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d isPermaLink="false">https://www.sciencedirect.com/science/article/pii/S0921883118302887Heavy metal ions adsorption and photodegradation of remazol black XP by iron oxide/silica monoliths: Kinetic and equilibrium modelling

Publication date: September 2018

Source: Advanced Powder Technology, Volume 29, Issue 9

Author(s): Jasminder Singh, Manisha Sharma, Soumen Basu

Abstract

The adsorption of heavy metal ions (Cr3+, Pb2+ and Cd2+) by metal oxide monoliths (Fe2O3 and Fe2O3/SiO2) synthesized via nanocasting method using SiO2 monoliths as a template was studied. The adsorption experiments were performed in different batches by varying key parameters and the equilibrium between the adsorbents and metal ion solution was achieved in ?120?min at pH 6. The maximum monolayer adsorption efficiency for Pb (II), Cr (III) and Cd (II) ions was 850, 770 and 690?mg/g, respectively, for the magnetic Fe2O3/SiO2 monoliths. The experimental data show best fit with the pseudo-second-order reaction type. The adsorption data found to be well fitted using Freundlich and Langmuir adsorption isotherms. The adsorption process was exothermic and spontaneous in nature, as confirmed by the thermodynamic parameters. Furthermore, the photocatalytic degradation of an industrial dye e.g., remazol black XP (RxP) by Fe2O3/SiO2 monoliths was done from wastewater and the photocatalytic efficiency of the monoliths (using different amount) has been evaluated under visible light source which gives the best results (97.8%) for the monolith concentration 0.10?g/L.

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https://www.sciencedirect.com/science/article/pii/S0921883118302759https://www.sciencedirect.com/science/article/pii/S0921883118302759APT Distinguished Paper Award 2017

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s):

https://www.sciencedirect.com/science/article/pii/S0921883118302498https://www.sciencedirect.com/science/article/pii/S0921883118302498In situ study of aggregate sizes formed in chalcopyrite-quartz mixture using temperature-responsive polymers

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Wei Sung Ng, Luke A. Connal, Elizaveta Forbes, Krishna Mohanarangam, George V. Franks

Abstract

An interesting property of temperature-responsive polymers, such as poly(N-isopropylacrylamide) (PNIPAM), is the ability to behave as flocculants above a lower critical solution temperature (LCST). This study examines the aggregation of a chalcopyrite-quartz mixture using a sulfide-selective temperature-responsive polymer, P(NIPAM-co-ethyl xanthate methacrylate (EXMA)) in a continuously-sheared suspension, relative to polyacrylamide (PAM). The investigation was carried out in situ using imaging and Focused Beam Reflectance Measurement techniques to obtain real-time chord length distributions. While particle aggregates were observed in the presence of PNIPAM only upon heating above the LCST, P(NIPAM-co-EXMA) induced particle aggregation below the LCST, due to the attraction between the xanthate moiety and the sulfide surfaces. The largest aggregates were observed with P(NIPAM-co-EXMA) (1.5 MDa), followed by PNIPAM, PAM, and P(NIPAM-co-EXMA) (115?kDa). Particle aggregates formed with PAM did not exhibit further breakage under increasing shear to 1100?s?1, while large-scale fragmentation was observed with the PNIPAM-based flocculants. Unlike PNIPAM, addition of P(NIPAM-co-EXMA) to suspension above the LCST was able to yield particle aggregation, attributed to the formation of charge-stabilised micelles. The influence of the shear rate on the size of the aggregates formed with P(NIPAM-co-EXMA) is unaffected by the polymer addition and measurement temperature below or above the LCST.

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https://www.sciencedirect.com/science/article/pii/S0921883118301808https://www.sciencedirect.com/science/article/pii/S0921883118301808ZnCo2O4 nanorods as a novel class of high-performance adsorbent for removal of methyl blue

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Kejun Lin, Ming Qin, Xingguo Geng, Liuding Wang, Hongjing Wu

Abstract

Spinel ZnCo2O4 nanorods were synthesized by a simple template-free hydrothermal method in the presence of zinc chloride, cobalt chloride, glucose, and urea. The phase structure, morphology and chemical composition have been characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The results showed that the typically porous and poly-crystalline structure was successfully grown on the surface of ZnCo2O4 nanorods. The ZnCo2O4 nanorods were further applied to remove methyl blue (MB), which was used as a model of organic pollutants in aqueous solution. In particular, the maximum equilibrium adsorption capacity of MB in ZnCo2O4 nanorods reaches up to 2400?mg/g, which is higher than that of most adsorbents. The adsorption isotherms and kinetics followed standard Langmuir and pseudo-second-order models, respectively. MB adsorption decreased with increasing solution pH at pH?>?7 implying that MB adsorption on ZnCo2O4 nanorods may via chemisorption between negatively charged MB molecular and positively charged adsorption sites on the surface of ZnCo2O4 nanorods. This study provides great promise of using ZnCo2O4 nanorods as adsorbent for removal of pollutant dyes.

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https://www.sciencedirect.com/science/article/pii/S0921883118301985https://www.sciencedirect.com/science/article/pii/S0921883118301985One-pot synthesis of oleic acid modified monodispersed mesoporous TiO2 nanospheres with enhanced visible light photocatalytic performance

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Junkai Cao, Xue-Zhi Song, Xiaolan Kang, Zideng Dai, Zhenquan Tan

Abstract

Herein, we report a facile one-pot solvothermal method to prepare unique oleic acid (OA) modified monodispersed mesoporous TiO2 nanospheres with carboxylate ligands from the oleic acid in the bidentate chelating linkage mode. The mesoporous OA-TiO2 nanospheres have a very large specific surface of nearly 510?m2/g. The oleic acid cannot only act as a binding ligand to control the shape of mesoporous TiO2 nanospheres, but also be benefit to enhance the visible-light absorption. The mesoporous OA-TiO2 nanospheres exhibit an excellent photocatalytic performance in the degradation of Rhodamine B and phenol under the visible light irradiation and show almost no attenuation after four cycles.

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Oleic acid modified mesoporous TiO2 nanospheres show an excellent photocatalytic performance in the degradation of Rhodamine B and phenol under visible light irradiation.

https://www.sciencedirect.com/science/article/pii/S0921883118301973https://www.sciencedirect.com/science/article/pii/S0921883118301973Formulation of olanzapine nanosuspension based orally disintegrating tablets (ODT); comparative evaluation of lyophilization and electrospraying process as solidification techniques

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Neelima Anup, Shreya Thakkar, Manju Misra

Abstract

Olanzapine (OLAN) as an antipsychotic agent has shown its potential in effective management of psychotic disorders however its use is limited because of its poor water solubility. The aim of present work was to improve solubility of OLAN by developing a stable nanocrystal based orally disintegrating tablets (ODTs), using hyperomellose as potential stabilizer. Comparative evaluation of electrospraying and lyophilization as solidification techniques was carried out to assess its effect on solid state properties of OLAN nanocrystals before transformation to ODTs.

OLAN Nanosuspension was developed using antisolvent precipitation method and exhibited particle size, polydispersity index and zetapotential value of 223.1?±?1.5?nm, 0.105?±?0.4 and ?17.9?±?3.5?mV respectively. Solid powders obtained from both the solidification techniques were compared in terms of size after re-dispersion, particle morphology, surface area, pore volume and solid state of drug present. Subsequently ODTs were prepared from these powders with needful excipients and % amount dissolved was evaluated. Rate of dispersion was found to be higher for ODTs prepared using lyophilized powder (?84% in 5?min) while other characterization parameters were comparatively similar. Overall, Lyophilization resulted in powders with better bulk level properties in comparison to electrospraying process.

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https://www.sciencedirect.com/science/article/pii/S092188311830195Xhttps://www.sciencedirect.com/science/article/pii/S092188311830195XDevelop an effective oxygen removal method for copper powder

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Lei Zhao, Xuhu Zhang, Taiqing Deng, Jun Jiang

Abstract

At present, one of crucial limitations for the hot isostatically pressed (HIPed) Cu-3Ag-0.5Zr alloy, which is used on the combustion chamber liner of aerospace engine, is the high oxygen content, which easily results in the intergranular fracture under high temperature, pressure, liquid hydrogen and oxygen environment during operation. In this study, a novel effective oxygen control method is developed, for which vacuum degassing process is integrated with a flowing hydrogen reduction reaction at an elevated temperature before HIP. For this technique, a container is designed with two gas pipes for hydrogen inflow and outflow, so the hydrogen circulation can be established. Allowing hydrogen to react effectively with oxygen, the oxygen content of HIPed alloy is found to drop significantly from 140?ppm (raw powder) to 28?ppm, which is equivalent to the oxygen-free copper and copper alloys. As a result of the reduction, no prior particle boundaries could be observed in the low oxygen content material. Although the tensile strength of the materials with and without employing this technique does not vary significantly, the ductility of low oxygen content material has improved by about 70% at 500?°C. This significant improvement of ductility is critical to ensure the safety critical PM components.

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https://www.sciencedirect.com/science/article/pii/S0921883118301833https://www.sciencedirect.com/science/article/pii/S0921883118301833Non-firing ceramics: Activation of silica powder surface for achieving high-density solidified bodies

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Yuki Nakashima, Hadi Razavi-Khosroshahi, Chika Takai, Masayoshi Fuji

Abstract

Sintering of most ceramic materials requires high temperatures over 1000 °C due to their high melting point. Sintering is a high-cost process, which can take several hours or days. Also, sintering at high temperatures can affect the microstructure of ceramics by causing undesired grain coarsening or changing the chemical stoichiometry of final product when volatile elements are present. In this study, a so-called “non-firing sintering” of silica particles is proposed, without using thermal energy. This method involves the chemical activation of powder surface via ball milling, where the surface of particles is rubbed against balls, and friction between particle/ball breaks the bonds of functional groups like SiOSi on the surface of particles. Results show that water adsorption increases as milling time is increased, while particle size is unchanged after ball milling according to nitrogen adsorption isotherms. Scanning electron microscopy results confirm the trans granular fracture of pellets prepared by ball milling, and transmission electron microscopy micrographs show a necking-like bonding between silica particles.

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https://www.sciencedirect.com/science/article/pii/S0921883118301821https://www.sciencedirect.com/science/article/pii/S0921883118301821A study of selective flotation recovery of rare earth oxides from hematite and quartz using hydroxamic acid as a collector

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): George Blankson Abaka-Wood, Jonas Addai-Mensah, William Skinner

Abstract

Monazite is a major rare earth elements (REE)-bearing phosphate mineral predominantly found in association with hematite and quartz in some Australian rare earth deposits. The flotation of rare earth oxides (REO) in monazite from mixtures containing monazite, hematite, and quartz with hydroxamic acid as a collector has been investigated using an IMN microflotation cell and a 1.2?L Denver flotation cell. Maximum flotation recovery of both monazite and hematite was attained at pH 7, whereas that of quartz, at pH 3. The flotation kinetics data indicated the need for depressants to achieve selective REO recovery from hematite and quartz mixtures. Sodium silicate and starch were thus tested as depressants of both hematite and quartz. The separation efficiency of REO in the absence of depressants was low and averaged 6.42% at 99% REO recovery, but could be increased to 44.78% with corresponding 93% REO recovery when 4000?g/t starch was used. However, the efficiencies of REO separation obtained with sodium silicate were generally lower (<18%), due to higher gangue minerals content in the flotation concentrates. A blend of sodium silicate and starch showed a good performance for REO recovery, with enhanced selectivity against hematite and quartz through a rougher-cleaner flotation test. This study presents the feasibility of upgrading REO from iron-oxide rich tailings using hydroxamic acid, in the presence of sodium silicate and starch as depressants.

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Separation efficiencies of REO from feed mixture 1 (comprising equal weight proportion of monazite, hematite, and quartz) as a function of (a) sodium silicate and (b) starch dosage in the presence of 2000?g/t hydroxamic acid at pulp pH 7.

https://www.sciencedirect.com/science/article/pii/S092188311830181Xhttps://www.sciencedirect.com/science/article/pii/S092188311830181XOptical and photocatalytic properties of the Fe-doped TiO2 nanoparticles loaded on the activated carbon

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Akbar Eshaghi, Halimeh Moradi

Abstract

In this work, Fe-doped (1?wt%) TiO2 loaded on the activated carbon nano-composite was prepared using a sol-gel method. A prepared nano-composite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), BET surface area, Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy and UV–Vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the nano-composite was evaluated through degradation of synthetic textile wastewater, reactive red 198, under visible light irradiations. The XRD result indicated that the TiO2 nano-composite contained only anatase phase. The surface area of the TiO2 increased from 48?m2/g to 100?m2/g through the fabrication of the nano-composite. The FE-SEM results indicate that the TiO2 particles with an average particle size of 35–70?nm can be deposited homogeneously on the activated carbon surface. DRS showed that the Fe doping in the TiO2 -activated carbon nano-composite induced a significant red shift of the absorption edge and then the band gap energy decreased from 3.3 to 2.9?eV. Photocatalytic results indicated that the photocatalytic activity of the Fe doped TiO2 increased under visible light irradiation in the presence of the activated carbon.

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https://www.sciencedirect.com/science/article/pii/S0921883118301791https://www.sciencedirect.com/science/article/pii/S0921883118301791Effect of microwave heating on the microstructures and kinetics of carbothermal reduction of pyrolusite ore

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Qianxu Ye, Jin Chen, Guo Chen, Jinhui Peng, C. Srinivasakannan, Rongsheng Ruan

Abstract

This article focuses on the development of phase transformation and morphology of low-grade pyrolusite during carbothermal reduction using microwave heating. The XRD, SEM and EDS results show that selective carbothermal reduction of MnxOy and FexOy in pyrolusite is easy to realize with microwave heating, which can reduce MnO2 to MnO, and Fe2O3 to Fe3O4, rather than FeO. It was also observed that the phases of Mn2O3, Mn3O4 and MnO appear at 300?°C, 450?°C and 500?°C, respectively. The MnO phase, formed by the accumulation of MnO sphere particle with a diameter of 266.75–420.05?nm, is loose and porous. At a temperature of 750?°C, the Mn2SiO4 layer of about 316?nm in thickness, tightly wrapping SiO2 particle is generated at the interface between MnO and SiO2 embedded with MnO. Above 650?°C, Fe2O3 in pyrolusite can be transformed into a very dense Fe3O4 phase.

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Schematic of the development of phase transformation and morphology of low-grade pyrolusite during selective carbothermal reduction by microwave heating.

https://www.sciencedirect.com/science/article/pii/S092188311830178Xhttps://www.sciencedirect.com/science/article/pii/S092188311830178XEffect of CNTs on morphology and electromagnetic properties of non-firing CNTs/silica composite ceramics

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Bo Peng, Chika Takai, Hadi Razavi-Khosroshahi, M S EL Salmawy, Masayoshi Fuji

Abstract

Carbon composite ceramics have much attention for industry because of their excellent properties such as strong toughness, high electrical conductivity as well as low percolation threshold. Therefore, carbon nanotubes (CNTs) were used to incorporate with silica ceramics in order to improve their electromagnetic properties. The amount of CNTs in CNTs/silica composite ceramics was varied in order to investigate its effect on morphologies and electromagnetic properties of those. The composites were successfully fabricated by non-firing process. The results revealed that the obtained CNTs/silica composite ceramic have an electrical resistivity of 66.6??·cm with a bending strength of 13.8?MPa. At the same time, the electromagnetic wave absorption ability achieved 70% over a wild frequency. This indicates that the CNTs in CNTs/silica composite ceramics may be potentially applied for an electromagnetic wave reflective material.

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https://www.sciencedirect.com/science/article/pii/S0921883118301778https://www.sciencedirect.com/science/article/pii/S0921883118301778Detonation spraying behaviour of refractory metals: Case studies for Mo and Ta-based powders

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Vladimir Yu. Ulianitsky, Igor S. Batraev, Alexandr A. Shtertser, Dina V. Dudina, Natalia V. Bulina, Igor Smurov

Abstract

In thermal spraying of refractory metal powders, two major issues need to be solved: particles of materials having high melting temperatures should be heated to reach a semi-molten/molten state or temperatures close to the melting point, while oxidation of the metals should be prevented. It has long been believed that it is rather difficult, if not impossible, to produce high-quality refractory metal coatings by detonation spraying. In this work, we demonstrated the capability of the detonation spraying method to produce tantalum-based and molybdenum coatings of low porosity. Using a computer-controlled detonation spray (CCDS2000) facility, the detonation spraying behaviour of a molybdenum powder and a partially oxidized tantalum powder was studied. Spraying was conducted onto steel substrates using an acetylene-oxygen mixture with O2/C2H2?=?1.1. The spraying process was studied by means of analyzing the splat morphology and calculating the particle temperatures and velocities. According to the X-ray diffraction phase analysis, the metals did not experience oxidation during the deposition. Rather, partial reduction of the oxide phase contained in the Ta-based powder occurred during spraying.

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https://www.sciencedirect.com/science/article/pii/S0921883118301766https://www.sciencedirect.com/science/article/pii/S0921883118301766Numerical simulation of gas-solid flow in a novel spouted bed: Influence of row number of longitudinal vortex generators

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Feng Wu, Jiejie Zhang, Xiaoxun Ma, Wenjing Zhou

Abstract

The flow characteristics in a novel cylindrical spouted bed with spherical longitudinal vortex generators is numerically investigated by two-fluid model (TFM) with kinetic theory for granular flow, the longitudinal vortex technology is adopted in the spouted bed so as to strengthen the particles radial mixing between spout and annulus zones, the row number effect (1–3 rows) of longitudinal vortex generators (LVGs) on gas–solid flow behavior in three dimensional spouted beds was numerically simulated. The CFD results show that, longitudinal vortices can effectively increase particle volume fraction near annulus zone in the spouted bed, the maximum increase of particle volume fraction near annulus region is 183?, and the pressure drop in spouted beds increases with increasing of LVGs’ row number. There exists an optimal row number (equal 2) of LVGs, at witch the radial velocity of particle phase reaches maximum in the limited spouted bed space, the value of turbulent kinetic energy of gas phase in spouted bed can be significantly promoted by longitudinal vortex, espeically in the spout zone and near the annulus region. Also, the enhancement effect of multi-row LVGs on turbulent kinetic energy of gas phase decreases when the cross section height of spouted beds increases.

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https://www.sciencedirect.com/science/article/pii/S0921883118301730https://www.sciencedirect.com/science/article/pii/S0921883118301730Influence of process control agent type on the mechanosynthesis of Fe3O4 particles

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): H.F. Chicina?, T.F. Marinca, B.V. Neam?u, G. Con?iu, O. Isnard, I. Chicina?

Abstract

The influence of the nature of the process control agent (PCA) used in the mechanosynthesis of the magnetite nanoparticles has been studied. The two-step route used here for obtaining nanocrystalline/nanoparticles Fe3O4 consists of a heat treatment, to prepare well-crystallised magnetite, followed by the mechanosynthesis process. Dry milled magnetite samples have been obtained as a reference, using the same conditions (duration and energy), to determine the influence of the process control agents (PCA). Three different PCAs have been used: benzene, ethanol and oleic acid. The characterisation of the magnetite particles has been performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), magnetic measurements M(H), differential scanning calorimetry (DSC) and thermogravimetric (TG) measurements and Scanning Electron Microscopy (SEM). XRD and SEM analysis revealed a different processing mechanism for the two milling modes, wet and dry. In the case of dry milling, even for short milling times, iron contamination and formation of a wüstite – FeO phase is noticed. The use of the PCA during the milling process limits the above-mentioned contamination. Ethanol and benzene uses as PCA lead to synthesis of fine uniform sized particles. SEM images reveal the presence on nanoparticles. In the case of oleic acid, DSC, TG and magnetic measurements revealed the presence of a thin layer of oleic acid adsorbed on the particles. FTIR analysis highlighted the presence of both free and bonded oleic acid. The magnetisation of the samples was found to be linked to the powder contamination (FeO or oleic acid), structural defects or finite size effects.

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https://www.sciencedirect.com/science/article/pii/S0921883118301729https://www.sciencedirect.com/science/article/pii/S0921883118301729Synthesis of Ag-AgBr/Al-MCM-41 nanocomposite and its application in photocatalytic oxidative desulfurization of dibenzothiophene

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Xuan Nui Pham, Ba Manh Nguyen, Hoa Tran Thi, Huan Van Doan

Abstract

A series of Ag-AgBr/Al-MCM-41 nanocomposites were synthesized by dispersion of Ag-AgBr on mesoporous silica Al-MCM-41 obtained from natural bentonite. The synthesized Ag-AgBr/Al-MCM-41 composites with Ag nanoparticles growing on the surface of Al-MCM-41 were used for photocatalytic oxidative desulfurization of dibenzothiophene. The physical properties of Ag-AgBr/Al-MCM-41 were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL) emission spectra, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity results showed that in the presence of 40% Ag-AgBr/Al-MCM-41 photocatalyst the oxidative desulfurization of dibenzothiophene reached the maximum efficiency at 99.22% and the photocatalytic activity still keeps high level after four cycles.

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https://www.sciencedirect.com/science/article/pii/S0921883118301717https://www.sciencedirect.com/science/article/pii/S0921883118301717Mechanochemical synthesis, structural, magnetic, optical and electrooptical properties of CuFeS2 nanoparticles

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Erika Dutková, Zdenka Buj?áková, Jaroslav Ková?, Ivan Škorvánek, María Jesus Sayagués, Anna Zorkovská, Jaroslav Ková?, Peter Baláž

Abstract

The rapid mechanochemical synthesis of nanocrystalline CuFeS2 particles prepared by high-energy milling for 60?min in a planetary mill from copper, iron and sulphur elements is reported. The CuFeS2 nanoparticles crystallize in tetragonal structure with mean crystallite size of about 38?±?1?nm determined by XRD analysis. HRTEM study also revealed the presence of nanocrystals with the size of 5–30?nm with the tendency to form agglomerates. The Raman spectrum confirms the chalcopyrite structure. Low temperature magnetic data for CuFeS2 support the coexistence of antiferromagnetic and paramagnetic spin structure. Moreover, the hysteresis loops taken at temperatures from 5?K to 300?K revealed a presence of very small amount of ferromagnetic phase, which seems to be associated with the non-consumed elemental Fe in as-prepared nanoparticles. The optical band gap of CuFeS2 nanoparticles has been detected to be 1.05?eV, larger than band gap of the bulk material. The wider gap possibly resulted from the nano-size effect. Photoresponses of CuFeS2 nanoparticles were confirmed by I-V measurements under dark and light illumination. It was demonstrated that mechanochemical synthesis can be successfully employed in the one step preparation of nanocrystalline CuFeS2 with good structural, magnetic, optical and electrooptical properties.

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https://www.sciencedirect.com/science/article/pii/S0921883118301663https://www.sciencedirect.com/science/article/pii/S0921883118301663The effects of morphology on physicochemical properties, bioactivity and biocompatibility of micro-/nano-bioactive glasses

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Qing Hu, Weihui Jiang, Yuli Li, Xiaofeng Chen, Jianmin Liu, Ting Chen, Guohou Miao

Abstract

We prepared micro-/nano-bioactive glasses (MNBG) with controlled morphologies by using a sol-gel method combined with a template (CTAB) centered self-assembly technology, and investigated the effect of the MNBG morphology on physicochemical properties, apatite-forming ability and biocompatibility. Results showed that the specific surface area of rod-like MNBG (RBG) with highly ordered mesoporous structure was higher than that of spherical MNBG (SBG) with irregular worm-like mesoporous structure. Both the MNBG showed the high apatite-forming ability, and the apatite-forming ability of RBG with higher specific surface area was higher than that of SBG. Futhermore, both SBG and RBG had good biocompatibility, could promote proliferation and ALP differentiation of human dental pulp cells (HDPCs), and SBG with a smaller aspect ratio could significantly increase the proliferation and differentiation of the cells, as compared to RBG. This study may motivate the development and applications of MNBG with controllable morphology in dental repair.

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https://www.sciencedirect.com/science/article/pii/S0921883118301651https://www.sciencedirect.com/science/article/pii/S0921883118301651A fast and facile microwave irradiation method for the synthesis of ZnO@ZrO2 core-shell nanocomposites and the investigation of their optical properties

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Md. Obaidullah, Takeshi Furusawa, Iqbal Ahmed Siddiquey, Newaz Mohammed Bahadur, Masahide Sato, Noboru Suzuki

Abstract

ZnO@ZrO2 core-shell nanocomposites (NCs) were prepared by a novel and accessible path employing microwave (MW) irradiation to regulate photocatalytic property of ZnO. The synthesized ZnO@ZrO2 NCs were further examined to discern their optical and chemical properties by FT-IR, XPS, XRF, XRD, FE-SEM, EDX, TEM, UV–vis, and PL analysis. XPS data analysis confirmed the presence of zirconium and oxygen on the coated surface. An almost similar zeta potential curve was observed for the pure ZrO2 and ZrO2 coated ZnO NCs, predicting the presence of the ZrO2 layer on ZnO. Photoluminescence studies show the enhanced intensity of ZnO@ZrO2 nanostructure compared to uncoated ZnO. Photocatalytic activity of ZnO could be controlled by the amorphous ZrO2 layer, which was guaranteed by the photo mineralization of methylene blue under UV irradiation at room temperature.

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https://www.sciencedirect.com/science/article/pii/S0921883118301559https://www.sciencedirect.com/science/article/pii/S0921883118301559Structure and mechanical properties of TiB2/TiC – Ni composites fabricated by pulse plasma sintering method

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): K. Cymerman, D. Oleszak, M. Rosinski, A. Michalski

Abstract

TiB2/TiC – Ni composites were synthesized starting from the powders of Ti, B4C and Ni, using Pulse Plasma Sintering (PPS) method. Typically used one-step (1100?°C–10?min.) and novel double-step sintering processes (900?°C–10?min. +1100?°C–5?min.) were applied and compared. XRD studies showed that the composite obtained by double-step sintering consisted of TiB2, TiC and Ni phases. For one-step processing additionally undesired Ni3B and graphite were detected. SEM observations revealed dark-grey grains of TiB2, light-grey grains of TiC (both around 25?µm in size) and Ni areas surrounded by TiC. The composites synthesized in one- and double-step processes revealed the hardness and relative density of 2335 HV5 (±110) and 97.8% and 2470 HV5 (±70) and 99.8%, respectively. Novel double-step sintering process allowed to avoid undesired phases (graphite, Ni3B) and only TiB2, TiC and Ni were present in the structure. Additionally it was possible to decrease the temperature of the process comparing to other fabrication methods.

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https://www.sciencedirect.com/science/article/pii/S0921883118301547https://www.sciencedirect.com/science/article/pii/S0921883118301547Investigation to rectangular flat pleated filter for collecting corn straw particles during pulse cleaning

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Mingxing Zhang, Haiyan Chen, Cuiping Yan, Qianqian Li, Jie Qiu

Abstract

This work investigated the amounts of dust residual of a rectangular flat pleated filter for collecting corn straw particles during pulse cleaning and attempted to explore the causes of incomplete cleaning. In this study, dust residual, filter’s pressure drops and static peak pressures were obtained across flat pleated filter during the pulse cleaning. The optimum parameters were obtained that the pulse electromagnetic valve size was one inch, the pulse pressure was 0.2–0.3?MPa, and the filtration velocity was 0.6?m/min for the nozzle type with 7 holes with a diameter of 7?mm (7?×??7?mm). Under this condition, the experimental results show that the dust residuals were 198.4 (64%), 52.7 (17%), 58.9 (19%)?g for initial collected dust residual 310?g at top, middle and bottom areas of the filter panel, respectively. The dust residuals were major on the top area of the filter panel, especially on the gap locations between the two-adjacent pulse airflows. Meanwhile, the more pulse interval or dust concentration was increased the dust residuals of the filter panel and the pressure drops of the filter were increased. Moreover, the static peak pressure distribution can give guidance to the dust residual distribution.

Graphical abstract

This work investigated the cleaning performance of a rectangular flat pleated filter for collecting corn straw particles and attempted to reduce the incidence of incomplete cleaning. We examined the dust residuals of a rectangular flat pleated filter during the pulse cleaning. The optimum nozzle type is 7?×??7 mm. The dust residual is 310?g. The dust residuals are 198.4 (64%), 52.7 (17%), 58.9 (19%) g at top, middle and bottom areas of the filter cartridge, respectively. The experimental shows that the dust residuals are major on the top area of the filter cartridge, especially on the gap locations between the two-pulse airflows.

https://www.sciencedirect.com/science/article/pii/S0921883118301535https://www.sciencedirect.com/science/article/pii/S0921883118301535The relationship between iron and Ilmenite for photocatalyst degradation

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s): Ru Bin Lee, Kian Mun Lee, Chin Wei Lai, Guan-Ting Pan, Thomas C.K. Yang, Joon Ching Juan

Abstract

Photocatalytic degradation of organic compounds is a key target for the development of sustainable environmental pollution management system. The use of pre-treated Ilmenite with low concentration of Fe ions via single step of chloride process is essential to generate a highly effective photocatalyst. In the present study, comprehensive investigations on Fe concentrations in Ilmenite has been conducted. Based on the findings, pre-treated Ilmenite with low Fe content (0.76–7.15 at%) was successfully synthesized through a single step chloride process by using 15–35 v/v% of HCl. Interestingly, Ilmenite with 1.62 at% Fe after pre-treated with 25 v/v% HCl was able to photodegrade 100% of the Reactive Black 5 (RB5) under visible light within 30?min. The improvement of photocatalytic degradation efficiency of the pre-treated Ilmenite is mainly attributed to the better photo-induced charge carrier mobility and low recombination losses.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118301523https://www.sciencedirect.com/science/article/pii/S0921883118301523Full title (Editorial Board Members)

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s):

https://www.sciencedirect.com/science/article/pii/S0921883118302528https://www.sciencedirect.com/science/article/pii/S0921883118302528Inside Front Cover (Aims & Scope, Editors)

Publication date: August 2018

Source: Advanced Powder Technology, Volume 29, Issue 8

Author(s):

https://www.sciencedirect.com/science/article/pii/S0921883118302516https://www.sciencedirect.com/science/article/pii/S0921883118302516Highly efficient degradation of 2-chlorophenol and methylene blue with Rb0.27WO3/NiFe-CLDH composites under visible light irradiation

Publication date: Available online 7 July 2018

Source: Advanced Powder Technology

Author(s): Guoqing Zhao, Dan Zhang, Yaliang Huang, Jingang Yu, Xinyu Jiang, Feipeng Jiao

Abstract

Novel magnetically composites photocatalyst Rb0.27WO3/NiFe-CLDH (RWCLDH) was fabricated via a simple method. The as-prepared catalysts were characterized using XRD, XPS, SEM, TEM, HRTEM, BET, UV–Vis DRS spectra and PL analysis. The RWCLDH-700 composites exhibit a two-fold enhancement in photocatalytic activity toward degradation of 2-chlorophenol (2-CP) and Methylene blue (MB) under visible light irradiation compared to that of Rb0.27WO3 and NiFe-CLDH. The photocatalytic efficiency of the Rb0.27WO3 and NiFe-CLDH is 39%, 45% and 42%, 34%, respectively, whereas for RWCLDH-700 composites are 91% and 93%. This enhancement in photocatalytic activity is attributed to the effective separation of electron-hole pairs. Moreover, the catalyst exhibited higher photocatalytic stability and retained its degradation efficiency up to 81% after four cycles. Finally, a possible decomposition mechanism was also discussed.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118303066https://www.sciencedirect.com/science/article/pii/S0921883118303066A novel route to prepare the metastable vaterite phase of CaCO3 from CaCl2 ethanol solution and Na2CO3 aqueous solution

Publication date: Available online 7 July 2018

Source: Advanced Powder Technology

Author(s): Jiuxin Jiang, Yue Wu, Chuanjie Chen, Xuelian Wang, Huakang Zhao, Songsong Xu, CanCan Yang, Bowen Xiao

Abstract

Vaterite, the least stable phase among three anhydrous polymorphs of calcium carbonate (CaCO3), was prepared via the reaction between the ethanol solution of calcium chloride (CaCl2) and the aqueous solution of sodium carbonate (Na2CO3), which is named ethanol-calcium method. The effects of aging times and reaction temperatures on the formation of vaterite were investigated. The polymorphs and morphologies were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, and Fourier transform infrared spectroscopy (FT-IR) was used to verify the existence of vaterite. XRD results indicate that the amount of vaterite decreases from 90.4% to 81.4% as increasing in aging times from 0?min to 42?h and decreases from 85.8% to 70.2% as increasing in reaction temperatures from 0?°C to 60?°C. SEM results show that vaterite and calcite as-prepared are their typical morphologies of spherical and rhombohedral, respectively. This research extends the route to prepare the metastable vaterite and provides new insights into its controllable synthesis.

Graphical abstract

Complexation between CaCl2 and ethanol occurs when CaCl2 powder is added in anhydrous ethanol. The complex CaCl2·nC2H5OH (n?=?4 or 6, taking n?=?6 as an example) distributes homogeneously in anhydrous ethanol, forming a transparent solution. Based on the fact that the system becomes turbid as soon as the addition of transparent Na2CO3 aqueous solution, it can be concluded that the decomplexation of CaCl2·6C2H5OH, the ionization of CaCl2 in water and the combination of Ca2+ and CO32? occur instantaneously and in sequence. According to previous research, amorphous calcium carbonate (ACC) nucleates firstly, followed by crystallization in different polymorphs, or crystallization as metastable vaterite phase and then transformation to the most stable calcite phase.

https://www.sciencedirect.com/science/article/pii/S092188311830284Xhttps://www.sciencedirect.com/science/article/pii/S092188311830284XEffects of specularity and particle-particle restitution coefficients on the recirculation characteristics of dispersed gas-particle flows through a sudden expansion

Publication date: Available online 6 July 2018

Source: Advanced Powder Technology

Author(s): Subrat Kotoky, Amaresh Dalal, Ganesh Natarajan

Abstract

We numerically investigate the effects of restitution and specularity coefficients on the characteristics of dispersed gas-particle flows through a sudden expansion. The studies are carried out using an indigenous finite volume flow solver in a collocated framework with two-fluid model. Parametric studies are performed to gain insights into the differences in recirculation patterns that arise due to variations in restitution and specularity coefficients. The simulations show that particle-particle interactions, quantified by restitution coefficient (e) have a greater impact on recirculation characteristics than particle-wall interactions, which are quantified by specularity coefficient (?). Studies reveal that the recirculation lengths tend to decrease as particle collisions become more elastic (as e tends to unity) while they increase, as the value of ? increases. However, the changes in recirculation length is very gradual and less pronounced when only particle-wall interactions are considered as compared to particle-particle interactions. From the range of parametric variations studied in this work, the maximum recirculation length has been found when the value of ? is maximum and that of e is minimum.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118303042https://www.sciencedirect.com/science/article/pii/S0921883118303042Synthesis of metastable cubic tungsten carbides by electrical explosion of tungsten wire in liquid paraffin

Publication date: Available online 6 July 2018

Source: Advanced Powder Technology

Author(s): Shigeru Tanaka, Ivan Bataev, Hayato Oda, Kazuyuki Hokamoto

Abstract

This paper describes experiments addressing the synthesis of WC1?x (metastable cubic tungsten carbide). The experiments involved exploding tungsten wires of different diameters by passing high-current electric pulses through them. This was done while the wire was immersed in a liquid-paraffin media. The explosion was studied using a high-speed video camera and by analysis of the voltage and current signals. The different stages of the wire explosion were explained based on an analysis of the recorded signals and simple thermodynamic considerations. In most of the experiments, the wire was sublimated, and the formation of carbide particles occurred due to a chemical reaction between the explosion products and the paraffin, as well as the rapid condensation of the vapors. The synthesized powders were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA). It was found that, regardless of the experimental conditions, the WC1?x phase contained approximately 42.5?at.% carbon. If the energy injected into the wire was not sufficient to completely evaporate the tungsten, large particles consisting of WC, W2C, and W phases were formed via the liquid-state diffusion mechanism.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118303029https://www.sciencedirect.com/science/article/pii/S0921883118303029Modeling and simulations of nanofluids using classical molecular dynamics: Particle size and temperature effects on thermal conductivity

Publication date: Available online 6 July 2018

Source: Advanced Powder Technology

Author(s): El Mehdi Achhal, Hicham Jabraoui, Soukaina Zeroual, Hamid Loulijat, Abdellatif Hasnaoui, Said Ouaskit

Abstract

We use molecular dynamics simulations to investigate the thermal conductivity of argon-based nanofluid with copper nanoparticles through the Green-Kubo formalism. To describe the interaction between argon-argon atoms, we used the well-known Lennard-Jones (L-J) potential, while the copper–copper interactions are modeled using the embedded atom method (EAM) potential that takes the metallic bonding into account. The thermal conductivity of the pure argon liquid obtained in the present simulation agreed with available experimental results. In the case of nanofluid, our simulation predicted thermal conductivity values larger than those found by the existing analytical models, but in a good accordance with experimental results. This implies that our simulation is more adequate, to describe the thermal conductivity of nanofluids than the previous analytical models. The efficiency of nanofluids is improved and the thermal conductivity enhancement is appeared when the particle size and temperature increase.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118303005https://www.sciencedirect.com/science/article/pii/S0921883118303005Investigating the fluidization of disk-like particles in a fluidized bed using CFD-DEM simulation

Publication date: Available online 5 July 2018

Source: Advanced Powder Technology

Author(s): Huaqing Ma, Yongzhi Zhao

Abstract

Fluidization of monodispersed disk-like particles with different aspect ratios in the fluidized bed is simulated by CFD-DEM, with disk-like particles being modeled by the super-ellipsoids. The relatively comprehensive investigations are performed in order to understand the fluidization behaviors of disk-like particles and to evaluate how the aspect ratio influences the fluidization. The results obtained demonstrate that disk-like particles with a larger aspect ratio possess stronger particle movement and more apparent fluidization. Comparisons between spherical particles and disk-like particles elucidate their differences in the fluidization behavior. Particle orientation is also investigated in this paper due to its important influence on the fluidization. Particles possess different preferred orientations in the static bed and in the fluidization state, and a reduced aspect ratio can drive particles to be in the preferred orientation. The existence of the walls will prompt particles to align their cross sections to be parallel to the plane of the walls.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302814https://www.sciencedirect.com/science/article/pii/S0921883118302814Densification and microstructural evolution of spark plasma sintered NiTi shape memory alloy

Publication date: Available online 4 July 2018

Source: Advanced Powder Technology

Author(s): C. Velmurugan, V. Senthilkumar, Krishanu Biswas, Surekha Yadav

Abstract

The effect of particle size and sintering temperature on the densification and microstructural characteristics of nickel-titanium shape memory alloy (NiTi-SMA) has been investigated using spark plasma sintering (SPS) process. The Ni and Ti elements in different particle sizes were alloyed in the composition of Ni50.6Ti49.4. The milled NiTi powders were consolidated using SPS process in a temperature range of 700–900?°C. The densification was characterized by plotting temperature, current and relative displacement of punch as a function of holding time. The results showed that a maximum relative density of ?98% can be achieved for NiTi-SMA with an average particle size of 10?µm at a sintering temperature of 900?°C. The microstructure of the sintered NiTi-SMA was examined using scanning electron microscope (SEM) and composition of NiTi alloy was analyzed using energy dispersive spectroscopy (EDS) analysis. The effect of sintering temperature on the microstructural evolution and transformation was also studied.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118303030https://www.sciencedirect.com/science/article/pii/S0921883118303030High purity synthesis of ZrB2 by a combined ball milling and carbothermal method: Structural and magnetic properties

Publication date: Available online 4 July 2018

Source: Advanced Powder Technology

Author(s): Mustafa Baris, Tuncay Simsek, Telem Simsek, Sadan Ozcan, Bora Kalkan

Abstract

The present work provides a new insight into the high purity synthesis of zirconium diboride (ZrB2) powders and a method of controlling impurity during the synthesis process. The single phase ZrB2 nano-powder was synthesized by a combined ball milling and carbothermal method using zirconium oxide (ZrO2), boron oxide (B2O3) and carbon (C) as starting materials. The reaction pathway, phase purity, and morphology of the ZrB2 produced are elucidated from X-ray diffraction (XRD) and scanning electron microscopy studies. The details of the impure phases generated during synthesis were obtained from multi-phase Rietveld refinements of XRD data. Experiments revealed that the method of synthesis carried out at 1750?°C involving ZrB2:B2O3:C at a molar ratio of 1:4.5:7.5 could produce highly pure ZrB2 nano-powders of 67?nm average crystallite size. The magnetometry studies on such pure form of ZrB2 nano-powders indicated that both paramagnetic and diamagnetic characteristics coexisted in ZrB2, which could be attributed to its polycrystallinity.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118303017https://www.sciencedirect.com/science/article/pii/S0921883118303017Enhancement of methane production by Methanosarcina barkeri using Fe3O4 nanoparticles as iron sustained release agent

Publication date: Available online 3 July 2018

Source: Advanced Powder Technology

Author(s): Rong Chen, Yasuhiro Konishi, Toshiyuki Nomura

Abstract

Anaerobic digestion has attracted attention because it does not require power for aeration, it reduces excess sludge and it generates methane gas. However, the growth rate of anaerobic microorganisms is slow, resulting in low treatment efficiency. In this study, the impact of Fe3O4 nanoparticles (NPs) on the growth of methanogens, which is the rate-determining step in anaerobic digestion, was investigated using a pure culture of Methanosarcina barkeri as the model methanogen. M. barkeri were cultivated in iron free medium, as well as in media amended with various concentrations of Fe3O4 NPs with a mean diameter of 8.1?±?2.4?nm. The production of methane gas was greatly increased when organisms were cultured in media containing NPs. After the methane production was saturated, methanol was newly added to the culture, which resulted in additional methane generation at a higher production rate than occurred during the initial round of cultivation in media containing 20?ppm Fe3O4 NPs. In addition, no evidence of negative impacts of Fe3O4 NPs on the growth of M. barkeri was observed. Taken together, these results strongly suggest that adding Fe3O4 NPs into the fermenter as an agent of sustained iron release can enable sustainable methane fermentation.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302863https://www.sciencedirect.com/science/article/pii/S0921883118302863Wavelet multi-resolution analysis on particle dynamics in a horizontal pneumatic conveying

Publication date: Available online 2 July 2018

Source: Advanced Powder Technology

Author(s): Yan Zheng, Akira Rinoshika

Abstract

The particle velocities are measured by the high-speed particle image velocimetry (PIV) in the acceleration and fully developed regimes of a horizontal pneumatic conveying. Based on the measured particle fluctuation velocities, continuous wavelet transform and one-dimensional orthogonal wavelet decomposition were applied to reveal particle dynamics in terms of time frequency analysis, the contribution from wavelet level to the particle fluctuation energy, spatial correlation and probability distribution of wavelet levels. The time frequency characteristics of particle fluctuation velocity suggest that the small-scale particle motions are suppressed and tend to transfer into large scale particle motions from acceleration regime to fully developed regime. In the near bottom part of pipe, the fluctuation energy of axial particle motion is mainly contributed from the wavelet levels of relatively low frequency, however, in the near top part of pipe, wavelet levels of relatively high frequency make comparable contribution to the axial particle fluctuation energy in the suspension flow regime, and this contribution decreases as particles are accelerated along the pipe. The low frequency wavelet levels exhibit large spatial correlation, and this spatial correlation increases as the particles flow from acceleration regime to fully developed regime. The skewness factor and kurtosis factor of wavelet level suggest that the deviation of Gaussian probability distribution is associated with the central frequency of wavelet level, and the deviation from Gaussian distribution is more evident as increasing central frequency. The higher wavelet levels can be linked to small sale particle motions, which lead to irregular particle fluctuation velocity.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302838https://www.sciencedirect.com/science/article/pii/S0921883118302838Effect of Mn doping concentration on structural, vibrational and magnetic properties of NiO nanoparticles

Publication date: Available online 2 July 2018

Source: Advanced Powder Technology

Author(s): Kiran N. Patel, M.P. Deshpande, Krishna Chauhan, Piyush Rajput, Vivek P. Gujarati, Swati Pandya, Vasant Sathe, S.H. Chaki

Abstract

The Ni1?xMnxO (x?=?0.00, 0.02, 0.04 and 0.06) nanoparticles were synthesized by chemical precipitation route followed by calcination at 500?°C for 4?h. The prepared samples were characterized by energy dispersive analysis of X-rays (EDAX), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). Rietveld refinement of XRD data confirms the structural phase purity and XRD patterns are well indexed to NaCl like rock salt fcc crystal structure with Fm-3m space group. The particle size of Mn doped samples is found to be less than that of pure NiO sample. However, the particle size increases slightly on increasing the Mn concentration due to surface/grain boundary diffusion. The vibrational properties of the synthesized nanoparticles were investigated by Raman and FT-IR spectroscopy. The results of room temperature magnetization (M-H) and temperature dependent magnetization (M-T) measurements are explained with a core-shell model. The synthesized nanoparticles show weak ferromagnetic and super-paramagnetic like behavior at room temperature.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302826https://www.sciencedirect.com/science/article/pii/S0921883118302826Synthesis of Ni-doped LaSrMnO3 nanopowders by hydrothermal method for SOFC interconnect applications

Publication date: Available online 30 June 2018

Source: Advanced Powder Technology

Author(s): Sang Yun Lee, Juyeon Yun, Weon-Pil Tai

Abstract

Ni-doped lanthanum strontium manganite (LSMN) nanopowders, La0.7Sr0.3Mn1?xNixO3 (0.05???x???0.3) were synthesized at 150?°C for 8?h by hydrothermal reaction as a function of Ni doping concentration. The SEM analyses suggested that the calcination treatment influenced the morphology of the nanopowders. The calcined nanopowders at 1300?°C had agglomerated spherical structure of 44–77?nm. Meanwhile, the XRD studies revealed that the nanopowders have single crystalline phase over the range x?=?0.05–0.2. In addition, the LSMN nanopowders were sintered at elevated temperatures, 1250–1350?°C to examine their electrical conductivity for solid oxide fuel cell (SOFC) interconnect applications under actual SOFC working condition. Their electrical conductivity gradually increased to 90.05?S/cm with Ni doping concentration x?=?0.2, which were sintered at 1300?°C. These results suggest La0.7Sr0.3Mn0.8Ni0.2O3 displays a good performance as an optimal composition of the LSMN.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302851https://www.sciencedirect.com/science/article/pii/S0921883118302851Improved dust management at a longwall top coal caving (LTCC) face – A CFD modelling approach

Publication date: Available online 28 June 2018

Source: Advanced Powder Technology

Author(s): Ting Ren, Zhongwei Wang, Jian Zhang

Abstract

Dust management at longwall faces has always been a concern for mine operators. Recent respirable dust monitoring at a longwall top coal caving (LTCC) face indicated that extremely high dust exposure levels have been experienced at the face. Dust contamination from intake ventilation and the incorrect use of ventilation arrangements (i.e. curtains) at maingate (MG) area were identified as the main cause of this issue. Computational Fluid Dynamics (CFD) modelling studies were therefore conducted to investigate the impact of different ventilation arrangements on the dispersion behaviour of respirable dust at the LTCC face, with a special focus on the airflow patterns and the aerodynamics of fugitive dust at the intersection of MG and face. Field investigation was first carried out to observe the dust issue and obtain essential data for the development and validation of base model. Then parametric studies were conducted to evaluate the effectiveness of two different curtain configurations at MG considering the worst scenario of intake dust contamination to face (dust from travel road and beam stage loader (BSL) discharge point flows towards face) with the shearer cutting into the MG. Model results demonstrate that the occurrence of flow separation and incorrect use of curtains account for the main reasons of high dust exposure level at the intersection of MG and face, especially when the shearer is cutting into the MG. Ventilation arrangements at the MG and face entry are critical to minimise the impact of flow separation on the dust flow patterns at the intersection. Based on model results, new ventilation arrangements at the MG and face entry have been proposed and evaluated through which significant dust mitigation effect can be achieved at face entry, contributing to the overall reduction of dust exposure levels along the face.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302802https://www.sciencedirect.com/science/article/pii/S0921883118302802An investigation into the parameters affecting the breakdown voltage and inter-particle bonding in the electrical discharge compaction of metal powders

Publication date: Available online 27 June 2018

Source: Advanced Powder Technology

Author(s): A. Darvizeh, M. Alitavoli, N. Namazi

Abstract

The aim of present investigation is to gain deeper understanding of breakdown behavior and inter-particle bonding by conducting experimental tests. This may lead to improve the state of compaction by relative arrangement of initial parameters to maintain uniform distribution of current density and producing compacts with sufficient mechanical strength. Experimental work was carried out using two different set-ups. The first arrangement was employed to provide steady-state alternating voltage. The effect of column geometry and particle size on breakdown voltage was investigated under this condition. The second set-up, capacitor discharge circuit, was used to provide impulse voltage. Under this condition, the influence of column geometry, particle size, application of axial pressure, evacuation of air, energy input, electrode material and configuration on breakdown voltage was studied. Also, scanning electron microscopy was employed to study the effect of different parameters on inter-particle bonding. The results of experiments conducted on the influence of each of the voltage and capacitance on the compaction properties are also discussed.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302784https://www.sciencedirect.com/science/article/pii/S0921883118302784Antibiofilm, anti cancer and ecotoxicity properties of collagen based ZnO nanoparticles

Publication date: Available online 23 June 2018

Source: Advanced Powder Technology

Author(s): Sekar Vijayakumar, Baskaralingam Vaseeharan

Abstract

The use of natural biopolymers in the synthesis of nanomaterials can have a low cost and eco-friendly approach. ZnO nanoparticles synthesized through biological method has been reported to have biomedical applications to control pathogenic microbes as it is cost effective compared to commonly used physical and chemical methods. In this work we would like to report the “bioinspired” synthesis of ZnO nanopowders (ZnO-NPs) using type 1 collagen. Collagen based ZnO NPs (Cl-ZnO NPs) were bio-physically characterized by UV–vis Spectroscopy, XRD, FTIR, HR-TEM, EDX and Zeta potential analysis. HR-TEM recorded the presence of hexagonal wurtzite structure of Cl-ZnO NPs with particle size ranged between 20–50?nm. Further, Cl-ZnO NPs exhibited antibacterial and antibiofilm activity against Gram positive Streptococcus mutans, Gram negative Proteus vulgaris and fungi Candida albicans at 75??g/ml. Moreover, the cytotoxicity assay demonstrated that the Cl-ZnO NPs was not toxic to murine (RAW 264.7) macrophage cells up to 75??g/ml. However, it exhibited cytotoxicity against human liver cancer (HepG2) cells at 75??g/ml. The HepG2 cell viability was significantly reduced at 75??g/ml. In addition, the ecotoxicity of Cl-ZnO NPs on the freshwater micro crustacean Daphnia longicephala showed no mortality up to 250??g/ml. The current study clearly demonstrated that the Cl-ZnO NPs had greater potential for antimicrobial and anticancer activities.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302772https://www.sciencedirect.com/science/article/pii/S0921883118302772Tweaking the diameter and concentration of carbon nanotubes and sintering duration in Copper based composites for heat transfer applications

Publication date: Available online 22 June 2018

Source: Advanced Powder Technology

Author(s): R. Vignesh Babu, Kunwar Avanish Verma, M. Charan, S. Kanagaraj

Abstract

Copper (Cu) gained its importance in several applications due to its attractive thermal characteristics. However, its applications are limited, wherever high strength and high thermal conductivity are desirable. Thus, an attempt was made to develop Cu/CNT composites having the improved mechanical and thermal properties. Initially, Cu/CNT composite powder was synthesized through molecular level mixing technique, where the functionalized 20–40?nm and 40–60?nm diameter CNT with varying concentrations from 0.25 to 1.0?wt.% with an increment of 0.25?wt.% were used. The powder was uniaxially compacted at 800?MPa and sintered in the range of 2–8?hr at 900?°C. The best characteristics of Cu/CNT composites obtained from the present study are as follows: Relative density (RD) – 89.1%, Hardness – 61.2?±?0.58 VHN, Thermal conductivity – 343?W/mK and these characteristics obtained their maximum value at 0.25?wt.% CNT concentration and started to decrease irrespective of CNT diameter.

Graphical abstract

https://www.sciencedirect.com/science/article/pii/S0921883118302796https://www.sciencedirect.com/science/article/pii/S0921883118302796Experimental and numerical investigation of effects of particle shape and size distribution on particles’ dispersion in a coaxial jet flow

Publication date: Available online 21 June 2018

Source: Advanced Powder Technology

Author(s): Wei Zhang, Kazuki Tainaka, Seongyool Ahn, Hiroaki Watanabe, Toshiaki Kitagawa

Abstract

In this study, an experimental and a numerical investigations are performed to investigate the effect of particle’s shape and size distribution on its dispersion behavior. Firstly, particle dispersion of pulverized coal and spherical polymer particles is observed by Particle Image Velocimetry (PIV) technique in the experiment. Secondly, a simulation is performed to analyze the particle dispersion in detail. Spherical and spheroidal motion models are appl

» Author: Jasminder Singh, Manisha Sharma, Soumen BasuAbstractThe adsorption of heavy metal ions (Cr3+, Pb2+ and Cd2+) by metal oxide monoliths (Fe2O3 and Fe2O3/SiO2) synthesized via nanocasting method using SiO2 monoliths as a template was studied. The adsorption

» Reference: Advanced Powder Technology, Volume 29, Issue 9Author(s): Jasminder Singh, Manisha Sharma, Soumen BasuAbstractThe adsorption of heavy metal ions (Cr3+, Pb2+ and Cd2+) by metal oxide monoliths (Fe2O3 and Fe2O3/SiO2) synthesized via nanocasting method using

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This project has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° [310187].