화학공학소재연구정보센터
Polymer Bulletin, Vol.65, No.2, 145-156, 2010
Polyelectrolyte adsorption study on polyethersulfone membrane during polymer-enhanced ultrafiltration by electrochemical impedance spectroscopy
Electrochemical impedance spectroscopy (EIS) was used to study the fouling produced due to the adsorption of poly(vinyl sulfonic acid) on polyethersulfone membrane during metal ion recovery by polymer-enhanced ultrafiltration (PEUF). A solution of PVSA (40 mM in monomeric unit and pH 3.0, 4.5, and 6.0) was placed in a ultrafiltration cell, and then a stream of metal ions (2.0 mM in Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+) was passed from reservoir to cell. Fouled membranes were studied by EIS at low and intermediate frequencies. Measurements of hydrodynamic permeability and ATR-FTIR spectra were also obtained. Different relaxation processes were observed with characteristic frequencies (f (0)) similar to 78 kHz and f (0) similar to 3562 kHz for active layer and clean membrane, respectively, while the frequencies for the fouled membrane f (0) = similar to 79.4 and f (0) = similar to 2511.9 kHz (pH 3.0). The value of f (0) could not be defined at pH 6.0. The relaxation times obtained were in the order of x10(-5) and x10(-3) s approximately for all cases. Our results suggest that relaxation mechanisms, at intermediate frequencies, can mainly be associated to polarization processes or to the migration of charge carriers.