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Modification of the AMX membrane surface by polyethyleneimine: Effect of ionic strength on the membrane ion exchange selectivity
Author(s) -
Louati Islem,
Guesmi Fatma,
Hannachi Chiraz,
Hamrouni Béchir
Publication year - 2016
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.22615
Subject(s) - selectivity , membrane , chemistry , ionic strength , ion exchange , adsorption , ionic bonding , ion , inorganic chemistry , equilibrium constant , langmuir adsorption model , aqueous solution , organic chemistry , catalysis , biochemistry
In order to improve the selectivity of the AMX membrane, a polyethyleneimine (PEI) layer was adsorbed on its surface by the immersion of the considered membrane in a solution of PEI. The adsorption process of PEI was studied and the results were well correlated with the Langmuir model and with Lagergren's pseudo‐first‐order kinetic model. Equilibrium ion exchange isotherms of ( Cl − / N O 3 − ) , ( Cl − / S O 4 2 −) , and ( N O 3 − / S O 4 2 −) systems, using modified AMX membrane, were established at various ionic strengths from 0.1 to 0.5 mol/L and at constant temperature of 298 K. The results obtained with the modified membrane, in this range of ionic strengths, showed that the affinity order was: N O 3 − > Cl − > S O 4 2 −at I = 0.1 mol/L and I = 0.2 mol/L and it wasCl − > N O 3 − > S O 4 2 −for I = 0.3 mol/L and I = 0.5 mol/L. The ion exchange selectivity coefficientsK A B , thermodynamic ion exchange equilibrium constantsK A ° B, and the standard free enthalpiesΔ r G ° of the ion exchange reactions were determined for the three binary systems. These results were compared with those obtained with the unmodified membrane. It was observed that for the modified membrane the ion exchange selectivity towards sulphate ions decreased and increased towards monovalent anions.