Removal of chromium(VI) from aqueous solution by activated carbons: Kinetic and equilibrium studies

Khezami, Lotfi; Capart, R.

doi:10.1016/j.jhazmat.2005.04.012

Cited by 568 publications

(296 citation statements)

References 34 publications

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“…As can be seen in this research, n values below 1 are found only for Pb 2+ adsorption by CNS NaOH and Cr 3+ CNS in natura, CNS H 2 O 2 and CNS H 2 SO 4 , and all other values were higher than 1 (Table 8). In cases where n values approach 1, it is a strong indication of the presence of highly energetic sites or the occurrence of cooperative adsorption, involving interactions between molecules of the own adsorbate (Khezami and Capart 2005). But to Skopp (2009), when n > 1, that do not reflect a good fit, for lack of physical sense.…”

Section: Efficiency Of Adsorption and Desorptionmentioning

confidence: 99%

Removal of Cd(II), Pb(II) and Cr(III) from water using modified residues of Anacardium occidentale L.

et al. 2018

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The pollution of water has been one of the greatest problems faced by the modern society, due to industrialization and urban growth. Rivers, lakes and seas have been continually suffering from the rising concentration of various pollutants, especially toxic elements. This study aimed to evaluate the use of cashew nut shell (Anacardium occidentale) (CNS), after chemical modification with H 2 O 2 , H 2 SO 4 and NaOH, as an new and renewable adsorbent material, for the removal of metals Cd 2+ , Pb 2+ and Cr 3+ in aqueous medium. The adsorbents were characterized by its chemical constitution, structure, infrared spectroscopy, morphology, by means of scanning electron microscopy, determination of the point of zero charge, thermogravimetrical analysis and porosimetry assessments. Tests were conducted to determine the optimal conditions (pH vs. adsorbent mass) for adsorption, by means of multivariate analysis using a central composite design. The adsorption kinetics was evaluated by models of pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion, while adsorption isotherms were linearized by Langmuir, Freundlich and Dubinin-Radushkevich. The effect of initial concentration, temperature and desorption was also performed. The adsorbents exhibited irregular, spongy and heterogeneous structure. FTIR analysis confirms the presence of hydroxyl, aliphatic, phenolic and carboxylic acid groups, which are favorable adsorption characteristics. The pH PZC of adsorbent is 4.35, 2.50 e 6.92, respectively, for CNS H 2 O 2 , H 2 SO 4 and NaOH. The optimum adsorption conditions were as follows: pH 5.0; relation of adsorbent mass/volume of water: 4 g L −1 ; 40 min of contact time for reaching the equilibration. Results suggest the predominance of chemisorption of Cd 2+ and Cr 3+ . Most of biosorbents exhibited good fit by Langmuir and Freundlich, suggesting the occurrence of adsorption on mono-and multilayers. The adsorbents of cashew nut shell exhibited high removal efficiency of Cd, Pb and Cr from waters.

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Section: Efficiency Of Adsorption and Desorptionmentioning

confidence: 99%

Removal of Cd(II), Pb(II) and Cr(III) from water using modified residues of Anacardium occidentale L.

et al. 2018

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“…Once the Cr(VI) is located on the outer nanoparticle surface, there might be electrostatic attraction occurring between the adsorbate and adsorbent (Singh et al 1993). In addition to this effect, varying the temperature would modify the equilibrium capacity (Khezami and Capart 2005). It is noteworthy that the efficiency increases from 10°C to reach a plateau at approximately 40°C and subsequently sharply increases at higher temperatures.…”

Section: Effect Of the Temperature On The Cr(vi) Recoverymentioning

confidence: 99%

“…These materials include activated carbon, activated alumina, natural zeolites and various biosorbents (Faghihian and Bowman 2005;Khezami and Capart 2005;Mor et al 2007). However, these adsorbents present a common problem, the need for a second separation process from solution, which increases operating costs.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of chromium(VI) onto electrochemically obtained magnetite nanoparticles

Martínez

Muñoz‐Bonilla

Mazarío

et al. 2015

Int. J. Environ. Sci. Technol.

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Well-dispersed magnetite nanoparticles of different sizes between 15 and 43 nm were synthesized by an electrochemical method in a controlled manner by simply changing the synthesis temperature. These nanoparticles were used as a reusable adsorbent to remove Cr(VI) from aqueous solution. The recovery efficiency was found to be highly dependent on environmental parameters, such as temperature and pH. In addition, it was demonstrated that the initial concentrations of both Cr(VI) and magnetite nanoparticles strongly influence the removal capability of these nanomaterials. Remarkably, the nanoparticle size has a key role on the Cr(VI) adsorption efficiency, which gradually increases as the diameter decreases due to the augmentation of the surface area. The low aggregation in the case of small particles that results from the low magnetization saturation values also contributes to the enhancement of the surface area available for Cr(VI) adsorption. In contrast, nanoparticles with larger sizes are more easily manipulated by a magnet, and the efficiency is largely maintained after five cycles. The adsorption process fits the Langmuir isotherm model well, and the reaction was found to follow a pseudo-second-order rate.

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“…Cr(VI) usually exists in wastewater as oxyanions such as chromate (CrO 4 2-) and dichromate (Cr 2 O 7 2-) ions. The latter form is the most toxic [3]. EPA (Environmental Protection Agency) has set the maximum level of total chromium concentration allowed in drinking water at 0.1 mg/L [4].…”

Section: Introductionmentioning

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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Removal of chromium(VI) from aqueous solution by activated carbons: Kinetic and equilibrium studies

Cited by 568 publications

References 34 publications

Removal of Cd(II), Pb(II) and Cr(III) from water using modified residues of Anacardium occidentale L.

Removal of Cd(II), Pb(II) and Cr(III) from water using modified residues of Anacardium occidentale L.

Adsorption of chromium(VI) onto electrochemically obtained magnetite nanoparticles

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

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