Adsorption of Pb(II) from aqueous solution to MX-80 bentonite: Effect of pH, ionic strength, foreign ions and temperature

Xu, Di; Tan, Xiaoli; Chen, C.L.; Wang, X.K.

doi:10.1016/j.clay.2007.09.004

Cited by 274 publications

(155 citation statements)

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“…e almost zero values of Δ * suggests that the entropy of the system is decreased or stayed constant. On the other hand, these almost zero values of entropy indicate that the sorption process is irreversible and favors the stability of value [29]. e low to negative values for Δ * indicate that the sorption process is more energy favorable at higher pH values, since we are talking about a heterogeneous and not a homogeneous system.…”

Section: Ermodynamics Of Sorption Onmentioning

confidence: 99%

“…In Langmuir model, max represents the maximum sorption of metal ions at monolayer coverage, whereas in D-R model it represents the maximum sorption of metal ions at the total speci�c micropore volume of the sorbent. ereby, the value of max derived from D-R model is lower than that derived from Langmuir model [29]. e values of , / , and for thorium(IV) and uranium(VI) are summarized in Table 8.…”

Section: Metal Sorption Studies Onmentioning

confidence: 99%

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Sorption of Uranium(VI) and Thorium(IV) by Jordanian Bentonite

Khalili

Salameh

Shaybe

2012

Journal of Chemistry

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Puri�cation of raw bentonite was done to remove quartz. is includes mixing the raw bentonite with water and then centrifuge it at �50 rpm; this process is repeated until white puri�ed bentonite is obtained. �RD, �RF, FTIR, and SEM techniques will be used for the characterization of puri�ed bentonite. e sorption behavior of puri�ed Jordanian bentonite towards UO 2 2+and  4+ metal ions in aqueous solutions was studied by batch experiment as a function of pH, contact time, temperature, and column techniques at 25.0 ∘ C and pH = 3. e highest rate of metal ions uptake was observed aer 18 h of shaking, and the uptake has increased with increasing pH and reached a maximum at pH = 3. Bentonite has shown high metal ion uptake capacity toward uranium(VI) than thorium(IV). Sorption data were evaluated according to the pseudo-second-order reaction kinetic. Sorption isotherms were studied at temperatures 25.0 ∘ C, 35.0 ∘ C, and 45.0 ∘ C. e Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) sorption models equations were applied and the proper constants were derived. It was found that the sorption process is enthalpy driven for uranium(VI) and thorium(IV). Recovery of uranium(VI) and thorium(IV) ions aer sorption was carried out by treatment of the loaded bentonite with different concentrations of HNO 3 1.0 M, 0.5 M, 0.1 M, and 0.01 M. e best percent recovery for uranium(VI) and thorium(IV) was obtained when 1.0 M HNO 3 was used.

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Section: Ermodynamics Of Sorption Onmentioning

confidence: 99%

Section: Metal Sorption Studies Onmentioning

confidence: 99%

Sorption of Uranium(VI) and Thorium(IV) by Jordanian Bentonite

Khalili

Salameh

Shaybe

2012

Journal of Chemistry

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“…In the case of E < 8 kJ/mol, physical forces may affect the adsorption. On the other hand, adsorption may be dominated by particle diffusion if E > 16 kJ/mol [23,24].…”

Section: Dubinin-radushkevich (D-r) Isothermmentioning

confidence: 99%

Adsorption and Reduction of Chromium(VI) from Aqueous Solution by Multiwalled Carbon Nanotubes

Hu¹,

Wang²,

Shao³

et al. 2009

TOEPTJ

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Abstract:The adsorption of Cr(VI) on the raw multiwalled carbon nanotubes (MWCNTs) as a function of initial Cr(VI) concentration, pH, temperature, and MWCNT dosage were studied. The removal of Cr(VI) from aqueous solution was dominated by adsorption of Cr(VI) and redox reaction of Cr(VI) to Cr(III). The adsorption of Cr(VI) decreased with increasing pH and increased with the rise in temperature and MWCNT dosage. The adsorption data of Cr(VI) on MWCNTs could be described well by Langmuir isotherm model. The thermodynamic values of Gibbs free energy ( G o ), enthalpy ( H o ), and entropy ( S o ) were calculated from temperature-dependent adsorption data, and the results indicated that the adsorption of Cr(VI) on the raw MWCNTs was a spontaneous process. The results suggest that MWCNTs are suitable materials in the preconcentration and solidification of Cr(VI) from large volume of solutions.

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“…Bentonite consists mostly of microcrystalline particles of montmorillonite which belongs to 2:1 clay minerals meaning that it has two tetrahedral sheets sandwiching a central octahedral sheet [1][2][3][4]. Since the existence of huge deposits of bentonite, there is a great potential for its utilization in removing various dilute pollutants and adsorption technology including the removal of heavy metal ions [5][6][7][8] [18][19][20]. To apply bentonite in adsorption, the textural properties including surface area, pore size, micropore volume and mesopore volume must be determined.…”

Section: Introductionmentioning

confidence: 99%

“…To apply bentonite in adsorption, the textural properties including surface area, pore size, micropore volume and mesopore volume must be determined. The textural properties of porous materils are very often determined by gas (N 2 ) adsorption isotherm data [8,21,22].The empirical form of an adsorption isotherm was recognized as early as 1926 by Freundlich [23], and was later derived theoretically from the Langmuir equation [24] extended to heterogeneous surfaces considered to be a composite surface, composed of many homogeneous patches [25]. By adopting the Langmuir mechanism, but introducing a number of simplifying assumptions, the Brunauer-Emmet-Teller (BET) equation was subsequently derived for multilayer adsorption [26].…”

mentioning

confidence: 99%

Accuracy of Dubinin-Astakov and Dubinin-Raduchkevic Adsorption Isotherm Models in Evaluating Micropore Volume of Bontonite

Saeidi

Parvini

2015

Period. Polytech. Chem. Eng.

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Accuracy of Dubinin-Astakhov (DA) and Dubinin-Radushkevich (DR) IntroductionClay can be used in several applications due to its physical and chemical properties, such as large specific surface area, cation exchange capacity and adsorptive affinity for inorganic and organic ions from aqueous solution and water. Among the clays, bentonite is considered as a main candidate in the removal of pollutants such as lead and other heavy metal ions. Bentonite consists mostly of microcrystalline particles of montmorillonite which belongs to 2:1 clay minerals meaning that it has two tetrahedral sheets sandwiching a central octahedral sheet [1][2][3][4]. Since the existence of huge deposits of bentonite, there is a great potential for its utilization in removing various dilute pollutants and adsorption technology including the removal of heavy metal ions [5][6][7][8] [18][19][20]. To apply bentonite in adsorption, the textural properties including surface area, pore size, micropore volume and mesopore volume must be determined. The textural properties of porous materils are very often determined by gas (N 2 ) adsorption isotherm data [8,21,22].The empirical form of an adsorption isotherm was recognized as early as 1926 by Freundlich [23], and was later derived theoretically from the Langmuir equation [24] extended to heterogeneous surfaces considered to be a composite surface, composed of many homogeneous patches [25]. By adopting the Langmuir mechanism, but introducing a number of simplifying assumptions, the Brunauer-Emmet-Teller (BET) equation was subsequently derived for multilayer adsorption [26]. It is unquestionable that together with the concept of multilayer adsorption (leading to the BET equation) the theory of volume filling of micropores is one of the most stimulating concepts occupying the principal position in adsorption science [27]. Developed formerly, and based on the Weibull distribution of adsorption potential, the proposed equation by M. M. Dubinin [28] was considered to be a semi-empirical one. The fundamental relations are the Dubinin-Astakhov and Dubinin-Radushkevich equations [28,29]. The surface area, mesopore volume and micropore volume of such porous materials can be evaluated by means of BET, BJH [30] and both HK [31] and density functional theory (DFT)

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Adsorption of Pb(II) from aqueous solution to MX-80 bentonite: Effect of pH, ionic strength, foreign ions and temperature

Cited by 274 publications

References 43 publications

Sorption of Uranium(VI) and Thorium(IV) by Jordanian Bentonite

Sorption of Uranium(VI) and Thorium(IV) by Jordanian Bentonite

Adsorption and Reduction of Chromium(VI) from Aqueous Solution by Multiwalled Carbon Nanotubes

Accuracy of Dubinin-Astakov and Dubinin-Raduchkevic Adsorption Isotherm Models in Evaluating Micropore Volume of Bontonite

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