Modelling and simulation of the ion exchange process for Zn2+(aq) removal using zeolite NaY

Andrezza De Araújo Silva Gallindo,Reinaldo Alves Da Silva Junior,Meiry Gláucia Freire Rodrigues,Wagner Brandão Ramos

doi:10.33448/rsd-v10i12.20362

Andrezza De Araújo Silva Gallindo, Reinaldo Alves Da Silva Junior + Show 2 more

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https://doi.org/10.33448/rsd-v10i12.20362

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Abstract

The treatment of water contaminated by toxic metals using ion exchange with zeolites is becoming attractive due to its low capital costs and high potential for removal capacity. Mathematical modelling of this process allows for operational control and estimation of the ability to remove these metals. In this work, the kinetic modelling was performed based on finite bath experimental data, with Intraparticle Diffusion (IPD) and External Liquid Film Mass Transfer (MTEF) models. The models Thomas (TH), Yoon-Nelson (YN) and Solid Film Mass Transfer (MTSF) were used to estimate the saturation time, ion exchange capacity and sizing variables of a fixed bed column. For the finite bath system, the results showed that the mass transfer was better represented by the IPD phenomenon. The breakthrough curve obtained by the Aspen Adsorption (MTSF) model presented the best fit, compared with experimental data, with R2≥0.9923. The average ion exchange capacities calculated for MTSF, TH and YN were respectively 2.22, 2.12 and 2.07 meq Zn2+(aq)/ g of zeolite. The model simulated with Aspen Adsorption was also used to analyze the continuous system behaviour, by varying the height of the bed. It was observed that increasing the height, the saturation time and ion exchange capacity also increase, while reducing the height makes axial dispersion the predominant mass transfer phenomenon, which reduces the diffusion of Zn2+(aq) ions.

Highlights

IntroductionHeavy metals are still causing environmental problems in the 21st century, such as the pollution of rivers connected to public water sources, due to unstructured urbanization and industrial processes (Oliveira et al, 2018)
Heavy metals are still causing environmental problems in the 21st century, such as the pollution of rivers connected to public water sources, due to unstructured urbanization and industrial processes (Oliveira et al, 2018).According to the 2019 Statistical Yearbook of the Metallurgical Sector, the Brazilian production of zinc was in 2nd place among non-ferrous metals
The kinetic modelling with finite bath data allowed to stablish that the limiting step of the exchange process, between the Intraparticle Diffusion (IPD) and MTEF models, is the intraparticle diffusion, with R2 = 0.9099 for the 1st stage of instantaneous ion exchange between Zn2+(aq) and the surface of zeolite NaY, and R2 = 0.8908 for the 2nd stage of gradual ion exchange within the pores of the zeolite

Summary

Introduction

Heavy metals are still causing environmental problems in the 21st century, such as the pollution of rivers connected to public water sources, due to unstructured urbanization and industrial processes (Oliveira et al, 2018). According to the 2019 Statistical Yearbook of the Metallurgical Sector, the Brazilian production of zinc was in 2nd place among non-ferrous metals. This intense production process results in high waste disposal. The EPA (United States Environmental Protection Agency) recommends the National Secondary Drinking Water Regulations (NSDWRs) 5 mg/L of Zinc. For example, present in battery, biomedical and food production industries, are related to the decrease in cellular antioxidant levels (Lazzaretti & Hupffer, 2018)

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