Journal articles: 'BET adsorption isotherms'

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Cascarini de Torre, Lydia Ethel, and Eduardo Jorge Bottani. "BET Adsorption Isotherm and Surface Heterogeneity." Collection of Czechoslovak Chemical Communications 57, no. 6 (1992): 1201–9. http://dx.doi.org/10.1135/cccc19921201.

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The BET adsorption isotherm is modified in order to take account of surface heterogeneity. The adsorption isotherm is obtained following the statistical mechanics formalism, proposed by Steele, and the effect of surface heterogeneity is limited to the first layer. A Gaussian adsorption energies distribution function is used to describe surface heterogeneity. The variations of the C parameter, multilayer formation and the inversion of adsorption isotherms are analysed.

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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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Bakaev, V. A., and W. A. Steele. "The Characteristic Curve in Physical Adsorption." Adsorption Science & Technology 10, no. 1-4 (March 1993): 123–36. http://dx.doi.org/10.1177/0263617499010001-411.

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The concept of the characteristic curve in physical adsorption and the rule of its temperature invariance is traced from the potential theory of adsorption by Polanyi to the Frenkel–Halsey–Hill equation, the theory of volume filling of micropores by Dubinin et al. and the theory of adsorption on heterogeneous surfaces. A computer simulation of an irregular atomic configuration at the surface of amorphous carbon is presented. In the submonolayer region, the isotherms of argon adsorption simulated on that surface are shown to correspond to the Freundlich equation and are close to the experimental isotherms on a diamond dust sample. Simulated isosteric heats of adsorption are also reasonably close to the experimental data for argon on a real carbon black. The BET C constant for the simulated isotherm is lower than for the real isotherm on untreated carbon black. However, the isotherms at two temperatures can be described by one absolute isotherm of adsorption.

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Mashile, Geaneth Pertunia, Kgokgobi Mogolodi Dimpe, and Philiswa Nosizo Nomngongo. "A Biodegradable Magnetic Nanocomposite as a Superabsorbent for the Simultaneous Removal of Selected Fluoroquinolones from Environmental Water Matrices: Isotherm, Kinetics, Thermodynamic Studies and Cost Analysis." Polymers 12, no. 5 (May 12, 2020): 1102. http://dx.doi.org/10.3390/polym12051102.

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The application of a magnetic mesoporous carbon/β-cyclodextrin–chitosan (MMPC/Cyc-Chit) nanocomposite for the adsorptive removal of danofloxacin (DANO), enrofloxacin (ENRO) and levofloxacin (LEVO) from aqueous and environmental samples is reported in this study. The morphology and surface characteristics of the magnetic nanocomposite were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption–desorption and Fourier transform infrared spectroscopy (FTIR). The N2 adsorption–desorption results revealed that the prepared nanocomposite was mesoporous and the BET surface area was 1435 m2 g−1. The equilibrium data for adsorption isotherms were analyzed using two and three isotherm parameters. Based on the correlation coefficients (R2), the Langmuir and Sips isotherm described the data better than others. The maximum monolayer adsorption capacities of MMPC/Cyc-Chit nanocomposite for DANO, ENRO and LEVO were 130, 195 and 165 mg g−1, respectively. Adsorption thermodynamic studies performed proved that the adsorption process was endothermic and was dominated by chemisorption.

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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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Ribeiro, Luciana C., José M. C. da Costa, and Marcos R. A. Afonso. "Hygroscopic behavior of lyophilized acerola pulp powder." Revista Brasileira de Engenharia Agrícola e Ambiental 20, no. 3 (March 2016): 269–74. http://dx.doi.org/10.1590/1807-1929/agriambi.v20n3p269-274.

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ABSTRACT Powder products are characterized by their practicality and long life. However, fruit powders have high hygroscopicity and tend to agglomerate due to its hydrophilic nature. The isotherms of equilibrium moisture content apply to the study of dehydrated food preservation potential. Acerola is a nutritionally rich fruit, with great economic and industrial potential. The objective of this study was to analyse acerola powder adsorption isotherms obtained by lyophilization and characterize the powder obtained from lyophilized acerola pulp. Analysis of hygroscopicity, solubility and degree of caking were performed. Isotherms were represented by the mathematical models of GAB, BET, Henderson and Oswin, at temperatures of 25, 35 and 45 °C. According to the results, the obtained powder showed hygroscopicity of 5.96 g of absorbed water 100g-1 of solids, solubility of 95.08% and caking of 14.12%. The BET model showed the best fit to the adsorption isotherms of the acerola pulp powder obtained by lyophilization. The obtained isotherm was of type III, with a "J" shape. There was an inversion of the effect of temperature on the isotherms of acerola powders.

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Yu, Wei, Kamy Sepehrnoori, and Tadeusz W. Patzek. "Modeling Gas Adsorption in Marcellus Shale With Langmuir and BET Isotherms." SPE Journal 21, no. 02 (April 14, 2016): 589–600. http://dx.doi.org/10.2118/170801-pa.

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Summary Production from shale-gas reservoirs plays an important role in natural-gas supply in the United States. Horizontal drilling and multistage hydraulic fracturing are the two key enabling technologies for the economic development of these shale-gas reservoirs. It is believed that gas in shale reservoirs is mainly composed of free gas within fractures and pores and adsorbed gas in organic matter (kerogen). It is generally assumed in the literature that the monolayer Langmuir isotherm describes gas-adsorption behavior in shale-gas reservoirs. However, in this work, we analyzed four experimental measurements of methane adsorption from the Marcellus Shale core samples that deviate from the Langmuir isotherm, but obey the Brunauer-Emmett-Teller (BET) isotherm. To the best of our knowledge, it is the first time to find that methane adsorption in a shale-gas reservoir behaves similar to multilayer adsorption. Consequently, investigation of this specific gas-desorption effect is important for accurate evaluation of well performance and completion effectiveness in shale-gas reservoirs on the basis of the BET isotherm. The difference in calculating original gas in place (OGIP) on the basis of both isotherms is discussed. We also performed history matching with one production well from the Marcellus Shale and evaluated the contribution of gas desorption to the well's performance. History matching shows that gas adsorption obeying the BET isotherm contributes more to overall gas recovery than gas adsorption obeying the Langmuir isotherm, especially at early time in production. This work provides better understanding of gas desorption in shale-gas reservoirs and updates our current analytical and numerical models for simulation of shale-gas production.

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Jabłoński, Maciej. "BET-Type Adsorption Isotherms for Gaseous Mixtures." Adsorption Science & Technology 23, no. 6 (July 2005): 487–96. http://dx.doi.org/10.1260/026361705774859875.

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A formalism for describing the adsorption of gaseous mixtures at solid surfaces was derived as an extension of the BET theory. The following additional assumptions were made; the composition of all the adsorbed layers is the same and interaction occurs between the component molecules in the adsorbed layers. The proposed equations were compared with the experimental data obtained from measurements of the adsorption of an acetone—methanol mixture onto N-type active carbon.

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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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Luo, Li Jun, Ping Bao Ban, Xue Jiao Huang, and Jun Hong Li. "Functionalized Mesporous Silica with Ethylenediamine for Removal of Pb(II)." Applied Mechanics and Materials 395-396 (September 2013): 610–14. http://dx.doi.org/10.4028/www.scientific.net/amm.395-396.610.

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Amine-functionalized mesporous silicas ((referred as NH2MS)) were synthesized by grafting with ethylenediamine. The obtained materials have been characterized by N2 adsorption desorption measurement (BET). Adsorption behaviors of the adsorbent for lead (containing effects factors, kinetics, isotherms, thermodynamics) were investigated. The result indicated that the obtained particles possessed mesoporous structrure. The Pb (II) adsorption isotherm and kinetic data fit Freundlich model and the pseudo second-order kinetic model respectively. the adsorption of Pb (II) onto NH2-MS was an enothermic nature.

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Bottani, E. J., J. R. Zarate, and L. E. Torre Cascarini De. "Argon and Nitrogen Physical Adsorption on Boron Nitride." Adsorption Science & Technology 4, no. 1-2 (March 1987): 121–30. http://dx.doi.org/10.1177/0263617487004001-211.

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Physical adsorption isotherms of N2 and Ar on boron nitride are analysed and the behaviour of the adsorbed phase is discussed. Different models are used to interpret the adsorbed states. The behaviour of the BET C parameter suggests that a phase-transition occurs in Ar adsorption which is not showed in its isotherm. Adsorption energies distribution functins are calculated using a double Gaussian as distribution function. Nitrogen cross-sectional areas, under experimental conditions are estimated respect to those of the Ar.

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Chen, Jun Tao, Yue Xin Han, Shu Fang Ding, and Shui Lin Zheng. "The Adsorption Performance Study of Acid Leaching Residue of Asbestos Tailings." Materials Science Forum 685 (June 2011): 246–52. http://dx.doi.org/10.4028/www.scientific.net/msf.685.246.

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Acid leaching residue of asbestos tailings was calcined at 600°C. N2adsorption and desorption isotherms of this modified mineral material were measured at low temperature and the adsorption characteristic of acid leaching residue as well as the mechanism were discussed. The specific surface area of acid leaching residue was calculated by BET model, and meanwhile micropore and mesopore structural parameters were calculated by means of ‘t-Plot’ and BJH theory, respectively. The results showed that the N2adsorption-desorption isotherms of acid leaching residue were in line withⅠpattern of the IUPAC isotherm criterions. The residue contained well-developed micropore and mesopore system. The adsorption performance of of Pb2+in simulated wastewater for the acid leaching residue was also performed. The results indicated that a predominant chemisorption, which could be fitted by Langmuir isotherm, occurs on the materials.

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13

Bağcı, Safiye, and Ayhan Ceyhan. "Adsorption of methylene blue onto activated carbon prepared from Lupinus Albus." Chemical Industry and Chemical Engineering Quarterly 22, no. 2 (2016): 155–65. http://dx.doi.org/10.2298/ciceq150522030b.

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The adsorption of methylene blue (MB) from synthetic aqueous solutions in batch experiments using Lupinus Albus-activated carbon (LAAC) by chemical activation with zinc chloride was investigated. Prior to adsorption experiments, surface/physical properties of LAAC were determined using Scanning Electron Microscopy, Fourier transform infrared Spectroscopy and nitrogen adsorption isotherm. In the adsorption experiments, effects of adsorption time, solution pH, MB concentration and amount of LAAC were investigated. The isotherm and kinetic parameters were used to describe the experimental data. The BET surface area was 1254 m2/g while its total pore volume was found to be 0.484 cm3/g. Maximum adsorption capacity occurred at solution pH value 10 and was recorded as 109.89 mg/g. Adsorption data were modeled using Langmuir, Freundlich and Temkin adsorption isotherms. Langmuir isotherm and pseudo-second-order models fit to the process and reaction kinetics correspondingly.

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14

Smith, Kyla, Xiaodan Zhang, and Ron Hofmann. "Assessment of alternate characterization tests for prediction of taste and odour control by granular activated carbon." Water Supply 12, no. 4 (July 1, 2012): 531–39. http://dx.doi.org/10.2166/ws.2012.026.

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The acetoxime number test was recently identified by the American Society for Testing and Materials as a method to characterize activated carbon. This adsorption isotherm gives information about the number of high energy adsorption sites on the surface of an activated carbon. A similar test uses tetrafluoromethane for the same purpose. In contrast, the more common iodine number and Brunauer, Emmet and Teller (BET) surface area parameters are a measure of the total number of adsorption sites. 2-Methylisoborneol (MIB) is reported to require high energy sites for removal, so it was hypothesized that data from acetoxime and tetrafluoromethane isotherm tests for different activated carbons would be better correlated to MIB removal than iodine numbers or BET surface areas. MIB breakthrough was monitored in rapid small-scale column tests (RSSCTs) using four natural waters and five activated carbons. Results showed no correlation between acetoxime or tetrafluoromethane isotherms and MIB breakthrough.

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Msaad, Asmaa, Mounir Belbahloul, and Abdeljalil Zouhri. "Adsorption of an anionic dye on a novel low-cost mesoporous adsorbent: kinetic, thermodynamic and isotherm studies." E3S Web of Conferences 37 (2018): 02002. http://dx.doi.org/10.1051/e3sconf/20183702002.

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Our activated carbon was prepared successfully using phosphoric acid as an activated agent. The activated carbon was characterized by Scanning Electron Micrograph (SEM), Brunauer-Emmett- Teller (BET), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The aim of our study is to evaluate the adsorption capacity of Methyl Orange (MO) on Ziziphus lotus activated carbon. Adsorption isotherms were studied according to Langmuir and Freundlich Model, and adsorption kinetics according to pseudo-first and second-order. Results show that the maximum adsorption was reached in the first 10min at ambient temperature with a yield of 96.31%. The Langmuir isotherm shows a correlation coefficient of 99.4 % higher than Freundlich model and the adsorption kinetic model follow a pseudo-second-order with a maximum adsorption capacity of 769.23 mg/g. FTIR and X-Ray spectroscopy indicate that our activated carbon has an amorphous structure with the presence of functional groups, where BET analysis revealed a high surface area of 553 mg/g, which facilitate the adsorption process

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van Erp, Titus S., and Johan A. Martens. "A standardization for BET fitting of adsorption isotherms." Microporous and Mesoporous Materials 145, no. 1-3 (November 2011): 188–93. http://dx.doi.org/10.1016/j.micromeso.2011.05.022.

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Bardina, I. A., E. V. Kalashnikova, N. V. Kovaleva, T. A. Rudnitskaya, and N. K. Shonya. "Adsorption Properties and Structure of Some Active Carbons." Adsorption Science & Technology 10, no. 1-4 (March 1993): 211–20. http://dx.doi.org/10.1177/0263617499010001-420.

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Gas chromatography has been used to determine the initial low-coverage heats of adsorption of C2–C6 hydrocarbons and their derivatives on active carbon and graphitized carbon black. The porous structure of the active carbon has been determined from the adsorption isotherms of benzene measured at 25°C by a vacuum static method. The isotherms have been analyzed with the help of the BET and Dubinin–Radushkevich theories.

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Kats, B. M., and V. V. Kutarov. "A Modified BET Equation for Polylayer Adsorption." Adsorption Science & Technology 16, no. 4 (April 1998): 257–62. http://dx.doi.org/10.1177/026361749801600402.

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A three-parameter equation was obtained in the BET theory framework taking into account the correction suggested by the authors. This equation allows the description of adsorption isotherms in the range of polylayer adsorption as well as in the range of cluster formation. This equation was demonstrated as true for a number of adsorption systems in the relative pressure range 0.05 ≤ x ≤ 0.97 for nitrogen, benzene and water vapour.

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Zhao, Zhun, Zhenhua Li, Penglei Cui, Shengli Li, and Lingqian Kong. "Adsorption of Basic Brown and Chrysophenine from Water Solution by Magnesium Silicate Gel." Journal of Chemistry 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/374190.

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Noncrystalline, high surface area magnesium silicate gel was successfully prepared by hydrothermal method. Such product was characterized by BET and XRD to determine surface area 576.4 m2·g−1, average pore width 2.76 nm, and amorphous surface. The adsorption behaviors of Basic Brown and Chrysophenine on magnesium silicate gel were investigated through changing initial concentration, adsorbent dosage, solution pH, contact time, and temperature. The experimental data was analyzed by the adsorption isotherms and kinetics. The results showed the adsorption progress was fast for Basic Brown, and the adsorption equilibrium was finished in 2 h, while the adsorption equilibrium of Chrysophenine was finished in 7 h. Freundlich isotherm model and second-order kinetic models described the adsorption process very well.

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Zhu, Hong Zhi, and Zhen Hua Xue. "Microstructure Analysis of Xanthoceras Sorbifolia Shell Activated Carbon." Advanced Materials Research 941-944 (June 2014): 1051–55. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.1051.

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The Xanthoceras sorbifolia shell activated carbon which was prepared by using zinc chloride as activating agent has a strong adsorption performance of cationic adsorbate (methylene blue) 845.275mg/g and anionic adsorbate (iodine) 1584.96mg/g. Specific surface area study showed that: the adsorption isotherms of activated carbonsamples are type I isotherm adsorption, BET specific surface area was 1455.233m2/g. Displayed by pore specific surface analyzer's measurement results that the pore radius ratio of activated carbon in the range of 3.2-3.4Å is the largest. This proves that these holes are mainly micropores. Meanwhile, the conclusions obtained by the SEM further proof.

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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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Piekarski, Jacek, Katarzyna Ignatowicz, and Tomasz Dąbrowski. "Analysis of Selected Methods Use for Calculation of the Coefficients of Adsorption Isotherms and Simplified Equations of Adsorption Dynamics with the Use of IZO Application." Materials 14, no. 15 (July 27, 2021): 4192. http://dx.doi.org/10.3390/ma14154192.

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The purpose of this paper is to present the IZO application that calculates and visualizes coefficients of adsorption isotherms according to Freundlich, Langmuir, and BET in a classic and linear system, in a simple communicative way. The application also calculates the working time of the adsorption bed based on the transformation of the mass balance equation, and according to the Zuchowicki, Zabieziński, Tichonow, and the Bohart-Adams equations. The laboratory tests of the adsorption process of leachate from a municipal landfill on selected active coals ORGANOSORB 10, DESOTEK, and BA-10, were conducted to check the program for accuracy. Results of tests confirm that the linearization method of the calculation of adsorption isotherms coefficients, used in the IZO application, gives sufficient accuracy and may be used as an alternative of, e.g., the nonlinear estimation method.

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Mohamad Yusop, Mohamad Firdaus, Mohd Azmier Ahmad, Nur Ayshah Rosli, Fadzil Noor Gonawan, and Soran Jalal Abdullah. "Scavenging malachite green dye from aqueous solution using durian peel based activated carbon." Malaysian Journal of Fundamental and Applied Sciences 17, no. 1 (February 27, 2021): 95–103. http://dx.doi.org/10.11113/mjfas.v17n1.2173.

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Physiochemical activation consists of heat treatment coupling with CO2 gasification and KOH chemical treatment were applied in preparing durian peel based activated carbon (DPAC) to remove basic dye, malachite green (MG) from aqueous solution. Several parameters namely, effect of initial MG concentration as well as contact time, solution temperature and initial solution pH were carried out in this study. Characterization study revealed that DPAC pose high BET surface area which is 886.31 m2/g and its surface was found to be mesoporous in nature with heterogeneous type of pore structures. Eight isotherms and four kinetic models were utilized and it was revealed that the adsorpttion system followed Freundlich isotherm and pseudo-first order (PFO) kinetic model. Mechanism study using intraparticle diffusion and Boyd plot confirmed that adsorption of MG onto DPAC was controlled by the film-diffusion mechanism. Thermodynamic study indicated that the adsorption system was exothermic, spontaneous, feasible and governed by physical-type of adsorption.

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Hu, Wenhai, Song Cheng, Hongying Xia, Libo Zhang, Xin Jiang, Qi Zhang, and Quan Chen. "Waste phenolic resin derived activated carbon by microwave-assisted KOH activation and application to dye wastewater treatment." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 408–15. http://dx.doi.org/10.1515/gps-2019-0008.

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Abstract The waste phenolic resin was utilized as the raw material to prepare activated carbon (AC) used KOH as the activating agent via microwave heating. The phenolic resin was carbonized at 500°C and then performed with a KOH/Char ratio of 4 and microwave power of 700 W for a duration of 15 min. The physic-chemical characteristics of the AC were characterized by N2 adsorption instrument, FTIR, SEM and TEM. The BET surface area and pore volume of AC were found to be 4269 m2/g and 2.396 ml/g, respectively. The activation process to generate such a phenomenally high surface area of the AC has little reported in open literatures and could pave way for preparation adsorbents that are far superior to the currently marketed adsorbents. The methylene blue (MB) was used as the model to assess its suitability to dye wastewater treatment. Towards this, the MB adsorption isotherms were conducted at three different temperatures and tested with different adsorption isotherm models. The adsorption isotherms could be modeled using Langmuir isotherm. While the kinetics could be used the pseudo-second order kinetics to describe. Thermodynamic results demonstrated that the adsorption process was a spontaneous, as well as an endothermic.

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Masuda, Yoshitake, and Kazumi Kato. "Influence of Synthesis Condition on N₂ Adsorption Characteristics of Anatase TiO₂ Particles Prepared in an Aqueous Solution." Key Engineering Materials 388 (September 2008): 103–6. http://dx.doi.org/10.4028/www.scientific.net/kem.388.103.

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TiO2 was crystallized to form particles in aqueous solutions containing ammonium hexafluorotitanate and boric acid. XRD diffraction patterns indicated they were in a single phase of anatase TiO2. TiO2 particles prepared at 90 °C exhibited N2 adsorption-desorption isotherms of type IV. BET specific surface area of the particles was estimated to 13 m2/g. On the other hand, TiO2 particles prepared at 50 °C exhibited N2 adsorption-desorption isotherms of type I. BET specific surface area of the particles was estimated to 168 m2/g. Crystal growth of TiO2 was strongly affected by synthesis temperature. Nano-sized pores or surface structure of TiO2 particles prepared at 50 °C would increase N2 adsorption volume to realize high BET specific surface area. Additionally, aqueous solution process described here had an advantage that TiO2 crystallized at ambient temperature. Anatase TiO2 was prepared without annealing at high temperature which caused aggregation of particles and disappearance of surface nanostructures. The particles with large surface area can be thus utilized for catalyst, cosmetic, photocatalyst, dye-sensitized solar cell or sensors.

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Harja, Maria, Gabriela Buema, Nicoleta Lupu, Horia Chiriac, Dumitru Daniel Herea, and Gabriela Ciobanu. "Fly Ash Coated with Magnetic Materials: Improved Adsorbent for Cu (II) Removal from Wastewater." Materials 14, no. 1 (December 25, 2020): 63. http://dx.doi.org/10.3390/ma14010063.

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Fly ash/magnetite material was used for the adsorption of copper ions from synthetic wastewater. The obtained material was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area, and vibrating sample magnetometer (VSM). Batch adsorption experiments were employed in order to investigate the effects of adsorbent dose, initial Cu (II) concentration and contact time over adsorption efficiency. The experimental isotherms were modeled using Langmuir (four types of its linearization), Freundlich, Temkin, and Harkins–Jura isotherm models. The fits of the results are estimated according to the Langmuir isotherm, with a maximum adsorption capacity of 17.39 mg/g. The pseudo-second-order model was able to describe kinetic results. The data obtained throughout the study prove that this novel material represents a potential low-cost adsorbent for copper adsorption with improved adsorption capacity and magnetic separation capability compared with raw fly ash.

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HUMPOLA, PABLO D., HECTOR S. ODETTI, ETHEL S. E. FLORES, and JOSE LUIS VICENTE. "DESCRIPTION OF DIFFERENT SOLID ADSORBENT SURFACES ADSORPTION MECHANISMS BASED ON A SEQUENTIAL DECOMPOSITION OF ISOTHERMS." Surface Review and Letters 20, no. 02 (April 2013): 1350022. http://dx.doi.org/10.1142/s0218625x13500224.

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In order to analyze the adsorption capacities of different solid substrates, we present a multi-step method to separately study the isotherm at different pressure ranges (steps). The method is based on simple gas isotherm measurements (nitrogen, methane, carbon dioxide, argon, and oxygen) and is tested to describe the adsorption process and characterize a graphitized surface (GCB) and two different granular activated carbons (GAC). The GCB isotherms are described as a sum of Fowler-Guggenheim-Langmuir shifted curves; isotherm behaviors are quite similar at different temperatures, but change below a certain threshold. In GAC the first steps show the same adsorption characteristics at low pressures (Dubinin's description), but this behavior changes at higher pressure regimes, which allows one to elucidate how heterogeneous the surfaces are or how strong the interactions between adsorbed molecules are for this marginal adsorption to occur. We tested different approaches (from BET multilayer to Aranovich) and found quite different features. We finally conclude that if the description of the adsorption on complex substrates, such as those presented here, is carried using only one model, e. g. Dubinin in case of GACs, the resulting characteristics of the adsorbent would be very biased.

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Beagan, Abeer M. "Investigating Methylene Blue Removal from Aqueous Solution by Cysteine-Functionalized Mesoporous Silica." Journal of Chemistry 2021 (June 15, 2021): 1–12. http://dx.doi.org/10.1155/2021/8839864.

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In this study, mesoporous silica nanoparticles (MSNs) were synthesised using the Stober method and functionalised with cysteine (MSN-Cys) for removal of Methylene Blue (MB) from aqueous solution using the batch method. The adsorbent nanoparticles were characterised by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), FTIR, BET, and TGA. Several influential factors on the adsorption of MB onto the surface of MSN-Cys particles were investigated, including pH, initial concentration, and contact time. The adsorption capacity of MB from aqueous solution increased from circa 70 mg/g MSN-Cys in acidic media to circa 140 mg/g MSN-Cys in basic media. Adsorption isotherms and kinetic models of adsorption were used to clarify the adsorption process. The measured adsorption isotherm was fitted with a Freundlich model for all solutions, and the kinetic model was determined to be pseudo-second-order.

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29

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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30

Faeza, I., Mohammad S. Subhani, Khalil A. Qureshi, Pervez K. Butt, and A. Riaz. "Adsorption of Aliphatic Alcohols on Yttria-Stabilized Zirconia." Adsorption Science & Technology 23, no. 2 (March 2005): 115–33. http://dx.doi.org/10.1260/0263617054037772.

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Yttria-stabilized zirconia powders with 3, 5, 8 and 10 mol% yttria added (Z3Y, Z5Y, Z8Y and Z10Y, respectively) were prepared. XRD studies indicated that the Z3Y and Z5Y samples were tetragonal whereas Z8Y and Z10Y were found to be cubic in shape. The specific surface areas of the various samples were obtained from nitrogen adsorption isotherms. These showed that as the mol% Y2O3 increased in the samples, an initial increase in surface area occurred up to 5 mol% Y2O3 but thereafter started to decrease. The microporosity of the powders was calculated by applying the Dubinin—Radushkevich (D—R) equation to the data obtained from the nitrogen adsorption studies. D—R plots were found to be linear over the low relative pressure region, followed by an upward deviation at higher relative pressures for all five systems examined. This deviation from linearity corresponded to the existence of a heterogeneous system of micropores, capillary condensation in the transitional pores or multilayer formation on the macropore walls. The adsorption of methanol (MeOH), ethanol (EtOH), n-propanol (PrOH) and n-butanol (BuOH) on pure and yttria-stabilized zirconia was undertaken at temperatures between 273 K and 303 K. The corresponding isotherms obtained were all of type II in the BDDT classification. Specific surface areas were calculated from these isotherms using the Langmuir and BET adsorption isotherm equations and found to be a maximum for the Z5Y powder.

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31

Liu, Lingjie, Min Ji, and Fen Wang. "Adsorption of Nitrate onto ZnCl2-Modified Coconut Granular Activated Carbon: Kinetics, Characteristics, and Adsorption Dynamics." Advances in Materials Science and Engineering 2018 (June 3, 2018): 1–12. http://dx.doi.org/10.1155/2018/1939032.

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Coconut granular activated carbon (CGAC) was modified by impregnating with ZnCl2solution to remove nitrate from aqueous solutions. Sorption isotherm and kinetic studies were carried out in a series of batch experiments. Nitrate adsorption of both ZnCl2-modified CGAC and CGAC fitted the Langmuir and Freundlich models. Batch adsorption isotherms indicated that the maximum adsorption capacities of ZnCl2-modified CGAC and CGAC were calculated as 14.01 mgN·g−1and 0.28 mgN·g−1, respectively. The kinetic data obtained from batch experiments were well described by pseudo-second-order model. The column study was used to analyze the dynamic adsorption process. The highest bed adsorption capacity of 1.76 mgN·g−1was obtained by 50 mgN·L−1inlet nitrate concentration, 20 g adsorbents, and 10 ml·min−1flow rate. The dynamic adsorption data were fitted well to the Thomas and Yoon–Nelson models with coefficients of correlationR2 > 0.834 at different conditions. Surface characteristics and pore structures of CGAC and ZnCl2-modified CGAC were performed by SEM and EDAX and BET and indicated that ZnCl2had adhered to the surface of GAC after modified. Zeta potential, Raman spectra, and FTIR suggested the electrostatic attraction between the nitrate ions and positive charge. The results revealed that the mechanism of adsorption nitrate mainly depended on electrostatic attraction almost without any chemical interactions.

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32

Balasubramani, Ushadevi, Sangeetha Subramaniam, Liviu Mitu, and Vairam Sundararajan. "Batch and column studies on methylene blue using activated carbon/Al2O3 nano-composite and its impregnated calcium alginate beads." JOURNAL OF ADVANCES IN CHEMISTRY 12, no. 12 (December 20, 2016): 5599–612. http://dx.doi.org/10.24297/jac.v12i12.3890.

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Activated carbon/Al2O3 nano-composite (ANC) was synthesized by simple pyrolysis after incorporating the aluminium acetate precursor in activated carbon (AC) matrix. The as-synthesized composite was characterized by FT-IR, XRD, BET isotherm, SEM, EDX, and TEM. The size of Al2O3 nanoparticles in carbon matrix was found to be in the range of 10-35 nm. Adsorption characteristics of nano-composite was evaluated using methylene blue dye (MB) by batch and column studies. In batch process, the effect of concentration, temperature and pH were investigated. Batch adsorption study was interpreted with Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Results showed that adsorption follows Freudlich isotherm model with an adsorption capacity of 116 mg/g at pH 7 at 30 Â°C and it increases with increase in pH. Kinetic data indicated that the adsorption of dye follows pseudo-second order kinetics model. The negative value of Î”G indicates the spontaneous nature of the adsorption process. For column study the nano-composite was fabricated into Calcium alginate beads (CAB). The performance of CAB was studied with different influent concentrations of MB, pH and bed depth and the results have been interpreted using Thomas and BDST models. The column shows an adsorption capacity of 285.57 mg/g of CAB at pH 7 with bed height of 10 cm and best fitted to BDST model. These outcomes indicate the capability of carbon/Al2O3 nano-composite for dye removal.

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Bohra, J. N., and K. S. W. Sing. "A Study of the Micropore Structure of Carbonized Rayon Yarn by Nitrogen Adsorption and Nonane Pre-Adsorption." Adsorption Science & Technology 2, no. 2 (June 1985): 89–95. http://dx.doi.org/10.1177/026361748500200203.

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Adsorption isotherms of nitrogen have been determined at 77 K on three samples of carbonized rayon yarn, both before and after the pre-adsorption of n-nonane. In their original state the three samples were all highly microporous. Application of the αs-method of isotherm analysis reveals that their micropore volumes were 0·17–0·19 cm3g−1 and their external surface areas 20–27 m2g−1 (the corresponding BET areas being 427–483 m2g−1). Nonane pre-adsorption resulted in blockage of the entire micropore structure only in the case of one sample: micropore volumes ∼0·1 cm3g−1 were still available for nitrogen adsorption in the other two samples. It appears that nitrogen molecules were able to gain access to some parts of these micropore structures through wider pore entrances which were not completely blocked by the pre-adsorbed nonane. The work has shown that the nonane pre-adsorption method requires further investigation before it can be used with confidence for the assessment of microporosity.

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34

Grehov, V., J. Kalnacs, L. Matzui, M. Knite, A. Murashov, and A. Vilken. "Solid State Physics. Nitrogen Adsorption by Thermoexfoliated Graphite / Slāpekļa Adsorbcija Uz Termoeksfoliētā Grafīta." Latvian Journal of Physics and Technical Sciences 50, no. 1 (February 1, 2013): 58–65. http://dx.doi.org/10.2478/lpts-2013-0003.

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Adsorption by thermochemically exfoliated graphite (TEG) is studied and compared with that by other carbon structures under the same conditions. In BET determination of the specific surface area (SBET) for the TEG samples it was found that good approximation could be observed in two different pressure ranges. Such ranges of BET approximation are also visible in the isotherms of aquadag and milled graphite. The experimental results are discussed and their interpretation proposed

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35

Holgado, M. J., and V. Rives. "A Comparative Study of the Suitability of Sircar's and BET Isotherms to Study the Adsorption of Vapours on Non-Porous Adsorbents." Adsorption Science & Technology 6, no. 3 (September 1989): 110–18. http://dx.doi.org/10.1177/026361748900600301.

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A comparative study is reported of the suitability of the BET and Sircar equations for the analysis of the adsorption isotherms of vapours on non-porous solids, by applying both equations to experimental data reported in the literature corresponding to the adsorption of nitrogen at 77 K on a non-porous carbon-coated silica. It is concluded that Sircar's method, despite its greater mathematical complexity, does not provide better precision in determining the parameters of the equation. In addition, the monolayer capacity values are very different in both cases. The BET equation remains the more reliable for the determination of the monolayer adsorption capacity of solids.

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36

Eslami, Akbar, Zahra Goodarzvand Chegini, Maryam Khashij, Mohammad Mehralian, and Marjan Hashemi. "Removal of acetaminophen (ACT) from aqueous solution by using nanosilica adsorbent: experimental study, kinetic and isotherm modeling." Pigment & Resin Technology 49, no. 1 (January 6, 2020): 55–62. http://dx.doi.org/10.1108/prt-06-2019-0057.

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Purpose A nanosilica adsorbent was prepared and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET. Design/methodology/approach The optimum conditions for the highest adsorption performance were determined by kinetic modeling. The adsorbent was used for the adsorption of acetaminophen (ACT), and the parameters affecting the adsorption were discussed like pH, initial concentration, contact time and adsorbent dosage. The adsorbent have been characterized by SEM, XRD and BET analysis. The kinetic models including pseudo-first-order and pseudo-second-order with Langmuir and Freundlich isotherm models were applied to investigate the kinetic and isotherms parameters. Findings The adsorption of ACT increased to around 95% with the increase of nanosilica concentration to 30 g/L. Moreover, the adsorption process of ACT follows the pseudo-second-order kinetics and the Langmuir isotherm with the maximum adsorption capacity of 609 mg/g. Practical implications This study provided a simple and effective way to prepare of nanoadsorbents. This way was conductive to protect environmental and subsequent application for removal of emerging pollutants from aqueous solutions. Originality/value The novelty of the study is synthesizing the morphological and structural properties of nanosilica-based adsorbent (specific surface area, pore volume and size, shape and capability) and improving its removal rate through optimizing the synthesis method; and studying the capability of synthesis of nanosilica-based adsorbent for removal of ACT as a main emerging pharmaceutical water contaminant.

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37

Borhan, Azry, Mohd Faisal Taha, and Athirah Amer Hamzah. "Characterization of Activated Carbon from Wood Sawdust Prepared via Chemical Activation Using Potassium Hydroxide." Advanced Materials Research 832 (November 2013): 132–37. http://dx.doi.org/10.4028/www.scientific.net/amr.832.132.

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The preparation of activated carbon from wood-based industrys residue is one of the most environmental friendly solutions of transforming negative-valued wastes to valuable materials. Wood sawdust was first chemically activated using potassium hydroxide, KOH and characterized by nitrogen adsorption-desorption isotherms measured in Micrometrices ASAP 2020 and Field Emission Scanning Electron Microscope (FESEM). By manipulating three different parameters, the optimal activation conditions were found at temperature of 500°C, activation time of 60 min and impregnation ratio of 1:3. Results showed that the BET surface area, total pore volume and diameter of activated carbon were 1876.16 m2g-1, 0.88 cm3g-1and 6.93 nm, respectively. Nitrogen adsorption desorption isotherm analysis proved the existence of mesopores in activated carbon produced, suggesting that it can be effectively used as an adsorption material.

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38

Nadiye-Tabbiruka, Misael Silas. "Interaction of Ethanol Vapour with Silane-Modified Surface of Corning Porous Glass CPG-10." ISRN Physical Chemistry 2012 (October 25, 2012): 1–6. http://dx.doi.org/10.5402/2012/254167.

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The interaction of ethanol vapour at 293 K with modified Corning controlled porous glass (CPG-10) samples of various pre-silylation is reported. Ethanol adsorption on CPG-10 was greatly reduced by silylation to extents largely depending on the silylation extent, type of silane used, and on the concentration and accessibility of residual silanols. The obtained adsorption isotherms, BET surface areas, as well as the observed changes at the various stages during the sorption particularly in the capillary condensation region also showed similar dependence. In the capillary condensation region, in the case of the dimethyl dichlorosilane-modified sample, hysteresis type was changed from H3 to H1. On the triethyl chlorosilane-modified sample an unexpected suppression of hysteresis effects occurred with a consequent transformation of type IV to type II adsorption isotherm.

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39

Ocheme, Ocheme Boniface, Chukwuma Charles Ariahu, and Emmanuel Kongo Ingbian. "Moisture Sorption Characteristics of Dakuwa (Nigerian Cereal/Groundnut Snack)." International Journal of Food Engineering 9, no. 4 (August 22, 2013): 499–504. http://dx.doi.org/10.1515/ijfe-2012-0242.

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AbstractThe moisture sorption characteristics of dakuwa at 10, 20, 30 and 400°C were studied. The experimental sorption data obtained were applied to BET, GAB, Oswin and Henderson equations to test fitness of the equations to moisture sorption of dakuwa. The sorption isotherms of dakuwa were type III isotherms (J shaped), and the equilibrium moisture content increased with increasing water activity but decreased with increasing temperature. The BET and GAB monolayer moisture contents all decreased with increasing temperature. For adsorption, the BET monolayer was higher (3.163–4.158 g/100 g solid) than that of GAB (2.931–3.728 g/100 g solid), but for desorption, the GAB monolayer (4.792–7.741 g/100 g solid) was higher than that of BET (3.962–4.480 g/100 g solid). Evaluation of goodness of fit of models revealed that moisture sorption of dakuwa was best modelled by GAB equation.

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40

Kovalenko, V., A. Borysova, I. Pliuta, and R. Likhnovsky. "ADSORPTION AS A BASIS OF PROTECTIVE ACTION OF FILTERS-ADSORBER." Науковий вісник: Цивільний захист та пожежна безпека 1, no. 2 (December 30, 2018): 59–63. http://dx.doi.org/10.33269/nvcz.2018.2.59-63.

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This article analyzes the regulatory documents on determination of protective action time of gas filters and FILTERS-ADSORBER, which are designed for individual and collective protection. The current absence of a current regulatory document in Ukraine is indicated according to which protective action time of filters is determined, adds relevance in the implementation of the method of determining this filter characteristic. The theoretical aspects of effect of absorbing capacity of filters are highlighted, the fundamental principles of adsorption are linked with the time of protective action time of filters against hazardous chemicals. The process of adsorption on the surface and formation of sorption layers in case of polymolecular adsorption is schematically shown, as described by the BET theory. It is indicated that protective action time on the direct depends on particular case of adsorption - chemisorption. The types of adsorption isotherms are considered, they are characterized and the Langmuir and BET equations are given. The protective action of filter as a phenomena of chemisorption on the surface of sorbent is described by the Langmuir isotherm, in particular, parts I and II. When determining protective action time the monomolecular adsorption of hazardous chemical substance occurs with formation of a chemical bond with the surface. The chemical bond is formed from the impregnated catalyst due to the redistribution of electrons. Solutions of metal salts are used as a catalyst, and the metal ion itself acts as an active center during the process of chemisorption. The role of adsorption kinetics in the implementation of sanitary cleaning of gas from the pollutant in the practical plane is considered. The possibility of calculating the amount of a chemical that a sorbent can absorb is shown by constructing an adsorption isotherm of a standard substance and a pollutant adsorption working line. Adsorption isotherm was captured for adsorbent from FG-130 FPK 95 filter on KELVIN 1042 sorptometr.

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Capra, Luiza, Mihaela Manolache, Ion Ion, Rusandica Stoica, Gabriela Stinga, Sanda Doncea, Elvira Alexandrescu, et al. "Adsorption of Sb (III) on Oxidized Exfoliated Graphite Nanoplatelets." Nanomaterials 8, no. 12 (November 30, 2018): 992. http://dx.doi.org/10.3390/nano8120992.

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In this work, Sb (III) adsorption on oxidized exfoliated graphite nanoplatelets (ox-xGnP) was evaluated for the first time, to the best of our knowledge. The ox-xGnP were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmet–Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray spectroscopy (EDX), and Zeta potential analysis. The adsorption parameters, such as pH and contact time, were optimized, and the best adsorption capacity obtained was 8.91 mg g−1 at pH = 7.0, 1.0 mg ox-xGnP/100 mL solution, T = 293 K, 1.0 mg L−1, Sb (III), 25 min contact time. The best correlation of the kinetic data was described by a pseudo-first-order kinetic model, with R2 = 0.999. The adsorption isotherms of Sb (III) onto ox-xGnP were best described by the Langmuir isotherm model. The thermodynamic parameters showed that the adsorption process was exothermic and spontaneous.

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Ganesan, Sumathi, and Gurumallesh Prabu Halliah. "Synergetic Performance of Graphene Oxide and Chitosan on the Removal of Direct Red 7." Oriental Journal of Chemistry 35, no. 6 (December 24, 2019): 1789–98. http://dx.doi.org/10.13005/ojc/350623.

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Graphene oxide/Chitosan (GOCH) composite was synthesized by hydrothermal method and structurally characterized by FT-IR, RAMAN, XRD and BET analyses which provide support for graphene oxide and chitosan incorporation. The synthesized composite was employed for the removal of direct red 7 (DR7) by batch adsorption process. Langmuir, Freundlich, Temkin, Dubinin-Radushkevic, Harkin-Jura, Scatchard plot analysis and Hasley isotherms were used to elucidate adsorption mechanism. The value of R2 revealed that isotherm was well explained by Langmuir model. The extent of monolayer adsorption capacity of GOCH was calculated as 34.2 mg/g. The pseudo first order kinetic studies were in agreement with experimental data. Thermodynamic parameters such as activation energy (Ea = 8.405 KJ/mol), enthalpy (ΔH = 89.417 KJ/mol), free energy change (ΔG) and entropy (ΔS = 0.2971 KJ/mol) were calculated. It propounded that the adsorption of DR7 on GOCH was favorable, spontaneous and an endothermic process.

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Nguyen, Thi Hang, Thi Thuy Linh Nguyen, Tien Duc Pham, and Thanh Son Le. "Removal of Lindane from Aqueous Solution Using Aluminum Hydroxide Nanoparticles with Surface Modification by Anionic Surfactant." Polymers 12, no. 4 (April 20, 2020): 960. http://dx.doi.org/10.3390/polym12040960.

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In the present study, we investigated the removal of an emerging pesticide lindane from aqueous solution using synthesized aluminum hydroxide Al(OH)3 (bayerite) nanomaterials with surface modification by an anionic surfactant sodium dodecyl sulfate (SDS). The Al(OH)3 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and zeta potential. The lindane removal using SDS-modified nano-aluminum hydroxide nanoparticles (SMNAH) achieved removal of up to 93.68%, which was 3.3 times higher than that of nano-aluminum hydroxide nanoparticles. The adsorptive removal conditions were studied and found to have an adsorption time of 60 min, a pH of 6, an adsorbent dosage of 25 mg/mL and an ionic strength of 10 mM NaCl. After reusing four times, the removal efficiency of lindane using SMNAH still reached 75%. Two-step adsorption can fit adsorption isotherms of lindane onto SMNAH at two salt concentrations. On the basis of the change in zeta potential, surface functional groups and adsorption isotherms, we suggest that the formation of a bilayer micelle induced the removal of lindane.

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Ke, Guo Jun, Zhou Zhou, Peng Fei Yang, and Bai Xing Song. "Preparation of CNTs/MgAl-LDHs Composites and their Adsorption Properties for Chloride Ions." Materials Science Forum 956 (June 2019): 305–13. http://dx.doi.org/10.4028/www.scientific.net/msf.956.305.

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Magnesium-aluminum hydrotalcite and carbon nanotube composites (CNTs/MgAl-LDHs) were prepared by one-step hydrothermal method using magnesium nitrate, aluminum nitrate and carbon nanotubes as raw materials and urea as precipitant. The samples were characterized by SEM, XRD, BET and other methods. The adsorption properties of CNTs/MgAl-LDHs on chloride ions and the factors affecting the adsorption of chloride ions were studied. The results show that the prepared CNTs/MgAl-LDHs exhibit a three-dimensional honeycomb structure with a specific surface area of 103.019 m2/g, which is larger than the specific surface area of MgAl-LDHs of 84.344 m2/g. The results showed that the optimal adsorption conditions were: adsorption temperature was 45°C, the pH value was 8, the adsorption time was 100 min, the Cl- concentration was 0.01 M (584 mg/L), and the adsorbent concentration was 1.0 g/L. CNTs/MgAl-LDHs has the best adsorption performance for chloride ions. The maximum adsorption capacity is 75.58 mg/g. The adsorption isotherms and adsorption kinetics are consistent with the Langmuir isotherm model and the quasi-secondary kinetic model.

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45

Moura Neto, Luis Gomes, Janaina De Paula da Costa, Denise Josino Soares, Emanuel Marques da Silva, and José Maria Correia da Costa. "Adição de lecitina de soja como adjuvante de secagem na obtenção de cajá em pó." Revista Principia - Divulgação Científica e Tecnológica do IFPB 1, no. 52 (November 9, 2020): 194. http://dx.doi.org/10.18265/1517-0306a2020v1n52p194-201.

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<p>Various drying techniques can be applied, depending on the raw material you want to dehydrate and what you want to obtain. One way to assess whether the dehydration method was efficient is through sorption isotherms. The objective of the work was to analyze and compare the adsorption isotherms of the cajá pulp powder obtained by atomization, with the use of maltodextrin (Test A) and maltodextrin and soy lecithin (Test B). The mathematical models of GAB, BET, Henderson and Oswin were used to represent the isotherms at 25, 30, 35 and 40 ° C. The results showed that the addition of lecithin gives a statistically different powder (p <0.05) from a powder without addition in relation to soluble solids, total sugars and its color. The BET model was the one that best fit Test A, and the Henderson model was the one that best fit Test B, which proved to be Type III in the J format. It was also observed that the addition of soy lecithin provided greater water adsorptio, which demonstrates that the product should be stored in a location with low levels of relative humidity or in packaging with low permeability.</p>

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46

Ghadiri, S., R. Nabizadeh, A. Mahvi, S. Nasseri, A. Mesdaghinia, and S. Talebi. "Potential of granulated modified nanozeolites Y for MTBE removal from aqueous solutions: Kinetic and isotherm studies." Polish Journal of Chemical Technology 14, no. 2 (January 1, 2012): 1–8. http://dx.doi.org/10.2478/v10026-012-0063-8.

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Potential of granulated modified nanozeolites Y for MTBE removal from aqueous solutions: Kinetic and isotherm studies Adsorption of methyl tert-butyl ether (MTBE) from aqueous solutions by granulated modified nanozeolites Y was investigated. Nanozeolite Y powders were converted into granulated zeolites and subsequently modified with two cationic surfactants (20 mmol/dm3), to be used as adsorbent. Granulated nanozeolites were characterized by BET surface area analysis, elemental analysis and X-ray diffractometer. -Hexade-cyltrimethylammonium (HDTMA-Cl) modified granulated zeolite had more effective performance than N-cetylpyridinium bromide (CPB) modified granulated zeolite. The most conventional adsorption isotherms and kinetic models were applied to describe MTBE adsorption and reaction dynamic, respectively. The equilibrium sorption data fitted the Langmuir 2 isotherm model and the kinetic study was followed the pseudo-second-order model. The maximum adsorption capacities for HDTMA-Cl modified zeolite and CPB modified granulated zeolite were 333.33 and 142.8 mg/g, respectively as calculated by the Langmuir model. This study demonstrated that the removal of mtbe by granulated modified nanozeolites Y is a promising technique.

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47

Faiz Haddad, Husam, Azhagapillai Prabhu, Ahmed Al Shoaibi, and Chandrasekar Srinivasakannan. "Assessment of various carbon-based adsorbents for separation of BTX from aqueous solution." Water Supply 15, no. 3 (February 9, 2015): 649–55. http://dx.doi.org/10.2166/ws.2015.020.

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The adsorption of benzene, toluene and xylene (BTX) was investigated covering different types of commercially available activated carbons with varied surface area and surface functional groups. The physico-chemical properties were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared (FTIR) spectroscopy and the Boehm titration method. Experiments to assess the adsorption isotherms and kinetics of adsorption were performed and the results are presented. An increase in the surface acid functional groups was found to decrease the adsorption capacity, with the highest adsorption capacity corresponding to carbon with lowest acid functionality.

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48

Lima, L. A., B. V. Sousa, and Meiry Glaúcia Freire Rodrigues. "Synthesis and Characterization of the Catalysts 5 wt.% and 10 wt.% Co/SBA-15." Materials Science Forum 660-661 (October 2010): 561–66. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.561.

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Catalysts supported on SBA-15 were obtained by wet impregnation using aqueous solution of cobalt nitrate, where different contents of cobalt (5 wt% and 10 wt%) were prepared. The molecular sieve SBA-15 was synthesized using tetra ethyl ortho silicate (TEOS) as silicate source, and triblock copolymer, poly-(ethylene oxide)-poly (propylene oxide)-poly-(ethylene oxide) PEO-PPO-PEO as the organic structure directing agent. These materials were characterized by X-ray diffraction (XRD), X-ray energy dispersion spectrophotometer (EDX) and Nitrogen adsorption–desorption isotherms (BET). The results from the XRD showed that the molecular sieve mesoporous (SBA-15) was identified by X-ray diffraction, especially from the (210) and (300) peaks, which represent a typical spectrum for the SBA-15. Characterization of catalysts by Nitrogen adsorption–desorption isotherms (BET) made it possible to verify the the samples had been of type IV with hysteresis of corresponding the H2 type the porous materials.

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Bazrafshan, Edris, Ferdos Kord Mostafapour, Ali Reza Hosseini, Ataolah Raksh Khorshid, and Amir Hossein Mahvi. "Decolorisation of Reactive Red 120 Dye by Using Single-Walled Carbon Nanotubes in Aqueous Solutions." Journal of Chemistry 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/938374.

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Dyes are one of the most hazardous chemical compound classes found in industrial effluents and need to be treated since their presence in water bodies reduces light penetration, precluding the photosynthesis of aqueous flora. In the present study, single-walled carbon nanotubes (SWCNTs) was used as an adsorbent for the successful removal of Reactive Red 120 (RR-120) textile dye from aqueous solutions. The effect of various operating parameters such as initial concentration of dye, contact time, adsorbent dosage and initial pH was investigated in order to find the optimum adsorption conditions. Equilibrium isotherms were used to identify the possible mechanism of the adsorption process. The optimum pH for removing of RR-120 dye from aqueous solutions was found to be 5 and for this condition maximum predicted adsorption capacity for RR-120 dye was obtained as 426.49 mg/g. Also, the equilibrium data were also fitted to the Langmuir, Freundlich and BET equilibrium isotherm models. It was found that the data fitted to BET (R2=0.9897) better than Langmuir (R2=0.9190) and Freundlich (R2=0.8819) model. Finally it was concluded that the single-walled carbon nanotubes can be used for dye removal from aqueous solutions.

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Huq, A. K. Obidul, Rosiyah Yahya, and Habibun Nabi Muhammad Ekramul Mahmud. "Equilibrium, kinetics, and thermodynamics studies of polypyrrole adsorbent for arsenic ions." Water Supply 18, no. 1 (June 14, 2017): 240–50. http://dx.doi.org/10.2166/ws.2017.078.

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Abstract Polypyrrole (PPy)-based adsorbents have successfully been prepared via oxidative polymerization in aqueous media as a new adsorbent for the removal of arsenic ions in a batch equilibrium system. The prepared adsorbent was characterized by the Brunauer–Emmet–Teller (BET) surface analyzer, field emission scanning electron microscopy (FESEM), and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR). The BET surface area and average particle size of the prepared PPy powder was 10.27 m2/g and ∼180–295 nm, respectively. Different adsorption parameters, such as adsorbent dosage, contact time, pH of the initial solution, temperature, initial ions and co-ions concentrations were investigated. The results showed that PPy powder acted as an effective sorbent for the removal of arsenic ions at the optimum conditions of pH 6.5 and a contact time of 6 h. The experimental data of PPy isotherms for arsenic ions followed the Freundlich isotherm model and kinetics data were well fitted to the pseudo-first-order model. Thermodynamically, the adsorption process was endothermic and spontaneous in nature. The FTIR and FESEM-EDX results also confirmed the presence of arsenic in adsorbents after adsorption. The presence of amine groups in PPy is believed to play the key role of adsorption of arsenic ions.

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Journal articles on the topic 'BET adsorption isotherms'

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