Papers by Keyword: Adsorption

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Authors: Radosław Zaleski, Waldemar Dolecki, Jacek Goworek
Abstract: Positron annihilation lifetime spectroscopy study of n-heptane adsorption and desorption on silica gel Si-60 gives insight into a free volume evolution during those processes. Analysis of the lifetime distribution allows to ascribe particular ortho-positronium components to silica walls, mesopores and n-heptane. Hysteresis loop of the intensities of the mesopore and n-heptane related components similar to classic adsorption/desorption isotherms is observed. Transition from an adsorbate multilayer structure to liquid when pores become completely filled, manifests itself as an intensity change. Kinetics of desorption and adsorption studies allows to determine the time of reaching the equilibrium by the Si 60–n-heptane system at various pressures.
Authors: Jing Jing Liang, Zong Bin Zhao, Han Hu, Jie Shan Qiu
Abstract: This work presents a facile approach to grow carbon nanotubes (CNTs) on the surface of carbon foams (CFs) for the fabrication of hierarchical CNTs/CF composites, which exhibit enhanced oil adsorption capability. The preparation of CFs is carried out by using commercially available polyurethane (PU) foams as hard template and resol as carbon precursor. Fe/Mg/Al layered double hydroxide (LDHs) is used as catalyst precursor for the efficient growth of CNTs on CFs via chemical vapor deposition (CVD), in which CNTs are controllably grown onto the strut of CFs. The presence of CNTs in the CFs can significantly improve the hydrophobicity of the composites and enable the selective separation of oil from water with the combination of hydrophobicity and capillary action. Such well-designed hierarchical nanostructures are benefit for maximum utilization of cell structure and surface property of the composites and display good oil adsorption performance. The synthesis procedure paves the way for the exploitation of the CFs as adsorbent for the removal of spill oil and environmental protection.
Authors: Chutarat Saengkul, Panee Pakkong, Katavut Pachana, Pichan Sawangwong
Abstract: Sediments play an important role on fate in the diffusion of radionuclide in aquatic systems. In this study, the investigation of the adsorption/desorption kinetic of 137Cs in two different characteristic of marine sediment samples (organic matter, CEC, and clay content). Batch experiment was carried out from the Upper of Gulf Thailand. The results have shown that there is a significant percentage of 137Cs is adsorbed in both marine sediments during the first 48 hour that increased adsorption percentage to 82 and 86% and after that become to stable. On the other hand, the desorption of 137Cs was found both marine sediment were desorbed less than 10 % and become to stable desorption after 24 hours. Among different marine sediments (St.1 and St.21), the Kd value (distribution coefficients) of 137Cs was different which Kd of sediment from station 1 more than station 21(342.9 and 247.5 L/kg respectively). Differences in the characteristics of marine sediments affect to different the Kd value.
Authors: Shan Yu, Chang Hai Li, Dong Mei Jia
Abstract: The hydroxyl alumina impregnated weakly basic resin composite (D301Al) successfully prepared through incorporation of hydroxyl alumina into the D301 resin for 2-naphthalenesulfonic acid (2-NSA) removal from aqueous solution. The structure of D301Al was examined using scanning electron microscopy and Fourier transform infrared spectroscopy. The adsorption behaviors of 2-NSA on D301Al were investigated by static adsorption experiments. Effects of pH of solution, temperature and contact time were determined. The results indicated D301Al reached the maximum adsorption capacity to 2-NSA with pH 2.4. Nonlinear regression was used to estimate of Langmuir and Freundlich model parameters. And the Langmuir model can give a satisfactory fit of the experimental equilibrium data. The kinetic studies indicated that the adsorption of D301Al for 2-NSA can establish adsorption equilibrium at 8 h. The pseudo-first-order and pseudo-second-order rate models could characterize the kinetic data of 2-NSA adsorption on D301Al.
Authors: Jozef Kačur, Jozef Minár
Abstract: We model the flow of the contaminated water through the porous media sample. We model the inflow of water, flux of water in the sample, flux of the contaminant in the water in the sample, adsorption of the contaminant in the sample and the outflow of the contaminated water from the sample. During the process, there appears fully saturated zone, partially saturated zone and dry zone. We consider Darcys law for flux of the water in fully saturated zone and Richards equation for flux in the partially saturated zone. Flux of the contaminant is governed by Ficks law and the adsorption of contaminant is modeled using Freundlich isotherm. Problem is solved in 1D using numerical solution based on the MOL method. Since flow of the water is independent of the contaminant, we compute separately saturation in the whole time interval and then contamination of water and adsorption of contaminant in the sample.
Authors: K. Hayashi, I. Inasaki, Toshiaki Wakabayashi, Satoshi Suda, Shinya Suzuki, H. Yokota, Tomohiro Aoyama, M. Nakamura
Authors: Qing Ming Jia, Shao Yun Shan, Li Hong Jiang, Ya Ming Wang
Abstract: Polyaniline with different morphologies doped by nitric acid were prepared using rapid mixture method. Scanning electron microscopy analysis showed that morphologies of polyaniline can be changed from unequal particles to nanowires with increasing the molar ratio of aniline to ammonium peroxydisulfate. The adsorption of rhodamine B dye was carried out using the polyaniline with different morphologies, and the effect of morphologies was studied. The results proved that adsorption of rhodamine B from aqueous solutions using polyaniline is an effective and economical method, and morphologies of polyaniline obviously affect its adsorption performance. The polyaniline nanowires present the best adsorption performance for removal rhodamine B among polyaniline with the three kinds of morphologies.
Authors: M. Johari Roudi, T. Mahmoodi
Abstract: Graphene is a 2D lattice of Carbon atoms which has a high potential to use it for hydrogen storage. In this paper we have studied theoretically the adsorption of hydrogen molecules on a single-layer graphene and we obtained the adsorption energy including optimized position and orientation of the hydrogen molecule with respect to the graphene surface in different points of the graphene lattice. We have done our calculations using Quantum-ESPRESSO code and applying pseudo-potential method in the framework of Density Functional Theory (DFT). We have used Local Density Approximation (LDA) for exchange correlation energy. Our result shows that adsorption energy is increased with decreasing the density of . However the maximum adsorption energy is occurred on the hollow position and for the surface homogenous arrangement.
Authors: Min Zhang, Xiao Cai Yu, Min Jing Li, Wei Chen
Abstract: Water-insoluble chitin betainate was environmentally friendly prepared by esterifying chitin with betaine hydrochloride in the presence of dicyandiamide by dry process. The process achieved free-pollution and easy treatment. The chitin betainate holds potential as an adsorbent by the results of the adsorption experiments.
Authors: M.A. Sri Asliza, K. Mohd Zaheruddin, Azmi Rahmat, Shamsul Baharin Jamaludin, Rafezi Ahmad Khairel
Abstract: Ni deposited Hydroxyapatite powder was prepared by electroless deposition technique without sensitization and activation treatments. The composition and phase of deposition were studied. The surface morphologies and composition of initial pure HA powder, as received Ni deposited HA powder and compacted Ni deposited HA powder after sintering were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) respectively. The phases in the powder before and after sintering were investigated by x-ray diffraction (XRD). From the experiment, with the increase of reduction agent, the plating time becomes shorter and optimal concentration of reduction agent and powder ratio is 3:1. The result shows that Ni succesfully deposited on HA powder and confirmed by EDX result. The Ni grain size distribution of 75nm to 250nm can be clearly observed on the HA surface from the micrograph after sintering. Decomposition of hydroxyapatite into α-TCP (α tricalcium phosphate) and TTCP (tetracalcium phosphate) did not occur in nickel deposited HA before and after sintering. On the other hand, a sharp Ni peak were detected
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