Papers by Keyword: Absorption

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Authors: Kreangkrai Maneeintr, Tawatchai Charinpanitkul
Abstract: Nowadays, the problems of climate change and global warming become more serious on environmental concern due to the higher amount of carbon dioxide in the atmosphere. Basically the main sources of carbon dioxide come from anthropogenic activities such as power generation, industries and so on. Currently, the effective technology to remove CO2 from these sources is absorption especially chemical absorption. Also, the chemicals used are one of the key parameters for effective CO2 removal. The widely used amine solutions are monoethanolamine (MEA) and diethanolamine (DEA). Nevertheless, they also have disadvantages such as low capacity, corrosion and high heat of regeneration thus making carbon capture technology more expensive. Therefore, many novel materials have been developed to improve the efficiency and compensate the disadvantages of some amines. Consequently, the objective of this work is to investigate the vapor-liquid equilibrium of CO2 in novel materials of 2-(methylamino) ethanol or 2-MAE and 3-Amino-1-Propanol or 3-AP at the temperature from 40 °C to 80 °C and CO2 partial pressures ranging from 5 to 100 kPa. The solubility results of CO2 in novel materials are compared with those of aqueous solution of MEA and DEA. For cyclic capacity, the results present that novel materials provide higher performance than that of MEA with less cost. This means that novel materials can save more energy and cost for solution regeneration and making it more economically viable.
Authors: Yun Zhang, Shi Quan Liu
Abstract: Silica sand is the main material in glass production. It can also be used for water purification. In this work, two types of silica sand used for the glass production were directly applied in the removal of Cr6+ from aqueous solutions. The chemical composition, loss-on-ignition, acid solubility and surface area of the two sands are compared. The results indicate that both sands are quite similar in chemical and mineral compositions. However, sand B has a higher organic content, a smaller crystalline grain size, a larger surface area and acid solubility. As a result, sand B shows a larger absorption of Cr6+ than sand A. In addition, both sands exhibit declined absorption of Cr6+ with increasing the pH of the solution from 1 to 3. No absorption occurred when the pH was higher than 3.
Authors: Brabha H. Nagaratnam, M.E. Rahman, M.A. Mannan
Abstract: The aim of this research is to investigate hardened state properties of Self Compacting Concrete (SCC) containing low calcium based fly ash. The mixtures were prepared using various proportions of Class F fly ash ranging from 0% to 30% cement replacement. Water to powder ratio is 0.38 – 0.39 and powder content was kept constant at 540 kg/m3. Properties investigated were strength properties (compressive strength and splitting tensile strength), and durability properties (complete immersion water absorption, apparent volume of permeable voids (AVPV), sorptivity, and RCIPT tests. These tests were done at various days. Results showed that fly ash replacement of up to 30% gave acceptable strength and durability properties for medium strength SCC.
Authors: Ervin Tal-Gutelmacher, Ryota Gemma, Eugen Nikitin, Astrid Pundt, Reiner Kirchheim
Abstract: Titanium and its conventional alloys reveal a high affinity for hydrogen, being capable to absorb up to 60 at.% hydrogen at 600°C, and even higher contents can be alloyed with titanium at lower temperatures. Hydrogen exhibits a low solubility in the low-temperature hexagonal closed-packed (hcp) α phase and a very high solubility (up to 50 at.%) in the high temperature body-centered cubic (bcc) β phase. The presence of hydrogen in the amount exceeding 200 ppm leads to formation of hydrides in α and α + β titanium alloys. While the aforementioned hydrogen behavior within bulk titanium has been well-established and reviewed, this is not the case with titanium thin films. The interpretation of results in these nanosized systems is complicated because the exact determination of the hydrogen concentration is difficult. However, using electrochemical hydrogen loading technique under the proper conditions, the hydrogen concentration can be accurately determined via Faraday’s law. In this study the thermodynamics of the titanium films during hydrogen absorption were investigated by electromotive force (EMF) measurements. Titanium films of different thicknesses were prepared on sapphire substrates in an UHV chamber with a base pressure of 10-8 mbar, using ion beam sputter deposition under Ar-atmosphere at the pressure of 1,5ּ10-4 mbar. The crystal structure was investigated by means of X-Ray diffraction using a Co-Kα radiation. For electrochemical hydrogen loading, the films were covered by a 30 nm thick layer of Pd in order to prevent oxidation and facilitate hydrogen absorption. The samples were step-by-step loaded with hydrogen by electrochemical charging, which was carried out in a mixed electrolyte of phosphoric acid and glycerin (1:2 in volume). An Ag/AgCl (sat.) and Pt wires were used as the reference and the counter electrode, respectively. XRD measurements were performed before and after hydrogenation in order to investigate the effect of hydrogen loading on the films microstructure. The role of varying thicknesses on the main characteristics of hydrogen's absorption behavior, as well as hydrogen-induced microstructural changes in titanium thin films, are discussed in detail.
Authors: Alexander Bakulin, Alexander Latyshev, Svetlana Kulkova
Abstract: The oxygen absorption and diffusion properties are studied in γ-TiAl and TiAl3 alloys within density functional theory using projector augmented wave method in the plane-wave basis. It is shown that the octahedral site inside the Ti-rich octahedron is preferable for oxygen in case of γ-TiAl alloy whereas the Al-rich octahedron is more favorable environment for oxygen in TiAl3. It is shown that the energy barriers for oxygen jumps between different sites in bulk alloys depend significantly on the local environments of oxygen and increase for its jump from Ti-rich sites. The trajectories with minimum energy barriers are determined for both Ti-Al alloys. It is shown that the increase of Al content in alloy leads to the decrease of barriers for oxygen jumps.
Authors: Hua Bin Xiong, Ming Hong Chen, Xin Xiang A, Meng Sheng Chen, Yu Cheng Chen, Yu Li
Abstract: Heavy metal accumulation is effect normal plant growth, and brings potential human health risk in edible and medicinal plants. Erigeron breviscapus is a famous and important traditional China medicine plant, but research of absorption and accumulation for heavy metal is very limited, however that will help the guarantee of quality and food safety as medicine, and offer cultivation guidance and selection of main medicinal parts. The results showed that in pollution-free soil four heavy metals (lead, chromium, cadmium and cuprum) are low concentration in Erigeron breviscapus, but with an increase of heavy metal concentration in soil its amount showed a rising trend in different organs. Lead and chromium enriched mainly by plant root, but cadmium and cuprum easily transfer into above-ground parts because of strongly translocation ability themselves. Therefore cultivate of medicine materials must select pollution-free soil to avoid direct and indirect danger from heavy metal pollution.
Authors: Bing Xu, Xiang Jun Xu, Hou Mei Dai, Zhen Wei Deng, Xiang Qun Lv
Abstract: Single Bi-doped and M/Bi co-doped silicate glass (M=Al, Y, La) were prepared and broadband NIR emission were observed when the glass samples were pumped by 514 nm and 808 nm LD, respectively. The absorption intensity and emission intensity of the Y/Bi co-doped glass and La/Bi co-doped glass decrease obviously compared to single Bi-doped glass. The absorption intensity in the region of 600-1100 nm and the NIR emission intensity pumped by an 808 nm LD were remarkably enhanced by the introduction of Al2O3 into the Bi-doped silicate glass. It is suggested that the Al/Bi co-doped silicate glass might be very useful for broadband fiber amplifiers and widely tunable lasers.
Authors: S. Torfi, S.M. Hosseini Nejad
Abstract: In this paper, a numerical model is developed to simulate single droplet heat and mass transfer in a two-pieces solution with a saturated solvent vapor environment. Finite volume method and transient SIMPLEC algorithm in spherical coordinates system used for simulation. For simulation of the mass transfer, dimensionless equations of motion, heat transfer and mass transfer (based on mass ratio) are solved simultaneously. All the thermodynamic and transitional solution properties have been considered as a function of temperature and concentration. Verification of method is done by compare these numerical results with analytical and numerical analysis of other studies. Evaporation, absorption and condensation contours in a water droplet at uniform temperature at superheated water vapor and Distribution of Droplet's Surface Temperature, Constant Temperature and concentration lines as the modeling results are presented. The results are shown that 0.5% increase of concentration of droplet cause increase 8 degree C of mean temperature of droplet.
Authors: Pao Chi Chen, Sheng Zhong Lin
Abstract: This work uses a continuous bubble-column scrubber for the absorption of CO2 with a 5M MEA solution under a constant pH environment to explore the effect of the pH of the solution and gas-flow rate (Qg) on the removal efficiency (E), absorption rate (RA), overall mass-transfer coefficient (KGa), liquid flow rate (QL), gas-liquid flow ratio (γ), and scrubbing factors (φ). From the outlet CO2 concentration with a two-film model, E, RA, KGa, QL, γ, and φ can be simultaneously determined at the steady state. Depending on the operating conditions, the results show that E (80-97%), RA(2.91x10-4-10.0x10-4mol/s-L), KGa (0.09-0.48 1/s), QL(8.74-230.8mL/min), γ (0.19-5.39), and φ (0.031-0.74 mol/mol-L) are found to be comparable with other solvents. In addition, RA, KGa, E, and QL have been used to correlate with pH and Qg, respectively, with the results further explained.
Authors: I. Földvári, Á. Péter, L.A. Kappers, R.H. Bartram, Rosanna Capelletti
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