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Membrane Water Treatment   Volume 7, Number 2, March 2016, pages 127-141
DOI: https://doi.org/10.12989/mwt.2016.7.2.127
 
Development of a predictive model of the limiting current density of an electrodialysis process using response surface methodology
Mourad Ben Sik Ali and Béchir Hamrouni

 
Abstract     [Buy Article]
    Electrodialysis (ED) is known to be a useful membrane process for desalination, concentration, separation, and purification in many fields. In this process, it is desirable to work at high current density in order to achieve fast desalination with the lowest possible effective membrane area. In practice, however, operating currents are restricted by the occurrence of concentration polarization phenomena. Many studies showed the occurrence of a limiting current density (LCD). The limiting current density in the electrodialysis process is an important parameter which determines the electrical resistance and the current utilization. Therefore, its reliable determination is required for designing an efficient electrodialysis plant. The purpose of this study is the development of a predictive model of the limiting current density in an electrodialysis process using response surface methodology (RSM). A two-factor central composite design (CCD) of RSM was used to analyze the effect of operation conditions (the initial salt concentration (C) and the linear flow velocity of solution to be treated (u)) on the limiting current density and to establish a regression model. All experiments were carried out on synthetic brackish water solutions using a laboratory scale electrodialysis cell. The limiting current density for each experiment was determined using the Cowan-Brown method. A suitable regression model for predicting LCD within the ranges of variables used was developed based on experimental results. The proposed mathematical quadratic model was simple. Its quality was evaluated by regression analysis and by the Analysis Of Variance, popularly known as the ANOVA.
 
Key Words
    electrodialysis; concentration polarization; limiting current density; response surface methodology; central composite design
 
Address
(1) Mourad Ben Sik Ali:
Engineering Preparatory Institute of Nabeul, Merezka University Campus, Merazka, 8000 Nabeul, Republic of Tunisia;

(2) Mourad Ben Sik Ali, Béchir Hamrouni:
Desalination and Water Treatment Research Unit, Chemistry Department, Faculty of Sciences of Tunis, El Manar II, 2092, Republic of Tunisia.
 

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