A comparative study of linear and non-linear regression analysis for ammonium exchange by clinoptilolite zeolite

Karadağ, Doğan; Koc, Yunus; Turan, Mustafa; Öztürk, Mustafa Çağdaş

doi:10.1016/j.jhazmat.2006.10.055

Cited by 135 publications

(75 citation statements)

References 27 publications

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“…The equilibrium patterns of ammonium on natural Turkish clinoptilolite, MesoLite and rice husk ash-synthesized zeolite Y fit well with the Langmuir isotherm [5,16,17]. However, the Freundlich model was better than Langmuir to represent equilibrium data of ammonium exchange by clinoptilolite and microwave-treated zeolite [3,18]. These results confirm that different zeolites have different characters and thus different equilibrium patterns.…”

Section: Freundlich Isothermsupporting

confidence: 57%

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Ammonium removal from aqueous solution by zeolites synthesized from low-calcium and high-calcium fly ashes

Zhang

et al. 2011

Desalination

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Keywords:Low-calcium fly ash High-calcium fly ash Synthesized zeolite Ammonium removal Select criteria of raw fly ash In this study, zeolites are synthesized from low-calcium (LC-Z) and high-calcium (HC-Z) fly ashes, respectively. The changes of mineralogy, morphology, cation exchange capacity (CEC) and specific surface area (SSA) are investigated during the synthesis process. The equilibrium uptake of ammonium on the two synthesized zeolites is compared. The main crystals of LC-Z and HC-Z are identified as faujasite and gismondine, respectively. The CEC and SSA increase significantly following the conversion process. The kinetic studies showed that the adsorption process of ammonium on both LC-Z and HC-Z follows Ho's pseudosecond-order model. Langmuir model agrees better with the equilibrium data for LC-Z, while Freundlich model gives the better fit for HC-Z. The obtained maximum ammonium uptake capacities are 23.8 mg/g for LC-Z and 3.17 mg/g for HC-Z in the synthetic solution. LC-Z also exhibits much better performance in ammonium uptake in effluent from a sewage treatment plant than HC-Z. These results indicate that LC-Z is a promising material for ammonium removal whereas HC-Z is not. The Ca 2+ leaching and the lower zeolite content in HC-Z account for its lower uptake capacity. Thus, the low-calcium fly ash should be chosen preferentially as the raw material of the zeolite synthesis for ammonium removal.

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Section: Freundlich Isothermsupporting

confidence: 57%

“…Different results about the suitable adsorption isotherm for various zeolites were also obtained in previous studies [3,5,[16][17][18]. The equilibrium patterns of ammonium on natural Turkish clinoptilolite, MesoLite and rice husk ash-synthesized zeolite Y fit well with the Langmuir isotherm [5,16,17].…”

Section: Freundlich Isothermmentioning

confidence: 61%

Ammonium removal from aqueous solution by zeolites synthesized from low-calcium and high-calcium fly ashes

Zhang

et al. 2011

Desalination

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“…The coefficient of determination values (r 2 ) were used in order to find the degrees of fit of the isotherm adsorption and thermodynamic models with the experimental data, 18 as defined by equation 2: (2) where N fEXP (mmol g -1 ) is the experimental amount of thorium cations exchanged by the unmodified and the modified phyllosilicate samples and N fCAL is the amount of cations obtained from the isotherm model.…”

Section: Non-linear Methodsmentioning

confidence: 99%

Adsorption of thorium(IV) on chemically modified Amazon clays

Guerra¹,

Viana²,

Airoldi³

2009

J. Braz. Chem. Soc.

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Amostras de caulinita e esmectita oriundas da região Amazônica, Brasil, foram modificadas com 2-mercaptobenzimidazol (MBI) usando rotas homogênea e heterogênea. As amostras de argilas modificadas (K HOM, S HOM , K HET e S HET ) foram caracterizadas por análise textural, MEV e espectroscopia 13 C NMR. As argilas modificadas quimicamente apresentaram modificações em suas propriedades físico-químicas incluindo: área específica 48,0 (S) para 869,8 m 2 g -1 (S HET ). A habilidade destes materiais para remover tório(IV) em soluções aquosas foi investigada por um série de isotermas de adsorção ajustadas pela equação de Sips em temperatura ambiente e pH 2,0. O número máximo de mols adsorvidos foi determinado em 8,29,8,86,9,57 e 9,89 10 -1 mmol g -1 para K HOM , K HET , S HOM e S HET , respectivamente. Os efeitos energéticos causados pela adsorção do cation tório(IV) foram determinados através de metodologia calorimétrica.Kaolinite and smectite clay samples from the Amazon region, Brazil, were modified with 2-mercaptobenzimidazole (MBI) using homogeneous and heterogeneous routes. The modified clay samples (K HOM , S HOM , K HET and S HET ) were characterized by textural analysis, SEM and 13 C NMR spectroscopy. The chemically modified clay samples showed modifications of their physicalchemical properties including: specific area 48.0 (S) to 869.8 m 2 g -1 (S HET ). The ability of these materials to remove thorium(IV) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature, and pH 2.0. The maximum number of moles adsorbed was determined to be 8. 29, 8.86, 9.57 and 9.89 10 -1 mmol g -1 for K HOM , K HET , S HOM and S HET , respectively. The energetic effects (∆ int H, ∆ int G and ∆ int S) caused by thorium(IV) cation adsorption were determined through calorimetry.

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“…The b or N s value is the upper limit and represents the maximum adsorption, determined by the number of reactive surface reactive sites [16][17]. The coefficient of determination values (r 2 ) were used in order to find the degrees of fit of the isotherm adsorption and kinetic models with the experimental data [18], as defined by equation B:…”

Section: Chemical Shift / Ppmmentioning

confidence: 99%

Performance of natural and modified smectite: kinetic and thermodynamics involving arsenic (V) adsorption

2010

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A natural smectite sample has been modified by organofunctionalization process using synthetic route involved the reaction of 2-mercaptopyrimidine with 3-chloropropyltriethoxysilane. The resulting material (S MPY ) was characterized by SEM, FTIR, textural analysis and 29 Si MAS-NMR. The ability of this material to removed As (V) from aqueous solution was followed by series of adsorption isotherms adjusted to the Langmuir equation at room temperature and pH 2.0. The kinetic parameters analyzed by Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k 2 in the 4.9 to 14.0 mmol -1 min -1 range for S MPY . The adsorption process was exothermic (D int H = -4.09 to -5.79 kJ.mol -1 ) accompanied by increase in entropy (D int S = 41.29 to 61.80 JK -1 .mol -1 ) and Gibbs energy (D int G = -22.34 to -24.19 kJmol -1 ). The energetic effect caused by arsenic cation adsorption was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant. Keywords: adsorption, smectite, kinetic, thermodynamic, arsenic. Resumo Uma amostra de esmectita natural foi modificada por processo de organofuncionalização usando rota sintética, envolvendo a reação de 2-mercaptopirimidina com 3-cloropropiltrietoxisilano. O material resultante (S MPY)

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A comparative study of linear and non-linear regression analysis for ammonium exchange by clinoptilolite zeolite

Cited by 135 publications

References 27 publications

Ammonium removal from aqueous solution by zeolites synthesized from low-calcium and high-calcium fly ashes

Ammonium removal from aqueous solution by zeolites synthesized from low-calcium and high-calcium fly ashes

Adsorption of thorium(IV) on chemically modified Amazon clays

Performance of natural and modified smectite: kinetic and thermodynamics involving arsenic (V) adsorption

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