Aluminum Pellets Research Articles

Fluidized-bed homogeneous crystallization of α-Al(OH)3 for continuous aluminum removal from aqueous solution: Parameter optimization and crystallization mechanism

Fluidized-bed homogeneous crystallization (FBHC) is utilized to recover dissolved aluminum from the solution. Aluminum is crystallized homogeneously using NaOH as a precipitant. Under the optimum pH of 9.7; cross-sectional surface loading (L) of 0.5 kg/m2.h; up-flow velocity (U) of 62 m/h, the total aluminum removal (TR%) in the FBHC reactor reached about 98.5% that is corresponding to the residual aluminum concentration of 10 mg/L. The crystallization ratio of aluminum pellets reached about 93%. The aging process of FBHC effluent solution in the sedimentation tank (SED) lowered the residual dissolved aluminum concentration to below 0.2 mg/L due to the polymorph change from amorphous Al(OH)3 to crystalline Al(OH)3. SEM image shows the round-shape pellet product of FBHC that consists of two different structures of the inner and outer parts due to the different operating supersaturation index. Meanwhile, XRD and FTIR patterns show that during 24 h of aging time, the precipitated compound was changed from amorphous Al(OH)3 to pseudo-AlOOH, and then α-Al(OH)3 crystal. Bayerite (α-Al(OH)3) was predominating the compound of the final pellet product. The production of low-moisture bayerite leads to a disposal cost reduction of up to 80%. FBHC proposed an alternative method to treat aluminum ions in the solution by reclaiming it as high separability and low moisture Al(OH)3 granulated crystal.

Nipple Shield Made from a Thermoplastic with Aluminum Properties.

Here, we report the preparation of a nipple shield from an inexpensive and re-formable thermoplastic with metallic properties as well as its favorable outcomes when used for patients who had undergone nipple reconstruction. The nipple shield was prepared from a material made of a mixture of a thermoplastic resin and special aluminum pellets (aluminum content, 70%). Each patient wore the nipple shield for 3 months after nipple reconstruction. The material was re-softened for re-forming into an adequate shape as required during this 3-month period. All reconstructed nipples were securely protected, with no complications (eg, ulceration, wound dehiscence, and wound infections) during the 3-month period. Also, there were no skin complications such as contact dermatitis or cellulitis in the area where the nipple shield was in contact with the skin. None of the patients stopped using the nipple shield because it came off frequently, or was uncomfortable or painful to wear, and there were no cases in which the nipple shield had to be remade due to damage. The thermoplastic material used in this study appeared to be extremely useful as a nipple protection material because of its good breathability, attributed to its nonwoven form, its low thermal conductivity and resulting cooling effect attributed to its aluminum content, its suitability for rapid re-forming, and its washability.

Relating Near-Infrared Light Path-Length Modifications to the Water Content of Scattering Media in Near-Infrared Spectroscopy: Toward a New Bouguer-Beer-Lambert Law.

In near-infrared spectroscopy (NIRS), the linear relationship between absorbance and an absorbing compound concentration has been strictly defined by the Bouguer-Beer-Lambert law only for the case of transmission measurements of nonscattering media. However, various quantitative calibrations have been successfully built both on reflectance measurements and for scattering media. Although the lack of linearity for scattering media has been observed experimentally, the sound multivariate statistics and signal processing involved in chemometrics have allowed us to overcome this problem in most cases. However, in the case of samples with varying water content, important modifications of scattering levels still make calibrations difficult to build due to nonlinearities. Moreover, even when calibration procedures are successfully developed, many preprocessing methods used do not guarantee correct spectroscopic assignments (in the sense of a pure chemical absorbance). In particular, this may prevent correct modeling and interpretation of the structure of water. In this study, dynamic near-infrared spectra acquired during a drying process allow the study of the physical effects of water content variations, with a focus on the first overtone OH absorbance region. A model sample consisting of aluminum pellets mixed with water allowed us to study this specifically, without any other absorbing interaction terms related to the dry mass-absorbing constituents. A new formulation of the Bouguer-Beer-Lambert law is proposed, by expressing path length as a power function of water content. Through this new formulation, it is shown that a better and simpler prediction model of water content may be developed, with more precise and accurate identification of water absorbance bands.

The mitigating effect of Ananas comosus on aluminum-induced oxidative stress on the testes of adult male Wistar rats

BackgroundThe mitigating effect of Ananas comosus (pineapple juice) extract on an aluminum-induced testicular toxicity in male Wistar rats was examined in this study. Thirty healthy adult male Wistar rats with an average weight of 200 g were grouped into six groups; distilled water and 1 ml of pineapple juice extracts were administered to the control and treated animals respectively for 3 weeks. The control group was given rat pellets and distilled water. Negative control was given 100mg/kg/d Aluminum Chloride and pellets; Group 1 was given 100mg/kg/d and 1ml of pineapple juice in distilled water orally; Group 2 was given 100mg/kg/d Aluminum Chloride and 1.5 ml of in distilled water orally; group 3 was given 100 mg/kg/day aluminum chloride and 2 ml of pineapple juice in distilled water orally; group 4 was given 100 mg/kg/day aluminum chloride and 2.5 ml of pineapple juice in distilled water orally. Testicular histology, semen parameters, and testosterone were assessed.ResultsThis study showed a significant (P < 0.05) decrease in testicular volume, motile sperm count, concentration, total count, progressive evaluation, and morphology in the negative control group relative to the normal control and extract control groups. In the groups co-treated with aluminum chloride and Ananas comosus extract, there was improvement in sperm volume, motility, total count, progressive assessment, and morphology. There was also a statistical decrease (P < 0.05) in testosterone hormone in the negative control group, but there was an increase in the aluminum chloride and Ananas comosus extract co-treated groups. Similarly, in co-treated aluminum chloride and Ananas comosus extract, the degenerative seminiferous tubule histoarchitecture due to aluminum chloride in the negative control group was enhanced.ConclusionBased on this current study, it was evident that aluminum chloride induced oxidative stress and retarded reproduction in males whereas Ananas comosus mitigated reproduction in males by improving sperm parameters and microarchitecture of the testes.

Plasma Spectroscopy on an Aluminum-Pellet Ablation Cloud in an LHD Plasma with an Echelle Spectrometer

We developed an echelle spectrometer for the simultaneous observation of the whole visible range with a high instrumental resolution, for example, 0.055 nm (full width at the half maximum) at 400 nm and 0.10 nm at 750 nm. With the spectrometer, the emission from an ablation cloud of an aluminum pellet injected into a high-temperature plasma generated in the Large Helical Device (LHD) was measured. We separated the emission lines into Al I, II, III and IV groups, and estimated the electron temperature and density of the ablation cloud from the line intensity distribution and Stark broadening respectively, of each of the Al I, II and III groups. We also determined the Stark broadening coefficients of many Al II and III lines from the respective Stark widths with the estimated electron temperature and density.

Radium Targets for the Reactor Production of Alpha-emitting Medical Radioisotopes

Radium 226 (t1/2 = 1600 years) can be irradiated in a reactor to produce a variety of important medical radioisotopes. These isotopes can be chemically separated and purified after irradiation, and the radium can be recycled for future use. Since radium is highly radioactive, there are unique challenges with using radium as a target material. Also, the chemical properties of radium are not yet fully explored, so stable surrogate materials, such as barium, are used to develop the process. To irradiate radium at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor, it must be in a stable chemical form and in a safe and thoroughly certified target configuration. Recent efforts at ORNL have focused on the identification and preparation of several radium compounds to be used as target material for irradiation followed by chemical processing to extract the desired product and recover the radium material. Radium in a stable chemical form can be blended into an aluminum pellet cermet and contained within a welded aluminum capsule. Due to the radioactive properties of radium, the material must be handled in a hot cell, which required design, testing, and construction of in-cell welding and certification capability to seal and certify target capsules. The development of a suitable radium target material, pellet fabrication process and capsule welding will be discussed.

Synthesis of Meso/Macroporous γ‐Alumina via Aluminum Pellet with Controllable Porosity: Ammonium Bicarbonate Influences through Drying and Calcination Steps

AbstractMesoporous and macroporous γ‐alumina have been synthesized using the economic source of aluminum pellets. To manipulate the porosity and overall porous characteristics, ammonium bicarbonate was incorporated into the gel and studied to determine its influence on the porous structure of the obtained γ‐alumina. The nanostructure of the synthesized γ‐alumina, characterized by the N2 sorption isotherms and FESEM analysis, indicated that the γ‐alumina of desired pore size distribution could be achieved using such economical source of aluminum when ammonium bicarbonate was considered to tailor its porous structure. The formation of macropores in synthesized γ‐alumina was confirmed by the FESEM images and the crystalline structure of the γ‐alumina of optimal porous structure was revealed via X‐ray diffraction pattern. Before and after being calcinated at 500 °C, TG‐DTA and FT‐IR analyses were also conducted to better assess the impact that thermal processes could have on ultimate γ‐alumina porous characteristics. Considering the embedded ammonium bicarbonate expander, a two‐step mechanism was finally proposed to explain the observed porosity developed through heating stages. Different porosity patterns developed through drying and calcination steps were then contributed to the reactions taking place at each, and N2 sorption isotherms, as well as the FESEM images, were used to evaluate the introduced pore forming mechanisms.

Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the Hα line profiles and Thomson scattering spectra

We have studied isothermal equilibrium in the laser-induced plasma from aluminum pellets in argon at pressure of 200 mbar by using a method which combines the standard laser Thomson scattering and analysis of the Hα, Stark-broadened, line profiles. Plasma was created using 4.5 ns, 4 mJ pulses from a Nd:YAG laser at 1064 nm. While electron density and temperature were determined from the electron feature of Thomson scattering spectra, the heavy particle temperature was obtained from the Hα full profile applying computer simulation including ion-dynamical effects. We have found strong imbalance between these two temperatures during entire plasma evolution which indicates its non-isothermal character. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium.

Influence of the V/III ratio in the gas phase on thin epitaxial AlN layers grown on (0001) sapphire by high temperature hydride vapor phase epitaxy

Thin (0001) epitaxial aluminum nitride (AlN) layers were grown on c-plane sapphire using high temperature hydride vapor phase epitaxy. The experimental set-up consists of a vertical cold-wall quartz reactor working at low pressure in which the reactions take place on a susceptor heated by induction. The reactants used are ammonia and aluminum chlorides in situ formed via hydrogen chloride reaction with high purity aluminum pellets. As-grown AlN layers have been characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, transmission electron microscopy, photoluminescence and Raman spectroscopies. The influence of the V/III ratio in the gas phase, from 1.5 to 15, on growth rate, surface morphology, roughness and crystalline quality is investigated in order to increase the quality of thin epitaxial AlN layers grown at high temperature. Typical growth rates of around 0.45μm/h were obtained for such thin epitaxial AlN layers. The growth rate was unaffected by the V/III ratio. An optimum for roughness, crystalline quality and optical properties seems to exist at V/III=7.5. As a matter of fact, for a V/III ratio of 7.5, best root mean square roughness and crystalline quality — measured on 0002 symmetric reflection — as low as 6.9nm and 898arcsec were obtained, respectively.

Effects of the V/III ratio on the quality of aluminum nitride grown on (0001) sapphire by high temperature hydride vapor phase epitaxy

AbstractA High Temperature Hydride Vapor Phase Epitaxy reactor (HT‐HVPE) was used to grow 5 µm‐thick (0001) epitaxial AlN layers on sapphire. The experimental set‐up consists of a vertical cold‐wall quartz reactor working at low pressure in which the reactions take place on a graphite susceptor heated by induction. The reactants used are ammonia (NH3) and aluminum chlorides (AlClx) in situ formed via chlorine (Cl2) reaction with high purity aluminum pellets. As‐grown AlN layers have been characterized by Scanning Electron Microscopy (SEM), X‐ray diffraction rocking curves (XRC) and Raman spectroscopy. First, the influence of the V/III ratio in the gas phase on surface morphology, crystalline quality and strain into the material is investigated in order to improve the quality of epitaxial AlN layers grown at high temperature. Parameters were adjusted to keep constant growth rate of about 5 µm/h. Second, a protective layer (growth of a 200 nm‐thick AlN layer at 1200 °C) was deposited before the main growth of a 5µm layer of AlN at 1500°C. A 430 arcsec FWHM value for the 0002 reflection of the AlN layer has been obtained for such experimental conditions. (© 2013 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Wideband High-Resolution Spectroscopy on Al-pellet Ablation Plasmas in Large Helical Device

An aluminum pellet has been injected into a high-temperature plasma produced in the Large Helical Device (LHD). Emission from an ablation cloud of the pellet in a whole visible range is simultaneously measured with an echelle spectrometer having an instrumental resolution from 0.055 nm at 400 nm to 0.10 nm at 750 nm. More than 50 of Al I, II, III and IV lines are resolved. We estimate the electron temperature and density of the ablation cloud from the intensity distribution and Stark broadening of the emission lines, respectively. The electron temperature and density are found to show increase and decrease, respectively, as an increase in the charge state of aluminum. We also determine the Stark broadening coefficients of several Al II lines from the observed Stark widths.

Ignition dynamics and activation energies of metallic thermites: From nano- to micron-scale particulate composites

Ignition behaviors associated with nano- and micron-scale particulate composite thermites were studied experimentally and modeled theoretically. The experimental analysis utilized a CO2 laser ignition apparatus to ignite the front surface of compacted nickel (Ni) and aluminum (Al) pellets at varying heating rates. Ignition delay time and ignition temperature as a function of both Ni and Al particle size were measured using high-speed imaging and microthermocouples. The apparent activation energy was determined from this data using a Kissinger isoconversion method. This study shows that the activation energy is significantly lower for nano- compared with micron-scale particulate media (i.e., as low as 17.4 compared with 162.5kJ∕mol, respectively). Two separate Arrhenius-type mathematical models were developed that describe ignition in the nano- and the micron-composite thermites. The micron-composite model is based on a heat balance while the nanocomposite model incorporates the energy of phase transformation in the alumina shell theorized to be an initiating step in the solid-solid diffusion reaction and uniquely appreciable in nanoparticle media. These models were found to describe the ignition of the Ni∕Al alloy for a wide range of heating rates.

A Spreadsheet-Based Analysis for Two-Dimensional Transient Laser Heating of a Cylindrical Solid

A two-dimensional transient conduction model was developed for cylindrical coordinates using a spreadsheet software package and an explicit finite difference scheme. The governing equations were derived using an energy balance approach in terms of thermal resistance and capacitance. An iterative macro was created to solve the governing temperature equations subjected to specific stability criteria. The model was used to predict the thermal behavior inside a cylindrical solid aluminum pellet subjected to Gaussian or uniform laser heating. This paper demonstrates the application of a common software tool to solve a variety of complicated heat transport problems associated with cylindrical geometries and provides such accuracy that the technique can readily be used for design purposes.

A Novel Way to Synthesize Yttrium Aluminum Garnet from Metal–Inorganic Precursors

Yttrium aluminum garnet (YAG, Y3Al5O12) was synthesized by sol–gel processing from the stoichiometric amounts of aluminum pellets, Y(NO3)3·6H2O, and Al(NO3)3·9H2O or AlCl3·6H2O, with suitable kinds of acid (citric acid, acetic acid, etc.) as catalysts. Polycrystalline YAG powder was obtained by drying the YAG precursor followed by calcination at temperatures above 900°C. Thermogravimetry/differential thermal analysis and Fourier transform infrared specotrscopic analyses in air showed an exothermic peak at ∼900°C, attributed to the formation of a polycrystalline YAG phase and weight loss of 60% at 1000°C, caused by the decomposition of hydroxyl and NO3−, etc. X‐ray diffraction analysis showed that YAG can be formed at 900°C, and no other intermediate was observed. In particular, the YAG sol can be used for dry‐spinning fibers with the aid of some organic polymer.

Separation Test of Rectangular Electroflotation Cell with Packed Bed Type Sacrificial Electrodes.

A separation test of an O/W emulsion was conducted by using a rectangular cell fitted with packed bed type sacrificial electrodes. The continuous separation process was represented by a first-order kinetic rate equation and a two tanks-in-series mixing model as previously reported (Osasa et al., 1996). Three types of electrodes were examined to increase the dissolution rate of aluminum pellets. The most efficient type of electrodes used was one in which aluminum pellets were placed on both an anode and a cathode and the polarity was switched at regular time intervals.

Aluminum micropellets for hot plasma diagnostics

A novel technique for the injection of small (diameter ≤30 μm) impurity pellets into fusion plasmas is proposed and investigated. The method may be easily applied by using a special target plate in conventional laser blow-off injection devices. In the present experiments 10×30×30 μm size aluminum pellets (≊5×1014 atoms) are accelerated to average velocities up to 1 km/s by a 700 mJ ruby laser pulse. The scaling law obtained from a rocket model to the pellet velocity versus laser fluence fits well to experimental data and enables one to extrapolate the capabilities of the technique.

Hydrogenation of (-)-α-pinene over nickel-phosphorus/aluminum oxide catalysts prepared by electroless deposition

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Aluminum oxide thin film deposition by reactive ion plating using the cathode system composed of LaB6 disc and Ta pipe

New type reactive ion plating with the pressure gradient plasma gun is used to deposit aluminum oxide thin films. The plasma gun has a cathode system composed of a LaB6 disc and a tantalum pipe. The 650 ℓ process chamber is made of an aluminum alloy. A 1800 ℓ/s compound molecular pump is used for the main pump. The ultimate pressure of the process chamber is 7.8×10−9 Torr. Argon is used for the carrier gas for the plasma, and oxygen is introduced to the process chamber to produce the oxygen plasma. The electron beam in plasma concentrated with magnetic field is applied to aluminum pellets in the hearth to vaporize the pellets. Aluminum vapor and oxygen radicals interact to make aluminum oxide thin films. The typical deposition rate of an aluminum oxide thin film is 60 Å/s. This film is regarded as a nonequilibrium phase of oxide or hydroxide film. The aluminum oxide thin film deposited on an aluminum alloy plate with constant contents of aluminum and oxygen was locally corroded in wet chlorine gas, but the film with the gradient in oxygen concentration was not corroded. The outgassing of an aluminum oxide thin film with gradient in oxygen concentration deposited on an aluminum plate was one order of magnitude lower than a conventional anodic oxide film formed on an aluminum alloy in sulfuric acid.

Efficacy of Perforated Tubing in Assisting Phosphine Distribution for In-Transit Fumigation of Export Corn

Corn aboard a tanker vessel was fumigated in transit with Detia aluminum phosphide tablets and pellets at the rate of 1.06 g (AI)/m3 and with Detia Gas EX-B Bag Blankets at the rate of 1.04 g (AI)/m3. Different lengths and configurations of perforated, polyethylene Advanced Drainage Systems, drainage tubing containing one-third of the dosage and positioned in some of the tanks effected rapid distribution of the phosphine gas throughout the grain mass. Phosphine concentrations achieved within the grain showed that the fumigations in tubing-rigged tanks were far superior to those in either a deep-probed (5 m) or a surface-treated tank not equipped with tubing. Survivors of caged insects and those insects found by incubation of post fumigation grain samples showed that the fumigation in the surface-treated tank was not as efficacious as any of the other treatments. Phosphine residues on the samples of corn taken at off-loading were well below the established tolerance of 0.1 ppm, regardless of the application method used.

Diagnosis of a cause of life test failure in alloy diodes

Removal of silicon by CF 4 /O 2 plasma etching combined with optical microscope and SEM examinations of the exposed aluminum surface have been used to determine that the cause of life test failure in aluminum/silicon-alloy diodes was the presence of traces of alkali metal in the aluminum pellets used.