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1
Vitázek, I., and J. Havelka. "Sorption isotherms of agricultural products." Research in Agricultural Engineering 60, Special Issue (December 30, 2014): S52—S56. http://dx.doi.org/10.17221/35/2013-rae.
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The aim of the paper is to expand the theory of sorption and equilibrium moisture contents as well as to present the methodology of developing two types of sorption isotherms – I and II. The attention is also paid to the importance of the isotherms in the thermodynamics of drying and in the process of storage of agricultural products. Presented methodology of obtaining the isotherms is based on selected equations of the theory of adsorption and on the results of experimental measurements of equilibrium moisture content. Definition of the new isotherm II is introduced as dependence of equilibrium moisture content dry basis on time at constant temperature, constant relative moisture of the ambient air and stable biological properties (e.g. germination). The results show following graphic dependences: isothermal distort plane; sorption isotherm I of maize grains at various temperatures; moisture loss rate in dependence on time and sorption isotherm II. These theoretical dependences supported by experimental measurements broaden the scope of the theory of sorption and may be successfully applied in long-term storage of maize grains.
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Pode, Rodica, Eveline Popovici, Laura Cocheci, Erika Reisz, Mihaela Seftel, and Vasile Pode. "Sorption of phosphates and thiocyanates on isomorphic substituted Mg/Zn-Al-type hydrotalcites." Journal of the Serbian Chemical Society 73, no. 8-9 (2008): 835–43. http://dx.doi.org/10.2298/jsc0809835p.
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The sorption equilibriums of phosphate and thiocyanate anions on isomorphic substituted Mg/Zn-Al-type hydrotalcites were investigated in this study. Langmuir and Freundlich isotherms were used to interpret the equilibrium data for phosphate. The sorption equilibriums of phosphate on Mg3Al, Mg2ZnAl and Mg1.5Zn1.5Al hydrotalcites were well described by the Langmuir isotherm. The highest maximum sorption capacities for these adsorbents were as follows: 111, 101 and 95 mg g-1. The equilibrium constant and standard Gibbs energy changes were also calculated from the sorption data. Standard Gibbs energy changes of about -20 kJ mol-1 indicated that the process might be considered as physical adsorption. The sorption equilibriums of phosphate on isomorphic substituted samples of MgZn2Al and Zn3Al were well described by the Freundlich isotherm. Thiocyanate showed a relative low affinity for the studied materials, as indicated by both the 'S'-shaped isotherms and low sorption capacities. The sorption of phosphate and thiocyanate on the investigated hydrotalcites showed a continuous decrease of the sorption capacity in the following order: Mg3Al > Mg2ZnAl > Mg1.5Zn1.5Al > MgZn2Al > Zn3Al.
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Agarwal, Ajay K., Mahendra S. Kadu, Chandrashekhar P. Pandhurnekar, and Ishwardas L. Muthreja. "Equilibrium isotherm studies for the sorption of Nickel ions onto coal fly ash." Environment Conservation Journal 15, no. 1&2 (June 18, 2014): 153–59. http://dx.doi.org/10.36953/ecj.2014.151220.
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The objective of the present study was to study equilibrium isotherm for the sorption of Nickel ions onto coal fly ash. In this study, BET adsorption isotherm was found to be best fitted among Langmuir, Freundlich, BET, Temkin and Harkins Jura adsorption isotherms using lest square fit method. The best fit adsorption isotherm is assessed by the linear coefficient of determination (R2) and non-linear Chi-square test. The theoretical value of qe calculated from the best fit linear equation of each adsorption isotherm and the experimental values of qe (0.08) are plotted against Ce, to compare the experimental and Theoretical value of qe.
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Tewari, Hemlata, and Vivekanand. "Removal of heavy metals from industrial effluent using Pinus roxburghii leaves as biosorbent: equilibrium modelling." Water Science and Technology 67, no. 9 (May 1, 2013): 1894–900. http://dx.doi.org/10.2166/wst.2013.034.
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In the present study, biosorption capability of pine (Pinus roxburghii) leaves for the removal Cr6+, Cu2+, Fe2+ and Zn2+ ions, present in brass and electroplating industry effluent, were investigated with respect to different adsorbent doses, contact time and pH. Heavy metals concentrations were estimated by atomic absorption spectrophotometry. Initial concentration of Cr6+, Cu2+, Fe2+ and Zn2+ ions in the effluent were found to be 2.741, 4.551, 8.820 and 5.529 mg/L respectively. Biosorption studies revealed that Cr6+, Cu2+, Fe2+ and Zn2+ showed maximum removal of 99.85, 94.54, 97.10 and 89% at pH 4, 4, 4 and 8, respectively, with 4 g pine leaves when shaken at 150 rpm for 60 min. The applicability of the three equilibrium isotherm models was investigated and the data obtained fitted the three investigated isothermal models in the order: Langmuir > Temkin > Freundlich for all the studied metal ions. The adsorption isotherm coefficients, Qmax, b, Kf, n, at, bt were also calculated. Very high regression correlation coefficients (R2 > 0.9) were found for Cu2+, Fe2+ and Zn2+; Cr6+ (Temkin isotherm) when pH (2–8) was varied; Cr6+, Cu2+,Fe2+ and Zn2+ when contact time (15–60 min) was varied; Cu2+ (Langmuir isotherm) Fe2+ (Freundlich and Temkin isotherms) when adsorbent was varied from 2 to 5 g. Results also revealed that among all the studied ions Cr6+ at varied pH and Fe2+ at different adsorbent doses satisfy the Temkin and Freundlich isotherm models to describe the biosorption equilibrium by pine (Pinus roxburghii) adsorbent.
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Önen, V., and E. Yel. "Adsorption of ferrocyanide onto raw and acid-activated clinoptilolite and sepiolite: equilibrium modelling by error minimization." Clay Minerals 48, no. 4 (September 2013): 613–26. http://dx.doi.org/10.1180/claymin.2013.048.4.15.
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AbstractThe experimental data on adsorption of Fe and CN of a ferrocyanide complex onto raw and acid-activated clinoptilolite/sepiolite on the basis of detention time and particle size was modelled by a linear and a non-linear approach. The linearized best-fit isotherm selection method and non-linear error minimization was applied through Freundlich, Langmuir and Temkin isotherms. ERRSQ, MPSD, HYBRID and ARE error functions were minimized by a developed MATLAB script to determine the isotherm parameters in non-linear optimization. The complex was not adsorbed as whole anions but the Fe and CN were adsorbed separately. 0.65 mg Fe/L. min and 4.84 mg CN/L. min initial adsorption rates were achieved with acid activated clinoptilolite. The Fe adsorption was not as successful as CN. The adsorption of Fe and CN was described by Freundlich and Langmuir isotherms respectively. The differences between the predicted isotherm parameter sets of linear models and minimized error function models indicated that both the best-fit isotherm selection and the isotherm constant determinations can be performed properly by error minimization as well as by conventional linear best fit modelling approach.
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Brdar, Mirjana, Aleksandar Takaci, Marina Sciban, and Dusan Rakic. "Isotherms for the adsorption of Cu(II) onto lignin: Comparison of linear and non-linear methods." Chemical Industry 66, no. 4 (2012): 497–503. http://dx.doi.org/10.2298/hemind111114003b.
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Equilibrium studies were carried out for the adsorption of Cu(II) onto Kraft lignin as an adsorbent. The experimental data were fitted to the Freundlich, Langmuir and Redlich-Peterson isotherms by linear and non-linear method. Comparison of linear and non-linear regression method was given in selecting the optimum isotherm for the experimental data. The coefficient of correlation r2 and Chi-square test ?2 was used to select the best linear theoretical isotherm. The best linear model is Redlich-Peterson isotherm model, where r2=0,985 and ?2=0,02. In order to predict the error ERRSQ, HYBRD, MPSD, ARE and EABS were used. Moreover, by minimizing these error functions the optimal values of parameters and also the optimum isotherm was found. The Redlich-Peterson isotherm was found to be the best representative for adsorption of Cu(II) on the adsorbent in the cases when ERRSQ, HYBRD, MPSD functions were used. There coefficients of determination are 0.986, 0.985, 0.984, respectively and Chi-square is 0.02 in all cases. Freundlich isotherms which were obtained by minimization of the ERRSQ, HYBRD, MPSD, ARE and EABS function showed very good agreement with experimental data. In all cases the coefficients of determination are greater than 0.91. Besides, it was observed that non-linear isotherm models were better for representation of equilibrium data than linearized models.
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Owabor, C. N., I. O. Oboh, and F. A. Omiojieahior. "Adsorption Isotherms for Naphthalene on Clay and Silt Soil Fractions: A Comparison of Linear and Nonlinear Methods." Advanced Materials Research 367 (October 2011): 359–64. http://dx.doi.org/10.4028/www.scientific.net/amr.367.359.
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Polycyclic aromatic hydrocarbons occur naturally in petroleum oil and coal and the burning of fuel and the activities of paper mills also release these compounds to the environment. Batch experimental adsorption study for both soil fractions was conducted in a soil slurry system at ambient temperature, using <0.02mm particle sizes. Comparison was made of the linear least-squares method and a trial-and-error nonlinear method of some widely used isotherm models for the adsorption of naphthalene on clay and silt fractions. The experimental results were fitted to the Langmuir, Freundlich, Radke-Prausnitz, Sips, Temkin and Redlich-Peterson isotherms to obtain their characteristic parameters of each model. The coefficient of determination obtained from the different models using the linear method showed that Freundlich isotherm had the highest values for both clay and silt soil fractions with values of 0.843 and 0.897 respectively. The equilibrium data did not fit the Langmuir isotherm with values of 0.287 and 0.021 for clay and silt soil respectively. Using the nonlinear method the equilibrium data gave good fit for Radke-Prausnitz, Sips, Temkin and Redlich-Peterson isotherms. Sips isotherm gave the best fit for silt soil with the r2value of 0.9779 and this was followed by Temkin isotherm for clay soil with the value of 0.9673.
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Luampon, Ratinun, and Suparerk Charmongkolpradit. "Temperature and relative humidity effect on equilibrium moisture content of cassava pulp." Research in Agricultural Engineering 65, No. 1 (April 12, 2019): 13–19. http://dx.doi.org/10.17221/112/2017-rae.
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The purpose of this research was to study the effect of temperature and relative humidity on the equilibrium moisture content of cassava pulp. In experiments, cassava pulp was tested with a static method that controlled the temperature at 30, 50 and 70°C and controlled relative humidity in a range 10–90% with standard saturated salt solutions as LiCl, MgCl2, NaBr, NaCl and KNO3. Five equations of equilibrium moisture isotherm were analysed to predict the equilibrium moisture content, which was a guideline to develop a new isotherm equation. The experimental results showed that the equilibrium moisture content was increased with increased relative humidity whereas it decreased with increased drying temperature. Therefore, the drying process and storage method of cassava pulp must control temperature and relative humidity of no more than 50°C and 60%, respectively. The analysis of isotherm equations revealed that the new isotherm equation has high accuracy to predict the equilibrium moisture content of cassava pulp and higher R2 correlation with the experimental data than five isotherm equations.
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Chen, Chiachung. "Evaluation of Equilibrium Sorption Isotherm Equations." Open Chemical Engineering Journal 7, no. 1 (December 13, 2013): 24–44. http://dx.doi.org/10.2174/1874123101307010024.
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The sorption isotherm is important information for evaluating the ability of an adsorption system to treat the industrial waste water. In this study, eleven datasets from literatures were selected and three two-parameter and three-parameter equations were used to evaluate adsorption systems. Quantitative criteria included six error functions, and the quantitative criterion was residual plots. Isotherm constants differed by linearization and nonlinear regression analysis, especially for the three-parameter equations. The results indicated the inconsistent results of the error functions for select-ing the adequate equations. Residual plots were useful to observe the fitting ability of isotherm equations. Temperature has a significant effect on isotherm constants.
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Ding, Wei, Shuqin Bai, Haorong Mu, and Gaowa Naren. "Investigation of phosphate removal from aqueous solution by both coal gangues." Water Science and Technology 76, no. 4 (April 25, 2017): 785–92. http://dx.doi.org/10.2166/wst.2017.241.
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Equilibrium studies were carried out for the adsorption of phosphate onto newly discharged coal gangue and spontaneous combustion coal gangue, which are industrial solid residues. The experimental data were fitted to the two-parameter equations of Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich and the three-parameter equations of the Redlich-Peterson, Sips and Toth isotherms by non-linear method. All three-parameter isotherm equations have a higher correlation coefficient than the two-parameter isotherm equations. For new discharged coal gangue, the maximum phosphate adsorption capacity is over 2.504 mg/g (as P), and the best two-parameter isotherm is Freundlich, which indicated multilayer adsorption takes place on the surface. For spontaneous combustion coal gangue, the maximum phosphate adsorption capacity is 7.079 mg/g (as P), two times larger than new discharged coal gangue, and the best two-parameter isotherm is Langmuir, suggesting that the adsorption process occurs on a homogenous surface by monolayer adsorption. The three-parameter isotherm model of Redlich-Peterson shows the best fitting in both cases, but parameter g is 0.6138 in new discharged coal gangue (the parameter g is nearly 1, which means that the equilibrium isotherm behaves as the Langmuir, not as the Freundlich isotherm), g approaches to unity in spontaneous combustion coal gangue, suggesting that the two kinds of coal gangues have different adsorption properties.
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James, François, Mauricio Sepúlveda, and Patrick Valentin. "Statistical Thermodynamics Models for Multicomponent Isothermal Diphasic Equilibria." Mathematical Models and Methods in Applied Sciences 07, no. 01 (February 1997): 1–29. http://dx.doi.org/10.1142/s0218202597000025.
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We propose in this paper a whole family of models for isothermal diphasic equilibrium, which generalize the classical Langmuir isotherm. The main tool to obtain these models is a fine modeling of each phase, which states various constraints on the equilibrium. By writing down the Gibbs conditions of thermodynamical equilibrium for both phases, we are led to a constrained minimization problem, which is solved through the Lagrange multipliers. If one of the phases is an ideal solution, we can solve explicitly the equations, and obtain an analytic model. In the most general case, we have implicit formulas, and the models are computed numerically. The models of multicomponent isotherm we obtain in this paper are designed for chromatography, but can be adapted mutatis mutandis to other cases.
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Nieszporek, Krzysztof, and Tomasz Banach. "Theoretical prediction of gas adsorption kinetics based on equilibrium data." Canadian Journal of Chemistry 90, no. 10 (October 2012): 828–35. http://dx.doi.org/10.1139/v2012-064.
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Based on the equilibrium adsorption isotherms, new expressions describing the rate of adsorption were developed. The theoretical model takes into account the influence of diffusional effects on the rate of adsorption. Other nonideal effects such as surface energetic heterogeneity or intermolecular interactions can be taken into account by using the adequate equilibrium isotherm. The accuracy of the presented rate equations was verified using real adsorption systems.
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Yang, Zi Ze, Wang Xiao, Chun Ma, Li Hua Lv, Chun Yan Wei, and Byung Gil Min. "Kinetics and Thermodynamics of Cd(II) Sorption onto Sodium Alginate/Poly(Vinyl Alcohol)/Hydroxyapatite Composite Fiber." Materials Science Forum 743-744 (January 2013): 480–85. http://dx.doi.org/10.4028/www.scientific.net/msf.743-744.480.
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In this paper, the sodium alginate (SA)/poly (vinylalcohol)(PVA)/hydroxyapatite (HAp) fiber was prepared via solution spinning. The adsorption properties of SA/PVA/HAp composite fiber were studied,and the adsorption kinetics and isotherms were investigated. The experimental results showed that the adsorption process was fast, in which half-equilibrium and equilibrium was obtained in 5 and 30 minutes, respectively. The pseudo-second-order kinetic model provided a better correlation of the experimental results. Both of Langmuir isotherm and Freundlich isotherm could describe the adsorption behavior of SA/PVA/HAp composite fiber towards cadmium. The positive H° value and increased absolute value of the G° with temperature indicate that high temperature is good to the adsorption process.
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Ou, Hong Xiang, Yu Jun Song, Ling Rui Li, and Wei Hong Huang. "Adsorption of Pb(II) by Silica/Yeast Composites from Aqueous Solution: Kinetic and Equilibrium Studies." Advanced Materials Research 496 (March 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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Burden, Conrad J., Yvonne E. Pittelkow, and Susan R. Wilson. "Statistical Analysis of Adsorption Models for Oligonucleotide Microarrays." Statistical Applications in Genetics and Molecular Biology 3, no. 1 (January 9, 2004): 1–27. http://dx.doi.org/10.2202/1544-6115.1095.
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Recent analyses have shown that the relationship between intensity measurements from high density oligonucleotide microarrays and known concentration is non linear. Thus many measurements of so-called gene expression are neither measures of transcript nor mRNA concentration as might be expected.Intensity as measured in such microarrays is a measurement of fluorescent dye attached to probe-target duplexes formed during hybridization of a sample to the probes on the microarray. We develop several dynamic adsorption models relating fluorescent dye intensity to target RNA concentration, the simplest of which is the equilibrium Langmuir isotherm, or hyperbolic response function. Using data from the Affymerix HG-U95A Latin Square experiment, we evaluate various physical models, including equilibrium and non-equilibrium models, by applying maximum likelihood methods. We show that for these data, equilibrium Langmuir isotherms with probe dependent parameters are appropriate. We describe how probe sequence information may then be used to estimate the parameters of the Langmuir isotherm in order to provide an improved measure of absolute target concentration.
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CASTRO, Douglas Azevedo, Douglas Henrique PEREIRA, and Paulo Vitor Brandão LEAL. "LANGMUIR ISOTHERM: KINETIC AND EQUILIBRIUM CONSIDERATIONS." Periódico Tchê Química 16, no. 31 (January 20, 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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Luthra, Kaushik, Soraya Shafiekhani, Sammy S. Sadaka, and Griffiths G. Atungulu. "Determination of Moisture Sorption Isotherms of Rice and Husk Flour Composites." Applied Engineering in Agriculture 36, no. 6 (2020): 859–67. http://dx.doi.org/10.13031/aea.13822.
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HighlightsMoisture sorption isotherms of rice and husk flour composites were determined.Adsorption isotherms were best modeled by the Chung-Pfost and Oswin equations.Desorption isotherms were best modeled by the Polynomial and Chung-Pfost equations.The Modified Oswin model was the best for both adsorption and desorption.Abstract. Empirical models describing isotherms specifically for adsorption and desorption have not been described for rough rice and husk flour composites. Such models are vital for process control and monitoring operations which use rice husk and rice flours or their mixtures for food or material processing. The current study was undertaken to determine the moisture sorption isotherms of rice husk flour, rough rice flour and their mixtures subjected to different temperature levels. Effects of rice husk flour to rough rice flour ratio of 0:1 (0.0%), 1:49 (2.0%), 1:16 (5.9%), and 1:0 g/g (100.0%) on rough rice moisture isotherms at temperature levels of 20°C, 40°C, and 60°C were investigated. The dynamic dewpoint isotherm technique (DDI) was used to generate accurate isotherms. Several empirical models were tested to fit the experimental EMC data. All the isotherms showed typical sigmoidal type 2 shapes. The equilibrium moisture content (EMC) over equilibrium relative humidity (water activity) ranging from 10% to 95% showed temperature dependence. Hysteresis was evident for all samples, with a decreasing level at a higher temperature. Rice husk flour to rough rice flour ratio, as a factor, showed a significant effect on the EMC of rough rice. The EMC decreased with an increase in rice husk flour levels. Chung-Pfost and Oswin were the two best models for describing adsorption isotherm, and Polynomial and Chung-Pfost were the best models for fitting the desorption isotherm. Modified Oswin model was the best model amongst the two-variable models for describing both adsorption and desorption isotherms. Keywords: Empirical models, Equilibrium moisture content, Rice husk flour, Rough rice flour, Sorption isotherms.
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Overah, L. C. "Nonlinear Kinetic and Equilibrium Adsorption Isotherm Study of Cadmium (II) Sorption by Dacryodes edulis Biomass." Nigerian Journal of Basic and Applied Sciences 28, no. 2 (April 26, 2021): 10–19. http://dx.doi.org/10.4314/njbas.v28i2.2.
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The kinetics and equilibrium adsorption isotherm of cadmium (II) adsorption onto Dacryodes edulis (native peer seed) biomass was studied using a nonlinear approach, which is unpopular but proven in some literature to be more reliable and easier. In optimizing the process, about 98% removal of the cadmium ion was achieved within five minutes at pH 7 by contacting just 30 mg of the Dacryodes edulis seed biomass with the adsorbate solution of a concentration of 100 mg/L. Non-linear investigation of the kinetics and adsorption isotherms of the process was done using the R console statistical and computing software. The results indicated that the Elovich mechanism and the Freundlich adsorption isotherm most suitably described the kinetics and adsorption isotherm, respectively, of the process as provided by their least values of the sum of squared residuals (SSR). This outcome implied a chemical adsorption (chemisorption) mechanism and a multi-layer coverage by the cadmium ions on heterogeneous active sites of the biomass surface with a Freundlich constant or capacity factor, Kf of 27.83 mg g-1, heterogeneity factor, 1/n of 0.2614 and Elovich constants, α and β of 7.0 mg g−1 s−1 and 1.0 g mg-1, respectively. These findings indicate that Dacryodes edulis seed biomass has a good potential for cadmium (II) adsorption.
Keywords: Dacryodes edulis, Elovich kinetic model, Freundlich isotherm, Langmuir isotherm, Nonlinear
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Fodeke, A. A., and O. J. Ayejuyone. "Adsorption of methylene blue on corncob charcoal: Thermodynamic studies." Ife Journal of Science 23, no. 1 (May 3, 2021): 131–44. http://dx.doi.org/10.4314/ijs.v23i1.13.
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To obtain the thermodynamic properties of adsorption of methylene blue (MB) on corncob carbonaceous adsorbents - untreated (UCC) and acid treated (TCC) - their equilibrium adsorption was determined between 10 o– 40o C at different pH conditions. The adsorption isotherms were fitted to Freundlich, Langmuir and Temkin isotherm models. The point of zero charge of each of the adsorbents was also determined. The point of zero charge was 10.58 ±0.09 for TCC, and 7.55 ± 0.10 for UCC. Only Freundlich model could account for the observed thermodynamic properties of MB adsorption by the adsorbents, though Temkin and Langmuir models have higher correlation coefficients. MB adsorption by TCC was an entropically driven process which depends on pH;ΔSo at pH 10.5 < ΔSo at pH 8.0 <ΔSo at pH 12.0. The ΔHo of the endothermic process at pH 12 is > ΔHo at pH 8 > ΔHo at pH 10.5. The results suggest that MB adsorption by the adsorbents occur by physisorption and is optimum when the pH is around the point of zero charge. It is important to ensure that in addition to fitting and equilibrium adsoption data by an isotherm model, the fit of the relevant equilibrium parameter should also be good and give thermodynamic quantities that could satisfactorily account for the observed adsorption properties of the system. Deciding the suitability of an isotherm model for fitting adsorption equilibrium experiment based on compared error function of the fitted curves or lines through single temperature isotherm could lead to erroneous conclusion.
Keywords: adsorption, adsorbent; methylene blue; enthalpy; entropy; Freundlich
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Dada, A. O., J. O. Ojediran, and Abiodun Paul Olalekan. "Sorption of Pb2+ from Aqueous Solution unto Modified Rice Husk: Isotherms Studies." Advances in Physical Chemistry 2013 (March 18, 2013): 1–6. http://dx.doi.org/10.1155/2013/842425.
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Investigation of the sorption potential of rice husk, an agricultural waste, as an adsorbent was carried out. The rice husk was modified with orthophosphoric acid and was used for adsorption of lead (II) ions (Pb2+) from aqueous solution. Physicochemical properties of the modified rice husk were determined. Equilibrium sorption data were confirmed with Langmuir, Freundlich and Temkin adsorption isotherms. On the basis of adsorption isotherm graphs, R2 values were determined to be 0.995, 0.916, and 0.797 for Langmuir, Temkin, and Freundlich isotherms, respectively, indicating that the data fitted well into the adsorption isotherms, but Langmuir isotherm is a better model. The maximum monolayer coverage from Langmuir studies, Qmax=138.89 mg/g, Langmuir isotherm constant, KL=0.699 L/mg, and the separation factor, RL=1.41×10−2 at 100 mg/L of lead(II) ions indicating that the sorption process, was favourable. The suitability of modified rice husk as an adsorbent for the removal of lead ions from aqueous solution and its potential for pollution control is established.
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Shi, Jingbo, Yasuo Kawai, Stavros Avramidis, Jiabin Cai, and Huijun Dong. "Water sorption hysteresis in wood near 100 °C." Holzforschung 75, no. 1 (January 26, 2021): 13–21. http://dx.doi.org/10.1515/hf-2019-0228.
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AbstractWhether water sorption hysteresis exists above 75 °C and the representation of its relationship with wood softening remains unclear. In this study, sorption hysteresis at three temperature levels, namely, 75, 90 and 99.5 °C, was investigated using accurately controlled conditioning chambers using powder samples from seven wood species. The dry mass loss percentage of the samples and proper equilibrium time was evaluated by pretests to ensure reliable sorption isotherms afterwards. The dry mass loss percentage after the entire sorption isotherm running needs to be kept within 0.5% to avoid complications in determining the equilibrium time. The abrupt increase of equilibrium moisture content at high relative humidity regions and the crossover of adsorption isotherms were not observed. Hysteresis was conspicuous at 75 and 90 °C and was statistically confirmed at 99.5 °C. High sample extractives content or unnecessarily long equilibrium time would cause significant sample dry mass loss, which may suppress the desorption isotherm to an extent that leads to unjustified hysteresis disappearance. The hysteresis behavior observed in this study suggests that wood softening does not necessarily result in hysteresis disappearance, and the explanation of hysteresis progression as a function of wood softening temperature must be evaluated with care in the future.
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Benzaoui, Thouria, Ammar Selatnia, and Djaafar Djabali. "Adsorption of copper (II) ions from aqueous solution using bottom ash of expired drugs incineration." Adsorption Science & Technology 36, no. 1-2 (January 25, 2017): 114–29. http://dx.doi.org/10.1177/0263617416685099.
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The use of bottom ash of expired drugs incineration for removal of Cu(II) ions from aqueous solution has been investigated. Analytical techniques have been employed to find characteristics of adsorbent materials. The removal of Cu(II) was conducted in batch system, and the effects of pH, adsorbent dosage, initial concentrations of copper ions, and contact time on adsorption efficiency were studied. Optimum adsorption was achieved at a pH 5 and equilibrium was established within 15 min of the process. The equilibrium adsorption data were analyzed using eight adsorption isotherm models: Langmuir, Freundlich, Temkin, Redlich–Peterson, Dubinin–Radushkevich, Toth, Harkin–Jura and Halsey isotherms. The energy value obtained by application of Dubinin–Radushkevich model was 2.593 kJ/mol indicating that physisorption was the dominant mechanism of sorption. The values of the correlation coefficient (R2) of the isotherms gave the best fit (>0.99) with the Langmuir, Toth, and Redlich–Peterson isotherms. The adsorption capacity (qm) from the Langmuir isotherm for Cu(II) was found as 13.335 mg/g. The equation constant n of Toth isotherm model is found to be close to 1 (0.945), confirming that the adsorbent studied presents homogeneous surface under conditions used. It is concluded that bottom ash of expired drugs incineration can be used as an effective adsorbent for removing Cu(II) from aqueous solution.
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Hsiao, H. C., S. M. Yih, and M. H. Li. "Adsorption Equilibrium of Xylene Isomers and p-Diethylbenzene in the Liquid Phase on a Y Zeolite." Adsorption Science & Technology 6, no. 2 (June 1989): 64–82. http://dx.doi.org/10.1177/026361748900600202.
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The saturated adsorptive capacity, adsorption equilibrium constant and adsorption isotherms of p-xylene, m-xylene, ethylbenzene (EB) and p-diethylbenzene (PDEB) on a K–BaY zeolite with n-heptane as the solvent have been studied at 25°C. The adsorption isotherms of the six binary pairs of these solutes with n-heptane as the solvent have also been determined at 25°C. The data cover a concentration range of xylene isomers from 0.05–0.3 mmol/ml. The molar adsorption capacity of the K–BaY zeolite for the different sorbates was found to be in the order: p-xylene > EB > m-xylene ≈ PDEB. PDEB is normally used as the desorbent for the Parex process. Three types of isotherm model, i.e. Langmuir, Freundlich and Langmuir–Freundlich, have been used to fit the data. The results indicate that the Langmuir–Freundlich isotherm provides a reasonable representation of the equilibrium data for the xylene isomers on a K–BaY zeolite.
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McKay, Gordon, Mohammed El-Geundi, and Mamdouh M. Nassar. "Adsorption Model for the Removal of Acid Dyes from Effluent by Bagasse Pith Using a Simplified Isotherm." Adsorption Science & Technology 15, no. 10 (November 1997): 737–52. http://dx.doi.org/10.1177/026361749701501002.
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The adsorption of two acid dyes, viz. Acid Red AR114 and Acid Blue AB25, on to bagasse pith, a waste material from the sugar cane industry, has been studied. Equilibrium isotherms and agitated batch contact time studies have been carried out. A mass-transfer model has been used based on a Langmuir-type isotherm at maximum saturation. This simple or pseudo-irreversible isotherm and the assumption of pore diffusion enables a pore diffusion mass-transfer model to theoretically predict the experimental concentration decay curves very rapidly.
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Shim, Wang-Geun, Hyun-Chul Kang, Chan Kim, Jae-Wook Lee, Sang-Chai Kim, Chul-Jin Lee, and Hee Moon. "Heterogeneity Analysis of Single-Walled Carbon Nanotubes from the Adsorption Equilibria of Nitrogen and Benzene." Journal of Nanoscience and Nanotechnology 6, no. 11 (November 1, 2006): 3583–88. http://dx.doi.org/10.1166/jnn.2006.17987.
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Nitrogen adsorption/desorption isotherms and gravimetric methods were employed to examine the structural and adsorption properties of selected adsorbent. The equilibrium data of benzene were also obtained at three different temperatures (303.15, 313.15, and 323.15 K) with pressures up to 7 kPa. The results of nitrogen and benzene sorption isotherm revealed that SWCNTs exhibit type II with the features of type I. The Toth and UNILAN models were found to provide a reasonable correlation between the adsorption isotherm data. In addition, the adsorption second virial coefficient and the isosteric heat of adsorption were determined by using these isotherm models. The isosteric heat of adsorption and adsorption energy distribution indicated that SWCNTs have energetically and structurally heterogeneous surfaces.
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Hong, Yong Pyo, and Keon Sang Ryoo. "Adsorption Of No3--N And Po43--P in Aqueous Solution Using Granular Activated Charcoal (Gac)." JOURNAL OF ADVANCES IN CHEMISTRY 15, no. 2 (December 3, 2018): 6296–305. http://dx.doi.org/10.24297/jac.v15i2.7881.
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In this study, adsorption of NO3- -N and PO43--P on granular activated charcoal (GAC) was investigated depending on pH, agitation time, GAC dosage, adsorption capacity and adsorption isotherms by employing batch adsorption type. The GAC was characterized by thermogravimetric analysis (TG-DTA), scanning electron micrograph coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) and BET surface area analyzer. The GAC exhibited nearly similar adsorption equilibrium time. Both NO3--N and PO43—P appeared to approach equilibrium after approximately 4 h of agitation time. In the adsorption equilibrium, the removal efficiencies of NO3- -N and PO43--P were found to be 14.6-66.0 % and 52.4-99.0 %, respectively. The adsorption data for NO3--N and PO43--P was correlated to Freundlich and Langmuir isotherm model and the equilibrium data was fitted well to the Langmuir isotherm model due to their higher correlation coefficient (R2) value. The Langmuir adsorption capacity was 1.54 and 2.56 mg g-1 for NO3--N and PO43--P, respectively, which suggests that the GAC is a good adsorbent for removal of NO3--N and PO43—P from water.
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Lee, Jun Sian, Shahab Sokhansanj, C. Jim Lim, Anthony Lau, and Tony Bi. "Comparative Analysis of Sorption Isotherms for Wood Pellets and Solid Wood." Applied Engineering in Agriculture 35, no. 4 (2019): 475–79. http://dx.doi.org/10.13031/aea.13238.
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Abstract.The published data on equilibrium moisture content vs. equilibrium relative humidity (EMC-ERH) for wood pellet do not cover the range of temperature and relative humidity to which a pellet is exposed to during its storage and handling. A few published EMC-ERH relations covering a wider range of temperatures and relative humidity are available for solid wood (lumber) and wood chips. The question is whether the data for solid wood is applicable to wood pellets. For this research, we examined the sorption isotherms of wood pellets and solid wood. The analysis shows that EMC for solid wood is higher than the EMC for wood pellet for a relative humidity larger than 30%. The slope of EMC-ERH isotherm for solid wood in the range of 30%-70% is slightly steeper than the slope of isotherm for wood pellet, indicating the pellet’s EMC is less sensitive to ERH when compared to EMC-ERH for solid wood. Keywords: EMC, ERH, Densified biomass, Equilibrium moisture content, Equilibrium relative humidity, Solid wood, Wood pellets.
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Al-Rufaie, M. M., Z. T. A. Alsultani, and A. S. Waheed. "Adsorption kinetics and thermodynamics of Azure C dye from aqueous solution onto activated charcoal." Koroze a ochrana materialu 60, no. 3 (September 1, 2016): 80–85. http://dx.doi.org/10.1515/kom-2016-0013.
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Abstract Adsorption thermodynamics and kinetics of Azure C and from the aqueous solution on activated charcoal was examined. The charcoal was activated by concentrated sulphuric acid and the adsorption kinetic and thermodynamic was tested in batch experiment. An experiments used the adsorption batch method to observe the effect of the variable parameters, i.e. concentration of dye, time of contact, pH, temperature and adsorbent dose. The ideal dosage of adsorbent was 0.3 g for Azure C. The equilibrium state was reached within 60 min for dye Azure C at activated charcoal. The isotherms of equilibrium were investigated to characterize the adsorption operation. The data for the kinetics study were adjusted utilizing the equation of pseudo- second-order and the model of diffusion (intra-particle). All data were evaluated by means of equilibrium Freundlich, Langmuir and Temkin isotherm on activated charcoal surface. Based on the adsorption isotherm evaluation on activated charcoal the result was 4S by using Giles classification. The thermodynamic factors like ΔH, ΔG and ΔS were estimated.
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Journal, Baghdad Science. "Adsorption Study for Trifluralin on Iraqi ? –Alumina." Baghdad Science Journal 9, no. 1 (March 4, 2012): 153–59. http://dx.doi.org/10.21123/bsj.9.1.153-159.
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Equilibrium adsorption isotherm for the removal of trifluralin from aqueous solutions using ? –alumina clay has been studied. The result shows that the isotherms were S3 according Giels classification. The effects of various experimental parameters such as contact time, adsorbent dosage, effect of pH and temperature of trifluralin on the adsorption capacities have been investigated. The adsorption isotherms were obtained by obeying freundlich adsorption isotherm with (R2 = 0.91249-0.8149). The thermodynamic parameters have been calculated by using the adsorption process at five different temperature, the values of ?H, ?G and ?S were (_1.0625) kj. mol-1, (7.628 - 7.831) kj.mol-1 and (_2.7966 - _2.9162) kg. k-1. mol-1 respectively. The kinetic study of adsorption process has been studied depending on three kinetic equations: 1- Allergen equation 2- Morris –weber eguation 3- Reichenberg eguation. In general, the result shows the isotherm were on ?- alumina according to Giels classification.? –alumina and thermodynamic
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Kuipa, Pardon K., and Olga Kuipa. "Removal of Pyrethrin from Aqueous Effluents by Adsorptive Micellar Flocculation." Journal of Chemistry 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/735631.
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The equilibrium adsorption of pyrethrin onto aggregates formed by the flocculation of micelles of the surfactant sodium dodecyl sulphate (SDS) with aluminium sulphate is reported. The experimental results were analysed using different adsorption isotherms (Langmuir, Freundlich, Redlich-Peterson, Sips, Radke-Prausnitz, Temkin, linear equilibrium, and the Dubin-Radushkevich isotherms). The Freundlich and linear equilibrium isotherms best describe the adsorption of pyrethrin onto SDS micellar flocs, with the Freundlich adsorption constant,KF, and the mass distribution coefficient,KD, of 64.266 ((mg/g)(L/mg)1/n) and 119.65 L/g, respectively. Applicability of the Freundlich adsorption model suggests that heterogeneous surface adsorption affects the adsorption. The mean free energy value estimated using the Dubinin-Radushkevich isotherm was 0.136 kJ/mol indicating that physisorption may be predominant in the adsorption process.
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Borys, Przemysław, and Zbigniew J. Grzywna. "On the fractality of the Freundlich adsorption isotherm in equilibrium and non-equilibrium cases." Physical Chemistry Chemical Physics 18, no. 30 (2016): 20784–89. http://dx.doi.org/10.1039/c6cp03356c.
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Ugbe, Fabian Audu, Patrick Onuh Anebi, and Victoria Abiola Ikudayisi. "Biosorption of an Anionic Dye, Eosin Yellow onto Pineapple Peels: Isotherm and Thermodynamic Study." International Annals of Science 4, no. 1 (February 4, 2018): 14–19. http://dx.doi.org/10.21467/ias.4.1.14-19.
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Eosin Yellow (EY), an anionic dye (acid dye) was adsorbed using an agricultural waste, pineapple peels (PP) as bio-sorbent in order to investigate its suitability as an alternative adsorbent, and to give insight into the mechanisms of binding. The study includes: equilibrium isotherms and thermodynamics studies. The adsorption isotherm and thermodynamics experiments were conducted using batch equilibrium techniques. The adsorption data were fitted into Langmuir, Freundlich and Temkin isotherm models; as a result, the data fitted well into the Langmuir model from which the adsorption capacity, qe was obtained as 11.76 mg/g. Experimental values of the thermodynamics parameters (ΔH, ΔS and ΔG) and separation factor (RL) in combination suggested that the adsorption process was endothermic, feasible, spontaneous, and had high degree of freedom. Combined results of the isotherms and thermodynamic study suggested a physisorption-chemisorption mechanism for the adsorption process. Therefore, the results of the study could provide useful information to evaluate the raw pineapple peel powder as a cheap source of adsorbent for the removal of EY from waste water.
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Ge, Mingliang, Xubin Wang, Mingyi Du, Guodong Liang, Guoqing Hu, and Jahangir S.M. "Adsorption Analyses of Phenol from Aqueous Solutions Using Magadiite Modified with Organo-Functional Groups: Kinetic and Equilibrium Studies." Materials 12, no. 1 (December 28, 2018): 96. http://dx.doi.org/10.3390/ma12010096.
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Organically-modified magadiite (MAG–CTAB–KH550) was synthesized via ion-exchange method and condensation reaction in the presence of pure magadiite (MAG), cetyltrimethylammonium bromide (CTAB) and γ-aminopropyltriethoxysilane (KH550) in aqueous solution in this research. This new adsorbent material was studied using scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and N2 adsorption/desorption isotherms process. It was found that the MAG–CTAB–KH550 has high Brunaur-Emmet-Teller (BET) specific surface area and mesoporous pore size distribution which enhanced its ability to remove phenol in aqueous solution; and, the value of pH has a relatively large impact on the adsorption behavior of the sorbent. Finally, the adsorptive behavior of the mesoporous material on phenol was followed pseudo-second-order kinetic adsorption model. In contrast, the adsorption equilibrium isotherm was better performed Langmuir isotherm model than the Freundlich isotherm model; in addition, the results also showed that the MAG–CTAB–KH550 had a better adsorption capacity and removal efficiency than MAG.
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Dong Chen, Xiao. "A new water sorption equilibrium isotherm model." Food Research International 30, no. 10 (December 1997): 755–59. http://dx.doi.org/10.1016/s0963-9969(98)00042-8.
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Asnaoui, H., A. Laaziri, and M. Khalis. "Study of the kinetics and the adsorption isotherm of cadmium(II) from aqueous solution using green algae (Ulva lactuca) biomass." Water Science and Technology 72, no. 9 (July 15, 2015): 1505–15. http://dx.doi.org/10.2166/wst.2015.359.
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Batch experiments were conducted to study the adsorption of hazardous cadmium onto low-cost algae biomass in aqueous solution with respect to concentration of adsorbate, adsorbent dosage, contact time, solution pH and temperature. Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The activation energy of adsorption was also evaluated for the adsorption of cadmium onto Ulva lactuca biomass. Experimental data were tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results showed that the biosorption processes of Cd(II) followed well pseudo-second-order kinetics. Langmuir and Freundlich models were applied to describe the biosorption isotherm of the metal ions by Ulva lactuca biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The biosorption capacity of Ulva lactuca biomass for cadmium was found to be 3.02 mg/g at pH 5.60 min equilibrium time and 20 °C. The mean free energy which was calculated was 6.24 kJ/mol for Cd(II) biosorption, which shows that the adsorption is physical. The calculated thermodynamic parameters (ΔG0, ΔH0 and ΔS0) showed that the biosorption of Cd(II) onto Ulva lactuca biomass was feasible, spontaneous and exothermic under examined conditions. The results indicate that algae Ulva lactuca could be employed as a low-cost material for the removal of metal ions from aqueous solution.
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Yildiz, Sayiter. "Kinetic and Isotherm Analysis of Cu(II) Adsorption onto Almond Shell (Prunus Dulcis)." Ecological Chemistry and Engineering S 24, no. 1 (March 1, 2017): 87–106. http://dx.doi.org/10.1515/eces-2017-0007.
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Abstract In the work, adsorption of Cu2+ ions onto almond shell were investigated under different operational conditions. Almond shell was used without any pretreatment prior to the tests. The optimum conditions for adsorption of Cu2+ ions through almond shell were determined to be; pH 5.0, temperature 20°C, shaking rate 125 rpm, sorbent dose 0.3 g and initial Cu2+ ion concentration 50 mg/dm3. The equilibrium duration of the system was 60 minutes. The sorption capacities of the sorbents were predicted with the aid of equilibrium and kinetic models. The interactions of peanut shell with metal ions were constituted by SEM, EDX, FT-IR, XRD and AFM. The pseudo-first-order, pseudo-second-order, Weber-Morris, Elovich model and Bangham kinetic models were applied to test the experimental data. The Cu+2 ions adsorption onto almond shell was better defined by the pseudo-second-order kinetic model, for initial pH. The equilibrium data were evaluated using Langmuir, Freundlich, Temkin, D-R and Harkins Jura isotherms. The highest R2 value in isotherm studies was obtained from Langmiur isotherm (R2 = 0.98) for the inlet concentration.
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Chen, Jianlong, and Xinwei Lu. "Equilibrium and kinetics studies of Cd(II) sorption on zeolite NaX synthesized from coal gangue." Journal of Water Reuse and Desalination 8, no. 1 (December 17, 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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Vasudevan, S., and J. Lakshmi. "Studies relating to an electrochemically assisted coagulation for the removal of chromium from water using zinc anode." Water Supply 11, no. 2 (April 1, 2011): 142–50. http://dx.doi.org/10.2166/ws.2011.032.
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In this work, an electrochemically assisted coagulation for the removal of chromium from water has been studied using zinc as anode and galvanized iron as cathode. The effects of pH, current density, concentration of chromium, temperature, adsorption kinetics and isotherms on the removal of chromium were investigated. The results showed that the optimum removal efficiency of 96.5% was achieved at a current density of 0.2 A/dm2, at a pH of 7.0. First- and second-order rate equations, Elovich and intraparticle diffusion models were applied to study adsorption kinetics. The adsorption process follows second-order kinetics model with good correlation. An equilibrium isotherm was measured experimentally and the results were analyzed by the Langmuir, Freundlich and Dubinin-Redushkevich model using linearized correlation co-efficient. The Langmuir adsorption isotherm was found to fit the equilibrium data for chromium adsorption. Temperature studies showed that the adsorption was endothermic and spontaneous in nature.
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Vijayakumaran, V., S. Arivoli, and S. Ramuthai. "Adsorption of Nickel Ion by Low Cost Carbon-Kinetic, Thermodynamic and Equilibrium Studies." E-Journal of Chemistry 6, s1 (2009): S347—S357. http://dx.doi.org/10.1155/2009/878037.
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A carbonaceous adsorbent prepared from an indigenous waste, by acid treatment was tested for its efficiency in removing nickel ion. The process parameters studied include agitation time, initial metal ion concentration, carbon dose, pH and temperature. The adsorption followed first order reaction equation and the rate is mainly controlled by intraparticle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacity (Qm) obtained from the Langmuir isotherm plot were found to around 43 mg/g at an initial pH of 7.0. The temperature variation study showed that the nickel ions adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying the pH of the nickel ion solutions. The Langmuir and Freundlich adsorption isotherms obtained, positive ΔH0value, pH dependent results and desorption of metal ions in mineral acid suggest that the adsorption of nickel ion on MCC involves chemisorption as well as physisorption mechanism.
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Chen, Chiachung. "Validation of the Component Model for Prediction of Moisture Sorption Isotherms of Two Herbs and other Products." Foods 8, no. 6 (June 1, 2019): 191. http://dx.doi.org/10.3390/foods8060191.
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Sorption isotherm is an essential property for the processing of biological materials. In this study, a component model for the prediction of the sorption isotherm was evaluated. In order to validate this component model, the moisture sorption isotherms for Chrysanthemum morifolium flowers and the orchid Anoectochilus formosanus Hayata were determined. The sorption isotherm was measured by using the equilibrium relative humidity technique for five temperatures. Seven sorption isotherm models were selected with four quantitative criteria and residual plots to evaluate fitting ability and prediction performance for these products. The results indicated that the sorption temperature did not significantly affect the adsorption isotherm. The Caurie and Henderson equations could be used for C. morifolium flowers and A. formosanus Hayata. The isotherm data of raw bamboo, elecampe and three varieties of corn kernels from the literature were adopted to validate the component model. Comparing with the predicted values of component values and actual isotherm moisture, the component model has good predictive ability at the aw range smaller than 0.7. Considering the practical application, the aw range below 0.7 is the main range for the processing of agricultural products, and the predictive values of this component model could be helpful for food engineering and for the food industry.
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Xue, Hai Yan, Fang Han, and Bao Yuan He. "Biosorption of Food Dye onto Gelatin Microspheres: Equilibrium Isotherm and Thermodynamic Analysis." Advanced Materials Research 476-478 (February 2012): 2239–42. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.2239.
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Gelatin microspheres (GMSs) were prepared by the inverse suspension cross-linking reaction, using glutaraldehyde as the cross-linking reagent. The GMSs was characterised by scanning electron microscopy and FTIR spectra. Langmuir, Freundlich isotherms were used to analyze the adsorption equilibrium of the food red 3 (FR3) onto GMSs and related correlation coefficients have been determined at different temperatures. The adsorption data fitted well with Langmuir isotherm model and the adsorption of FR3 onto GMSs is a favorable process. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° have also been evaluated and it has been proved that the adsorption process is spontaneous and endothermic.
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He, Shao Hua, Dan Wang, Qing Qiu Kong, and Xi Wu. "Thermodynamic Studies for Adsorption of Cd2+ and Pb2+ from Waster Water on Modified Walnut Shell." Applied Mechanics and Materials 737 (March 2015): 622–26. http://dx.doi.org/10.4028/www.scientific.net/amm.737.622.
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The adsorption isothermal curve and thermodynamic adsorption of Cd2+ and Pb2+ on modified walnut shell from waster water were investigated using batch technique. The equilibrium adsorption data are fitted to Langmuir and Freundlich isotherm models and the model parameters are evaluated. The Langmuir isotherm model shows a better fit to adsorption data than the Freundlich isotherm model for the sorption of Cd2+ and Pb2+ on modified walnut shell. The maximum adsorption capacity of Cd2+ and Pb2+ by modified walnut shell is found to be 32.68 mg·g-1 and 84.75 mg·g-1 at 298K temperature, respectively. The adsorption processes of Cd2+ and Pb2+ has feasibility and spontaneous nature. Thermodynamic parameters depict the endothermic nature of sorption and the process is spontaneous and favorable.
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Downarowicz, Dorota, and Katarzyna Ziętarska. "Adsorption of propan-1-ol vapour on Sorbonorit 4 activated carbon – equilibrium and dynamic studies." Polish Journal of Chemical Technology 19, no. 4 (December 1, 2017): 59–64. http://dx.doi.org/10.1515/pjct-2017-0068.
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Abstract The study examined the adsorption of propan-1-ol (1PN) vapour on Sorbonorit 4 (S4) activated carbon in cyclic Electrothermal Temperature Swing Adsorption (ETSA) process. Dynamic adsorption capacity and breakthrough time were determined based on column studies. Thomas model was used to describe experimental breakthrough curves. Adsorption isotherms for 1PN vapour on S4 activated carbon were tested at 293 to 413 K. The experimental data were examined by using three multi-temperature isotherm models: Toth, Sips and hybrid Langmuir-Sips. Results indicate that S4 activated carbon is a heterogeneous adsorbent and the hybrid Langmuir-Sips model provides the best-fit experimental data. The energy requirement for 1PN electrothermal desorption from S4 bed (ca. 170–200 kJ/mol) was about 3 to 3.5 times larger than the isosteric heat of adsorption (56.8 kJ/mol), which was calculated using Toth adsorption isotherm.
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Fu, Dan. "Study on Fly Ash for Oil-Containing Wastewater Treatment." Applied Mechanics and Materials 448-453 (October 2013): 1408–11. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.1408.
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In this paper, the adsorption properties of oil-containing wastewater on Fly Ash （FA）were investigated. The effects of contact time, adsorbent dosage, pH value and the temperature were examined. The equilibrium adsorption data are analyzed using Langmuir and Freundlich isotherms. The Langmuir isotherm fits the experimental results well. The study indicates that FA is a potential adsorbent for oil-containing wastewater treatment.
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Bordoloi, Neonjyoti, Manash Deep Dey, Rupak Mukhopadhyay, and Rupam Kataki. "Adsorption of Methylene blue and Rhodamine B by using biochar derived from Pongamia glabra seed cover." Water Science and Technology 77, no. 3 (November 13, 2017): 638–46. http://dx.doi.org/10.2166/wst.2017.579.
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Abstract Biochar obtained through the pyrolysis of Pongamia glabra seed cover (PGSC) at 550 °C with a heating rate of 40 °C/min was characterized and its ability to adsorb the dyes Methylene blue (MB) and Rhodamine B (RB) from aqueous solutions was investigated. The effect of pH, temperature and initial concentration of the dyes on adsorption behavior were investigated. The equilibrium sorption data were analyzed by using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherms. Equilibrium data were well fitted for D-R isotherm in case of MB and Langmuir isotherm in case of RB dyes. The kinetics of dye adsorption on PGSC biochar was well described by applying pseudo-second-order rate equations. The surface of adsorbent before and after the removal of dyes was characterized by using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis. The study suggested that PGSC biochar could be used as a highly efficient adsorbent for the removal of synthetic dyes.
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Xu, Hong Ying, and Chan Zhang. "Kinetic and Equilibrium of Biosorption of Methylene Blue by Anaerobic Granular Sludge in Wastewater." Advanced Materials Research 550-553 (July 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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Mohammed, H. J., B. J. Kadhim, and Aseel Sh Mohammed. "Adsorption Study of Some Sulphanilic Azo Dyes on Charcoal." E-Journal of Chemistry 8, no. 2 (2011): 739–47. http://dx.doi.org/10.1155/2011/487287.
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Studies on the removal of two dyes (sulphanilic azo antipyrine and sulphanilic azo imidazole) from aqueous solution by adsorption on charcoal as an adsorbent were carried out. A series of experiments were under taken in a batch adsorption technique to access the effect of the process variablesi.e. contact time, initial dye concentration, initial pH, adsorbent dose and temperature. Adsorbent dosage (0.1 g) higher value for both dyes. The equilibrium in the solution was observed within (35 min) of two sulphanilic dyes on charcoal. The equilibrium isotherms for both dyes were determined to describe the adsorption process. The results showed that the equilibrium data was fitted by of the Freundlich isotherms on charcoal surface. The result obtained shows that the adsorption isotherm for both dyes on charcoal was according to Giles classification. The thermodynamic factors such as ∆Η, ∆G and ∆S were calculated.
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Al Mamun, Abdullah, Yehya M. Ahmed, Ma'an Fahmi R. AlKhatib, Ahmad Tariq Jameel, and Mohammed Abdul Hakeem Abdul Rahman AlSaadi. "Lead Sorption by Carbon Nanofibers Grown on Powdered Activated Carbon — Kinetics and Equilibrium." Nano 10, no. 02 (February 2015): 1550017. http://dx.doi.org/10.1142/s1793292015500174.
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Carbon nanofibers (CNFs) were synthesized by using a safe and less hazardous method, compared to using floating catalysts in chemical vapor deposition (CVD) process. This process used C 2 H 2 as carbon source and oil palm kernel shell-based powdered activated carbon (PAC) as cheap solid substrate. Use of nickel ( Ni 2+) impregnated PAC as fixed substrate for the synthesis of CNF is one of the novelties of the research work accomplished by the authors. The PAC–CNFs porous nanocomposite product was used for the sorption of lead ions ( Pb 2+) from synthetic aqueous solution. Kinetics of Pb 2+ adsorption and isotherms were investigated by varying initial concentration of lead and contact time. PAC–CNFs were found to remove Pb 2+ better at acidic pH of about 5.5. Langmuir and Freundlich isotherms were applied to the sorption equilibrium data to find the best fitted model. Langmuir isotherm model with R2 = 0.965 fitted the adsorption data better than the Freundlich isotherm. The kinetic processes of Pb 2+ adsorption on CNFs were investigated by applying different kinetic models, namely zero-order, pseudo-first-order and pseudo-second-order. The pseudo-second-order rate equation exhibited the best results with R2 = 0.999, qe = 74.79 (mg/g) and K2 = 0.029 (min ⋅ g/mg). The novel nanocomposite product seemed to have the potential to remove Pb 2+ ions from aqueous solution.
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Luo, An Kai, Xue Gang Luo, and Xiao Yan Lin. "The Adsorption of Cd(II) Ions on Sodium Hydroxide-Treated Bamboo Powder." Materials Science Forum 695 (July 2011): 73–76. http://dx.doi.org/10.4028/www.scientific.net/msf.695.73.
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The adsorption of Cd(II) ions from aqueous solution by sodium hydroxide-treated bamboo powder（STB） was studied in a batch adsorption system. Characteristics of STB were investigated by scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). Factors influencing adsorption such as pH of the solution, adsorbent dosage, cadmium concentration and temperature have been studied. The adsorption process was relatively fast and equilibrium was achieved after 120 min, and the maximum adsorption of Cd(II) ions occurred at around pH 6.5. The equilibrium data were fitted using Langmuir, Temkin and Freundlich isotherm models to calculate isotherm constants. And the adsorption isotherm fitted well Langmuir isotherm, and the maximum adsorption capacity was 8.987 mg/g.
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Ruthiraan, M., E. C. Abdullah, N. M. Mubarak, and Sabzoi Nizamuddin. "Adsorptive Removal of Methylene Blue Using Magnetic Biochar Derived from Agricultural Waste Biomass: Equilibrium, Isotherm, Kinetic Study." International Journal of Nanoscience 17, no. 05 (October 2018): 1850002. http://dx.doi.org/10.1142/s0219581x18500023.
Full textAbstract:
Wastewater discharge from textile industries contribute much to water pollution and threaten the aqua ecosystem balance. Synthesis of agriculture waste based adsorbent is a smart move toward overcoming the critical environmental issues as well as a good waste management process implied. This research work describes the adsorption of methylene blue dye from aqueous solution on nickel oxide attached magnetic biochar derived from mangosteen peel. A series of characterization methods was employed such as FTIR, FESEM analysis and BET surface area analyzer to understand the adsorbent behavior produced at a heating temperature of 800[Formula: see text]C for 20[Formula: see text]min duration. The adsorbate pH value was varied to investigate the adsorption kinetic trend and the isotherm models were developed by determining the equilibrium adsorption capacity at varied adsorbate initial concentration. Equilibrium adsorption isotherm models were measured for single component system and the calculated data were analyzed by using Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich isotherm equations. The Langmuir, Freundlich and Tempkin isotherm model exhibit a promising R2-correlation value of more than 0.95 for all three isotherm models. The Langmuir isotherm model reflectsan equilibrium adsorption capacity of 22.883[Formula: see text]mg[Formula: see text]g[Formula: see text].