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1
Rahman, Muttakin, Pal, Shafiullah, and Saha. "A Statistical Approach to Determine Optimal Models for IUPAC-Classified Adsorption Isotherms." Energies 12, no. 23 (November 29, 2019): 4565. http://dx.doi.org/10.3390/en12234565.
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Adsorption heat transformation (AHT) systems can play a major role in protecting our environment by decreasing the usage of fossil fuels and utilizing natural and alternative working fluids. The adsorption isotherm is the most important feature in characterizing an AHT system. There are eight types of International Union of Pure and Applied Chemistry (IUPAC) classified adsorption isotherms for different “adsorbent-adsorbate” pairs with numerous empirical or semi-empirical mathematical models to fit them. Researchers face difficulties in choosing the best isotherm model to describe their experimental findings as there are several models for a single type of adsorption isotherm. This study presents the optimal models for all eight types of isotherms employing several useful statistical approaches such as average error; confidence interval (CI), information criterion (ICs), and proportion tests using bootstrap sampling. Isotherm data of 13 working pairs (which include all eight types of IUPAC isotherms) for AHT applications are extracted from literature and fitted with appropriate models using two error functions. It was found that modified Brunauer–Emmet–Teller (BET) for Type-I(a) and Type-II; Tóth for Type-I(b); GAB for Type-III; Ng et al. model for Type-IV(a) and Type-IV(b); Sun and Chakraborty model for Type-V; and Yahia et al. model for Type-VI are the most appropriate as they ensure less information loss compared to other models. Moreover; the findings are affirmed using selection probability; overall; and pairwise proportion tests. The present findings are important in the rigorous analysis of isotherm data.
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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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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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Costa, Joyce Maria Gomes da, Jefferson Luiz Gomes Corrêa, Bruno Elyeser Fonseca, Flávio Meira Borém, and Soraia Vilela Borges. "DRYING AND ISOTHERMS OF SUGAR CANE BAGASSE - DOI: 10.13083/1414-3984/reveng.v23n2p128-142." REVISTA ENGENHARIA NA AGRICULTURA - REVENG 23, no. 2 (April 30, 2015): 128–42. http://dx.doi.org/10.13083/reveng.v23i2.504.
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Sugarcane is nowadays considered an important source of energy. One of its products is sugarcane bagasse. Bagasse is largely used as a boiler fuel. The goal of this work was to study bagasse drying in a fixed bed and its desorption isotherm. Air was used as drying agent at 40, 50 and 60 ºC at flow rate of 0.9 m s-1. Desorption isotherms were also obtained at 40 and 50 ºC. Several models from literature were tested with regards to their fit to fixed bed drying and desorption isotherm data. The best adjustments were obtained with Modified Page 2 model for drying kinetics and both the Jaafar and Michalowski model and modified Henderson 2 model for the desorption isotherm.
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Liu, Junsheng, and Xin Wang. "Novel Silica-Based Hybrid Adsorbents: Lead(II) Adsorption Isotherms." Scientific World Journal 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/897159.
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Water pollution caused by the lead(II) from the spent liquor has caught much attention. The research from the theoretical model to application fundaments is of vital importance. In this study, lead(II) adsorption isotherms are investigated using a series of hybrid membranes containing mercapto groups (–SH groups) as the hybrid adsorbents. To determine the best fitting equation, the experimental data were analyzed using six two-parameter isotherm equations (i.e., Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, Harkins-Jura, and Halsey isotherm models). It was found that the lead(II) adsorption on these samples followed the Freundlich, Dubinin-Radushkevich (D-R), and Halsey isotherm models. Moreover, the mean free energy of adsorption was calculated using Dubinin-Radushkevich (D-R) isotherm model and it was confirmed that the adsorption process was physical in nature. These findings are very meaningful in the removal of lead(II) ions from water using the hybrid membranes as adsorbents.
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Hussain, Zainab, Zeyad Fadhil, Sameer Kareem, Salam Mohammed, and Emad Yousif. "Removal of Organic Contaminants from Textile Wastewater by Adsorption on Natural Biosorbent." Materials Science Forum 1002 (July 2020): 489–97. http://dx.doi.org/10.4028/www.scientific.net/msf.1002.489.
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In the present study, removal of safranin dye from water bodies was investigated using natural biosorbent (Thyme leaves (TEL)). The influence of multiple factors such as as contact time (15 – 105 mins), adsorbent dose (25 to 350) mg/l , adsorbate dose (5 to 40)mg\L, and temperature (25 to 55)o C were taken for investigation. The adsorption isotherms were described by utilized Langmuir, Freundlich and Dubnin-Radushkevich models, Freundlich isotherm model found to be best suited with experimental data out of 3 isotherm The adsorption process followed pseudo second order model.
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Chen, Qing, Yuanyuan Tian, Peng Li, Changhui Yan, Yu Pang, Li Zheng, Hucheng Deng, Wen Zhou, and Xianghao Meng. "Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation." Journal of Chemistry 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/1496463.
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Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller) adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.
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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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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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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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Sahin, Rubina, and Kavita Tapadia. "Comparison of linear and non-linear models for the adsorption of fluoride onto geo-material: limonite." Water Science and Technology 72, no. 12 (August 27, 2015): 2262–69. http://dx.doi.org/10.2166/wst.2015.449.
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The three widely used isotherms Langmuir, Freundlich and Temkin were examined in an experiment using fluoride (F−) ion adsorption on a geo-material (limonite) at four different temperatures by linear and non-linear models. Comparison of linear and non-linear regression models were given in selecting the optimum isotherm for the experimental results. The coefficient of determination, r2, was used to select the best theoretical isotherm. The four Langmuir linear equations (1, 2, 3, and 4) are discussed. Langmuir isotherm parameters obtained from the four Langmuir linear equations using the linear model differed but they were the same when using the nonlinear model. Langmuir-2 isotherm is one of the linear forms, and it had the highest coefficient of determination (r2 = 0.99) compared to the other Langmuir linear equations (1, 3 and 4) in linear form, whereas, for non-linear, Langmuir-4 fitted best among all the isotherms because it had the highest coefficient of determination (r2 = 0.99). The results showed that the non-linear model may be a better way to obtain the parameters. In the present work, the thermodynamic parameters show that the absorption of fluoride onto limonite is both spontaneous (ΔG < 0) and endothermic (ΔH > 0). Scanning electron microscope and X-ray diffraction images also confirm the adsorption of F− ion onto limonite. The isotherm and kinetic study reveals that limonite can be used as an adsorbent for fluoride removal. In future we can develop new technology for fluoride removal in large scale by using limonite which is cost-effective, eco-friendly and is easily available in the study area.
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Nazreen, Aqila Zulaikha, Junaidah Jai, Sherif Abdulbari Ali, and Norasmah Mohamed Manshor. "Moisture Adsorption Isotherm Model for Edible Food Film Packaging – A Review." Scientific Research Journal 17, no. 2 (August 28, 2020): 221. http://dx.doi.org/10.24191/srj.v17i2.10160.
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Bioplastic has been extensively studied due to its ability to replace synthetic plastics. Its biodegradability is seen as a significant advantage to be used as edible food film packaging. As a food packaging, the film should be able to retain moisture from the food and the surrounding environment. The ability of the film to retain moisture varies with the type of material the film is made of. Moisture sorption isotherms are used to study the moisture content and water activity of food or film packaging at a given temperature. There are many models to describe moisture sorption isotherm. Some researchers modified the models to account for varying temperatures. The purpose of this paper is to review types of adsorption isotherms and the most common models used for film packaging. The general and modified models are described in this paper as well as its best-fit use on film packaging. The advantages of studying adsorption isotherm include shelf-life determination, physical and chemical stability, and others.
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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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Mitrevski, Vangelce, Cvetanka Mitrevska, Vladimir Mijakovski, Ivan Pavkov, and Tale Geramitcioski. "Mathematical modelling of the sorption isotherms of quince." Thermal Science 21, no. 5 (2017): 1965–73. http://dx.doi.org/10.2298/tsci170118095m.
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The moisture adsorption isotherms of quince were determined at four temperatures 15, 30, 45, and 60?C over a range of water activity from 0.110 to 0.920 using the standard static gravimetric method. The experimental data were fitted with generated three parameter sorption isotherm models on Mitrevski et al., and the referent Anderson model known in the scientific and engineering literature as Guggenheim- Anderson-de Boer model. In order to find which models give the best results, large number of numerical experiments was performed. After that, several statistical criteria for estimation and selection of the best sorption isotherm model was used. The performed statistical analysis shows that the generated three parameter model M11 gave the best fit to the sorption data of quince than the referent three parameter Anderson model.
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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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Tavakolipour, Hamid, and Mohsen Mokhtarian. "New approach to the calculation of pistachio powder hysteresis." International Agrophysics 30, no. 2 (April 1, 2016): 245–51. http://dx.doi.org/10.1515/intag-2015-0093.
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Abstract Moisture sorption isotherms for pistachio powder were determined by gravimetric method at temperatures of 15, 25, 35 and 40°C. A selected mathematical models were tested to determine the best suitable model to predict isotherm curve. The results show that Caurie model had the most satisfactory goodness of fit. Also, another purpose of this research was to introduce a new methodology to determine the amount of hysteresis at different temperatures by using best predictive model of isotherm curve based on definite integration method. The results demonstrated that maximum hysteresis is related to the multi-layer water (in the range of water activity 0.2-0.6) which corresponds to the capillary condensation region and this phenomenon decreases with increasing temperature.
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Hastuti, Budi, Mudasir Mudasir, Dwi Siswanta, and Triyono Triyono. "Preparation and Pb(II) Adsorption Properties of Crosslinked Pectin-Carboxymethyl Chitosan Film." Indonesian Journal of Chemistry 15, no. 3 (November 12, 2015): 248–55. http://dx.doi.org/10.22146/ijc.21192.
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A modified pectin has been synthesized by reacting/combining -OH group among pectin and chitosan with BADGE (Bisphenol A diglycidyl ether) crosslinker agent. The structure and morphology of the new material were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray Diffraction (XRD) analysis. Thermogravimetric studies showed an improvement in thermal characteristic. Adsorption experiments were performed in batch processes; sorption isotherms and kinetics were also studied. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherms and isotherm constants for the adsorption of Pb(II) ion onto adsorbent pectin-carboxymethyl chitosan-BADGE (pec-CMC-BADGE). The dynamic study showed that the sorption process followed the second-order kinetic equation. Result indicated also that Pb(II) ion uptake could be well described by the Langmuir and Freundlich adsorption model of pec-CMC-BADGE and CMC with DG° of 25.3 and 23.1 kJ mol-1,respectively, while that of pectin followed Freundlich isotherm with DG° of 16.6 kJ mol-1.
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El maguana, Y., N. Elhadiri, M. Benchanaa, and R. Chikri. "Activated Carbon for Dyes Removal: Modeling and Understanding the Adsorption Process." Journal of Chemistry 2020 (September 14, 2020): 1–9. http://dx.doi.org/10.1155/2020/2096834.
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Batch adsorption experiments have been conducted to investigate the removal of methyl orange from aqueous solution by an activated carbon prepared from prickly pear seed cake by phosphoric acid activation. The adsorption process has been described by using kinetic and isotherm models. The kinetic of adsorption was examined by pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Adsorption isotherm was modeled using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. The adsorption process of methyl orange was well explained by the pseudo-second-order model and Freundlich isotherm. Also, pseudo-n-order model has been applied to estimate the order of adsorption kinetic and it was found equal to 2 which confirm the good accuracy of the pseudo-second order. Moreover, Dubinin–Radushkevich isotherm reveals that the adsorption of methyl orange onto activated carbon was a physisorption process in nature. The adsorption capacity of activated carbon was found to be 336.12 mg/g at temperature 20°C and pH∼7. These results demonstrated that the prickly pear seed cake is a suitable precursor for the preparation of appropriate activated carbon for dyes removal from aqueous solution.
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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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Shojaat, Rahim, Afzal Karimi, Naghi Saadatjoo, and Soheil Aber. "Dye removal from artificial wastewater using heterogeneous bio-fenton system." Chemical Industry and Chemical Engineering Quarterly 23, no. 4 (2017): 447–56. http://dx.doi.org/10.2298/ciceq160621058s.
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In the present study, GOx/MnFe2O4/calcium alginate nano-composite was prepared by the trapping enzyme/nanoparticles in calcium alginate. The prepared absorbent was applied for decolorization of artificial dye wastewater of acid red 14 (AR14) by heterogeneous bio-Fenton system. Kinetic and isotherm studies were carried out. The decolorization of acid red 14 followed the Michaelis- Menten, pseudo-first order and pseudo-second order kinetic models. Good correlation coefficients were obtained by fitting the experimental data to Michaelis- Menten and pseudo-second order kinetic models. The adsorption isotherms were described by Langmuir, Freundlich and Temkin isotherms. Among the three isotherm models, the Freundlich model was fitted with the equilibrium data obtained from adsorption of AR14 onto MnFe2O4/calcium alginate; while Temkin isotherm gave the best correlation for adsorption on MnFe2O4 nanoparticles. The effect of various parameters such as initial pH of solution, initial dye concentration, and contact time on the adsorption of AR14 on MnFe2O4 and MnFe2O4/ /calcium alginate as well as dye enzymatic decomposition was studied. The decolorization of AR14 with initial concentration of 10 mg.L?1 by using GOx/ /MnFe2O4/calcium alginate was 60.17%.
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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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Wang, Jianhong, Qi Zhang, Hao Yang, and Congzhen Qiao. "Adsorptive Desulfurization of Organic Sulfur from Model Fuels by Active Carbon Supported Mn (II): Equilibrium, Kinetics, and Thermodynamics." International Journal of Chemical Engineering 2020 (June 16, 2020): 1–12. http://dx.doi.org/10.1155/2020/2813946.
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Mn (II)/AC adsorbents were prepared by ultrasonic impregnation. The 2 wt. % Mn/AC showed best adsorptive performance, and the optimal adsorption temperature was 313 K. Benzene, methylbenzene, and naphthalene were used to explore the adsorptive selectivity of Mn/AC, indicating that Mn could enhance the adsorptive capacity but could not improve the adsorptive selectivity. The adsorptive mechanism was mostly like to be π-complex. Adsorptive isotherms and kinetics were investigated, and the parameters were calculated. The R2, RMSE, and AICc were used to assess the optimal model. The results showed that Temkin adsorptive isotherm was more suitable to describe the isothermal data; the MPnO kinetics model was more superior to other kinetic models. The order of reaction was between 1 and 2. The outcome of adsorptive thermodynamics indicated that removal of DBT onto Mn/AC was a spontaneous and exothermic process.
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Suriyatem, Rungsiri, and Pornchai Rachtanapun. "Prediction Modeling for Moisture Sorption Isotherms of Rice Starch/Carboxymethyl Cellulose from Durian Rind Blend Films." Applied Mechanics and Materials 431 (October 2013): 32–36. http://dx.doi.org/10.4028/www.scientific.net/amm.431.32.
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Rice starch/carboxymethyl cellulose from durian rind (RS/CMCd) blend films were prepared by solution casting. The effect of different ratios between rice starch and CMCd (100:0, 88:12, 67:33, 50:50, 33:67, 12:88 and 0:100) on moisture sorption isotherm of blend films was investigated. The sorption isotherm of RS/CMCd blend films was determined at various relative humidity (RH) at 25°C. The isotherm curves revealed that the highest equilibrium moisture content (EMC) was obtained from CMCd film, at aw=85. Knowledge of sorption isotherms is important to predict the moisture sorption properties of the filmsviamoisture sorption empirical models. The Lewicki, Peleg, Guggenheim-Anderson-deBoer (GAB), BrunauerEmmettTeller (BET), and Oswin models were tested to fit the experimental data. The root mean squares percentage error (%RMS) of Lewicki, Peleg, GAB, BET and Oswin was in the range of 5.3-83.1, 2.2-20.0, 6.9-20.2, 3.4-26.4 and 4.7-41.2, respectively. The Peleg model was found to be the best fitted model for RS/CMCd blend films.
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Liu, Fengtai, Shanshan Song, Ge Cheng, Wenjing Xiong, Lei Shi, and Yibo Zhang. "MIL-101(Cr) metal–organic framework functionalized with tetraethylenepentamine for potential removal of Uranium (VI) from waste water." Adsorption Science & Technology 36, no. 7-8 (July 30, 2018): 1550–67. http://dx.doi.org/10.1177/0263617418789516.
Full textAbstract:
The metal–organic frameworks material functionalized by grafting amino group of tetraethylenepentamine on the coordinative unsaturated Cr (III) centers is described. The obtained tetraethylenepentamine-functionalized adsorbents with different mass ratios of tetraethylenepentamine have been characterized by scanning electron microscopy, Fourier-transform infrared, X-ray powder diffraction, and N2 adsorption and desorption isotherms. Significantly, MIL-101-tetraethylenepentamine 60% exhibited high adsorption capacity (350 mg/g) for removal of uranium (VI) from water at pH 4.5. At uranium concentration <20 mg/L, the isothermal plot was best represented by Freundlich model. At U(VI) concentration approximately >30 mg/L, the isotherm was best described by Langmuir model.
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Mwevura, Haji, Peter Nkedi-Kizza, Michael Kishimba, and Henrik Kylin. "Adsorption-desorption of chlorpyrifos in soils and sediments from the Rufiji Delta, Tanzania." Western Indian Ocean Journal of Marine Science 19, no. 1 (October 29, 2020): 77–97. http://dx.doi.org/10.4314/wiojms.v19i1.7.
Full textAbstract:
Batch adsorption-desorption equilibrium techniques were used to investigate the adsorption capacity and influence of salinity on partitioning of the insecticide chlorpyrifos between water and soil or water and sediments from the Rufiji Delta. The data were fitted to different adsorption-desorption models and the hysteresis index was calculated using the ratio between the Freundlich exponents for desorption and adsorption, and secondly, the difference in area under the normalized adsorption and desorption isotherms using the maximum adsorbed and solution concentrations. The data showed non-linear adsorption and that chlorpyrifos was strongly adsorbed to soil and sediments from the Rufiji Delta. The linearized adsorption coefficient (KD) and Freundlich adsorption coefficient (Kf) correlated significantly with organic carbon content. Chlorpyrifos adsorption as well as hysteresis calculated by both methods decreased with salinity (i.e. the sediment adsorbs increasing amounts of chlorpyrifos with decreasing salinity). This indicates that settling of freshwater sediments is among the major removal pathways of the chemical from the water column, but increased turbulence during high tides may resuspend settled sediment simultaneously increasing salinity and re-dissolve chlorpyrifos. However, discharge of fresh water, particularly during heavy rains, increases the trapping efficiency of the sediments. The theoretical approach developed showed that the Langmuir model describes the desorption data better than the Freundlich model, and that a better index of hysteresis is one that considers areas under the adsorption and desorption isotherms, provided the desorption isotherm is described by the normalized Langmuir isotherm and the adsorption isotherm by the normalized Freundlich isotherm.
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Liu, Xiangyao, Baohui Wang, Guolin Jing, and Ya'nan Sun. "Adsorption behaviors of methylene blue on sunflower stem pith." Water Science and Technology 79, no. 8 (April 15, 2019): 1458–66. http://dx.doi.org/10.2166/wst.2019.142.
Full textAbstract:
Abstract Adsorption behaviors of methylene blue (MB) from aqueous solution using sunflower stem pith (SSP) as adsorbent were investigated. The effects of adsorption conditions such as adsorption time, initial concentration of MB and dosage of SSP on the detoxification of MB were examined. The equilibrium adsorption data were analyzed using three well-known isotherms: Langmuir, Freundlich and Temkin. The results indicated that the Langmuir isotherm fitted well to the data as compared with another isotherm model. The maximum adsorption capacity calculated by the Langmuir isotherm model was 277 mg/g at 338 K. Kinetic analyses were conducted using pseudo first order, pseudo second order and the Elovich model. The regression results showed that the MB adsorption was described by the pseudo second order model. Different thermodynamic parameters such as Gibb's free energy (ΔGo), standard enthalpy change (ΔHo) and standard entropy change (ΔSo) were also evaluated. The results showed that the detoxification of MB using SSP as adsorbent was feasible, non-spontaneous and exothermic under experimental conditions.
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Bharat, Tadikonda Venkata. "Selection and Configuration of Sorption Isotherm Models in Soils Using Artificial Bees Guided by the Particle Swarm." Advances in Artificial Intelligence 2017 (January 18, 2017): 1–22. http://dx.doi.org/10.1155/2017/3497652.
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A precise estimation of isotherm model parameters and selection of isotherms from the measured data are essential for the fate and transport of toxic contaminants in the environment. Nonlinear least-square techniques are widely used for fitting the isotherm model on the experimental data. However, such conventional techniques pose several limitations in the parameter estimation and the choice of appropriate isotherm model as shown in this paper. It is demonstrated in the present work that the classical deterministic techniques are sensitive to the initial guess and thus the performance is impeded by the presence of local optima. A novel solver based on modified artificial bee-colony (MABC) algorithm is proposed in this work for the selection and configuration of appropriate sorption isotherms. The performance of the proposed solver is compared with the other three solvers based on swarm intelligence for model parameter estimation using measured data from 21 soils. Performance comparison of developed solvers on the measured data reveals that the proposed solver demonstrates excellent convergence capabilities due to the superior exploration-exploitation abilities. The estimated solutions by the proposed solver are almost identical to the mean fitness values obtained over 20 independent runs. The advantages of the proposed solver are presented.
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Rachtanapun, Pornchai, and R. Suriyatem. "Prediction Models for Moisture Sorption Isotherms of Soy Protein Isolate/Carboxymethyl Chitosan/Oleic Acid Blend Films." Advanced Materials Research 506 (April 2012): 595–98. http://dx.doi.org/10.4028/www.scientific.net/amr.506.595.
Full textAbstract:
Soy protein isolate/carboxymethyl chitosan/oleic acid (SPI/CMCH/O) blend films were prepared by solution casting. The effect of various oleic acid content (0, 2.5, 5.0, 10.0, 20.0 pph of SPI and CMCH) on water sorption isotherm of SPI/CMCH base film was investigated. The sorption isotherm of SPI/CMCH/O blend films was evaluated at serveral relative humidity (0, 16, 35, 55 and 76% RH), at 25±1°C. The isotherms showed equilibrium moisture content (%EMC) of SPI/CMCH/O blend films decreased when oleic acid content increased. Understanding of sorption isotherms is an importance for prediction of moisture sorption properties of films via moisture sorption empirical models. Guggenheim-Anderson-de Boer (GAB), BrunauerEmmettTeller (BET) and Oswin sorption models were tested to fit the experimental data. The root mean squares (RMS) of GAB, BET and Oswin were in the range of 68.60-87.02, 22.86-79.38 and 694.78-3797.23, respectively. BET model was found to be the better-fitted model for SPI/CMCH/O blend films at 25±1°C.
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Dorkó, Zsanett, Anett Szakolczai, Blanka Tóth, and George Horvai. "Relationship between Commonly Used Adsorption Isotherm Equations Impedes Isotherm Selection." Periodica Polytechnica Chemical Engineering 61, no. 1 (January 23, 2017): 10. http://dx.doi.org/10.3311/ppch.10103.
Full textAbstract:
If the measured isotherm data of an adsorption system are well described by the Freundlich equation, then they can similarly well be described by the bi-Langmuir or tri-Langmuir model in most practical cases. This is proved by Monte Carlo simulation and by comparison of the mathematical functions of the respective isotherm models.
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Romero-González, Jaime, Jorge L. Gardea-Torresdey, José R. Peralta-Videa, and Elena Rodríguez. "Determination of Equilibrium and Kinetic Parameters of the Adsorption of Cr(III) and Cr(VI) from Aqueous Solutions toAgave LechuguillaBiomass." Bioinorganic Chemistry and Applications 3, no. 1-2 (2005): 55–68. http://dx.doi.org/10.1155/bca.2005.55.
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This investigation reveals the capability ofAgave lechuguillafor trivalent and hexavalent chromium removal from aqueous solutions. Experimentation included pH profile, time dependence, adsorption capacity (KFand QL), adsorption intensity (nand RL) and saturation capacity (qs) studies. Batch experiments were conducted at22°C to characterize and model the adsorption equilibrium as well as biomass adsorption rates. pH 4 was the optimum for Cr(III) binding, while Cr(VI) optimum binding was at pH 2. Time profile experiments indicated that the adsorption of Cr(VI) by lechuguilla biomass was time-dependent and that of Cr(III) was not. Kinetic models demonstrated that a pseudo-second order reaction model best described the kinetic data for Cr(VI). The adsorption isotherms showed that the binding pattern for Cr(VI) followed the Freundlich isotherm model, while that for Cr(III) followed the Langmuir isotherm.
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Yusuff, Adeyinka Sikiru, Lekan Taofeek Popoola, and Idowu Iyabo Olateju. "Application of Parametric Isotherm Models to Quaternary Adsorption System of Phenol, Butanol, Butan-2-ol and 2-Methyl Butan-2-ol." International Journal of Engineering Research in Africa 33 (November 2017): 56–67. http://dx.doi.org/10.4028/www.scientific.net/jera.33.56.
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Equilibrium adsorption of quaternary component mixture (phenol, butanol, butan-2-ol and 2-methyl butan-2-ol) onto activated carbon derived from oil-palm empty fruit bunch was studied. Henry isotherm 2-parameter model was used as an improvement to Langmuir and Freundlich 2-parameter isotherm model. The 3-parameter isotherm models applied to the quaternary adsorption system included Redlich Peterson, Sips and Toth. Trial and error method of excel solver was used to evaluate the parameters in the models. Data fitness was based on correlation coefficient (R2) and average percentage error (APE). For the two-parametric isotherm models, Langmuir predicted the adsorption equilibrium well with APE and R2 values of 0.20883 and 0.9868; 0.007669509 and 0.9338; and 3.64355718 and 0.9410 for butanol, butan-2-ol and 2-methyl butan-2-ol respectively. The maximum mono-layer capacity (qm) obtained from Langmuir model for butanol, butan-2-ol and 2-methyl butan-2-ol adsorption were 3558.962mg/g, 2.064233mg/g and 22.6423mg/g respectively. Sip and Toth fitted excellently well among the three- parametric isotherm models. The Sip isotherm model gives APE and R2 values of 0.010536 and 0.9346; and 5.14458 and 0.9250 for phenol and 2-methyl butan-2-ol respectively. The Toth isotherm model gives APE and R2 values of 4.83521 and 0.9866; and 0.02595 and 0.9411 for butanol and butan-2-ol respectively. The isotherm models prove applicable for the quaternary adsorption system.
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Ilic, Irena, Natasa Jovic-Jovicic, Predrag Bankovic, Zorica Mojovic, Davor Loncarevic, Ivan Grzetic, and Aleksandra Milutinovic-Nikolic. "Adsorption of nicotine from aqueous solutions on montmorillonite and acid-modified montmorillonite." Science of Sintering 51, no. 1 (2019): 93–100. http://dx.doi.org/10.2298/sos1901093i.
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Montmorillonite (Mt) and acid modified montmorillonite (MtA) were tested as nicotine adsorbents. The samples were characterized using FT-IR spectroscopy and low temperature nitrogen physisorption. Nicotine adsorption was performed with respect to contact time, pH and initial nicotine concentration. The kinetics of adsorption obeyed the pseudo-second-order kinetics. The optimal pH values for nicotine adsorption were 6 and 9 for Mt and MtA, respectively. The isotherms related to adsorption on Mt at pH = 6 and 9 as well as for MtA at pH=6 were best fitted with Sips isotherm model, while adsorption onto MtA at pH=9 obeyed Langmuir isotherm model.
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Oyedoh, Eghe A., and Michael C. Ekwonu. "EXPERIMENTAL INVESTIGATION ON CHROMIUM(VI) REMOVAL FROM AQUEOUS SOLUTION USING ACTIVATED CARBON RESORCINOL FORMALDEHYDE XEROGELS." Acta Polytechnica 56, no. 5 (October 31, 2016): 373–78. http://dx.doi.org/10.14311/ap.2016.56.0373.
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The adsorption of chromium(VI) metal ion in aqueous solutions by activated carbon resorcinol formaldehyde xerogels (ACRF) was investigated. The results showed that pore structure, surface area and the adsorbent surface chemistry are important factors in the control of the adsorption of chromium(VI) metal ions. The isotherm parameters were obtained from plots of the isotherms and from the application of Langmuir and Freundlich Isotherms. Based on regression analysis, the Langmuir isotherm model was the best fit. The maximum adsorption capacity of ACRF for chromium (VI) was 241.9 mg/g. The pseudo-second-order kinetic model was the best fit to the experimental data for the adsorption of chromium metal ions by activated carbon resorcinol formaldehyde xerogels. The thermodynamics of Cr(VI) ions adsorption onto ACRF was a spontaneous and endothermic process.
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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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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.
Full textAbstract:
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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Wu, Xiu-Hong, and Bing-Chang Lin. "Model Modification of Binary Competitive Isotherm." Journal of Liquid Chromatography & Related Technologies 32, no. 17 (October 5, 2009): 2465–83. http://dx.doi.org/10.1080/10826070903248254.
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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.
Full textAbstract:
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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Alwi, Ratna Surya, Ramakrishnan Gopinathan, Avijit Bhowal, and Chandrasekhar Garlapati. "Adsorption Characteristics of Activated Carbon for the Reclamation of Eosin Y and Indigo Carmine Colored Effluents and New Isotherm Model." Molecules 25, no. 24 (December 18, 2020): 6014. http://dx.doi.org/10.3390/molecules25246014.
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The adsorption response of eosin Y and indigo carmine acid dyes on activated carbon as a function of system temperature for a fixed concentration was investigated at various temperatures via adsorption isotherms and their thermodynamic quantities such as enthalpy, entropy, and Gibbs free energy changes. The adsorption data were exploited to develop a new adsorption isotherm. The new isotherm was developed with the spirit of solid–liquid phase equilibrium and regular solution theory. The proposed model has four adjustable constants and correlates adsorption isotherm in terms of the system temperature and melting temperature of the dye. The effect of pH on the removal of acid dyes was reported. The pH variation was observed to affect the adsorption efficiency. The removal of eosin Y and indigo carmine decreased from 99.4% to 82.6% and 92.38% to 79.48%, respectively, when the pH of the solution varied from 2 to 12. The thermodynamic analysis of the process reveals that the process of the removal of acid dyes is exothermic and spontaneous. Moreover, the kinetics parameters of the batch process are reported.
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Chaudhary, D. S., S. Vigneswaran, V. Jegatheesan, H. H. Ngo, H. Moon, W. G. Shim, and S. H. Kim. "Granular activated carbon (GAC) adsorption in tertiary wastewater treatment: experiments and models." Water Science and Technology 47, no. 1 (January 1, 2003): 113–20. http://dx.doi.org/10.2166/wst.2003.0030.
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Wastewater treatment has always been a major concern in the developed countries. Over the last few decades, activated carbon adsorption has gained importance as an alternative tertiary wastewater treatment and purification process. In this study, granular activated carbon (GAC) adsorption was evaluated in terms of total organic carbon (TOC) removal from low strength synthetic wastewater. This paper provides details on adsorption experiments conducted on synthetic wastewater to develop suitable adsorption isotherms. Although the inorganics used in the synthetic wastewater solution had an overall unfavourable effect on adsorption of organics, the GAC adsorption system was found to be effective in removing TOC from the wastewater. This study showed that equation of state (EOS) theory was able to fit the adsorption isotherm results more precisely than the most commonly used Freundlich isotherm. Biodegradation of the organics with time was the most crucial and important aspect of the system and it was taken into account in determining the isotherm parameters. Initial organic concentration of the wastewater was the determining factor of the model parameters, and hence the isotherm parameters were determined covering a wide range of initial organic concentrations of the wastewater. As such, the isotherm parameters derived using the EOS theory could predict the batch adsorption and fixed bed adsorption results of the multi-component system successfully. The isotherm parameters showed a significant effect on the determination of the mass transfer coefficients in batch and fixed bed systems.
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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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Papurello, Gandiglio, Kafashan, and Lanzini. "Biogas Purification: A Comparison of Adsorption Performance in D4 Siloxane Removal Between Commercial Activated Carbons and Waste Wood-Derived Char Using Isotherm Equations." Processes 7, no. 10 (October 22, 2019): 774. http://dx.doi.org/10.3390/pr7100774.
Full textAbstract:
Biogas production from organic waste could be an option to reduce landfill and pollutant emissions into air, water, and soil. These fuels contain several trace compounds that are crucial for highly efficient energy generators or gas injection into the grid. The ability of adsorbents to physically remove such adsorbates was investigated using adsorption isotherms at a constant temperature. We experimentally modelled isotherms for siloxane removal. Siloxanes were considered due to their high impact on energy generators performance even at low concentrations. Octamethylcyclotetrasiloxane was selected as a model compound and was tested using commercially available carbon and char derived from waste materials. The results show that recyclable material can be used in an energy production site and that char must be activated to improve its removal performance. The adsorption capacity is a function of specific surface area and porous volume rather than the elemental composition. The most common adsorption isotherms were employed to find the most appropriate isotherm to estimate the adsorption capacity and to compare the sorbents. The Dubinin-Radushkevich isotherm coupled with the Langmuir isotherm was found to be the best for estimating the adsorption capacity.
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Olafadehan, Olaosebikan A., and Alfred A. Susu. "Numerical Solution of Binary Liquid-Phase Adsorption onto Porocel Clay Using Linear, Freundlich and Langmuir Isotherms." Adsorption Science & Technology 23, no. 3 (April 2005): 195–213. http://dx.doi.org/10.1260/0263617054353627.
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A generalized mathematical model is presented to describe the process of multi-component adsorption onto porous media in fixed beds. The model was applied to the binary adsorption, without reaction, of aromatics and sulphur compounds onto a fixed bed of Porocel clay for kerosene deodorization using linear, Freundlich and Langmuir isotherms independently. A computational scheme for the solution of the model equations is presented. The scheme is based on orthogonal collocation for spatial discretization of the resulting set of coupled hyperbolic and parabolic partial differential equations for the macro-and micro-system, respectively. Michelsen's modified third-order semi-implicit Runge-Kutta method combined with step-size adjustment strategy was used to integrate the resulting 4N ordinary differential equations. Excellent agreement between the simulated results and pilot plant data was obtained for the breakthrough profiles for the non-linear adsorption isotherms of Freundlich and Langmuir. No agreement was obtained for the linear isotherm. Also, using the Freundlich and Langmuir isotherms, the exit concentration of the less preferentially adsorbed component (aromatics) exceeded its inlet concentration to the adsorption column for a certain period. This is indicative of the behaviour of competitive multi-component adsorption: relative to aromatics, sulphur compounds are selectively adsorbed onto Porocel clay. The relationship between solid- and liquid-phase concentration profiles for the Freundlich isotherm revealed the formation of multiple adsorption layers upon the primary mono-molecular layer. Again, for the Freundlich isotherm, the structure of the profiles exhibited a highly pronounced maximum for sulphur. An experimental breakthrough time of 8 h was also predicted for both aromatics and sulphur compounds using the non-linear Freundlich and Langmuir isotherms.
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Adejo, S. O., M. M. Ekwenchi, J. A. Gbertyo, T. Menengea, and J. O. Ogbodo. "Determination of Adsorption Isotherm model best fit for methanol leaf extract of Securinega virosa as corrosion inhibitor for corrosion of mild steel in HCl." JOURNAL OF ADVANCES IN CHEMISTRY 10, no. 5 (June 3, 2014): 2737–42. http://dx.doi.org/10.24297/jac.v10i5.891.
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The adsorption isotherm model best fit of the methanol leaf extract of Securinega virosa as corrosion inhibitor for the corrosion of mild steel in 2 M HCl medium was determined with the assistance of the Adejo-Ekwenchi adsorption isotherm. The corrosion inhibition study was carried out using the weight loss method at the temperature range of 301 K to 313 K. The inhibition efficiency, %IE, of the extract was found to increase with increase in both concentration and temperature. On the account of, R2 this adsorption process well fitted into Langmuir, Freundlich, Temkin isotherm, Flory-Huggins and Adejo-Ekwenchi models. However, through the parameter b of the Adejo-Ekwenchi isotherm, which clearly shows the adsorption process to be chemisorption, the best isotherm fit for the extract has been resolved to be the Langmuir isotherm and Temkin isotherm models.
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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.
Full textAbstract:
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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Oribayo, O., O. O. Olaleye, A. S. Akinyanju, K. O. Omoloja, and S. O. Williams. "Coconut shell-based activated carbon as adsorbent for the removal of dye from aqueous solution: equilibrium, kinetics, and thermodynamic studies." Nigerian Journal of Technology 39, no. 4 (March 24, 2021): 1076–84. http://dx.doi.org/10.4314/njt.v39i4.14.
Full textAbstract:
The need to develop more efficient adsorbent, comparable to commercially available adsorbent, is attracting significant interest as promising adsorbent for waste water treatment. In this study, the potential of activated carbon prepared from waste coconut shell (CSAC) for the removal of methylene blue (Mb) from aqueous solution was reported. Batch experiments were conducted to determine the adsorption isotherm and kinetics of Mb on CSAC. Langmuir, Freundlich and Temkin isotherm models were employed to fit and analyze the adsorption equilibrium data. The result shows Langmuir isotherm model gave the best fit and an adsorption capacity of 320.5 mg/g was obtained for Mb at pH value of 7, 0.02 g adsorbent dosage and contact time of 4.5 hour. The experimental kinetic data at different initial Mb concentrations was also analyzed with pseudo-first order, pseudo-second order and intraparticle diffusion models. The obtained results showed that the pseudo-second order model fits the adsorption kinetic data with R2 range of0.9985-0.9996. Finally, the thermodynamic parameters show that the adsorption of Mb on CSAC was spontaneous and endothermic in nature. This therefore suggests that (CSAC) is a viable adsorbent for effective removal of dye from wastewater effluent.
Keywords: Activated carbon, Adsorption isotherms, Coconut shells, Methylene blue, kinetics.
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Ekundayo, Jamiu M., Reza Rezaee, and Chunyan Fan. "Measurement of gas contents in shale reservoirs – impact of gas density and implications for gas resource estimates." APPEA Journal 61, no. 2 (2021): 606. http://dx.doi.org/10.1071/aj20177.
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Gas shale reservoirs pose unique measurement challenges due to their ultra-low petrophysical properties and complicated pore structures. A small variation in an experimental parameter, under high-pressure conditions, may result in huge discrepancies in gas contents and the resource estimates derived from such data. This study illustrates the impact of the equation of state on the gas content determined for a shale sample. The gas content was determined from laboratory-measured high-pressure methane adsorption isotherms and theoretically described by a hybrid type model. The modelling involved the use of the Dubinin–Radushkevich isotherm to obtain the adsorbed phase density followed by the Langmuir isotherm to describe the resultant absolute adsorptions. Significant variations were observed in measured adsorption isotherms due to the variations in gas densities calculated from different equations of states. The model parameters and the gas in-place volumes estimated from those parameters also varied significantly.
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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.
Full textAbstract:
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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Jung, Y., Jei Won Yeon, and Yeong Keong Ha. "Preparation and Cu(II) Complexation Characteristics of Carboxymethylated Polyethyleneimine (CM-PEI) / Microporous Activated Carbon Composite." Solid State Phenomena 119 (January 2007): 303–6. http://dx.doi.org/10.4028/www.scientific.net/ssp.119.303.
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We present the preparation and Cu(II) adsorption characteristics of a new and innovative composite which was composed of a carboxymethylated polyethyleneimine (CM-PEI) and an activated carbon with a nanopore less than 2 nm in diameter. In this study, we examined the adsorption phenomena of Cu(II) on the CM-PEI/F400 composite and evaluated the adsorption data using three kinds of isotherm models (Langmuir, Freundlich, and Temkin isotherms). It was found that the adsorption of Cu(II) on the CM-PEI/F400 composite obeys the Langmuir isotherm model. Furthermore, The Cu element mapping results showed that Cu was well distributed throughout all the surface of the composite particle, suggesting that the surface of the F400 particle was uniformly covered with CM-PEI.
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Ekundayo, Jamiu M., and Reza Rezaee. "Volumetric Measurements of Methane-Coal Adsorption and Desorption Isotherms—Effects of Equations of State and Implication for Initial Gas Reserves." Energies 12, no. 10 (May 27, 2019): 2022. http://dx.doi.org/10.3390/en12102022.
Full textAbstract:
This study presents the effects of equations of state (EOSs) on methane adsorption capacity, sorption hysteresis and initial gas reserves of a medium volatile bituminous coal. The sorption experiments were performed, at temperatures of 25 °C and 40 °C and up to 7MPa pressure, using a high-pressure volumetric analyzer (HPVA-II). The measured isotherms were parameterized with the modified (three-parameter) Langmuir model. Gas compressibility factors were calculated using six popular equations of state and the results were compared with those obtained using gas compressibility factors from NIST-Refprop® (which implies McCarty and Arp’s EOS for Z-factor of helium and Setzmann and Wagner’s EOS for that of methane). Significant variations were observed in the resulting isotherms and associated model parameters with EOS. Negligible hysteresis was observed with NIST-refprop at both experimental temperatures, with the desorption isotherm being slightly lower than the adsorption isotherm at 25 °C. Compared to NIST-refprop, it was observed that equations of state that gave lower values of Z-factor for methane resulted in “positive hysteresis”, (one in which the desorption isotherm is above the corresponding adsorption curve) and the more negatively deviated the Z-factors are, the bigger the observed hysteresis loop. Conversely, equations of state that gave positively deviated Z-factors of methane relatively produced “negative hysteresis” loops where the desorption isotherms are lower than the corresponding adsorption isotherms. Adsorbed gas accounted for over 90% of the calculated original gas in place (OGIP) and the larger the Langmuir volume, the larger the proportion of OGIP that was adsorbed.
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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.
Full textAbstract:
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.