Abstract
In order to improve the selectivity of anion exchange resin, the surface of gel type anion exchange resin was modified with polyethyleneimine (PEI). In the proposed work an attempt to the utilization of commercial anion exchange resin modified by adsorption of polyethyleneimine was investigated. Many conditions of modification of anion exchange resin surface were studied. The influent parameters on the DOWEX 1X8 resin modification were determined using a factorial experimental design. The ion exchange reactions were studied for modified and unmodified resin and electrolyte solutions containing Cl-，NO3-，SO42-. All experiments were performed at constant ionic strength I = 0.3 mol·L-1 and constant temperature T = 298 K. Ionic exchange isotherms were established for the binary systems:Cl-/NO3-，Cl-/SO42- and NO3-/SO42-. The obtained results show that nitrate ion was more sorbed than chloride and sulfate. The order of preference for the anions studied in this investigation is:NO3->Cl->SO42-. All the results given by this resin were compared with those obtained with the AMX anion exchange membrane. Selectivity coefficients and thermodynamic constants for the three binary systems and for the two resins were determined. The modified resin became more selective towards monovalent anions.
Highlights
Ion exchange resins and membranes are widely used in various fields such as electrodialytic concentration of seawater to produce sodium chloride and demineralization of saline water
The objective of this study is to determine the optimal conditions for modification of the DOWEX 1X8 anion exchange resin
The modification of ion exchange resin by adsorption of a polyelectrolyte and in particular by simple immersion of the resin in a solution of polyelectrolyte led us to choose three factors, namely, the initial concentration of polyethyleneimine (X1), the molecular weight of the polyethyleneimine (X2) and the pH of the medium (X3) [22]. We studied in this part the influence of these factors on the modification of the anionic resin DOWEX 1X8
Summary
Ion exchange resins and membranes are widely used in various fields such as electrodialytic concentration of seawater to produce sodium chloride and demineralization of saline water. Matsusaki et al [17] tried to modify the surface of geltype anion exchange resin by adsorption of anionic polyelectrolyte in order to change the ion exchange selectivity of this resin, especially to make the ion exchange of divalent anions more difficult. Berbar et al [18] used anion exchange resin Amberlite IRA 900 modified with polyethyleneimine to separate nitrate and chloride ions. They found that the modified resin became more selective toward nitrate when the modification was attempted at pH = 9.8 during 3 days
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