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Transport in Porous Media

, Volume 72, Issue 1, pp 71–82 | Cite as

Transfer model and kinetic characteristics of \({\rm NH}_{4}^{+}\) –K+ ion exchange on K-zeolite

  • Junsheng YuanEmail author
  • Qingmin Chen
  • Jingkang Wang
Article

Abstract

Based on the mass transfer theory, a new mass transfer model of ion-exchange process on zeolite under liquid film diffusion control is established, and the kinetic curves and the mass transfer coefficients of \({\rm NH}_{4}^{+}\) –K+ ion-exchange under different conditions were systemically determined using the shallow-bed experimental method. The results showed that the \({\rm NH}_{4}^{+}\) –K+ ion-exchange rates and transfer coefficients are directly proportional to solution flow rate and temperature, and inversely proportional to solution viscosity and the size of zeolite granules. It also showed that the transfer coefficient is not influenced by the ion concentrations. For a large ranges of operational conditions including temperatures (10 − 75°C), flow rates (0.031 m s−1 −0.26 m s−1), liquid viscosities (1.002 ×  10−3 N s m−2 − 4.44 ×  10−3 N s m−2), and zeolite granular sizes (0.2 − 1.45 mm), the average mass transfer coefficients calculated by the model agree with the experimental results very well.

Keywords

K-zeolite Ammonium Ion exchange Kinetics Mass transfer mechanism Mass transfer model 

Nomenclature

AC

Concentration of ion A in zeolite, dimensionless

AS

Concentration of ion A in solution, dimensionless

a

Interfacial area per granule volume, m2 m−3

CA

Concentration of ion A in solution, mol L−1

CA0

Primal concentration of ion A in solution, mol L−1

CA*

Equilibrium concentration of ion A on zeolite, mol L−1

DA

Diffusion coefficient of ion A, m2 s−1

F

Exchange rate of ion A in zeolite, F = q/Q, %

Kfx

Mass transfer coefficient, m s−1

Kf

Average mass transfer coefficient, m s−1

L

Size of zeolite granule, m

nA

Mass transfer rate of ion A, kg m−2 s−1

q

\({\rm NH}_{4}^{+}\) concentration in zeolite, kg (kg zeolite)−1

Q

\({\rm NH}_{4}^{+}\) saturated exchange capacities of zeolite, kg (kg zeolite)−1

Rex

Local Reynolds number, \({\rm Re}_x = {\rho u \circ x}/\mu\) , dimensionless

Sc

Schmidt number, Sc = μ /(ρ D A), dimensionless

T

Temperature, °C

t

Time, s

U

Flow rate of liquid, m s−1

u0

Main flow rate of liquid, m s−1

ux

Flow rate of liquid in film, m s−1

V

Volume of liquid, m3

V1

Volume of liquid at certain time, m3

v

Flux of liquid, m3 s−1

w

Weight of zeolite, kg

δ

Motion boundary layer thickness, m

δD

Concentration boundary layer thickness , m

ɛ

Interspace Ratio of zeolite layer, dimensionless

μ

Viscosity of liquid, N s m−2

γ

Dynamic viscosity of liquid, m2 s−1

ρ

Density of liquid, kg m−3

ρA

Mass concentration of ion A in solution, kg m−3

ρA

Average mass concentration of ion A in solution, kg m−3

ρA0

Primal mass concentration of ion A in solution, kg m−3

ρA*

Equilibrium mass concentration of ion A on zeolite, kg m−3

ρs

Density of zeolite, kg m−3

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.School of Chemical EngineeringHebei University of TechnologyTianjinChina
  2. 2.School of Chemical EngineeringTianjin UniversityTianjinChina

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