Papers by Keyword: Adsorption

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Authors: Farhat Bensalah, Abdelkader Iddou, Hafida Hentit, Abdallah Aziz, Andrei Shishkin
Abstract: Activated carbon prepared from industrial wastewater treatment plant dry sludge was proven to be efficient for the removal of refractory dye red scarlet nylosan (F3GL). Mixed treatment (chemical followed by thermal) considerably improved the adsorption capacity of the sludge. Batch tests at 40 °C gave maximal adsorption capacity. Application of Langmuir model gave 434.78 mg/g for treated material (SNHC) and 169.49 mg/g for the unmodified material (S). Thermodynamic parameters indicated that the adsorption is favored by an increase of temperature. The values of the enthalpy revealed physic-sorption. The results clearly showed that the mixed treatment of the adsorbent is the most adequate for the removal of toxic substances such as dyes present in industrial wastewaters.
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.
Authors: V. Krishnan, B.V. Jay Dhwarak, N. Nithyanandan, I. Paul Theophilus Rajakumar
Abstract: Vehicular pollution is one of the main reasons for air pollution in many cities. According to Industrial Environment Carbon, every gallon of gasoline produces 14% total volume of carbon dioxide, this will ultimately lead to air pollution and global warming [10]. To minimize the emission level, physical adsorption [4] can be used for the removal of organic molecule from exhaust gas stream by impulse collision. So our proposed system consists of a filter matrix bed, made of activated carbon, calcium hydroxide, lithium hydroxide [8,9]. Activated carbon is the most widely used adsorbent. It can adsorb a wide range of pollutants with varying dimensions by its broad pore distribution, micro and mesophores. Calcium group can naturally adsorb carbon component and get transformed into lime. Lithium hydroxide is widely used as carbon capturing material in space craft for adsorbing carbon dioxide exhaled by astronaut as a breathing scrubber. So collectively these three carbon sequestrating material can efficiently remove the pollutant by chemisorptions [2].
Authors: Hao Ding, Yue Bo Wang, Ning Liang, Bai Kun Wang
Abstract: Activation methods to improve the adsorption property of natural zeolite by inorganic acid and heat treatments at high temperature were investigated and its function of adsorbing harmful gases was evaluated. The results show that both methods can improve the adsorption property. Natural zeolite which was heat treated for 24 h has an adsorption ratio of 14.67% to H2O in air, which indicates the remarkable improvement of adsorption property. Meanwhile, the adsorption ratios to simulated refrigerator smelling gas such as NH3 and H2S after 10 min are 99.00% and 95.20%, respectively.
Authors: G. Gu, Li Jun Su, Guan Zhou Qiu, Y. Hu
Abstract: Acidithiobacillus caldus and Leptospirillum ferriphilum cells grown in different energy substances (ferrous ion, sulfur and pyrite) were used. The adhesion of A. caldus and L. ferriphilum cells on pyrite and their effect on pyrite surface properties were studied by adsorption, zeta-potential and FT-IR methods, and the corrosion images of pyrite interaction with bacteria were examined using atomic force microscopy. Research showed that pyrite isoelectric point (IEP) after interaction with bacterial cells shifted towards cells isoelectric point, and the shift degree in case of interaction with A. caldus was observed to be much more pronounced than for interaction with L. ferriphilum, which can be due to higher affinity of A. caldus towards pyrite. The FT-IR spectra of pyrite treated with bacterial cells revealed the presence of the cell functional groups signifying cells adsorption. Although the adsorption density of A. caldus on pyrite was higher than that of L. ferriphilum, L. ferriphilum with strong ability to oxidize ferrous ion showed better leaching efficiency than A. caldus with strong ability to oxidize sulfur for pyrite leaching. The results demonstrated that more important of indirect action (L. ferriphilum) than direct action (A. caldus) on pyrite.Introduction Bacterial adsorption to minerals is an initial step in bacterial leaching for metal recovery [1]. It has been reported that bacterial adhesion is dependent not only on the biochemical properties of the organism but also on the interfacial properties of the various interfaces existing in a bioleaching system[2].The bacteria-mineral interactions result in the changes of their surface properties. The elucidation of their alternate will be beneficial for bioleaching processes. Both Acidithiobacillus caldus and Leptospirillum ferriphilum are known for their ability to inhabit acidic environments and derive energy from oxidation of inorganic substances with natural occurrence in ore deposits and acid mine drainage and high affinity towards sulfide minerals [3-5]. In this work, the alterations of surface properties of pyrite after interaction with L. ferriphilum and A. caldus are studied, and the changes in surface properties caused by bacterial adsorption are discussed with reference to bioleaching behavior of pyrite.
Authors: Peng Ge, Li Juan Wan, Ya Jing Xu
Abstract: Among the investigated clays and minerals (kaolinite, natural zeolite, manual zeolite, bentonite, sepiolite, sepiolite amianthus, tremolite amianthus, vermiculite and baritite), the baritite clay was selected as the optimal adsorbent for aqueous Cr (VI). The Cr (VI) adsorption capacity on baritite clay reached as high as 39.01 mg∙g−1 at 20°C. Then the adsorption kinetics of Cr (VI) by the baritite clay were investigated in details. Results showed that the pseudo-second-order model was a suitable description for the adsorption kinetics and fitted well with the experimental data.
Authors: Yi Nan Hao, Xi Ming Wang
Abstract: Xanthoceras Sorbifolia Bunge crust was used as source material to make carbon by chemically impregnated by sodium hydroxide、carbonized at 220°C and activated under the protection of the nitrogen. Experiments were carried out as function of contact time, pH (4-10) and temperature (293,303 and 313K). Adsorption isotherms were modeled with the Langmuir and Freundlich isotherms. Adsorption isotherms of Basic Fuchsin on Xanthoceras Sorbifolia Bunge crust activated carbon are consistent with Langmuir equation. The Langmuir monolayer saturation capacities of BF adsorbed onto activated carbon were 286.545, 303.617 and 323.816 mg/g at 293,303, and 313 K, respectively.and adsorption kinetics were found to conform to the pseudo-second-order kinetics with good correlation.Using the equilibrium concentration contents obtained at different temperatures, various thermodynamic parameters,such as △G,△H and △S, have been calculated. The thermodynamics parameters of system indicated spontaneous and endothermic process.
Authors: Fan Сhun Meng, Fang Jiang, Yong Zhou, Jin Hua Zhang
Abstract: In order to improve the properties of titania nanotubes (TNTs), Fe-doped TNTs were prepared by impregnation method. The crystalline phase, tubular structure and special surface area of TNTs were characterized by XRD, TEM and BET. XRD spectra results revealed that the crystalline phase of TNTs was unchanged after doping iron. The TEM revealed that the materials prepared by hydrothermal method had a complete tubular structure and that structure was completely intact after doping iron. The special surface areas of Fe-doped and bare TNTs were 233.9m2/g and 298.2m2/g , respectively, which indicated that the surface area was decreased after doping iron. The adsorption amount of As(Ⅴ) results reached 35.5 mg/g at 15°C for the Fe-doped TNTs, while just 10.5 mg/g for the bare ones at the same condition, suggesting the application in the treatment of low concentrations of pollutants in water as an efficient adsorbent for Fe-doped TNTs.
Authors: Jian Feng Ma, Jian Ming Yu, Bing Ying Cui, Ding Long Li, Juan Dai
Abstract: Inorganic-organic-bentonite was synthesized by modification of bentonite by Hydroxy-iron and surfactant, which could be applied in dye removal by adsorption and catalysis. The removal of acid dye Orange II was studied at various factors such as time and pH of solution. The results showed that the inorganic-organic-bentonite could efficiently remove the dye with efficiency of 96.22%. The maximum adsorption capacity is 76 mg/g. The pH of solution has significant effect on both adsorption and catalysis. When pH was 4, the maximum removal efficiency of adsorption and catalysis were 97.57% and 87.23%, respectively. After degradation, the secondary pollution was diminished and the bentonite could be reused.
Authors: Ning Liu, Tao Liu
Abstract: Eggshell membrane is a natural biomaterial with macropores lattice and high surface area. The bio-sorption and decolorization of organic dye eosin B was investigated based on eggshell membrane. The effect of adsorption time, pH value and temperature of eggshell membrane on the decolorization of eosin B was studied. Time for adsorption to reach equilibrium is 100 min. Optimum pH value is 2.0 for the adsorption. And the amount of dye removed by egg shell membrane was increasing as temperature ascending. At room temperature and optimum conditions, 95% of eosin B could be removed and maximum adsorption of 40.9 mg/g had been achieved. The adsorption behavior of eggshell membrane towards eosin B fit well with Freundlich isotherm.
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