Experimental studies and modeling of clinoptilolite and vermiculite fixed beds for Mn2+, Zn2+, and Cr3+ removal

V. J. Inglezakis, M. A. Stylianou, M. Loizidou, A. A. Zorpas

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

In the present study, batch and fixed bed experiments were conducted in order to compare clinoptilolite and vermiculite for the removal of Mn2+, Zn2+, and Cr3+ from aqueous solutions under the same experimental conditions. Ion-exchange equilibrium is examined by use of batch equilibrium isotherms, distribution coefficients, and maximum exchange levels (MEL). Fixed bed experiments were conducted, and breakthrough curves and operational capacity were determined. Furthermore, diffusion coefficients were estimated by use of simplified fixed bed models. Concerning the comparison of the two minerals, in all experiments, for both batch (distribution coefficients and MEL) and fixed bed (breakthrough points and operating capacity (OC)), vermiculite showed better performance than clinoptilolite for all metals. Vermiculite selectivity series derived from batch distribution coefficients as well as in fixed beds is Cr3+ > Zn2+ > Mn2+ and is the same for clinoptilolite for liquid-phase equilibrium at relative concentration of X 3+ and remains the same for the other two metals, i.e. Zn2+ > Mn2+ > Cr3+. MEL are 14.4–26.9 mg/g and 34.2–43.6 mg/g for clinoptilolite and vermiculite, respectively, and OC is found to be 3.6–7.9 mg/g and 12.8–29.3 mg/g for clinoptilolite and vermiculite, respectively, 25–75% lower than MEL. The application of the simplified fixed bed model is successful for Zn in both minerals and Cr3+-vermiculite system. For Cr3+-clinoptilolite system, the model is not applicable due to the sigmoidal shape of the isotherm while for Mn, the model fails in low concentrations for both minerals, and it seems to approach experimental data only for X > 0.2–0.3. Solid-phase diffusion confidents were estimated to be in the order of magnitude of 10−8 cm2/s for clinoptilolite and 10−9 cm2/s for vermiculite.

Original languageEnglish
JournalDesalination and Water Treatment
DOIs
Publication statusAccepted/In press - Jun 18 2015

Fingerprint

clinoptilolite
vermiculite
experimental study
Minerals
modeling
Isotherms
Experiments
Metals
Phase equilibria
isotherm
mineral
Ion exchange
experiment
metal
breakthrough curve
phase equilibrium
removal
Liquids
ion exchange
aqueous solution

Keywords

  • Clinoptilolite
  • Fixed beds reactors
  • Heavy metals
  • Ion-exchange
  • Vermiculite

ASJC Scopus subject areas

  • Pollution
  • Water Science and Technology
  • Ocean Engineering

Cite this

Experimental studies and modeling of clinoptilolite and vermiculite fixed beds for Mn2+, Zn2+, and Cr3+ removal. / Inglezakis, V. J.; Stylianou, M. A.; Loizidou, M.; Zorpas, A. A.

In: Desalination and Water Treatment, 18.06.2015.

Research output: Contribution to journalArticle

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abstract = "In the present study, batch and fixed bed experiments were conducted in order to compare clinoptilolite and vermiculite for the removal of Mn2+, Zn2+, and Cr3+ from aqueous solutions under the same experimental conditions. Ion-exchange equilibrium is examined by use of batch equilibrium isotherms, distribution coefficients, and maximum exchange levels (MEL). Fixed bed experiments were conducted, and breakthrough curves and operational capacity were determined. Furthermore, diffusion coefficients were estimated by use of simplified fixed bed models. Concerning the comparison of the two minerals, in all experiments, for both batch (distribution coefficients and MEL) and fixed bed (breakthrough points and operating capacity (OC)), vermiculite showed better performance than clinoptilolite for all metals. Vermiculite selectivity series derived from batch distribution coefficients as well as in fixed beds is Cr3+ > Zn2+ > Mn2+ and is the same for clinoptilolite for liquid-phase equilibrium at relative concentration of X 3+ and remains the same for the other two metals, i.e. Zn2+ > Mn2+ > Cr3+. MEL are 14.4–26.9 mg/g and 34.2–43.6 mg/g for clinoptilolite and vermiculite, respectively, and OC is found to be 3.6–7.9 mg/g and 12.8–29.3 mg/g for clinoptilolite and vermiculite, respectively, 25–75{\%} lower than MEL. The application of the simplified fixed bed model is successful for Zn in both minerals and Cr3+-vermiculite system. For Cr3+-clinoptilolite system, the model is not applicable due to the sigmoidal shape of the isotherm while for Mn, the model fails in low concentrations for both minerals, and it seems to approach experimental data only for X > 0.2–0.3. Solid-phase diffusion confidents were estimated to be in the order of magnitude of 10−8 cm2/s for clinoptilolite and 10−9 cm2/s for vermiculite.",
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AU - Zorpas, A. A.

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N2 - In the present study, batch and fixed bed experiments were conducted in order to compare clinoptilolite and vermiculite for the removal of Mn2+, Zn2+, and Cr3+ from aqueous solutions under the same experimental conditions. Ion-exchange equilibrium is examined by use of batch equilibrium isotherms, distribution coefficients, and maximum exchange levels (MEL). Fixed bed experiments were conducted, and breakthrough curves and operational capacity were determined. Furthermore, diffusion coefficients were estimated by use of simplified fixed bed models. Concerning the comparison of the two minerals, in all experiments, for both batch (distribution coefficients and MEL) and fixed bed (breakthrough points and operating capacity (OC)), vermiculite showed better performance than clinoptilolite for all metals. Vermiculite selectivity series derived from batch distribution coefficients as well as in fixed beds is Cr3+ > Zn2+ > Mn2+ and is the same for clinoptilolite for liquid-phase equilibrium at relative concentration of X 3+ and remains the same for the other two metals, i.e. Zn2+ > Mn2+ > Cr3+. MEL are 14.4–26.9 mg/g and 34.2–43.6 mg/g for clinoptilolite and vermiculite, respectively, and OC is found to be 3.6–7.9 mg/g and 12.8–29.3 mg/g for clinoptilolite and vermiculite, respectively, 25–75% lower than MEL. The application of the simplified fixed bed model is successful for Zn in both minerals and Cr3+-vermiculite system. For Cr3+-clinoptilolite system, the model is not applicable due to the sigmoidal shape of the isotherm while for Mn, the model fails in low concentrations for both minerals, and it seems to approach experimental data only for X > 0.2–0.3. Solid-phase diffusion confidents were estimated to be in the order of magnitude of 10−8 cm2/s for clinoptilolite and 10−9 cm2/s for vermiculite.

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