: Schiff base ligands, crystal engineering, fluorescence properties, Metal Containing Polymers (MCPs)

Procedia PDF Downloads 324

Authors: A. Szabó Nagy, J. Szabó, I. Vass

Abstract:

Water and sediment samples from the Danube River and Moson Danube Arm (Hungary) have been collected and analyzed for contamination by 18 polycyclic aromatic hydrocarbons (PAHs) and eight trace metal(loid)s (As, Cu, Pb, Ni, Cr, Cd, Hg and Zn) in the period of 2014-2015. Moreover, the trace metal(loid) concentrations were measured in the Rába and Marcal rivers (parts of the tributary system feeding the Danube). Total PAH contents in water were found to vary from 0.016 to 0.133 µg/L and concentrations in sediments varied in the range of 0.118 mg/kg and 0.283 mg/kg. Source analysis of PAHs using diagnostic concentration ratios indicated that PAHs found in sediments were of pyrolytic origins. The dissolved trace metal and arsenic concentrations were relatively low in the surface waters. However, higher concentrations were detected in the water samples of Rába (Zn, Cu, Ni, Pb) and Marcal (As, Cu, Ni, Pb) compared to the Danube and Moson Danube. The concentrations of trace metals in sediments were higher than those found in water samples.

Keywords: surface water, sediment, PAH, trace metal

Procedia PDF Downloads 288

Authors: Lav Kesharwani, Nalini Shankar, A. K. Gupta

Abstract:

A serial number is a unique code assigned for identification of a single unit. Serial number are present on many objects. In an attempt to hide the identity of the numbered item, the numbers are often obliterated or removed by mechanical methods. The present work was carried out with an objective to develop less toxic, less time consuming, more result oriented chemical etching reagent for restoration of serial number on the copper metal plate. Around nine different reagents were prepared using different combination of reagent along with standard reagent and it was applied over 50 erased samples of copper metal and compared it with the standard reagent for restoration of erased marks. After experiment, it was found that the prepared Etching reagent no. 3 (10 g FeCl3 + 20 ml glacial acetic acid + 100 ml distilled H2O) showed the best result for restoration of erased serial number on the copper metal plate .The reagent was also less toxic and less time consuming as compared to standard reagent (19 g FeCl3 + 6 ml cans. HCl + 100 ml distilled H2O).

Keywords: serial number restoration, copper plate, obliteration, chemical method

Procedia PDF Downloads 532

Authors: A. G. More

Abstract:

Bioelectrochemical system (BES) is an alternative technology for chromium Cr (VI) removal from industrial wastewater to overcome the existing drawbacks of high chemical and energy consumption by conventional metal removal technologies. A well developed anaerobic sludge was developed in laboratory and used in the batch study of BES at different Cr (VI) concentrations (10, 20, 50, and 50 mg/L) with different COD concentrations (500, 1000, 1500 and 2000 mg/L). Sodium acetate was used as carbon source, whereas Cr (VI) contaminated synthetic wastewater was prepared and added to the cathode chamber. Initially, operating conditions for the BES experiments were optimized. During the study, optimum cathode pH of 2, whereas optimum HRT of 72 hr was obtained. During the study, cathode pH 2 ± 0.1 showed maximum chromium removal efficicency (CRE) of 88.36 ± 8.16% as compared to other pH (1-7) in the cathode chamber. Maximum CRE obtained was 85.93 ± 9.62% at 40°C within the temperature range of 25°C to 45°C. Conducting the BES experiments at optimized operating conditions, CRE of 90.2 %, 93.7 %, 83.75 % and 74.6 % were obtained at cathodic Cr concentration of 10, 20, 50, and 50 mg/L, respectively. BES is a sustainable, energy efficient technology which can be suitably used for metal removal from industrial wastewater.

Keywords: bioelectrochemical system, metal removal, microorganisms, pH and temperature, substrate

Procedia PDF Downloads 107

Authors: K. A. Ghazaryan, G. A. Gevorgyan, H. S. Movsesyan, N. P. Ghazaryan, K. V. Grigoryan

Abstract:

The heavy metal pollution degree in the soils around the Zangezur copper and molybdenum combine in Syunik Marz, Armenia was aessessed. The results of the study showed that heavy metal pollution degree in the soils mainly decreased with increasing distance from the open mine and the ore enrichment combine which indicated that the open mine and the ore enrichment combine were the main sources of heavy metal pollution. The only exception was observed in the northern part of the open mine where pollution degree in the sites (along the open mine) situated 600 meters far from the mine was higher than that in the sites located 300 meters far from the mine. This can be explained by the characteristics of relief and air currents as well as the weak vegetation cover of these sites and the characteristics of soil structure. According to geo-accumulation index (I-geo), contamination factor (Cf), contamination degree (Cd) and pollution load index (PLI) values, the pollution degree in the soils around the open mine and the ore enrichment combine was higher than that in the soils around the tailing dumps which was due to the proper and accurate operation of the Artsvanik tailing damp and the recultivation of the Voghji tailing dump. The high Cu and Mo pollution of the soils was conditioned by the character of industrial activities, the moving direction of air currents as well as the physicochemical peculiarities of the soils.

Keywords: Armenia, Zangezur copper and molybdenum combine, soil, heavy metal pollution degree

Procedia PDF Downloads 277

Authors: Deniz Sahin

Abstract:

Growing concern for the presence and contamination of heavy metals in our water supplies has steadily increased over the last few years. A number of specialized technologies including precipitation, coagulation/flocculation, ion exchange, cementation, electrochemical operations, have been developed for the removal of heavy metals from wastewater. However, these technologies have many limitations in the application, such as high cost, low separation efficiency, Recently, numerous approaches have been investigated to overcome these difficulties and membrane filtration, advanced oxidation technologies (AOPs), and UV irradiation etc. are sufficiently developed to be considered as alternative treatments. Many factors come into play when selecting wastewater treatment technology, such as type of wastewater, operating conditions, economics etc. This study describes these various treatment technologies employed for heavy metal removal. Advantages and disadvantages of these technologies are also compared to highlight their current limitations and future research needs. For example, we investigated the applicability of the ultrafiltration technology for treating of heavy metal ions (e.g., Cu(II), Pb(II), Cd(II), Zn(II)) from synthetic wastewater solutions. Results shown that complete removal of metal ions, could be achieved.

Keywords: heavy metal, treatment methodologies, water, water treatment

Procedia PDF Downloads 129

Authors: Sai Snehitha Yadavalli, K. Sruthi, Swati Ghosh Acharyya

Abstract:

Heavy metal ions are toxic to humans and all living species when exposed in large quantities or for long durations. Though Fe acts as a nutrient, when intake is in large quantities, it becomes toxic. These toxic heavy metal ions, when consumed through water, will cause many disorders and are harmful to all flora and fauna through biomagnification. Specifically, humans are prone to innumerable diseases ranging from skin to gastrointestinal, neurological, etc. In higher quantities, they even cause cancer in humans. Detection of these toxic heavy metal ions in water is thus important. Traditionally, the detection of heavy metal ions in water has been done by techniques like Inductively Coupled Plasma Mass Spectroscopy (ICPMS) and Atomic Absorption Spectroscopy (AAS). Though these methods offer accurate quantitative analysis, they require expensive equipment and cannot be used for on-site measurements. Anodic Stripping Voltammetry is a good alternative as the equipment is affordable, and measurements can be made at the river basins or lakes. In the current study, Square Wave Anodic Stripping Voltammetry (SWASV) was used to detect the heavy metal ions in water. Literature reports various electrodes on which deposition of heavy metal ions was carried out like Bismuth, Polymers, etc. The working electrode used in this study is a polyvinyl chloride (PVC) modified glassy carbon electrode (GCE). Ag/AgCl reference electrode and Platinum counter electrode were used. Biologic Potentiostat SP 300 was used for conducting the experiments. Through this work of simultaneous detection, four heavy metal ions were successfully detected at a time. The influence of modifying GCE with PVC was studied in comparison with unmodified GCE. The simultaneous detection of Cd⁺², Fe⁺², Co⁺², Pb⁺² heavy metal ions was done using PVC modified GCE by drop casting 1 wt.% of PVC dissolved in Tetra Hydro Furan (THF) solvent onto GCE. The concentration of all heavy metal ions was 0.2 mg/L, as shown in the figure. The scan rate was 0.1 V/s. Detection parameters like pH, scan rate, temperature, time of deposition, etc., were optimized. It was clearly understood that PVC helped in increasing the sensitivity and selectivity of detection as the current values are higher for PVC-modified GCE compared to unmodified GCE. The peaks were well defined when PVC-modified GCE was used.

Keywords: cadmium, cobalt, electrochemical sensing, glassy carbon electrodes, heavy metal Ions, Iron, lead, polyvinyl chloride, potentiostat, square wave anodic stripping voltammetry

Procedia PDF Downloads 73