Search results for: trace of heavy metal

Authors: Robin Singh, Mayank Nautiyal, Priyank Jain, Vatasta Koul, Vaibhav Sharma

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The curiosity to investigate the space and its mysteries was dependably the main impetus of human interest, as the particle of livings exists from the "debut de l'Univers" (beginning of the Universe) typified with its few other living things. The sharp drive to uncover the secrets of stars and their unusual deportment was dependably an ignitor of stars investigation. As humankind lives in civilizations and states, stars likewise live in provinces named ‘clusters’. Clusters are separates into 2 composes i.e. open clusters and globular clusters. An open cluster is a gathering of thousand stars that were moulded from a comparable goliath sub-nuclear cloud and for the most part; contain Propulsion I (extremely metal-rich) and Propulsion II (mild metal-rich), where globular clusters are around gathering of more than thirty thousand stars that circles a galactic focus and basically contain Propulsion III (to a great degree metal-poor) stars. Futurology of this paper lies in the spectroscopic investigation of globular clusters like M92 and NGC419 and open clusters like M34 and IC2391 in different color bands by using software like VIREO virtual observatory, Aladin, CMUNIWIN, and MS-Excel. Assessing the outcome Hertzsprung-Russel (HR) diagram with exemplary cosmological models like Einstein model, De Sitter and Planck survey demonstrate for a superior age estimation of respective clusters. Colour-Magnitude Diagram of these clusters was obtained by photometric analysis in g and r bands which further transformed into BV bands which will unravel the idea of stars exhibit in the individual clusters.

Keywords: color magnitude diagram, globular clusters, open clusters, Einstein model

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Authors: Annu Sheokand, Vinay Kumar

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Hydrogen sulfide (H₂S) detection is essential for environmental monitoring and industrial safety due to its high toxicity, even at low concentrations. This study explores the H₂S gas sensing properties of Cu-doped Fe₂O₃ materials derived from metal-organic frameworks (MOFs), which offer high surface area and controlled porosity for optimized gas sensing. The structural and morphological characteristics of the synthesized material were thoroughly analyzed using techniques such as X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), and UV-Vis Spectroscopy. The resulting sensor exhibited remarkable sensitivity and selectivity, achieving a detection limit at the ppb level for H₂S. The study indicates that Cu doping significantly enhances the gas sensing performance of Fe₂O₃ by introducing abundant active sites within the material. These enhanced sensing properties emphasize the potential of MOF-derived Cu-doped Fe₂O₃ as a highly effective material for H₂S gas sensors in various applications.

Keywords: detection limit, doping, MOF, sensitivity, sensor

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Authors: Kaivan Karami, Sahalu Hassan, Sanna Taking, Afesome Ofiare, Aniket Dhongde, Abdullah Al-Khalidi, Edward Wasige

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We have made a comparative study on the influence of Al₂O₃ and HfO₂ grown using atomic layer deposition (ALD) technique as dielectric in the AlGaN/GaN metal oxide semiconductor high electron mobility transistor (MOS-HEMT) structure. Five samples consisting of 20 nm and 10 nm each of Al₂O₃ and HfO₂ respectively and a Schottky gate HEMT, were fabricated and measured. The threshold voltage shifts towards negative by 0.1 V and 1.8 V for 10 nm thick HfO2 and 10 nm thick Al₂O₃ gate dielectric layers respectively. The negative shift for the 20 nm HfO2 and 20 nm Al₂O₃ were 1.2 V and 4.9 V respectively. Higher gm/IDS (transconductance to drain current) ratio was also obtained in HfO₂ than Al₂O₃. With both materials as dielectric, a significant reduction in the gate leakage current in the order of 10^4 was obtained compared to the sample without the dielectric material.

Keywords: AlGaN/GaN HEMTs, Al2O3, HfO2, MOSHEMTs.

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Authors: Neslihan Beyazit, Sahin Bayraktar, Cahit Demetgul

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Transition metal ions have an important role in biochemistry and biomimetic systems and may provide the basis of models for active sites of biological targets. The presence of copper(II), iron(II) and zinc(II) is crucial in many biological processes. Tetradentate N2O2 donor Schiff base ligands are well known to form stable transition metal complexes and these complexes have also applications in clinical and analytical fields. In this study, we present salient structural features and the details of cathecholase activity of Fe(II) complex of a new Schiff Base ligand. A new asymmetrical N2O2 donor Schiff base ligand and its Fe(II) complex were synthesized by condensation of 4-nitro-1,2 phenylenediamine with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one and by using an appropriate Fe(II) salt, respectively. Schiff base ligand and its metal complex were characterized by using FT-IR, 1H NMR, 13C NMR, UV-Vis, elemental analysis and magnetic susceptibility. In order to determine the kinetics parameters of catechol oxidase-like activity of Schiff base Fe(II) complex, the oxidation of the 3,5-di-tert-butylcatechol (3,5-DTBC) was measured at 25°C by monitoring the increase of the absorption band at 390-400 nm of the product 3,5-di-tert-butylcatequinone (3,5-DTBQ). The compatibility of catalytic reaction with Michaelis-Menten kinetics also investigated by the method of initial rates by monitoring the growth of the 390–400 nm band of 3,5-DTBQ as a function of time. Kinetic studies showed that Fe(II) complex of the new N2O2 donor Schiff base ligand was capable of acting as a model compound for simulating the catecholase properties of type-3 copper proteins.

Keywords: catecholase activity, Michaelis-Menten kinetics, Schiff base, transition metals

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Authors: Renata Swislocka, Grzegorz Swiderski, Agata Jablonska-Trypuc, Wlodzimierz Lewandowski

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Forming a complex of a phenolic compound with a metal not only alters the physicochemical properties of the ligand (including increase in stability or changes in lipophilicity), but also its biological activity, including antioxidant, antimicrobial and many others. As part of our previous projects, we examined the physicochemical and antimicrobial properties of phenolic acids and their complexes with metals naturally occurring in foods. Previously we studied the complexes of manganese(II), copper(II), cadmium(II) and alkali metals with ferulic, caffeic and p-coumaric acids. In the framework of this study, the physicochemical and biological properties of cicoric acid, its sodium salt, and complexes with copper and zinc were investigated. Cichoric acid is a derivative of both caffeic acid and tartaric acid. It has first been isolated from Cichorium intybus (chicory) but also it occurs in significant amounts in Echinacea, particularly E. purpurea, dandelion leaves, basil, lemon balm and in aquatic plants, including algae and sea grasses. For the study of spectroscopic and biological properties of cicoric acid, its sodium salt, and complexes with zinc and copper a variety of methods were used. Studies of antioxidant properties were carried out in relation to selected stable radicals (method of reduction of DPPH and reduction of FRAP). As a result, the structure and spectroscopic properties of cicoric acid and its complexes with selected metals in the solid state and in the solutions were defined. The IR and Raman spectra of cicoric acid displayed a number of bands that were derived from vibrations of caffeic and tartaric acids moieties. At 1746 and 1716 cm-1 the bands assigned to the vibrations of the carbonyl group of tartaric acid occurred. In the spectra of metal complexes with cichoric these bands disappeared what indicated that metal ion was coordinated by the carboxylic groups of tartaric acid. In the spectra of the sodium salt, a characteristic wide-band vibrations of carboxylate anion occurred. In the spectra of cicoric acid and its salt and complexes, a number of bands derived from the vibrations of the aromatic ring (caffeic acid) were assigned. Upon metal-ligand attachment, the changes in the values of the wavenumbers of these bands occurred. The impact of metals on the antioxidant properties of cicoric acid was also examined. Cichoric acid has a high antioxidant potential. Complexation by metals (zinc, copper) did not significantly affect its antioxidant capacity. The work was supported by the National Science Centre, Poland (grant no. 2015/17/B/NZ9/03581).

Keywords: chicoric acid, metal complexes, natural antioxidant, phenolic acids

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Authors: S. Jahangir, S. H. I. Jaffery, M. Khan, Z. Zareef, A. Yar, A. Mubashir, S. Butt, L. Ali

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In this work, drilling responses and behavior of MMC was investigated in Al-Mg2Si composites. For the purpose Al-15% wt. Mg2Si, was selected from the hypereutectic region of Al- Mg2Si phase diagram. Based on hardness and tensile strength, drill bit of appropriate material and morphology was selected. The performance of different drill bits of different morphology and material was studied and analysed using experimental data. For theoretical calculations of axial thrust force and required power calculation, material factor “K” was obtained from different data charts and at the same time cutting forces (drilling forces) were practically obtained using a Peizo electric force dynamometer. These results show the role of reinforcement particles on the machinability of MMCs and provide a useful guide for a better control and optimized drilling parameters for the drilling process. Furthermore, in this work, comparison of MMC with non -reinforced Aluminum Alloy regarding drilling operation was also studied.

Keywords: drilling, metal matrix composite (MMC), cutting forces, thrust force

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Authors: Doris Fovwe Ogeleka, L. E. Tudararo-Aherobo, F. E. Okieimen

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The ecological effects of oil spill in the environment were studied in Warri riverine areas of Ubeji and Jeddo, Delta State. In the two communities, water and sediment samples were analysed for organics (polyaromatic hydrocarbon; total petroleum hydrocarbon (TPH)) and heavy metals (lead, copper, zinc, iron and chromium). The American Public Health Association (APHA) and the American Society for Testing and Materials (ASTM) methods were employed for the laboratory test. The results indicated that after a long period of oil spill (above one year), there were still significant concentrations (p<0.05) of organics indicating hydrocarbon pollution. Mean concentrations recorded for TPH in Ubeji and Jeddo waters were 23.60 ± 1.18 mg/L and 29.96 ± 0.14 mg/L respectively while total PAHs was 0.009 ± 0.002 mg/L and 0.008 ± 0.001 mg/L. Mean concentrations of TPH in the sediment was 48.83 ± 1.49 ppm and 1093 ± 74 ppm in the above order while total PAHs was 0.012 ± 0.002 ppm and 0.026 ± 0.004 ppm. Low concentrations were recorded for most of the heavy metals in the water and sediment. The observed concentrations of hydrocarbons in the study areas should provide the impetus for regulatory surveillance of oil discharged intentionally/unintentionally into the Warri riverine waters and sediment since hydrocarbon released into the environment sorb to the sediment particles where they cause harm to organisms in the sediment and overlying waters.

Keywords: crude oil, PAHs, TPH, oil spillage, water, sediment

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Authors: Rajesha Kumar Alambi, Mansour Ahmed, Garudachari Bhadrachari, Safiyah Al-Muqahwi, Mansour Al-Rughaib, Jibu P. Thomas

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Membrane-based pressure assisted osmosis (PAO) for seawater desalination has the potential to overcome the challenges of forward osmosis technology. PAO technology is gaining interest among the research community to ensure the sustainability of freshwater with a significant reduction in energy. The requirements of PAO membranes differ from the FO membrane; as it needs a slightly higher porous with sufficient mechanical strength to overcome the applied hydraulic pressure. The porous metal-organic framework (MOF) as a filler for the membrane synthesis has demonstrated a great potential to generate new channels for water transport, high selectivity, and reduced fouling propensity. Accordingly, this study is aimed at fabricating the UiO-66 MOF-based thin film nanocomposite membranes with specific characteristics for water desalination by PAO. A PAO test unit manufactured by Trevi System, USA, was used to determine the performance of the synthesized membranes. Further, the synthesized membranes were characterized in terms of morphological features, hydrophilicity, surface roughness, and mechanical properties. The 0.05 UiO-66 loaded membrane produced highest flux of 38L/m2h and with low reverse salt leakage of 2.1g/m²h for the DI water as feed solution and 2.0 M NaCl as draw solutions at the inlet feed pressure of 0.6 MPa. The new membranes showed a good tolerance toward the applied hydraulic pressure attributed to the fabric support used during the membrane synthesis.

Keywords: metal organic framework, composite membrane, desalination, salt rejection, flux

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Authors: Shiyi He, Yan Xia, Xiaoping Ouyang, Liang Chen, Zhongbing Zhang, Jinlu Ruan

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As the key system of the spacecraft, various propelling system have been developing rapidly, including ion thrust, laser thrust, solar sail and other micro-thrusters. However, there still are some shortages in these systems. The ion thruster requires the high-voltage or magnetic field to accelerate, resulting in extra system, heavy quantity and large volume. The laser thrust now is mostly ground-based and providing pulse thrust, restraint by the station distribution and the capacity of laser. The thrust direction of solar sail is limited to its relative position with the Sun, so it is hard to propel toward the Sun or adjust in the shadow.In this paper, a novel nuclear thruster based on alpha decay and spontaneous fission is proposed and the principle of this radiation-thrust with alpha particle has been expounded. Radioactive materials with different released energy, such as 210Po with 5.4MeV and 238Pu with 5.29MeV, attached to a metal film will provides various thrust among 0.02-5uN/cm2. With this repulsive force, radiation is able to be a power source. With the advantages of low system quantity, high accuracy and long active time, the radiation thrust is promising in the field of space debris removal, orbit control of nano-satellite array and deep space exploration. To do further study, a formula lead to the amplitude and direction of thrust by the released energy and decay coefficient is set up. With the initial formula, the alpha radiation elements with the half life period longer than a hundred days are calculated and listed. As the alpha particles emit continuously, the residual charge in metal film grows and affects the emitting energy distribution of alpha particles. With the residual charge or extra electromagnetic field, the emitting of alpha particles performs differently and is analyzed in this paper. Furthermore, three more complex situations are discussed. Radiation element generating alpha particles with several energies in different intensity, mixture of various radiation elements, and cascaded alpha decay are studied respectively. In combined way, it is more efficient and flexible to adjust the thrust amplitude. The propelling model of the spontaneous fission is similar with the one of alpha decay, which has a more complex angular distribution. A new quasi-sphere space propelling system based on the radiation-thrust has been introduced, as well as the collecting and processing system of excess charge and reaction heat. The energy and spatial angular distribution of emitting alpha particles on unit area and certain propelling system have been studied. As the alpha particles are easily losing energy and self-absorb, the distribution is not the simple stacking of each nuclide. With the change of the amplitude and angel of radiation-thrust, orbital variation strategy on space debris removal is shown and optimized.

Keywords: alpha decay, angular distribution, emitting energy, orbital variation, radiation-thruster

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Authors: F. Ghasim-akbari, A. M. Hadian, A. M. Aminazad

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Fluid transmission pipes made of aluminum are widely use in petrochemical industries. For many applications they have to be brazed to each other. The brazed joints, in many cases, are encountered with corrosive medias. This paper reports a part of a work to investigate the corrosion behavior of brazed Al6061 using Al4047 as filler metal with and without the use of flux to discover the effect of different brazing atmospheres. The samples brazed under air, vacuum, argon, and hydrogen atmospheres. The interfacial area of the joints was examined to ensure being free of any defects. The sides of each test piece were covered with insulator and the surface of the joint was encountered to polarization test. The results revealed a significant difference of corrosion resistance. The samples that brazed under argon and hydrogen atmospheres had better corrosion resistance than other samples. Microstructure of the corroded joints revealed that the amount of the filler metal is a critical parameter on corrosion resistance of the joints.

Keywords: brazing, corrosion behavior, Al6061, polarization

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Authors: Sami Aboujafar

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Oil recovery in petroleum reservoirs is greatly affected by fluid-rock and fluid-fluid interactions. These interactions directly control rock wettability, capillary pressure and relative permeability curves. Laboratory core-floods and centrifuge experiments were conducted on sandstone and carbonate cores to study the effect of low and high brine salinity and viscosity and oil viscosity on residual saturations and relative permeability. Drainage and imbibition relative permeability in two phase system were measured, refined lab oils with different viscosities, heavy and light, and several brine salinities were used. Sensitivity analysis with different values for the salinity and viscosity of the fluids,, oil and water, were done to investigate the effect of these properties on water/oil relative permeability, residual oil saturation and oil recovery. Experiments were conducted on core material from viscous/heavy and light oil fields. History matching core flood simulator was used to study how the relative permeability curves and end point saturations were affected by different fluid properties using several correlations. Results were compared with field data and literature data. The results indicate that there is a correlation between the oil viscosity and/or brine salinity and residual oil saturation and water relative permeability end point. Increasing oil viscosity reduces the Krw@Sor and increases Sor. The remaining oil saturation from laboratory measurements might be too high due to experimental procedures, capillary end effect and early termination of the experiment, especially when using heavy/viscous oil. Similarly the Krw@Sor may be too low. The effect of wettability on the observed results is also discussed. A consistent relationship has been drawn between the fluid parameters, water/oil relative permeability and residual saturations, and a descriptor may be derived to define different flow behaviors. The results of this work will have application to producing fields and the methodologies developed could have wider application to sandstone and carbonate reservoirs worldwide.

Keywords: history matching core flood simulator, oil recovery, relative permeability, residual saturations

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Authors: Mozhgan Aliakbari, Sara Moridpour

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In recent years, much attention has been given to truck drivers’ fatigue management. Long working hours negatively influence truck drivers’ physiology, health, and safety. However, there is little empirical research in the heavy vehicle transport sector in Australia to identify the influence of working hours’ management on drivers’ fatigue and consequently, on the risk of crashes and injuries. There is no national legislation regulating the number of hours or kilometres travelled by truck drivers. Consequently, it is almost impossible to define a standard number of hours or kilometres for truck drivers in a safety management system. This paper reviews the existing studies concerning safe system interventions such as tachographs in relation to fatigue caused by long working hours. This paper also reviews the literature to identify the influence of frequency of rest breaks on the reduction of work-related road transport accidents involving trucks. A framework is presented to manage truck drivers’ fatigue, which may result in the reduction of injuries and fatalities involving heavy vehicles.

Keywords: fatigue, time management, trucks, traffic safety

Procedia PDF Downloads 289

Authors: E. Yazıcı, H. Sundu, E. Veli Veliev

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In order to understand the nature of strong interactions and QCD vacuum, investigation of the meson coupling constants have an important role. The knowledge on the temperature dependence of the form factors is very important for the interpretation of heavy-ion collision experiments. Also, more accurate determination of these coupling constants plays a crucial role in understanding of the hadronic decays. With the increasing of CM energies of the experiments, researches on meson interactions have become one of the more interesting problems of hadronic physics. In this study, we analyze the temperature dependence of the strong form factor of the BcBcJ/ψ vertex using the three point QCD sum rules method. Here, we assume that with replacing the vacuum condensates and also the continuum threshold by their thermal version, the sum rules for the observables remain valid. In calculations, we take into account the additional operators, which appear in the Wilson expansion at finite temperature. We also investigated the momentum dependence of the form factor at T = 0, fit it into an analytic function, and extrapolate into the deep time-like region in order to obtain a strong coupling constant of the vertex. Our results are consistent with the results existing in the literature.

Keywords: QCD sum rules, thermal QCD, heavy mesons, strong coupling constants

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Authors: A. Guerrero, A. Leon, S. Munoz, M. Sandoval

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The addition of solvent to cyclic steam stimulation is done in order to reduce the solvent-vapor ratio at late stages of the process, the moment in which this relationship increases significantly. The study of the use of naphtha in addition to the cyclic steam stimulation has been mainly oriented to the effect it achieves on the incremental recovery compared to the application of steam only. However, the effect of naphtha on the reactivity of crude oil components under conditions of cyclic steam stimulation or if its effect is the only dilution has not yet been considered, to author’s best knowledge. The present study aims to evaluate and understand the effect of naphtha and the conditions of cyclic steam stimulation, on the remaining composition of the improved oil, as well as the main mechanisms present in the heavy crude - naphtha interaction. Tests were carried out with the system solvent (naphtha)-oil (12.5° API, 4216 cP @ 40° C)- steam, in a batch micro-reactor, under conditions of cyclic steam stimulation (250-300 °C, 400 psi). The characterization of the samples obtained was carried out by MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) and NMR (Nuclear Magnetic Resonance) techniques. The results indicate that there is a rearrangement of the microstructure of asphaltenes, resulting in a decrease in these and an increase in lighter components such as resins.

Keywords: composition change, cyclic steam stimulation, interaction mechanism, naphtha

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Authors: Hanan. Al Chaghouri, Mohammad Azad Malik, P. John Thomas, Paul O’Brien

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The process of assembling metal nanoparticles at the interface of two liquids has received a great deal of attention over the past few years due to a wide range of important applications and their unusual properties as compared to bulk materials. We present a low cost, simple and cheap synthesis of metal nanoparticles, core/shell structures and semiconductors followed by assembly of these particles between immiscible liquids. The aim of this talk is divided to three parts: Firstly, to describe the achievement of a closed loop recycling for producing cadmium sulfide as powders and/or nanostructured thin films for solar cells or other optoelectronic devices applications by using a different chain length of commercially available secondary amines of dithiocarbamato complexes. The approach can be extended to other metal sulfides such as those of Zn, Pb, Cu, or Fe and many transition metals and oxides. Secondly, to synthesis significantly cheaper magnetic particles suited for the mass market. Ni/NiO nanoparticles with ferromagnetic properties at room temperature were among the smallest and strongest magnets (5 nm) were made in solution. The applications of this work can be to produce viable storage devices and the other possibility is to disperse these nanocrystals in solution and use it to make ferrofluids which have a number of mature applications. The third part is about preparing and assembling of submicron silver, cobalt and nickel particles by using polyol methods and liquid/liquid interface, respectively. Coinage metals like gold, copper and silver are suitable for plasmonic thin film solar cells because of their low resistivity and strong interactions with visible light waves. Silver is the best choice for solar cell application since it has low absorption losses and high radiative efficiency compared to gold and copper. Assembled cobalt and nickel as films are promising for spintronic, magnetic and magneto-electronic and biomedics.

Keywords: metal nanoparticles, core/shell structures and semiconductors, ferromagnetic properties, closed loop recycling, liquid/liquid interface

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Authors: Amna Shoaib, Sidrah Hanif, Rashid Mehmood

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Current research work was carried out to check influence of farmyard manure (FYM) in Lycopersicon esculentum L. against Fusarium oxysporum f. sp. lycopersici (FO) in copper polluted soil. Silt-loam soil naturally enriched with 70 ppm of Cu was inoculated with 1 x 106 spore suspensions of FO and incorporated with 0%, 1%, 1.5% or 2% FYM. The multilateral interaction of host-pathogen-metal-organic amendment was assessed in terms of morphology, growth, yield, physiology, biochemistry and metal uptake in tomato plant after 30 and 60 days of sowing. When soil was inoculated with FO, plant growth and biomass were significantly increased during vegetative stage, while declining during flowering stage with substantial increase in productivity over control. Infected plants exhibited late wilting and disease severity was found on 26-50% of plant during reproductive stage. Incorporation of up to 1% FYM suppressed disease severity, improved plant growth and biomass, while it decreased yield. Rest of manure doses was found ineffective in suppressing disease. Content of total chlorophyll, sugar and protein were significantly declined in FO inoculated plants and incorporation of FYM caused significant reduction or no influence on sugar and chlorophyll content, and no pronounced difference among different FYM doses were observed. On the other hand, proline, peroxidase, catalase and nitrate reductase activity were found to be increased in infected plants and incorporation of 1-2% FYM further enhanced the activity of these enzymes. Tomato plant uptake of 30-40% of copper naturally present in the soil and incorporation of 1-2% FYM markedly decreased plant uptake of metal by 15-30%, while increased Cu retention in soil. Present study concludes that lower dose (1%) of FYM could be used to manage disease, increase growth and biomass, while being ineffective for yield and productivity in Cu-polluted soil. Altered physiology/biochemistry of plant in response to any treatment could be served as basis for resistant against pathogen and metal homeostasis in plants.

Keywords: Lycopersicon esculentum, copper, Fusarium wilt, farm yard manure

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Authors: Hilary Rutto, Linda Sibali

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In this study, the adsorption of lead and zinc ions from aqueous solutions by modified millet husk has been investigated. The effects of different parameters, such as pH, adsorbent dosage, concentration, temperature, and contact time, have been investigated. The results of the experiments showed that the adsorption of both metal ions increased by increasing pH values up to 11. Adsorption process was initially fast. The adsorption rate decreased then until it reached to equilibrium time of 120 min for both lead and zinc ions. The Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and thermodynamic models (Gibbs free energy) were used to determine the isotherm parameters associated with the adsorption process. The positive values of Gibbs free energy change indicated that reaction is not spontaneous. Experimental data were also evaluated in terms of kinetic characteristics of adsorption, and it was found that adsorption process for both metal ions followed pseudo-first order for zinc and pseudo-second-order for lead.

Keywords: zinc, lead, adsorption, millet husks

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Authors: Hikmet Cicek

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Transition metal nitrides are widely used as protective coatings on machine parts and cutting tools to protect the surfaces from abrasion and corrosion for decades. In this study, the ternary TiNbVN thin coatings were produced with closed field unbalanced magnetron sputtering system and their structural, mechanical and fatigue-like (multi-pass scratch test) properties were investigated. Two different substrates (M2 and H13 steels) were used to explore substrates effects. X-Ray diffractometer, scanning electron microscope, and energy dispersive spectroscopy were used for the structural and chemical analysis of the coatings. Nanohardness tests were proceed for mechanical properties. The fatigue-like properties of the coatings obtained from the multi-scratch test under three different cycle passes. The results showed that TiNbVN films have excellent fatigue resistance and the coatings deposited on M2 steel substrate have higher hardness and better fatigue resistance.

Keywords: physical vapor deposition, fatigue, metal nitride, multipass scratch test

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Authors: Ramdani Nadia, Kheddaoui Abdelkrim, Nemmich Said, Tilmatine Amar

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The waste production nationwide is increasing every year, on account of therapid urbanization and growing populations, also consumption modes. Algerian political authorities have chosen Technical Landfill Centres (TLC) as a competitive and safe technique of waste management. However, storing these wastes in a bad way poses several environmental challenges, especially in the Department of Saïda, the latter have significant groundwaters. The major problem registered on this Landfill is the leachate resulting from the degradation of buried wastes which were disposed off the outside of the leachate basin and present a source of pollution for the local groundwaters by heavy metals and pathogenic germs. The present paper investigates the leachate treatment ozone process produced by Dielectric Barrier Discharge (DBD) under high potential. The experimental results obtained allowed us to show the efficiency of the treatment process by ozone based on the micro pollutant analysis (DCO, DBO5 , COT, heavy metals) and microbial analysis, after ozonation treatment. The results show that 80% of micro pollutants are eliminated and 100% destruction of all bacteria which reveals the high efficiency of the process.

Keywords: landfill, leachate, treatment, ozone, polluants, bacteria, micropolluant

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Authors: Suchhanda Ghosh, A. K. Paul

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Nickel, an industrially important metal is not mined in India, due to the lack of its primary mining resources. But, the chromite deposits occurring in the Sukinda and Baula-Nuasahi region of Odhisa, India, is reported to contain around 0.99% of nickel entrapped in the goethite matrix of the lateritic iron rich ore. Weathering of the dumped chromite mining overburden often leads to the contamination of the ground as well as the surface water with toxic nickel. Microbes inherent to this metal contaminated environment are reported to be capable of removal as well as detoxification of various metals including nickel. Nickel resistant fungal isolates obtained in pure form from the metal rich overburden were evaluated for their potential to biosorb nickel by using their dried biomass. Penicillium simplicissimum SAU203 was the best nickel biosorbant among the 20 fungi tested and was capable to sorbing 16.85 mg Ni/g biomass from a solution containing 50 mg/l of Ni. The identity of the isolate was confirmed using 18S rRNA gene analysis. The sorption capacity of the isolate was further standardized following Langmuir and Freundlich adsorption isotherm models and the results reflected energy efficient sorption. Fourier-transform infrared spectroscopy studies of the nickel loaded and control biomass in a comparative basis revealed the involvement of hydroxyl, amine and carboxylic groups in Ni binding. The sorption process was also optimized for several standard parameters like initial metal ion concentration, initial sorbet concentration, incubation temperature and pH, presence of additional cations and pre-treatment of the biomass by different chemicals. Optimisation leads to significant improvements in the process of nickel biosorption on to the fungal biomass. P. simplicissimum SAU203 could sorb 54.73 mg Ni/g biomass with an initial Ni concentration of 200 mg/l in solution and 21.8 mg Ni/g biomass with an initial biomass concentration of 1g/l solution. Optimum temperature and pH for biosorption was recorded to be 30°C and pH 6.5 respectively. Presence of Zn and Fe ions improved the sorption of Ni(II), whereas, cobalt had a negative impact. Pre-treatment of biomass with various chemical and physical agents has affected the proficiency of Ni sorption by P. simplicissimum SAU203 biomass, autoclaving as well as treatment of biomass with 0.5 M sulfuric acid and acetic acid reduced the sorption as compared to the untreated biomass, whereas, NaOH and Na₂CO₃ and Twin 80 (0.5 M) treated biomass resulted in augmented metal sorption. Hence, on the basis of the present study, it can be concluded that P. simplicissimum SAU203 has the potential for the removal as well as detoxification of nickel from contaminated environments in general and particularly from the chromite mining areas of Odhisa, India.

Keywords: nickel, fungal biosorption, Penicillium simplicissimum SAU203, Indian chromite mines, mining overburden

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Authors: Elaf Ahmed, Shahid Rasul, Ohoud Alharbi, Peng Wang

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Ultra-Small Nanoparticles of metals (USNPs) have attracted the attention from the perspective of both basic and developmental science in a wide range of fields. These NPs exhibit electrical, optical, magnetic, and catalytic phenomena. In addition, they are considered effective catalysts because of their enormously large surface area. Many chemical methods of synthesising USNPs are reported. However, the drawback of these methods is the use of different capping agents and ligands in the process of the production such as Polyvinylpyrrolidone, Thiol and Ethylene Glycol. In this research ultra-small nanoparticles of gold, palladium and platinum metal have been successfully produced using electrochemically active biofilm (EAB) after optimising the pH of the media. The production of ultra-small nanoparticles has been conducted in a reactor using a simple two steps method. Initially biofilm was grown on the surface of a carbon paper for 7 days using Shewanella Loihica bacteria. Then, biofilm was employed to synthesise platinum, palladium and gold nanoparticles in water using sodium lactate as electron donor without using any toxic chemicals at mild operating conditions. Electrochemically active biofilm oxidise the electron donor and produces electrons in the solution. Since these electrons are a strong reducing agent, they can reduce metal precursors quite effectively and quickly. The As-synthesized ultra-small nanoparticles have a size range between (2-7nm) and showed excellent catalytic activity on the degradation of methyl orange. The growth of metal USNPs is strongly related to the condition of the EAB. Where using low pH for the synthesis was not successful due to the fact that it might affect and destroy the bacterial cells. However, increasing the pH to 7 and 9, led to the successful formation of USNPs. By changing the pH value, we noticed a change in the size range of the produced NPs. The EAB seems to act as a Nano factory for the synthesis of metal nanoparticles by offering a green, sustainable and toxic free synthetic route without the use of any capping agents or ligands and depending only on their respiration pathway.

Keywords: electrochemically active biofilm, electron donor, shewanella loihica, ultra-small nanoparticles

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Authors: Nhan N. T. Ton, Anh T. N. Dao, Kouichirou Katou, Toshiaki Taniike

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Facile electron-hole recombination and the broad band gap are two major drawbacks of titanium dioxide (TiO₂) when applied in visible-light photocatalysis. Hybridization of TiO₂ with graphene is a promising strategy to lessen these pitfalls. Recently, there have been many reports on the synthesis of TiO₂/graphene nanocomposites, in most of which graphene oxide (GO) was used as a starting material. However, the reduction of GO introduced a large number of defects on the graphene framework. In addition, the sensitivity of titanium alkoxide to water (GO usually contains) significantly obstructs the uniform and controlled growth of TiO₂ on graphene. Here, we demonstrate a novel technique to synthesize TiO₂/graphene nanocomposites without the use of GO. Graphene dispersion was obtained through the chemical exfoliation of graphite in titanium tetra-n-butoxide with the aid of ultrasonication. The dispersion was directly used for the sol-gel reaction in the presence of different catalysts. A TiO₂/reduced graphene oxide (TiO₂/rGO) nanocomposite, which was prepared by a solvothermal method from GO, and the commercial TiO₂-P25 were used as references. It was found that titanium alkoxide afforded the graphene dispersion of a high quality in terms of a trace amount of defects and a few layers of dispersed graphene. Moreover, the sol-gel reaction from this dispersion led to TiO₂/graphene nanocomposites featured with promising characteristics for visible-light photocatalysts including: (I) the formation of a TiO₂ nano layer (thickness ranging from 1 nm to 5 nm) that uniformly and thinly covered graphene sheets, (II) a trace amount of defects on the graphene framework (low ID/IG ratio: 0.21), (III) a significant extension of the absorption edge into the visible light region (a remarkable extension of the absorption edge to 578 nm beside the usual edge at 360 nm), and (IV) a dramatic suppression of electron-hole recombination (the lowest photoluminescence intensity compared to reference samples). These advantages were successfully demonstrated in the photocatalytic decomposition of methylene blue under visible light irradiation. The TiO₂/graphene nanocomposites exhibited 15 and 5 times higher activity than TiO₂-P25 and the TiO₂/rGO nanocomposite, respectively.

Keywords: chemical exfoliation, photocatalyst, TiO₂/graphene, sol-gel reaction

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Authors: Yogendar Singh, Parasmani Rajput, Pawan Kumar Kulriya

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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

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Authors: Mohamed A. Deyab, Ahmed E. Awadallah

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Under various conditions, we present a promising method for producing pure hydrogen energy from the electrochemical reaction of Mg metal in waste oilfield water (WOW). Mg metal and WOW are primarily consumed in this process. The results show that the hydrogen gas output is highly dependent on temperature and solution pH. The best conditions for hydrogen production were found to be a low pH (2.5) and a high temperature (338 K). For the first time, the Allyl methylimidazolium bis-trifluoromethyl sulfonyl imide) (IL) ionic liquid is used to regulate the rate of hydrogen generation. It has been confirmed that increasing the solution temperature and decreasing the solution pH accelerates Mg dissolution and produces more hydrogen per unit of time. The adsorption of IL on the active sites of the Mg surface is unrestricted by mixing physical and chemical orientation. Inspections using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and FT-IR spectroscopy were used to identify and characterise surface corrosion of Mg in WOW. This process is also completely safe and can create energy on demand.

Keywords: hydrogen production, Mg, wastewater, ionic liquid

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Authors: Martin Juckel

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Probably no other field of inorganic chemistry has undergone such a rapid development in the past two decades than the low oxidation state chemistry of main group elements. This rapid development has only been possible by the development of new bulky ligands. In case of our research group, super-bulky monodentate amido ligands and β-diketiminate ligands have been used to a great success. We first synthesized the unprecedented magnesium(I) dimer [ᴹᵉˢNacnacMg]₂ (ᴹᵉˢNacnac = [(ᴹᵉˢNCMe)₂CH]-; Mes = mesityl, which has since been used both as reducing agent and also for the synthesis of new metal-magnesium bonds. In case of the zinc bromide precursor [L*ZnBr] (L*=(N(Ar*)(SiPri₃); (Ar* = C₆H₂{C(H)Ph₂}₂Me-2,6,4, the reduction with [ᴹᵉˢNacnacMg]₂ led to such a metal-magnesium bond. This [L*ZnMg(ᴹᵉˢNacnac)] compound can be seen as an ‘inorganic Grignard reagent’, which can be used to transfer the metal fragment onto other functional groups or other metal centers; just like the conventional Grignard reagent. By simple addition of (TBoN)GeCl (TBoN = N(SiMe₃){B(DipNCH)₂) to the aforesaid compound, we were able to transfer the amido-zinc fragment to the Ge center of the germylene starting material and to synthesize the first example of a germanium(II)-zinc bond: [:Ge(TBoN)(ZnL*)]. While these reactions typically led to complex product mixture, [:Ge(TBoN)(ZnL*)] could be isolated as dark blue crystals in a good yield. This new compound shows interesting reactivity towards small molecules, especially dihydrogen gas. This is of special interest as dihydrogen is one of the more difficult small molecules to activate, due to its strong (BDE = 108 kcal/mol) and non-polar bond. In this context, the interaction between H₂ σ-bond with the tetrelylene p-Orbital (LUMO), with concomitant donation of the tetrelylene lone pair (HOMO) into the H₂ σ* orbital are responsible for the activation of dihydrogen gas. Accordingly, the narrower the HOMO-LUMO gap of tertelylene, the more reactivity towards H₂ it typically is. The aim of a narrow HOMO-LUMO gap was reached by transferring electropositive substituents respectively metal substituents with relatively low Pauling electronegativity (zinc: 1.65) onto the Ge center (here: the zinc-amido fragment). In consideration of the unprecedented reactivity of [:Ge(TBoN)(ZnL*)], a computational examination of its frontier orbital energies was undertaken. The energy separation between the HOMO, which has significant Ge lone pair character, and the LUMO, which has predominantly Ge p-orbital character, is narrow (40.8 kcal/mol; cf.∆S-T= 24.8 kcal/mol), and comparable to the HOMO-LUMO gaps calculated for other literature known complexes). The calculated very narrow HOMO-LUMO gap for the [:Ge(TBoN)(ZnL*)] complex is consistent with its high reactivity, and is remarkable considering that it incorporates a π-basic amide ligand, which are known to raise the LUMO of germylenes considerably.

Keywords: activation of dihydrogen gas, narrow HOMO-LUMO gap, first germanium(II)-zinc bond, inorganic Grignard reagent

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Authors: Emrah Çimen, Mustafa Demirelli, Burcu Yilmaz Şahinbaşkan, Mahmure Üstün Özgür

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Natural colours are used on a large area such as textile, food and pharmaceutical industries by many researchers. When tannic acid is used together with metal salts for dyeing with natural dyes, antibacterial and fastness properties of textile materials are increased. In addition, the allegens are removed on wool fabrics. In this experimental work, some red rose petals were applied as a natural dye with three different dyeing methods and eight different mordant salts. The effect of tannic acid and different metal salts on dyeing of wool fabric was studied. Colour differences ΔECMC (2:1) and fastness properties of dyed fabrics were investigated and compared with each other. Finally, dark colours and adequate colour fastness results (4+) were obtained after dyeing of wool fabrics with FeSO4.7H2O, FeCl3.6H2O and CuCl2.2H2O in the presence of the tannic acid.

Keywords: natural dye, red rose petals, tannic acid, mordant salts, wool fabric

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Authors: Cahya Wimar Wicaksono, Reynara Davin Chen, Alvian Kristianto Santoso

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Grasberg Cu-Au ore deposit as one of the biggest porphyry deposits located in Papua Province, Indonesia produced by several intrusion that restricted by Heavy Sulphide Zone (HSZ) in peripheral. HSZ is the rock that becomes the contact between Grassberg Igneous Complex (GIC) with sedimentary and igneous rock outside, which is rich in sulphide minerals such as pyrite ± pyrrhotite. This research is to obtain the characteristic of HSZ based on geotechnical, geochemical and mineralogy aspect and those implication for daily mining operational activities. Method used in this research are geological and alteration mapping, core logging, FAA (Fire Assay Analysis), AAS (Atomic absorption spectroscopy), RQD (Rock Quality Designation) and rock water content. Data generated from methods among RQD data, mineral composition and grade, lithological and structural geology distribution in research area. The mapping data show that HSZ material characteristics divided into three type based on rocks association, there are near igneous rocks, sedimentary rocks and on HSZ area. And also divided based on its location, north and south part of research area. HSZ material characteristic consist of rock which rich of pyrite ± pyrrhotite, and RQD range valued about 25%-100%. Pyrite ± pyrrhotite which outcropped will react with H₂O and O₂ resulting acid that generates corrosive effect on steel wire and rockbolt. Whereas, pyrite precipitation proses in HSZ forming combustible H₂S gas which is harmful during blasting activities. Furthermore, the impact of H₂S gas in blasting activities is forming poison gas SO₂. Although HSZ high grade Cu-Au, however those high grade Cu-Au rich in sulphide components which is affected in flotation milling process. Pyrite ± pyrrhotite in HSZ will chemically react with Cu-Au that will settle in milling process instead of floating.

Keywords: combustible, corrosive, heavy sulphide zone, pyrite ± pyrrhotite

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Authors: Han-Bin Kim, Sooim Shin, Moonsung Choi

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There is a growing interest in introducing a desired functional group on enzymes in the field of protein engineering. In here, various redox centers were newly created using histidine tag, which is widely used for protein purification, plus cobalt in one of cupredoxins, amicyanin. The coordination of Cobalt-His tag and reactivity of the Co²⁺ loaded His-tag also were characterized. 3xHis-tag, 6xHis-tag, and 9xHis-tag were introduced on amicyanin by site-directed mutagenesis, and then Co²⁺ was loaded on each His-tagged amicyanin. The spectral changes at 330 nm corresponding to cobalt binding on His-tag site indicated the binding ratio of 3xHis-tag, 6xHis-tag, and 9xHis-tag to cobalt as 1:1, 1:2, 1:3 respectively. Based on kinetic studies of binding cobalt to 3xHis-tag, 6xHis-tag, and 9xHis-tagged amicyanin, the nature of the sites was elucidated. In addition, internal electron transfer properties between Cu¹⁺ site and engineered site of amicyanin were determined. These results provide insight into improvement of metal coordination and alternation of the redox properties of metal as a new catalytic site on proteins.

Keywords: amicyanin, cobalt, histidine, protein engineering

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Authors: Siba Soren, Purnendu Parhi

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Today, the world is facing a severe challenge due to depletion of traditional fossil fuels. Scientists across the globe are working for a solution that involves a dramatic shift to practical and environmentally sustainable energy sources. High-capacity energy systems, such as metal-air batteries, fuel cells, are highly desirable to meet the urgent requirement of sustainable energies. Among the fuel cells, Direct methanol fuel cells (DMFCs) are recognized as an ideal power source for mobile applications and have received considerable attention in recent past. In this advanced electrochemical energy conversion technologies, Oxygen Reduction Reaction (ORR) is of utmost importance. However, the poor kinetics of cathodic ORR in DMFCs significantly hampers their possibilities of commercialization. The oxygen is reduced in alkaline medium either through a 4-electron (equation i) or a 2-electron (equation ii) reduction pathway at the cathode ((i) O₂ + 2H₂O + 4e⁻ → 4OH⁻, (ii) O₂ + H₂O + 2e⁻ → OH⁻ + HO₂⁻ ). Due to sluggish ORR kinetics the ability to control the reduction of molecular oxygen electrocatalytically is still limited. The electrocatalytic ORR starts with adsorption of O₂ on the electrode surface followed by O–O bond activation/cleavage and oxide removal. The reaction further involves transfer of 4 electrons and 4 protons. The sluggish kinetics of ORR, on the one hand, demands high loading of precious metal-containing catalysts (e.g., Pt), which unfavorably increases the cost of these electrochemical energy conversion devices. Therefore, synthesis of active electrocatalyst with an increase in ORR performance is need of the hour. In the recent literature, there are many reports on transition metal oxide (TMO) based ORR catalysts for their high activity TMOs are also having drawbacks like low electrical conductivity, which seriously affects the electron transfer process during ORR. It was found that 2D graphene layer is having high electrical conductivity, large surface area, and excellent chemical stability, appeared to be an ultimate choice as support material to enhance the catalytic performance of bare metal oxide. g-C₃N₄ is also another candidate that has been used by the researcher for improving the ORR performance of metal oxides. This material provides more active reaction sites than other N containing carbon materials. Rare earth oxide like CeO₂ is also a good candidate for studying the ORR activity as the metal oxide not only possess unique electronic properties but also possess catalytically active sites. Here we will discuss the ORR performance (in alkaline medium) of N-rGO/C₃N₄ supported nano Cerium Oxides hybrid synthesized by microwave assisted Solvothermal method. These materials exhibit superior electrochemical stability and methanol tolerance capability to that of commercial Pt/C.

Keywords: oxygen reduction reaction, electrocatalyst, cerium oxide, graphene

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Authors: Ahmed A. Alghamdi

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Single-walled carbon nanotubes (SWCNTs) are an outstanding material for applications in thermoelectric power generation, nanoelectronics, electrochemical energy storage, photovoltaics, and light emission. They are ultra-lightweight and possess electrical as well as thermal conductivity, flexibility, and mechanical strength. SWCNT is applicable in water treatment, brine desalination, removal of heavy metal ions associated with pollutants, and oil-water separation. Carbon nanotube (CNT) is believed to tackle the trade-off issue between permeability, selectivity, and fouling issues in membrane filtration applications. Studying these CNT structures, as well as their interconnection in nanotechnology, assists in finding the precise position to be placed for water desalination. Reverse osmosis (RO) has been used globally for desalination, resulting in purified water. Thin film composite (TFC) membranes were utilized in the RO process for desalination. The sheet thickness increases the salt rejection and decreases the water flux when CNT is utilized as a support layer to this membrane. Thus, through a temperature-induced phase separation technique (TIPS), axially aligned SWCNT (AASWCNT) is fabricated, and its use enhances the salt rejection and water flux at short reaction times with a modified procedure. An evaluation was conducted and analogized with prior works in the literature, which exhibited that the prepared TFC membrane showed a better outcome.

Keywords: single-walled carbon nanotubes, thin film composite, axially aligned swcnt, temperature induced phase separation technique, reverse osmosis

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