Papers by Keyword: Adsorption

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Authors: Azhar Ismail, Wai Soong Loh, Kyaw Thu, Kim Choon Ng
Abstract: Experimental kinetics results of propane in Maxsorb III activated carbon is obtained at temperatures of 10°C and 30°C, and pressures up to 800kPa using a magnetic suspension balance. A multi-gradient linear driving force (LDF) approximation is used for adsorbate uptake as a function of time. The LDF mass-transfer-rate coefficients were thus determined. Using this approach, the experimentally derived LDF coefficients based on independently measured kinetic parameters for propane in the activated-carbon bed agree very well with experimental results. The computational efficiency is gained by adopting this extended LDF model.
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Authors: Jing Wen Xue, Zhe Wang
Abstract: Activated carbon from hydrolytic lignin was prepared in microwave activated with ZnCl2. The property of activated carbon was determined. Iodine and methylene blue adsorption were 1060mg/g and 99.98mg/g, respectively. The adsorption property of activated carbon on Cr(VI) was determined and results showed that pH and temperature had little effects on adsorption of activated, and the proper adsorbing time was 5-20min. The adsorbing ability of hydrolytic lignin activated carbon was batter than that of commercial product. 1g of activated carbon could adsorb 25mg Cr(VI).
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Authors: Wei Wei Ju, Tong Wei Li, Jing Han You, Zheng Xin Tang, Xiao Yang Gong, Hui Wang, Zhi Qiang Zhen, Qing Guo Zhang
Abstract: Performing ab-initio total-energy calculations to investigate the adsorption and diffusion processes of the Au atoms with both the clean Si(001)-(1×1) and H-terminated Si(001)-(2×1) surfaces. It was found that, on the clean Si(001)-(1×1) surface, the most stable adsorption sites for Au atoms are middle part of four Si atoms, while on H-terminated Si(001)-(2×1) surface, the most stable sites are the middle part of a Si-Si dimer. The result showed that surface hydrogenation make most stable site transfer and affect the adsorption of Au on Si(001) surface.
1699
Authors: Ling Die Meng, Min Wu, Ye Tian, Shigenori Kuga, Yong Huang
Abstract: This work reports a cationic modified cellulose hydrogel for fluoride and arsenic adsorption. This adsorbent had a high efficiency in removal of F-, AsO2- and AsO43- simultaneously from aqueous solutions, even at low initial concentrations. Adsorption kinetics showed the relatively rapid rate to reach equilibrium, as could be explained by the pseudo-second-order model and the intraparticle diffusion model within 20 min before the equilibrium. Freundlich model could fit the adsorption process best, and the results showed the improved arsenic adsorption performances especially for AsO43-, much larger than other reported absorbents.
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Authors: Hui Xu, Yao Xu, Yong Chen
Abstract: Polyaniline/attapulgite (PANI/ATP) nanocomposites doped by hydrochloric acid (HCl) were prepared by in-situ polymerization method. The structure and absorption mechanism for eriochrome blue black of nanocomposite were investigated. Amount of absorbent and influence of pH for absorbent effect were also studied. The results reveal that the nanocomposites have not only the structure of ATP but also the property of the PANI. The nanocomposites hold an excellent adsorption for eriochrome blue black when the pH value is 5. The adsorption thermodynamics of the nanocomposites follows the Langmuir isothermal adsorption equation. The maximum adsorption capacity can reach 192.67mg/g. The calculate results show that the adsorption enthalpy is 4.15kJ/mol, the Gibbs free energy is (–22.98 to –19.26) kJ/mol, and the entropy of 81J/(mol·K), which imply that the adsorption is an endothermal and spontaneous process.
488
Authors: Yue Zhou, Wei Guo Pan, Rui Tang Guo, Xiao Bo Zhang, Xue Ping Wen, Ming Fu He
Abstract: In order to reduce power plant nitric oxide emission with gaining economical adsorbent, activated carbon was prepared from the raw materials of orange peel under different operating conditions in this paper. The methylene blue adsorption value of different activated carbon has also been tested, and the effects on the methylene blue adsorption performance of different dipping concentration, activation time and carbonization temperature were studied. The finding is that the dipping concentration has the most important impact on methylene blue adsorption value. The highest methylene blue adsorption value of orange peel activated carbon has shown as 277.746mg/g under the following conditions: phosphoric acid concentration was 40%, activation time was 12 hours and carbonization temperature was 500°C. It is a economically feasible absorbent material through a great deal of experiments and analysis.
2298
Authors: Juan Wang, Qin Zhong
Abstract: With the aim to use anaerobic granular sludge, the methanogenic activity inhibition and recovery of anaerobic granular sludge from an industrial anaerobic reactor (s1) were investigated by measuring the methane volume at low pH. A lab-scale upflow anaerobic sludge blanket (UASB) reactor was inoculated with s1.s1 was used to remove Zn2+ in wastewater. The results show that activity of s1 is similar when the pH value is 6.5 to 7.0. The methane volume is obviously decreased when the pH value is 6.0. The activity is completely inhibited when the pH value is 4.5. The activity is fully recovered when the pH is above 6.5 and hardly recovers when the pH fell to 4.5. The main Zn2+ removal mechanism is chemical adsorption.
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Authors: Lin Zhi Zhai, Gang Li
Abstract: Peanut shell-based activated carbon was prepared by 60% zinc chloride activation. The activation temperature was 923K and activation time was 90min. The activated carbon was applied on the removal of acid light yellow from wastewater. The effects of the amount of adsorbent, the initial dye concentration and pH value of solution were investigated. The results showed that the optimum conditions for dye removal: activated carbon dosage of 2.5g/L, initial dye concentration of 50mg/L, pH value of 3. The color removal efficiency attained above 95%. It is concluded that activated carbon developed from peanut shell could be effective and practical for utilizing in dye wastewater treatment.
1694
Authors: Maxim М. Sychov, Sergey V. Mjakin, Alexander I. Ponyaev, Victor V. Belyaev
Abstract: Distribution of active surface centers (DAC) spectroscopy is applied to study acid-base properties of solids. Surface characteristics of solid influences interface interaction in which this solid participates. Efficient approach to consider such interactions is to view them as acid-base ones, since acid-base interactions determine adsorption and bonding of organic molecules to solid surface. Paper describes application of method to study surface properties of components of luminescent materials, catalysts, gas sensors, proton membranes and polymer composites, and it was shown that their functional properties strongly depend on distribution of acid-base active surface centers.
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Authors: Mirko Kunowsky, Juan Pablo Marco-Lozar, Ángel Linares-Solano
Abstract: Porous adsorbents are currently investigated for hydrogen storage application. From a practical point of view, in addition to high porosity developments, high material densities are required, in order to confine as much material as possible in a tank device. In this study, we use different measured sample densities (tap, packing, compacted and monolith) for analyzing the hydrogen adsorption behavior of activated carbon fibres (ACFs) and activated carbon nanofibres (ACNFs) which were prepared by KOH and CO2 activations, respectively. Hydrogen adsorption isotherms are measured for all of the adsorbents at room temperature and under high pressures (up to 20 MPa). The obtained results confirm that (i) gravimetric H2 adsorption is directly related to the porosity of the adsorbent, (ii) volumetric H2 adsorption depends on the adsorbent porosity and importantly also on the material density, (iii) the density of the adsorbent can be improved by packing the original adsorbents under mechanical pressure or synthesizing monoliths from them, (iv) both ways (packing under pressure or preparing monoliths) considerably improve the storage capacity of the starting adsorbents, and (v) the preparation of monoliths, in addition to avoid engineering constrains of packing under mechanical pressure, has the advantage of providing high mechanical resistance and easy handling of the adsorbent.
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