Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Jun 26;10(6):134.
doi: 10.3390/membranes10060134.

Characterization of Poly(Acrylic) Acid-Modified Heterogenous Anion Exchange Membranes with Improved Monovalent Permselectivity for RED

Ivan Merino-Garcia  1 , Francis Kotoka  1 , Carla A M Portugal  1 , João G Crespo  1 , Svetlozar Velizarov  1
Affiliations

Characterization of Poly(Acrylic) Acid-Modified Heterogenous Anion Exchange Membranes with Improved Monovalent Permselectivity for RED

Ivan Merino-Garcia et al. Membranes (Basel). .

Abstract

The performance of anion-exchange membranes (AEMs) in Reverse Electrodialysis is hampered by both presence of multivalent ions and fouling phenomena, thus leading to reduced net power density. Therefore, we propose a monolayer surface modification procedure to functionalize Ralex-AEMs with poly(acrylic) acid (PAA) in order to (i) render a monovalent permselectivity, and (ii) minimize organic fouling. Membrane surface modification was carried out by putting heterogeneous AEMs in contact with a PAA-based aqueous solution for 24 h. The resulting modified membranes were firstly characterized by contact angle, water uptake, ion exchange capacity, fixed charge density, and swelling degree measurements, whereas their electrochemical responses were evaluated through cyclic voltammetry. Besides, their membrane electro-resistance was also studied via electrochemical impedance spectroscopy analyses. Finally, membrane permselectivity and fouling behavior in the presence of humic acid were evaluated through mass transport experiments using model NaCl containing solutions. The use of modified PAA-AEMs resulted in a significantly enhanced monovalent permselectivity (sulfate rejection improved by >35%) and membrane hydrophilicity (contact angle decreased by >15%) in comparison with the behavior of unmodified Ralex-AEMs, without compromising the membrane electro-resistance after modification, thus demonstrating the technical feasibility of the proposed membrane modification procedure. This study may therefore provide a feasible way for achieving an improved Reverse Electrodialysis process efficiency.

Keywords: anion exchange membranes; antifouling strategies; monovalent permselective membranes; poly(acrylic) acid modification; reverse electrodialysis.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Anion exchange membrane diagram including both electric double-layer (EDL) and diffusion boundary layer (DBL) effects, adapted with permission from [40]. Copyright 2016 Elsevier.
Figure 2
Figure 2
Two-compartment diffusion cell layout.
Figure 3
Figure 3
Hydrophilicity analysis: contact angle data.
Figure 4
Figure 4
Fourier attenuated atomic force microscopy (ATR-FTIR) spectra of unmodified and poly(acrylic) acid (PAA)-modified AEMs.
Figure 5
Figure 5
Cyclic voltammetry analyses: effect of PAA concentration in AEM modification at Ag electrodes.
Figure 6
Figure 6
Equivalent circuit diagram showing the combination of membrane, electric double-layer, and diffusion boundary layer resistances.
Figure 7
Figure 7
Electrochemical impedance spectroscopy (EIS) study of the unmodified membrane including experimental (continuous line) and fitting data (dotted lined): (a) Bode plot; (b) Nyquist plot.
Figure 8
Figure 8
Sulfate evolution with time during mass transport experiments as a function of the AEM used in the absence of humic acid (HA) in the feed compartment.
Figure 9
Figure 9
HA studies: sulfate evolution with time during mass transport experiments as a function of the one side modified AEM used.
See this image and copyright information in PMC

References

    1. Pawlowski S., Huertas R.M., Galinha C.F., Crespo J.G., Velizarov S. On operation of reverse electrodialysis (RED) and membrane capacitive deionisation (MCDI) with natural saline streams: A critical review. Desalination. 2020;476:114183. doi: 10.1016/j.desal.2019.114183. - DOI
    1. Gao H., Zhang B., Tong X., Chen Y. Monovalent-anion selective and antifouling polyelectrolytes multilayer anion exchange membrane for reverse electrodialysis. J. Membr. Sci. 2018;567:68–75. doi: 10.1016/j.memsci.2018.09.035. - DOI
    1. Vermaas D.A., Kunteng D., Veerman J., Saakes M., Nijmeijer K. Periodic feedwater reversal and air sparging as antifouling strategies in reverse electrodialysis. Environ. Sci. Technol. 2014;48:3065–3073. doi: 10.1021/es4045456. - DOI - PubMed
    1. Gómez-coma L., Ortiz-martínez V.M., Carmona J., Palacio L., Prádanos P., Fallanza M., Ortiz A., Ibañez R., Ortiz I. Modeling the influence of divalent ions on membrane resistance and electric power in reverse electrodialysis. J. Membr. Sci. 2019;592:117385. doi: 10.1016/j.memsci.2019.117385. - DOI
    1. Veerman J., Vermaas D.A. Sustainable Energy from Salinity Gradients. Elsevier Ltd; Amsterdam, The Netherlands: 2016. Reverse electrodialysis: Fundamentals.

LinkOut - more resources