Articles de revues : « Langmuir kinetic »

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Kazmi, Mohsin, Anwar R. Saleemi, Nadeem Feroze, Amir Yaqoob et Syed Waqas Ahmad. « Removal of phenol from wastewater using activated waste tea leaves ». Polish Journal of Chemical Technology 15, n^o 2 (1 juillet 2013) : 1–6. http://dx.doi.org/10.2478/pjct-2013-0016.

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This investigation enumerates the treatment of phenol contaminated synthetic wastewater by Activated Waste Tea Leaves (AWTL). Phosphoric acid was used for the modification of waste tea leaves. The effects of initial pH, biosorbent dose, contact time, and initial phenol concentration were studied on the phenol uptake from the synthetic solution. Kinetic modelling was performed using pseudo 1st and 2nd order kinetics. The Langmuir and Freundlich’s Models were employed to interpret the AWTL behaviour at various mass transfer gradients. The results show that the optimum values for pH, biosorbent dose and contact time were 2.2 g/L and 180 minutes, respectively. Pseudo 2nd order kinetic and the Langmuir’s Models best described the kinetic and equilibrium behaviours, respectively.

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Kreuzer, H. J., et Jun Zhang. « Kinetic lattice gas model : Langmuir, Ising and interaction kinetics ». Applied Physics A Solids and Surfaces 51, n^o 3 (septembre 1990) : 183–90. http://dx.doi.org/10.1007/bf00323999.

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Dong, Xiao Ping, Jie Fu, Jun Hao Jin et Chen Chen. « Adsorption of Basic Dye in Aqueous Solution by Mesoporous Carbon Materials ». Advanced Materials Research 441 (janvier 2012) : 559–63. http://dx.doi.org/10.4028/www.scientific.net/amr.441.559.

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Mesoporous carbon CMK-3 with high surface area and opened pore structure was used to adsorb the basic dye, Malachite green (MG). The equilibrium adsorption data was well described by the Langmuir model, and a very high Langmuir adsorption capacity was obtained by this adsorbent. The adsorption kinetics was found to be best represented by a pseudo-second-order kinetic model.

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Mu, Jin Xia, Ming Juan Shi, Xiao Ying Wu et Jin Ye Li. « Adsorptive Removal of Methylene Blue by Ginkgo Leaf Powder ». Applied Mechanics and Materials 130-134 (octobre 2011) : 829–32. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.829.

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The adsorption of methylene blue (MB) from aqueous solution using a low-cost adsorbent, ginkgo leaf powder, has been studied. The equilibrium data were fitted to Langmuir and Freundlich isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model with maximum monolayer adsorption capacities found to be 39 mg/g. The sorption was analyzed using pseudo-first-order and pseudo-second order kinetic models, and the sorption kinetics was found to follow a pseudo-second order kinetic model. Ginkgo leaf appears as a prospective adsorbent for the removal of methylene blue from aqueous solution.

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Palastro, J. P., E. A. Williams, D. E. Hinkel, L. Divol et D. J. Strozzi. « Kinetic dispersion of Langmuir waves. I. The Langmuir decay instability ». Physics of Plasmas 16, n^o 9 (septembre 2009) : 092304. http://dx.doi.org/10.1063/1.3234245.

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Konicki, Wojciech, Małgorzata Aleksandrzak et Ewa Mijowska. « Equilibrium and kinetics studies for the adsorption of Ni2+ and Fe3+ ions from aqueous solution by graphene oxide ». Polish Journal of Chemical Technology 19, n^o 3 (1 septembre 2017) : 120–29. http://dx.doi.org/10.1515/pjct-2017-0058.

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Abstract In this study, the adsorption of Ni2+ and Fe3+ metal ions from aqueous solutions onto graphene oxide (GO) have been explored. The effects of various experimental factors such as pH of the solution, initial metal ion concentration and temperature were evaluated. The kinetic, equilibrium and thermodynamic studies were also investigated. The adsorption rate data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. Kinetic studies indicate that the adsorption of both ions follows the pseudo-second-order kinetics. The isotherms of adsorption data were analyzed by adsorption isotherm models such as Langmuir and Freundlich. Equilibrium data fitted well with the Langmuir model. The maximum adsorption capacities of Ni2+ and Fe3+ onto GO were 35.6 and 27.3 mg g−1, respectively. In addition, various thermodynamic parameters, such as enthalpy (ΔHO), entropy (ΔSO) and Gibbs free energy (ΔGO), were calculated.

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Krishnaveni, S., et V. Thirumurugan. « A Study on Removal of Heavy Metal Chromium from Aqueous Chromium Solution Using Ipomoea carnea Root as Biosorbent ». Journal of Drug Delivery and Therapeutics 9, n^o 4-A (30 août 2019) : 409–14. http://dx.doi.org/10.22270/jddt.v9i4-a.3504.

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Pollution is the main problem due to heavy metal discharges from industries . In this study Ipomoea carnea (Family:Convolvulaceae) is selected to remove the heavy metal chromium from aqueous chromium solution using biosorbent . The present work focuses to evaluate the effectiveness of low cost absorbent Ipomoea carnea root powder. Various parameters like pH, biosorbent, dose, contact time and metal ion concentration are investigated using batch studies. A kinetic model study and isotherm model fitting study are studied using Langmuir and Freundlich isotherms. The Thermodyamic parameters ∆G, ∆H and ∆S are also seen. The results reveal that it follows pseudo first order kinetic model and also fit in the Langmuir and Freundlich isotherms. The results are very much encouraging. So, it can be used as low cost biosorbent in controlling the pollution. Keywords: Pollution, Heavy metal, chromium, Ipomoea carnea, Batch adsorption study, Kinetics Langmuir and Freundlich isotherms and Thermodynamic study.

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Baigenzhenov, Omirserik, Alibek Khabiyev, Brajendra Mishra, M. Deniz Turan, Merey Akbarov et Tatyana Chepushtanova. « Uranium (VI) Recovery from Black Shale Leaching Solutions Using Ion Exchange : Kinetics and Equilibrium Studies ». Minerals 10, n^o 8 (31 juillet 2020) : 689. http://dx.doi.org/10.3390/min10080689.

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This work studies the removal of uranium ions from chemically leached solutions by sorption using two weak and two strong base anionites. Batch sorption experiments were performed to evaluate the optimum conditions at pH 1.2–2.2, 1.0 g resin dose for 1–12 h contact time at room temperature. These experiments addressed sorption kinetics and sorption isotherm. The maximum sorption capacity reached 55.8 mg/g at room temperature. The kinetics data are well described by the pseudo-second-order kinetic model at initial uranium concentration of 0.62 mg·L−1. To describe sorption kinetics pseudo-first-order, pseudo-second-order and intraparticle diffusion models were proposed. Studies indicated that the sorption of uranium can be fitted by a pseudo-second-order kinetic model very well. Equilibria were described by Langmuir, Freundlich, and Dubinin–Radushkevich equations. The experimental sorption isotherm is successfully described by the Langmuir model.

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Nahed, Naghmouchi, et Nahdi Kais. « Adsorption of textile dyes on raw Tunisian clay : Equilibrium, kinetics and thermodynamics ». JOURNAL OF ADVANCES IN CHEMISTRY 11, n^o 6 (16 septembre 2015) : 3685–97. http://dx.doi.org/10.24297/jac.v11i6.857.

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Natural clay from Nabeul region (north of Tunisia) was investigated for the removal of two anionic textile dyes (RR120 and BB150) from aqueous solution. The raw clay was characterized by means of XRD, IR spectroscopic, chemical analysis, cation exchange capacity and BET surface area analysis.Adsorption studies were carried out under various parameters such as pH, contact time, initial dye concentration and temperature. The adsorption kinetic data was tested by pseudo-first order, pseudo second-order and intra-particle diffusion kinetic models. The equilibrium data were analyzed using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The thermodynamic parameters (DH°, DS° and DG°) of the adsorption were also evaluated. The adsorption process was found spontaneous and endothermic in nature. The kinetics of adsorption were best described by pseudo-second order kinetic model. The Langmuir adsorption model totally agrees with the experimental data.

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Kuśmierek, Krzysztof, Paulina Idźkiewicz, Andrzej Świątkowski et Lidia Dąbek. « Adsorptive removal of pentachlorophenol from aqueous solutions using powdered eggshell ». Archives of Environmental Protection 43, n^o 3 (1 septembre 2017) : 10–16. http://dx.doi.org/10.1515/aep-2017-0029.

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AbstractThe usefulness of untreated powdered eggshell as low-cost adsorbent for the removal of pentachlorophenol (PCP) from aqueous solutions was investigated. The most important parameters affecting the adsorption process, including the pH and ionic strength, were examined. The adsorption characteristics of PCP onto eggshell were evaluated in terms of kinetic and equilibrium parameters. The kinetic data were studied in terms of the pseudo-first order, pseudo-second order and intra-particle diffusion kinetic models. The equilibrium data were analyzed using the Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. The pseudo-second order model best described the adsorption kinetics. Using the Langmuir equation, the monolayer adsorption capacity of eggshell for PCP was found to be 0.127 mg/g. The results showed that PCP can be effectively removed from aqueous solution employing eggshell as a cheap adsorbent.

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Sari, Fahriya Puspita, Dede Heri Yuli Yanto et Gustan Pari. « Activated Carbon Derived From OPEFB by One Step Steam Activation and Its Application for Dye Adsorption : Kinetics and Isothermal Studies ». Reaktor 19, n^o 2 (11 août 2019) : 68–76. http://dx.doi.org/10.14710/reaktor.19.2.68-76.

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Activated carbon was prepared from OPEFB by one step steam activation method. The adsorption performance for the removal of acid orange 52 (AO 52), reactive blue 19 (RB 19), basic violet 1 (BV 1) was investigated. Each dye has a different chemical structure such as azoic, anthraquinone, triarylmethane for AO 52, RB 19, and BV 1 respectively. The effects of adsorbent dosage, pH, and contact time on the adsorption process were studied. Experimental data were analyzed by model equations such as Langmuir, Freundlich and Temkin isotherms and it was found that the Langmuir isotherm model best fitted for all three dyes with R2 values is higher than 0.95. Langmuir model assumes a homogeneous nature and monolayer coverage of dye molecules at the outer surface of activated carbon. Adsorption kinetics was determined using pseudo-first-order, pseudo-second-order rate equations, Elovich model and also intraparticle diffusion models. Kinetic studies showed that the pseudo-second-order kinetic model better described the adsorption process with R2 values exceeds 0,99 compared with the other kinetics model. The SEM images showed AC pores was well developed with steam activation while wider porosity is created in the macropore range. FT-IR analysis had shown that the AC functional groups were disappeared because of vaporization the volatile materials when the heating process. Keywords: Activated Carbon, Adsorption Isotherms, Kinetic, OPEFB, Steam Activation

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CASTRO, Douglas Azevedo, Douglas Henrique PEREIRA et Paulo Vitor Brandão LEAL. « LANGMUIR ISOTHERM : KINETIC AND EQUILIBRIUM CONSIDERATIONS ». Periódico Tchê Química 16, n^o 31 (20 janvier 2019) : 324–34. http://dx.doi.org/10.52571/ptq.v16.n31.2019.330_periodico31_pgs_324_334.pdf.

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Adsorption processes present increasing applications in the most diverse matrices of systems. In this scenario the Langmuir isotherm has highlight and importance. Although it is the simplest isotherm model, in most adsorption studies it is considered, since it is the basis for the formulation of almost all other models proposed in literature. Thus the Langmuir model is applied in the most diverse types of adsorption processes, such as: removal of metallic ions, organic compounds, pollutants generated by agriculture, dyes, mining effluents, among others. The types of adsorbents are also the most varied with highlight: alternative adsorbents, activated carbon and zeolites. Thus, the Langmuir isotherm evaluation, its origin and approximations is of extreme relevance for students and teachers who are interested and / or working with adsorptive processes. The isotherm was first published in 1916 and it parts of simple concepts for its formulation. Thus, this paper presents deductions from the Langmuir equation in two ways: (a) via kinetic considerations and (b) via equilibrium considerations. In addition, it proposes an evaluation of Gibbs energy of the process and some ways of estimating the number of surface adsorption sites.

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Liu, Yan-Ping, Chun-Chun Wang et Shi-Jie Li. « A fractal Langmuir kinetic equation and its solution structure ». Thermal Science 25, n^o 2 Part B (2021) : 1351–54. http://dx.doi.org/10.2298/tsci200320033l.

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The Langmuir kinetic equation is analyzed by the variational iteration method, its solution property is revealed analytically. The effects of desorption time and adsorption coefficient on the solution properties are also discussed, and a fractal modification of Langmuir kinetic equation is suggested.

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Zhang, Zefei, Cholhwan Kim, Carlos Fernandez, Manickam Minakshi Sundaram, Thippeswamy Ramakrishnappa, Yuhong Wang, Linshan Wang, Ting Sun et Xiaomin Hu. « Adsorption removal of methylene blue from aqueous solution on carbon-coated Fe3O4 microspheres functionalized with chloroacetic acid ». Science and Engineering of Composite Materials 25, n^o 2 (28 mars 2018) : 353–61. http://dx.doi.org/10.1515/secm-2016-0138.

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AbstractWe report the preparation and employability of carbon-coated Fe3O4(Fe3O4/C) microspheres functionalized with chloroacetic acid (CAA) for the removal of methylene blue (MB) in aqueous solution. The prepared magnetic microspheres (Fe3O4/C-CAA) were characterized by the following techniques: X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectrometer, vibrating sample magnetometry, and Brunauer-Emmett-Teller. The characterization results showed that Fe3O4/C microspheres were modified by CAA without any phase change. Fe3O4/C-CAA microspheres have higher adsorption capacity for MB compared to Fe3O4/C microspheres. The Langmuir, Freundlich, and Temkin adsorption models were applied to describe the equilibrium isotherms, and the Langmuir adsorption model fitted well with the equilibrium data. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetics data. However, the pseudo-second-order kinetic model fitted better with the adsorption kinetics data.

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Marczewski, Adam W. « Analysis of Kinetic Langmuir Model. Part I : Integrated Kinetic Langmuir Equation (IKL) : A New Complete Analytical Solution of the Langmuir Rate Equation ». Langmuir 26, n^o 19 (5 octobre 2010) : 15229–38. http://dx.doi.org/10.1021/la1010049.

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Uskov, Sergey I., Dmitriy I. Potemkin, Leniza V. Enikeeva, Pavel V. Snytnikov, Irek M. Gubaydullin et Vladimir A. Sobyanin. « Propane Pre-Reforming into Methane-Rich Gas over Ni Catalyst : Experiment and Kinetics Elucidation via Genetic Algorithm ». Energies 13, n^o 13 (2 juillet 2020) : 3393. http://dx.doi.org/10.3390/en13133393.

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Pre-reforming of propane was studied over an industrial nickel-chromium catalyst under pressures of 1 and 5 bar, at a low steam to carbon molar ratio of 1, in the temperature range of 220–380 °C and at flow rates of 4000 and 12,000 h−1. It was shown that propane conversion proceeded more efficiently at low pressure (1 atm) and temperatures above 350 °C. A genetic algorithm was applied to search for kinetic parameters better fitting experimental results in such a wide range of experimental conditions. Power law and Langmuir–Hinshelwood kinetics were considered. It was shown that only Langmuir–Hinshelwood type kinetics correctly described the experimental data and could be used to simulate the process of propane pre-reforming and predict propane conversion under the given reaction conditions. The significance of Langmuir–Hinshelwood kinetics increases under high pressure and temperatures below 350 °C.

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Tomoaia, Gheorghe, Andrada Tomoaia-Cotisel, Maria Tomoaia-Cotisel et Aurora Mocanu. « Kinetic study of adsorption of some biocompounds at the oil/water interface ». Open Chemistry 3, n^o 2 (1 juin 2005) : 347–60. http://dx.doi.org/10.2478/bf02476001.

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AbstractThe adsorption kinetics of some local anesthetics, like dibucaine and tetracaine, and of stearic acid from bulk solutions at the oil/water interface was studied by using the pendent drop and ring methods. The anesthetics were dissolved in aqueous solutions (pH 2), and the fatty acid was dissolved in benzene, each biocompound at several different concentrations in bulk solutions. Kinetic equations for Langmuir mechanism of adsorption at oil/water interface were tested. The kinetic analysis shows that Langmuir kinetic approach describes the dynamic interfacial pressures within the limits of the experimental errors over a wide range of time and for different surfactant concentrations in bulk solutions. It is also concluded that this approach allows the calculation of the ratio of the adsorption and desorption rate constants of these biocompounds at the oil/water interface. Obtained results are in substantial agreement with earlier reported data for the surfactant adsorption as, well as with their molecular structure.

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Chen, Jianlong, et Xinwei Lu. « Equilibrium and kinetics studies of Cd(II) sorption on zeolite NaX synthesized from coal gangue ». Journal of Water Reuse and Desalination 8, n^o 1 (17 décembre 2016) : 94–101. http://dx.doi.org/10.2166/wrd.2016.137.

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Abstract The adsorption of Cd(II) from aqueous solution by synthesized zeolite NaX from coal gangue was investigated in a batch adsorption system. The studies include both equilibrium adsorption isotherms and kinetics. Different isotherm models were examined and the adsorption isotherm could be best represented with Langmuir. The adsorption kinetic experimental data were found to be better fitted with the pseudo-second-order kinetic model. An intra-particle diffusion model was employed to investigate the adsorption mechanism. The results showed that the intra-particle diffusion step was not the only rate limiting step. According to the Langmuir equation, the maximum adsorption capacity was 38.61 mg/g, suggesting that zeolite NaX synthesized from coal gangue can be used as a potential green alternative for the removal of Cd(II) from aqueous solution.

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Xu, Hong Ying, et Chan Zhang. « Kinetic and Equilibrium of Biosorption of Methylene Blue by Anaerobic Granular Sludge in Wastewater ». Advanced Materials Research 550-553 (juillet 2012) : 2291–95. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2291.

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With anaerobic granular sludge as adsorbent, the adsorption kinetics and thermodynamics of methylene blue (MB) from aqueous solution was studied by batch adsorption technique.The pseudo-first order, pseudo- second order models and Langmuir, Freundlich isotherms models were used to describe the kinetic data.The experimental results show that the anaerobic granular sludge had strong and fast speed adsorption capacity for MB adsorption in wastewater. The adsorption equilibrium could be reached in 2h, and the maximum adsorption rate was 98.6%. the pseudo-second order equation is the best model that describes the adsorption behavior.The equilibrium data were fitted to Langmuir isotherms and the equilibrium adsorption was well described by the Langmuir isotherm model. The calculation values of thermodynamic parameters present that the adsorption is spontaneous and endothermic in nature.Our results suggest the anaerobic granular sludge is a potential MB cleaner in wastewater.

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Ou, Hong Xiang, Yu Jun Song, Ling Rui Li et Wei Hong Huang. « Adsorption of Pb(II) by Silica/Yeast Composites from Aqueous Solution : Kinetic and Equilibrium Studies ». Advanced Materials Research 496 (mars 2012) : 476–79. http://dx.doi.org/10.4028/www.scientific.net/amr.496.476.

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Silica/yeast composites were prepared for removal of Pb(II) from aqueous solution. The effects of pH, contact time and initial concentration were examined. The optimum pH was 5.0. The kinetic data were investigated by pseudo-ﬁrst-order and pseudo-second-order models. The kinetic rates were better fitted to the pseudo-second-order model. The experimental data were fitted with the Langmuir and Freundlich models to analyze the equilibrium isotherms. The maximum adsorption capacity calculated from Langmuir isotherm was 73.53 mg/g. The Langmuir isotherm was more favorable to describe the experimental data.

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Thi Thanh Chau, Vo, Huynh Thi MinhThanh, Pham Dinh Du, Tran Thanh Tam Toan, Tran Ngoc Tuyen, Tran Xuan Mau et Dinh Quang Khieu. « Metal-Organic Framework-101 (MIL-101) : Synthesis, Kinetics, Thermodynamics, and Equilibrium Isotherms of Remazol Deep Black RGB Adsorption ». Journal of Chemistry 2018 (24 juin 2018) : 1–14. http://dx.doi.org/10.1155/2018/8616921.

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In the present paper, the synthesis of metal-organic framework-101 (MIL-101) and Remazol Deep Black RGB (RDB) adsorption on MIL-101 were demonstrated. The kinetics of RDB adsorption on MIL-101 was studied using Weber’s intraparticle diffusion model and the pseudo-first- and pseudo-second-order kinetic models. Particularly, the statistical method of piecewise linear regression and multi-nonlinear regression was employed to analyse the adsorption data according to the previously mentioned kinetic models. The results indicated that the adsorption process followed the three-step pseudo-first-order kinetic equation, which was consistent with the results of the intraparticle diffusion model with three linear segments. This model best described the experimental data. In addition, the adsorption isotherm data were studied using five adsorption models, namely, Langmuir, Freundlich, Redlich–Peterson, Toth, and Sips in nonlinear forms, and the Langmuir model is the most appropriate for the experimental data. The values of energies of activation of adsorption were calculated, and they revealed that the adsorption process was of endothermic chemical nature. A statistical comparison using Akaike information criterion to estimate the goodness of fit of the kinetic and isotherm models was presented.

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Adeola, Adedapo O., et Patricia B. C. Forbes. « Optimization of the sorption of selected polycyclic aromatic hydrocarbons by regenerable graphene wool ». Water Science and Technology 80, n^o 10 (15 novembre 2019) : 1931–43. http://dx.doi.org/10.2166/wst.2020.011.

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Abstract A novel graphene wool (GW) material was used as adsorbent for the removal of phenanthrene (PHEN) and pyrene (PYR) from aqueous solution. Adsorption kinetics, adsorption isotherms, thermodynamics of adsorption and effect of pH, ionic strength, and temperature on the adsorption of PHEN and PYR onto GW were comprehensively investigated. Isothermal and kinetic experimental data were fitted to Langmuir, Freundlich, Temkin, Sips and Dubinin–Radushkevich models, as well as pseudo-first-order and pseudo-second-order kinetic models. The adsorption kinetic data best fit the pseudo-second-order kinetic model for PHEN and PYR sorption with R2 value >0.999, whilst the Sips model best fit isotherm data. Kinetic data revealed that 24 hr of contact between adsorbent and polycyclic aromatic hydrocarbons (PAHs) was sufficient for maximum adsorption, where the Langmuir maximum adsorption capacity of GW for PHEN and PYR was 5 and 20 mg g−1 and the optimum removal efficiency was 99.9% and 99.1%, respectively. Thermodynamic experiments revealed that adsorption processes were endothermic and spontaneous. Desorption experiments indicated that irreversible sorption occurred with a hysteresis index greater that zero for both PAHs. The high adsorption capacity and potential reusability of GW makes it a very attractive material for removal of hydrophobic organic micro-pollutants from water.

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Yu, Yan, et Feng Yuan Huang. « Kinetics and Thermodynamics of Adsorption of Copper Ions from Aqueous Solutions onto Carboxymethylcellulose Sulfate ». Advanced Materials Research 393-395 (novembre 2011) : 1268–72. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.1268.

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Batch experiments were carried out to study the adsorption characteristics of Cu(II) onto Carboxymethylcellulose Sulfate(CMC-S). Previous studies had shown that Acidic/neutral pH was favorable to the adsorption of Cu(II). The Kinetic and thermodynamic analysis were performed in detail. Kinetic studies indicated that Cu(II) adsorption on CMC-S in the system followed the pseudo-second order kinetics. Moreover, the experimental equilibrium data was analyzed using the linearized form of Langmuir, and the Langmuir isotherm was found to provide the best theoretical correlation of the experimental data for the adsorption of Cu(II). The monolayer adsorption capacity was determined to be 127 mg of Cu(II) per gram of CMC-S at 25°C. Thermodynamic analysis showed that adsorption process obeys an exothermic path of the negative value of and spontaneous with negative value of .

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Tonk, Szende, Andrada Măicăneanu, Cerasella Indolean, Silvia Burca et Cornelia Majdik. « Application of immobilized waste brewery yeast cells for Cd2+ removal : Equilibrium and kinetics ». Journal of the Serbian Chemical Society 76, n^o 3 (2011) : 363–73. http://dx.doi.org/10.2298/jsc100527032t.

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In this investigation, the removal of Cd2+ ions by a brewery waste biomass in immobilized (Ca-alginate beads) form was studied. The removal process was conducted at room temperature under batch conditions (magnetic stirring) using different initial cadmium concentrations. The equilibrium of biosorption was reached in 150 minutes for all employed initial concentrations. The maximum biosorption capacity was calculated to be 5.96 mg Cd2+ g-1 yeast for an initial Cd2+ concentration of 169 mg L-1. Langmuir and Freundlich adsorption isotherms were used to correlate the equilibrium adsorption data. Based on the correlation coefficients, it was concluded that the Langmuir isotherm is more suitable for describing the equilibrium data of cadmium biosorption. In addition, first and pseudo-second order kinetic models were applied to describe the biosorption process. The kinetic parameters for the pseudo-second order kinetics were determined.

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Erofeev, Vasily I. « High-informative version of nonlinear transformation of Langmuir waves to electromagnetic waves ». Journal of Plasma Physics 80, n^o 2 (13 décembre 2013) : 289–318. http://dx.doi.org/10.1017/s002237781300127x.

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AbstractThe concept of informativeness of nonlinear plasma physical scenario is discussed. Basic principles for heightening the informativeness of plasma kinetic models are explained. Formerhigh-informative correlation analysis of plasma kinetics(Erofeev, V. 2011High-Informative Plasma Theory, Saarbrücken: LAP) is generalized for studies of weakly turbulent plasmas that contain fields of solenoidal plasma waves apart from former potential ones. Respective machinery of plasma kinetic modeling is applied to an analysis of fusion of Langmuir waves with transformation to electromagnetic waves. It is shown that the customary version of this phenomenon (Terashima, Y. and Yajima, N. 1963Prog. Theor. Phys.30, 443; Akhiezer, I. A., Danelia, I. A. and Tsintsadze, N. L. 1964Sov. Phys. JETP19, 208; Al'tshul', L. M. and Karpman, V. I. 1965Sov. Phys. JETP20, 1043) substantially distorts the picture of merging of Langmuir waves with long wavelengths (λ ≳c/ωpe).

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He, Hua Ling, Zhi Cai Yu et Peng Liang. « Adsorption of Acid Red G Dye from Solutions by Raw Bentonite and Bentonite-Cationic Starch Composite ». Advanced Materials Research 821-822 (septembre 2013) : 540–44. http://dx.doi.org/10.4028/www.scientific.net/amr.821-822.540.

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The adsorption of acid red G dye onto raw bentonite/cationic starch (RB/CS) and raw bentonite (RB) was investigated in aqueous solution in a bath system with respect to the adsorption kinetics and adsorption isotherms, respectively. For RB and RB/CS composite, the kinetic data showed that the kinetics of adsorption was best described by a pseudo-second-order expression than the pseudo-first-order. Adsorption isotherms of acid red G dye onto RB and RB/CS composite were determined with common isotherm equations such as the Langmuir and Freundlich models. The results showed that for RB/CS composite, the Langmuir model agreed very well with the experimental data, whereas the RB was fitted to both Langmuir and Freundlich models. In summary, the results showed that RB/CS could be employed as low-cost materials for the removal of acid red G dye from effluents compared to RB.

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Muschietti, L., I. Roth et R. E. Ergun. « Kinetic localization of beam-driven Langmuir waves ». Journal of Geophysical Research 100, A9 (1995) : 17481. http://dx.doi.org/10.1029/95ja00595.

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Willes, A. J., et Iver H. Cairns. « Generalized Langmuir waves in magnetized kinetic plasmas ». Physics of Plasmas 7, n^o 8 (août 2000) : 3167–80. http://dx.doi.org/10.1063/1.874180.

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Mutongo, Farai, Olga Kuipa et Pardon K. Kuipa. « Removal of Cr(VI) from Aqueous Solutions Using Powder of Potato Peelings as a Low Cost Sorbent ». Bioinorganic Chemistry and Applications 2014 (2014) : 1–7. http://dx.doi.org/10.1155/2014/973153.

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Potato peels which are a low cost, renewable agroindustry by-product were used for the removal of hexavalent chromium from aqueous effluents. Batch experiments were carried out with an artificial effluent comprising of potassium dichromate in deionised water. The effects of the initial hexavalent chromium concentration, dose of biosorbent, and removal kinetics were explored. An adsorbent dosage of 4 g/L was effective in complete removal of the metal ion, at pH 2.5, in 48 minutes. The kinetic process of Cr(VI) adsorption onto potato peel powder was tested by applying pseudo-first-order and pseudo-second-order models as well as the Elovich kinetic equation to correlate the experimental data and to determine the kinetic parameters. The adsorption data were correlated by the Langmuir and Freundlich isotherms. A maximum monolayer adsorption capacity of 3.28 mg/g was calculated using the Langmuir adsorption isotherm, suggesting a functional group limited adsorption process. The results confirmed that potato peels are an effective biosorbent for the removal of hexavalent chromium from effluent.

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Jamaliniya, Sara, O. D. Basu, Saumya Suresh, Eustina Musvoto et Alexis Mackintosh. « Kinetic analysis of sucrose activated carbon for nutrient removal in water ». H2Open Journal 3, n^o 1 (1 janvier 2020) : 208–20. http://dx.doi.org/10.2166/h2oj.2020.012.

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Abstract A renewable, green activated carbon made from sucrose (sugar) was compared with traditional bituminous coal-based granular activated carbon (GAC). Single and multi-component competitive adsorption of nitrate and phosphate from water was investigated. Langmuir and Freundlich isotherm models were fitted to data obtained from the nitrate and phosphate adsorption experiments. Nitrate adsorption fits closely to either Freundlich or Langmuir model for sucrose activated carbon (SAC) and GAC with a Langmuir adsorption capacity of 7.98 and 6.38 mg/g, respectively. However, phosphate adsorption on SAC and GAC demonstrated a selective fit with the Langmuir model with an adsorption capacity of 1.71 and 2.07 mg/g, respectively. Kinetic analysis demonstrated that adsorption of nitrate and phosphate follow pseudo-second-order kinetics with rate constant values of 0.061 and 0.063 g/(mg h), respectively. Competitive studies between nitrate and phosphate were demonstrated in preferential nitrate removal with GAC and preferential phosphate removal with SAC. Furthermore, nitrate and phosphate removals decreased from 75% removal to 35% removal when subject to multi-component solutions, which highlights the need for adsorption analysis in complex systems. Overall, SAC proved to be competitive with GAC in the removal of inorganic contaminants and may represent a green alternative to coal-based activated carbon.

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Choi, Sung-kyu, Min-jun Kim, Tae-geon Kim et Tae-jin Lee. « Removal of Heavy Metals (Fe, Mn and Cd) from Aqueous Solutions by Natural Zeolite and FeS Media ». Journal of Korean Society of Environmental Engineers 43, n^o 7 (31 juillet 2021) : 524–36. http://dx.doi.org/10.4491/ksee.2021.43.7.524.

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Objectives : The adsorption characteristics of Fe, Cd, and Mn in aqueous solution using zeolite and FeS media were investigated by the adsorption isotherm and kinetic model analysis.Methods : The adsorption characteristics of the heavy metals (Fe, Mn, Cd) were investigated using Langmuir or Freundlich adsorption isotherm. The analysis of pseudo-first or pseudo-second order reaction was also attempted to evaluate the rate limiting factor such as molecular diffusion or chemical adsorption on the absorbents.Results and discussion : The adsorption of the heavy metals on the zeolite and FeS media was more suitable for the Langmuir adsorption isotherm, representing that mono-layer absorption on the surface and no interaction between the absorbed solutes. The order of adsorption preference to zeolite was Fe > Cd > Mn, whereas the order of adsorption preference to FeS media was Cd > Fe > Mn. The adsorption kinetics of zeolite and FeS media were more suitable for pseudo-secondary reactions than for pseudo-primary reaction.Conclusions : The absorption capacity of FeS media for the heavy metals (Fe, Cd and Mn) in aqueous solution was higher than that of zeolite. The adsorption pattern was suitable for the Langmuir adsorption isotherm, and has kinetic characteristic by chemisorption.

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Elwakeel, K. Z., A. A. El-Bindary, A. Z. El-Sonbati et A. R. Hawas. « Magnetic alginate beads with high basic dye removal potential and excellent regeneration ability ». Canadian Journal of Chemistry 95, n^o 8 (août 2017) : 807–15. http://dx.doi.org/10.1139/cjc-2016-0641.

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The adsorption of crystal violet (CV) dye onto magnetic alginate (MAlg) composite from aqueous solutions was studied. Experiments were carried out as function of contact time, dosage, temperature, pH, and CV concentration in the solutions. Optimum CV uptake was observed at equilibrium pH 7 and most of the CV was sorbed within 30 min. The equilibrium adsorption data were analyzed using two common adsorption models: Langmuir and Freundlich. The results revealed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity obtained from Langmuir isotherm equation was 0.113 mmol g−1 at 298 ± 1 K. The kinetics adsorption of CV onto MAlg composite was investigated using the pseudo first-order and pseudo second-order kinetic models. The results showed that the adsorption of CV onto MAlg composite followed pseudo second-order kinetic model. Thermodynamic data indicated that the adsorption process is an endothermic and spontaneous reaction. Due to its outstanding adsorption capacities, MAlg composite is an excellent adsorbent for the removal of CV. The composite regeneration was greater than 98.6% with 0.01 mol/L HCl, and MAlg composite could be repeatedly utilized for CV removal with negligible loss in sorption capacity.

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Gao, Jing Li, Ying Hui Han, Yu Juan Li et Xiao Hong Zhang. « Photocatalytic Degradation of Methylene Blue by the La-N/TiO₂ Composite and its Kinetic Enumeration ». Applied Mechanics and Materials 863 (février 2017) : 20–25. http://dx.doi.org/10.4028/www.scientific.net/amm.863.20.

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Photocatalytic degradation kinetics of methylene blue in aqueous solution was systematically investigated using Ti-based composite material as the photocatalyst. The single-variable-at-a-time ( SVAT) method was employed. It studied the individual and synergistic effects of several classical parameters on photocatalytic efficiencies. The kinetic mechanism was systematically explored. The kinetics effects of the doping amount of La and N, calcination temperature and time, light intensity were studied in detail. The factors on the degradation of MB were in accordance with the pseudo first order kinetic model. This kinetic model followed the Langmuir–Hinshelwood model. The best preparation conditions were found in the experiments. It is proved that the Ti-based composite material is an effective adsorbent for the degradation of dye contaminated water.

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Bello, Olugbenga Solomon, Oladipo Mary Adelaide, Misbaudeen Abdul Hammed et Olalekan Abdul Muiz Popoola. « Kinetic and equilibrium studies of methylene blue removal from aqueous solution by adsorption on treated sawdust ». Macedonian Journal of Chemistry and Chemical Engineering 29, n^o 1 (15 juin 2010) : 77. http://dx.doi.org/10.20450/mjcce.2010.181.

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The aim of this study is to use treated sawdust as an adsorbent for the removal of methylene blue (MB) dye. The adsorption equilibrium and kinetics of methylene blue dye on this adsorbent were then examined at 25 ºC. The adsorption isotherm of the methylene blue on the treated adsorbent was determined and correlated with common isotherm equations. The sorption data were then correlated with the Langmuir and the Freundlich adsorption isotherm models. The Langmuir isotherm exhibited a better fit for the adsorption data than the Freundlich isotherm with maximum monolayer adsorption capacity of 236.16 mg g–1. The kinetics of methylene blue adsorption on the treated adsorbent has also been studied by fitting the data in the Lagergren’s first order, the Ho-McKay’s pseudo second order, the Elovich and the Intraparticulate kinetic models. It was observed that the removal of methylene blue over the treated adsorbent undergoes the second order processes at all the concentrations of the dye. The kinetic parameters of this best-fit model were calculated and discussed.

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Heraldy, Eddy, Sri Juari Santosa, Triyono Triyono et Karna Wijaya. « Anionic and Cationic Dyes Removal from Aqueous Solutions by Adsorption onto Synthetic Mg/Al Hydrotalcite-Like Compound ». Indonesian Journal of Chemistry 15, n^o 3 (12 novembre 2015) : 234–41. http://dx.doi.org/10.22146/ijc.21190.

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The current investigation reports an effective adsorption of both anionic species and cationic dyes on Mg/Al hydrotalcite-like compounds (Mg/Al HTlc) synthetic from brine water, as novel, inexpensive available alternative to the commercial hydrotalcite. The feasibility of the Mg/Al HTlc, for the adsorptive removal of both anionic (Eosin Yellow-EY and Methyl Orange-MO) and cationic (Methylene blue-MB) dyes from aqueous solution was evaluated in a batch process. Dyes adsorption process was thoroughly studied from both kinetic and equilibrium points of view for all adsorbents. The adsorption kinetics was tested for the pseudo-first order and pseudo-second order kinetic models at different experimental conditions. The dyes adsorption follows the pseudo-second order kinetics model, with correlation coefficients close to unity when experimental data were fitted in the model. The experimental isotherm data were analyzed using Langmuir and Freundlich isotherms. The results from Langmuir isotherm indicated that the capacity of Mg/Al HTlc for the adsorption of anionic dyes was higher than that for cationic dyes.

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Doukeh, Rami, Mihaela Bombos et Ion Bolocan. « Comparative Study Between two Reaction Kinetic Mechanisms of Thiophene Hydrodesulphurization over CoMo /gama - Al2O3 Supported Catalyst ». Revista de Chimie 70, n^o 7 (15 août 2019) : 2481–84. http://dx.doi.org/10.37358/rc.19.7.7365.

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The kinetic study of the thiophene hydrodesulphurisation process was carried out for CoMo/gama-Al2O3 catalyst, at temperatures between 175 and 275 �C, pressure ranged from 30bar to 60 bar and the liquid hourly space velocity from 1h-1 to 4 h-1. For the reaction mechanism, the Langmuir-Hinshelwood-Hougen-Watson model (LHHW) was used and two kinetic models were proposed: the first model, that considered that H2 is adsorbed on a different type of active center than thiophene and the second model, that considered that the two reactants are adsorbed on the same type of active sites. The values obtained for the average relative error (ARE) and the correlation coefficient between the experimental and the calculated data (R2) indicate that the Langmuir-Hinshelwood model, describing the adsorption on two active sites, best describes the kinetics of the thiophene hydrodesulfurization reaction over CoMo/gama-Al2O3 tested catalyst.

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Assoumani, A., L. Favier-Teodorescu et D. Wolbert. « Adsorption kinetics and isotherm characteristics of selected endocrine disrupting compounds on activated carbon in natural waters ». Water Supply 9, n^o 1 (1 mars 2009) : 51–58. http://dx.doi.org/10.2166/ws.2009.063.

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Bisphenol A (BPA) and ethynylestradiol (EE2), two representative endocrine disrupting compounds (EDCs), were tested for their adsorbabilities onto two powdered activated carbons (PACs). The main aim of the study was to create a prediction tool for the determination of the EDCs adsorbabilities at low ng.L−1 level. Single solute solution adsorption isotherms at high concentrations, for prediction purposes, and low concentrations, for verification of the prediction, were performed for one EDC/PAC couple. Over the whole range of concentration, results showed that the Langmuir-Freundlich model better suits the adsorption phenomenon than the Freundlich or Langmuir model. Kinetics experiments were carried out on the same EDC/PAC couple. HSDM modelling of single solute adsorption kinetics at high concentration allowed determining the kinetic coefficients kf and Ds; both were shown to dominate the mass transfer mechanism. Competitive adsorption isotherms at high and low concentrations showed that downward extrapolation of low concentration adsorption capacities from solely high concentration information results in acceptable error compared to the total range isotherm. The IAST-EBC approach combined with the Langmuir-Freundlich single solute model, for the target compound, and the Langmuir model, for the EBC, appears as an acceptable global model.

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Saha, Tapan K., Subarna Karmaker et Md F. Alam. « Kinetics, mechanism and thermodynamics involved in sorption of meso-tetrakis(4-sulfonatophenyl)porphyrin onto chitosan in aqueous medium ». Journal of Porphyrins and Phthalocyanines 18, n^o 03 (mars 2014) : 240–50. http://dx.doi.org/10.1142/s1088424613501174.

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Sorption of meso-tetrakis(4-sulfonatophenyl)porphyrin ( H 2 tpps ) onto chitosan has been investigated in aqueous medium. Kinetic and isotherm studies were carried out by considering the effects of various parameters, such as pH, initial concentration of H 2 tpps solution, and temperature. The kinetic data obtained from different batch experiments were analyzed using pseudo first-, second-order, intraparticle, and film diffusion kinetic models. The equilibrium sorption data was analyzed by using Tempkin, Langmuir and Freundlich models. The best results were achieved with the pseudo second-order kinetic, Langmuir and Freundlich isotherm models. The intraparticle diffusion and film diffusion are the rate limiting steps. The amount of sorbate adsorbed at equilibrium (qe) increased with increasing the initial concentration of H 2 tpps solution, showing maximum sorption capacity of 445.21 μmol.g-1. The activation energy (Ea) of sorption kinetics was found to be 19.47 kJ.mol-1. Thermodynamic parameters such as change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were evaluated by applying the Van't Hoff equation. Thermodynamic activation parameters such as change in enthalpy of activation (ΔH‡), entropy of activation (ΔS‡), and free energy of activation (ΔG‡) were also calculated. The thermodynamics of H 2 tpps sorption onto chitosan in aqueous medium indicates its spontaneous and endothermic nature.

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Yuan, Xiaoli, Wentang Xia, Juan An, Jianguo Yin, Xuejiao Zhou et Wenqiang Yang. « Kinetic and Thermodynamic Studies on the Phosphate Adsorption Removal by Dolomite Mineral ». Journal of Chemistry 2015 (2015) : 1–8. http://dx.doi.org/10.1155/2015/853105.

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The efficiency of dolomite to remove phosphate from aqueous solutions was investigated. The experimental results showed that the removal of phosphate by dolomite was rapid (the removal rate over 95% in 60 min) when the initial phosphate concentration is at the range of 10–50 mg/L. Several kinetic models including intraparticle diffusion model, pseudo-first-order model, Elovich model, and pseudo-second-order model were employed to evaluate the kinetics data of phosphate adsorption onto dolomite and pseudo-second-order model was recommended to describe the adsorption kinetics characteristics. Further analysis of the adsorption kinetics indicated that the phosphate removal process was mainly controlled by chemical bonding or chemisorption. Moreover, both Freundlich and Langmuir adsorption isotherms were used to evaluate the experimental data. The results indicated that Langmuir isotherm was more suitable to describe the adsorption characteristics of dolomite. Maximum adsorption capacity of phosphate by dolomite was found to be 4.76 mg phosphorous/g dolomite. Thermodynamic studies showed that phosphate adsorption was exothermic. The study implies that dolomite is an excellent low cost material for phosphate removal in wastewater treatment process.

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Nor, Norhusna Mohamad, Nur Hidayahtul Nazrah Kamil, Amirul Izan Mansor et Hawaiah Imam Maarof. « Adsorption Analysis of Fluoride Removal Using Graphene Oxide/Eggshell Adsorbent ». Indonesian Journal of Chemistry 20, n^o 3 (9 mai 2020) : 579. http://dx.doi.org/10.22146/ijc.43481.

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Graphene oxide with eggshells (GO/ES) adsorbent has been studied for fluoride ions (F–) removal. An adsorption study was conducted in batch experiments at different adsorption parameters, which are initial F– concentration, contact time, and temperature. The effects of these adsorption parameters towards F– removal by using GO/ES adsorbent were investigated. The adsorption parameters were then analyzed with adsorption isotherms (Langmuir and Freundlich), kinetics (pseudo-first-order and second-order) and thermodynamic studies. Under various parameters, GO/ES is proven as an effective adsorbent with an adsorption capacity of F– are up to 48 mg/g. The experimental data were satisfactorily fitted with Langmuir isotherm, which illustrated the monolayer pattern of F– adsorption into GO/ES adsorbent. The adsorption kinetic analysis indicated that the adsorption data could be well described by Pseudo-second-order kinetic model, which indicated the chemisorption process, while thermodynamic studies revealed that the adsorption of F– was an exothermic process.

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Hao, Yi Nan, Xi Ming Wang, Li Jun Ding et Da Yan Ma. « Ultrasonic Treatment of Activated Carbon Used in Adsorption of Basic Fuchsin ». Materials Science Forum 704-705 (décembre 2011) : 486–91. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.486.

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Xanthoceras Sorbifolia Bunge hull activated carbon (XSBHAC) developed by phosphoric acid activation for removing basic fuchsin (BF) has been investigated. Experiments were carried out as function of contact time, pH (4-10) and temperature (303,313 and 323K). Adsorption isotherms were modeled with the Langmuir and Freundlich isotherms. The data fitted well with the Langmuir isotherm. The Langmuir monolayer saturation capacities of BF adsorbed onto activated carbon were 351.35, 354.96 and 355.94 mg/g at 303,313, and 323 K, respectively.The kinetic models were also studied .The rates of adsorption 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. Key words: Xanthoceras sorbifolia bunge hull;biosorption; basic fuchsin

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Wagh, Prakash Bhila, V. S. Shrivastava et V. S. Shrivastava. « Removal of crystal violate dye from aqueous solution by adsorption on mixture of activated carbon : A kinetic & ; equilibrium study ». JOURNAL OF ADVANCES IN CHEMISTRY 11, n^o 9 (29 juillet 2015) : 3876–87. http://dx.doi.org/10.24297/jac.v11i9.2682.

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The kinetics and equilibrium study of crystal violate dye adsorption on mixture of activated carbon (PWCAC) and (CSAC) was studied. The use of low cost ecofriendly adsorbent has been investigated as an ideal alternative to the current expensive methods of removing of dye from aqueous solution. This study was done by batch adsorption techniques. The quantitative adsorption kinetic and equilibrium parameter for crystal violate dye were studied using uv-visible adsorption spectroscopy. The effect of initial dye concentration, pH,adsorbent dose, temperature, particle size were determined to find the optimal condition for adsorption. The percentage removal of dye was found to be most effective at pH10and contact time 120 min and at an adsorbent dose 4 g/L of dye. The study indicates that’s, the percentage removal of dye increases with increasing initial dye concentration, adsorption dose and contact time and attains equilibrium at optimum conditions.The equilibrium study of adsorption of crystal violate dye on to mixture of activated carbon was investigated using pseudo first order and pseudo second order kinetic models. The adsorption kinetics was found to follow pseudo second order kinetic model. The equilibrium adsorption data of crystal violate dye on PWCAC and CSAC mixture was analyzed by Langmuir and Freundlich adsorption model. The results show that the Langmuir model provides the best correlation.

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Wagh, Prakash Bhila, V. S. Shrivastava et V. S. Shrivastava. « Removal of crystal violate dye from aqueous solution by adsorption on mixture of activated carbon : A kinetic & ; equilibrium study ». JOURNAL OF ADVANCES IN CHEMISTRY 11, n^o 9 (29 juin 2015) : 3876–87. http://dx.doi.org/10.24297/jac.v11i9.848.

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The kinetics and equilibrium study of crystal violate dye adsorption on mixture of activated carbon (PWCAC) and (CSAC) was studied. The use of low cost ecofriendly adsorbent has been investigated as an ideal alternative to the current expensive methods of removing of dye from aqueous solution. This study was done by batch adsorption techniques. The quantitative adsorption kinetic and equilibrium parameter for crystal violate dye were studied using uv-visible adsorption spectroscopy. The effect of initial dye concentration, pH,adsorbent dose, temperature, particle size were determined to find the optimal condition for adsorption. The percentage removal of dye was found to be most effective at pH10and contact time 120 min and at an adsorbent dose 4 g/L of dye. The study indicates that’s, the percentage removal of dye increases with increasing initial dye concentration, adsorption dose and contact time and attains equilibrium at optimum conditions.The equilibrium study of adsorption of crystal violate dye on to mixture of activated carbon was investigated using pseudo first order and pseudo second order kinetic models. The adsorption kinetics was found to follow pseudo second order kinetic model. The equilibrium adsorption data of crystal violate dye on PWCAC and CSAC mixture was analyzed by Langmuir and Freundlich adsorption model. The results show that the Langmuir model provides the best correlation.

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Ganse, Urs, Felix Spanier et Rami Vainio. « Kinetic Simulations of Type II Radio Burst Emission Processes ». Proceedings of the International Astronomical Union 6, S274 (septembre 2010) : 470–72. http://dx.doi.org/10.1017/s1743921311007526.

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AbstractUsing a fully relativistic, 3D particle in cell code we have studied Langmuir- and electromagnetic wave processes in a CME foreshock plasma with counterstreaming electron beams. Langmuir wave excitation in resonance with the plasma frequency is observed, with timescales in accordance with theoretical predictions. However, no three wave interaction leading to emission of electromagnetic waves were detectable within the timeframe of our simulations.

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Mahmoodi, Niyaz Mohammad, Zahra Mokhtari-Shourijeh et Asieh Ghane-Karade. « Synthesis of the modified nanofiber as a nanoadsorbent and its dye removal ability from water : isotherm, kinetic and thermodynamic ». Water Science and Technology 75, n^o 10 (2 mars 2017) : 2475–87. http://dx.doi.org/10.2166/wst.2017.022.

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In this paper, poly(vinyl alcohol) (PVA) nanofiber was prepared and modified by diethylenetriamine (DETA) and ethylenediamine (EDA) in the presence of glutaraldehyde (GA). Dye removal ability of the modified nanofiber (PVA/DETA/EDA/GA) as a nanoadsorbent from water was studied. Fourier transform Infrared (FTIR) and scanning electron microscopy (SEM) were used to investigate the characteristics of the modified nanofiber. Direct Red 23 (DR23) and Direct Blue (DB78) were used. The effect of operational parameters such as pH, initial dye concentration, contact time, temperature and adsorbent dosage on dye removal was studied. The dye adsorption isotherms, kinetics and thermodynamics were investigated. The maximum dye adsorption capacity of the modified nanofiber was 370 and 400 mg/g for DR23 and DB78, respectively. Four isotherms, the Langmuir, the Freundlich, Tempkin and a modified Langmuir–Freundlich model were used. Dye adsorption on the modified nanofiber followed the Langmuir isotherm and pseudo-second kinetic order. Thermodynamic data showed that dye removal was a spontaneous, endothermic and physisorption process.

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Xu, Huan Yan, Xue Li, Yan Li, Ping Li et Wei Chao Liu. « Photocatalytic Degradation of Methyl Orange by TiO₂/Schorl Photocatalyst : Kinetics and Thermodynamics ». Applied Mechanics and Materials 713-715 (janvier 2015) : 2789–92. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.2789.

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An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.

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Wang, Chongxia, Qingping Song et Jiangang Gao. « Investigation of adsorption capacity of N-carboxymethyl chitosan for Pb(II) ions ». Water Science and Technology 68, n^o 8 (1 octobre 2013) : 1873–79. http://dx.doi.org/10.2166/wst.2013.438.

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N-carboxymethyl chitosan (NCMC) was prepared by reacting chitosan (CTS) with chloroacetic acid and characterized by 13C-NMR spectroscopy to confirm that carboxymethylation occurred only in the amino groups. The adsorption properties of CTS, NCMC and O-carboxymethyl chitosan (OCMC) towards Pb(II) ions were evaluated and the order of the adsorption capacity was as follows: NCMC > OCMC > CTS. The effects of initial pH value (2.0–5.5) of the solutions and contact time (5–120 min) on adsorption of Pb(II) were investigated and the kinetic data were evaluated using the pseudo-first-order and pseudo-second-order models. Kinetics study showed that the adsorption process followed second-order kinetics rather than the first-order one. Furthermore, the experimental equilibrium data of Pb(II) on the NCMC were analyzed using the Langmuir and Freundlich isotherm models and the results indicated that the Langmuir model gave a better fit than the Freundlich equation and the maximum adsorption capacity obtained from the Langmuir model was 421.9 mg g−1.

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Mehrvar, Mehrab, William A. Anderson et Murray Moo-Young. « Photocatalytic degradation of aqueous tetrahydrofuran, 1,4-dioxane, and their mixture with TiO2 ». International Journal of Photoenergy 2, n^o 2 (2000) : 67–80. http://dx.doi.org/10.1155/s1110662x00000106.

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Photocatalytic degradation of tetrahydrofuran, 1,4-dioxane, and their mixture in a slurry photoreactor was studied. Using both GC/MS and ion chromatography (IC) methods, possible intermediates were detected and the reaction mechanism pathways for both compounds were proposed. Kinetic models were developed and the kinetic parameters were estimated using a statistical method of non-linear parameter estimation in which all experimental data were utilized. It was shown that tetrahydrofuran was disappeared via direct oxidation as well as hydroxyl radical attack. A modified Langmuir-Hinshelwood described the degradation behavior of tetrahydrofuran and the binary system. 1,4-Dioxane obeyed a simple Langmuir-Hinshelwood kinetic form in the single compound system.

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Hao, Yi Nan, Xi Ming Wang et Fang Liang Pang. « Removal of Cationic Dye from Aqueous Solution by Adsorption on Activated Carbon Developed from Xanthoceras Sorbifolia Bunge Hull ». Advanced Materials Research 123-125 (août 2010) : 367–70. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.367.

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Adsorption of cationic dye, methylene blue (MB) onto Xanthoceras Sorbifolia Bunge hull activated carbon (XSBHAC) developed by zinc chloride solution activation has been investigated. Exp eriments were carried out as function of contact time, pH (2-10) and temperature (293, 303, 313 and 323K). Adsorption isotherms were modeled with the Langmuir and Freundlich isotherms. The data fitte d well with the Langmuir isotherm. The Langmuir monolayer saturation capacities of MB adsorbed onto activated carbon were 501.32, 534.54, 588.30 and 593.28mg/g at 293, 303,313, and 323 K, respect ively. The kinetic models were also studied. The rates of adsorption were found to conform to the pseu do-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 calc ulated.The thermodynamics parameters of system indicated spontaneous and endothermic process.

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Frontistis, Z., M. Papadaki et D. Mantzavinos. « Modelling of sonochemical processes in water treatment ». Water Science and Technology 55, n^o 12 (1 juin 2007) : 47–52. http://dx.doi.org/10.2166/wst.2007.376.

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The mechanisms and kinetics of the sonochemical degradation of organic molecules in water are relatively complex since several parameters such as physicochemical properties, substrate concentration, water matrix, reactor geometry, ultrasound properties (frequency, power, emission system) all typically affect the process. In this work, simple kinetic models were used to predict the degradation of 2-chlorophenol and sodium dodecylbenzene sulphonate in aqueous solutions and verified against experimental data taken from previous studies. A pseudo-first order kinetic expression can adequately describe the degradation of the phenolic substrate, while a heterogeneous model based on the Langmuir-Hinshelwood equation is suitable for the surfactant degradation.

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