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

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 NH + 4 -K + ion-exchange under different conditions were systemically determined using the shallow-bed experimental method. The results showed that the 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 A C Concentration of ion A in zeolite, dimensionless A S Concentration of ion A in solution, dimensionless a Interfacial area per granule volume, m 2 m −3 C A Concentration of ion A in solution, mol L −1 C A0 Primal concentration of ion A in solution, mol L −1 C A * Equilibrium concentration of ion A on zeolite, mol L −1 D A Diffusion coefficient of ion A, m 2 s −1 F Exchange rate of ion A in zeolite, F = q/Q, % 123 72 Y. Junsheng et al. K fx Mass transfer coefficient, m s −1 K f Average mass transfer coefficient, m s −1 L Size of zeolite granule, m n A Mass transfer rate of ion A, kg m −2 s −1 q NH + 4 concentration in zeolite, kg (kg zeolite) −1 Q NH + 4 saturated exchange capacities of zeolite, kg (kg zeolite) −1 Re x Local Reynolds number, Re x = ρu • x/µ, dimensionless Sc Schmidt number, Sc = µ/(ρD A ), dimensionless T Temperature, • C t Time, s U Flow rate of liquid, m s −1 u 0 Main flow rate of liquid, m s −1 u x Flow rate of liquid in film, m s −1 V Volume of liquid, m 3 V 1 Volume of liquid at certain time, m 3 v Flux of liquid, m 3 s −1 w Weight of zeolite, kg δ Motion boundary layer thickness, m δ D Concentration boundary layer thickness , m ε Interspace Ratio of zeolite layer, dimensionless µ Viscosity of liquid, N s m −2 γ Dynamic viscosity of liquid, m 2 s −1 ρDensity of liquid, kg m −3 ρ A Mass concentration of ion A in solution, kg m −3 ρ A Average mass concentration of ion A in solution, kg m −3 ρ A0 Primal mass concentration of ion A in solution, kg m −3 ρ A * Equilibrium mass concentration of ion A on zeolite, kg m −3 ρ s Density of zeolite, kg m −3

A Comparison of Natural and Synthetic Zeolites in Continuous Column-Based Experiments for Removing Ammonia From Wastewater

“…The range of EBCTs operated in the current study equates to Reynolds (Re) numbers between 0.1 and 1.6 such that flow is laminar and boundary layer thicknesses are expected to be relatively large. This is consistent with previous work investigating mass transfer effects with Clinoptilolite where the overall mass transfer coefficient was reported to be film diffusion controlled (Yuan et al, 2008). The fact that the capacity increased with Re supports this and is in contrast to previous column studies with hybrid ion exchange media where intra particle diffusion was seen to dominate (Muhammad et al, 2018).…”

Recent Advances in Agronomic and Physio-Molecular Approaches for Improving Nitrogen Use Efficiency in Crop Plants

“…Kavoosi (2007) found that application of 16 tons zeolite ha −1 increased apparent N recovery up to 65%, agronomic efficiency up to 22 Kg grain kg −1 N, and ensured good retention of soil-exchangeable cations, available P, and NO 3− within the soil in maize at Malaysia (Rabai et al, 2013). The application of zeolites along with rock phosphate tremendously increased the uptake of P by crop plants through exchanged induced dissolution (Yuan et al, 2008). Surface application of zeolite has the potential for mitigating NH 3 losses thereby reducing losses of nitrogen to the environment (Waldrip et al, 2014).…”