The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Metin Guru - One of the best experts on this subject based on the ideXlab platform.
-
effect of ethanol content on supercritical carbon dioxide extraction of caffeine from tea stalk and fiber wastes
Journal of Supercritical Fluids, 2010Co-Authors: Hacer Icen, Metin GuruAbstract:Abstract This study presents the effect of ethanol content on supercritical carbon dioxide extraction of caffeine from tea plant wastes. Tea stalk and fiber wastes of Turkish tea plants that have no economical value were evaluated as raw material throughout the caffeine extraction experiments. These wastes were supplied from tea factory marked “Caykur” in the east blacksea region. They were separately ground, sieved and dried at 105 °C temperature in an oven. Parameters affecting caffeine leaching from tea wastes were determined to be, ethanol flow rate, extraction time, extraction temperature, carbon dioxide flow rate, Process Pressure and particle size. The maximum yield of caffeine from tea stalk wastes and fiber wastes were 14.95 mg/g tea stalk and 18.92 mg/g tea fiber, respectively. When the supercritical extraction conditions used of ethanol as cosolvent have been compared with the conditions of used only carbon dioxide, approximately the same yield has been reached at 2 h extraction period instead of 7 h. Beside of saving of the time and the amount of carbon dioxide, the supercritical extraction yield with cosolvent increase had been recorded as 62.5% and 63.1%, respectively, in comparison with the chloroform extraction as conventional method of tea stalk and fiber wastes.
Kuan Yan Lin - One of the best experts on this subject based on the ideXlab platform.
-
hydrometallurgical Process for tantalum recovery from epoxy coated solid electrolyte tantalum capacitors
Materials, 2019Co-Authors: Wei Sheng Chen, Kuan Yan LinAbstract:Tantalum is a critical metal that is widely used in electronic products. The demand for tantalum is increasing, but the supply is limited. As tantalum waste products have increased in Taiwan in recent years, the treatment of spent tantalum capacitors has become necessary and important. The recycling of tantalum from tantalum capacitors will not only decrease pollution from waste, but will also conserve tantalum resources. The tantalum content in epoxy-coated solid electrolyte tantalum capacitors (EcSETCs) is over 40 wt.%. Here, we designed a recycling Process that includes pre-treatment, leaching, and solvent extraction to recover tantalum. In the pre-treatment Process, epoxy resin and wires were removed. During hydrometallurgical Process, Pressure leaching by hydrofluoric acid was used to leach tantalum and manganese from solid electrolyte tantalum capacitors (SETCs). During our testing of this proposed Process, the acid concentration, reaction time, temperature, and solid–liquid ratio were examined for leaching. After the leaching Process, Alamine 336 was used to extract tantalum from the leaching solution. The pH value, extractant concentration, extraction time, and aqueous–organic ratio were investigated. Then, tantalum was stripped using HNO3, and the HNO3 concentration, stripping time, and organic–aqueous ratio were analyzed in detail. Under optimal conditions, the recovery efficiency of tantalum reached over 98%, and a final product of tantalum pentoxide with 99.9% purity was obtained after chemical precipitation and calcination.
Hacer Icen - One of the best experts on this subject based on the ideXlab platform.
-
effect of ethanol content on supercritical carbon dioxide extraction of caffeine from tea stalk and fiber wastes
Journal of Supercritical Fluids, 2010Co-Authors: Hacer Icen, Metin GuruAbstract:Abstract This study presents the effect of ethanol content on supercritical carbon dioxide extraction of caffeine from tea plant wastes. Tea stalk and fiber wastes of Turkish tea plants that have no economical value were evaluated as raw material throughout the caffeine extraction experiments. These wastes were supplied from tea factory marked “Caykur” in the east blacksea region. They were separately ground, sieved and dried at 105 °C temperature in an oven. Parameters affecting caffeine leaching from tea wastes were determined to be, ethanol flow rate, extraction time, extraction temperature, carbon dioxide flow rate, Process Pressure and particle size. The maximum yield of caffeine from tea stalk wastes and fiber wastes were 14.95 mg/g tea stalk and 18.92 mg/g tea fiber, respectively. When the supercritical extraction conditions used of ethanol as cosolvent have been compared with the conditions of used only carbon dioxide, approximately the same yield has been reached at 2 h extraction period instead of 7 h. Beside of saving of the time and the amount of carbon dioxide, the supercritical extraction yield with cosolvent increase had been recorded as 62.5% and 63.1%, respectively, in comparison with the chloroform extraction as conventional method of tea stalk and fiber wastes.
Wei Sheng Chen - One of the best experts on this subject based on the ideXlab platform.
-
hydrometallurgical Process for tantalum recovery from epoxy coated solid electrolyte tantalum capacitors
Materials, 2019Co-Authors: Wei Sheng Chen, Kuan Yan LinAbstract:Tantalum is a critical metal that is widely used in electronic products. The demand for tantalum is increasing, but the supply is limited. As tantalum waste products have increased in Taiwan in recent years, the treatment of spent tantalum capacitors has become necessary and important. The recycling of tantalum from tantalum capacitors will not only decrease pollution from waste, but will also conserve tantalum resources. The tantalum content in epoxy-coated solid electrolyte tantalum capacitors (EcSETCs) is over 40 wt.%. Here, we designed a recycling Process that includes pre-treatment, leaching, and solvent extraction to recover tantalum. In the pre-treatment Process, epoxy resin and wires were removed. During hydrometallurgical Process, Pressure leaching by hydrofluoric acid was used to leach tantalum and manganese from solid electrolyte tantalum capacitors (SETCs). During our testing of this proposed Process, the acid concentration, reaction time, temperature, and solid–liquid ratio were examined for leaching. After the leaching Process, Alamine 336 was used to extract tantalum from the leaching solution. The pH value, extractant concentration, extraction time, and aqueous–organic ratio were investigated. Then, tantalum was stripped using HNO3, and the HNO3 concentration, stripping time, and organic–aqueous ratio were analyzed in detail. Under optimal conditions, the recovery efficiency of tantalum reached over 98%, and a final product of tantalum pentoxide with 99.9% purity was obtained after chemical precipitation and calcination.
G F Iriarte - One of the best experts on this subject based on the ideXlab platform.
-
effect of substrate target distance and sputtering Pressure in the synthesis of aln thin films
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2011Co-Authors: G F Iriarte, J G Rodriguez, F CalleAbstract:In this work, we analyze the influence of the Processing Pressure and the substrate–target distance on the synthesis by reactive sputtering of c-axis oriented polycrystalline aluminum nitride thin films deposited on Si(100) wafers. The crystalline quality of AlN has been characterized by high-resolution X-ray diffraction (HR-XRD). The films exhibited a very high degree of c-axis orientation especially when a low Process Pressure was used. After growth, residual stress measurements obtained indirectly from radius of curvature measurements of the wafer prior and after deposition are also provided. Two different techniques are used to determine the curvature—an optically levered laser beam and a method based on X-ray diffraction. There is a transition from compressive to tensile stress at a Processing Pressure around 2 mTorr. The transition occurs at different Pressures for thin films of different thickness. The degree of c-axis orientation was not affected by the target–substrate distance as it was varied in between 30 and 70 mm.
-
reactive sputter deposition of highly oriented aln films at room temperature
Journal of Materials Research, 2002Co-Authors: G F Iriarte, Fredrik Engelmark, Ilia KatardjievAbstract:Textured as well as epitaxial thin AlN films are of great interest for a wide range of electro-acoustic and optoelectronic applications. Reduction of the deposition temperature is of vital importance in a number of applications due to thermal budget limitations. In this work we systematically studied the influence of the Process parameters on the film properties and identified the factors leading to improved film quality as well as reduced deposition temperature with pulsed direct current sputtering in an Ar/N 2 atmosphere. We demonstrated that fully textured (0002) films can be grown under a wide range of conditions. At the same time the full width at half-maximum (FWHM) of the rocking curve of the (0002) XRD peak was found to vary systematically with Process conditions-depostion rate, Process Pressure, gas composition, and substrate temperature. The best films showed a FWHM of 1.2°. We found that by far the most important factor is the arrival energy of the sputtered Al atoms, which is primarily controlled by the Process Pressure. We report for the first time that fully textured AlN films with a FWHM of under 2° can be grown at room temperature. Other important factors are the ion and electron bombardment of the films and substrate temperature as well as gas composition, although their influence is not as dramatic. Generally, the film quality increases with temperature. Bias and electron bombardment within a certain range also lead to better films.
-
structural and electroacoustic studies of aln thin films during low temperature radio frequency sputter deposition
Journal of Vacuum Science and Technology, 2001Co-Authors: Fredrik Engelmark, G F Iriarte, Ilia Katardjiev, Mikael Ottosson, P Muralt, Soren BergAbstract:AIN is a material used in a wide variety of applications such as electroacoustic devices, blue diodes, IR windows, thermal conductors, metal-insulator-semiconductor structures, integrated circuit packaging, etc. In this work thin piezoelectric AIN polycrystalline films have been grown on Si and SiO2 using rf magnetron sputter deposition in an Ar/N-2 gas mixture. The structural properties of the film have been optimized by varying the deposition parameters, such as Process Pressure, gas mixture, substrate temperature, discharge power, etc. [K. Tominaga et al., Jpn. J. Appl. Phys., Part 1 35, 4972 (1996); H. Okana et al., ibid. 31, 3446 (1992); K. Kazuya, T. Hanabusa, and K. Tominaga, Thin Solid Films 281-282, 340 (1996)]. It was found that the best film texture was obtained for a particular set of parameters, namely Process Pressure of 4 mTorr, substrate temperature 350 degreesC, discharge power 350 W, and a gas mixture of 25% Ar and 75% N-2. The films as examined by x-ray diffraction exhibited a columnar structure with a strong (001) texture, and a fall width at half maximum (FWHM) rocking curve of 1.6 degrees. Atomic force microscopy measurements indicated a surface roughness with a rms value of 8 Angstrom. Classical nonapodized transversal surface acoustic wave filters operating at a frequency of 534 MHz were fabricated to characterize the electroacoustic properties of the films. The measurements indicated a coupling coefficient of 0.37% and a phase velocity of 4900 m/s. Further, thin epitaxial films were grown on (001)alpha -Al2O3 (sapphire) under the same deposition conditions except the substrate temperature. The films exhibited a (001)AlN//(001)alpha -Al2O3 plane orientation with a (002) rocking curve FWHM value of about 0.4 degrees, showing a relatively good alignment of the c axis. The in-plane orientation was [110]AlN//[120]alpha -Al2O3 corresponding to a rotation of the AIN film of 30 degrees with respect to the (001)alpha -Al2O3 surface. Cross-sectional transmission electron microscopy studies indicated a population of both thread and edge dislocations with decreasing concentrations with film thickness. (C) 2001 American Vacuum Society.