ATR-FTIR Analysis of Electrodialysis Membranes

As an example of spectroscopic detection of changes occurring during membrane operation, we provide attenuated total reflection Fourier transform infrared spectra of MK-40 membrane and two series of membranes produced by the similar technique that operated in electrodialysis of mixed solution (15 mM NaCl and 7.5 mM CaCl₂) for 50 h in under-limiting current mode (approximately 0.5 theoretical limiting values calculated by the approach described in [60 (link)]). Membrane preparation and operation are described in [21 (link)]; in brief, the membranes were also based on MK-40 and underwent surface homogenization with LF-4SC layer and layer-by layer absorption of three layers total: two of polyamine (polyallylamine orpolyethylenimine, depending on series) and one middle layer of sodium polystyrene sulfonate (purchased from Merck KGaA, Darmstadt, Germany). The ATR-FTIR spectra were registered by the “Diagnostics of structure and properties of nanomaterials” Centre for Collective Use of Kuban State University using a Bruker Optics Vertex 70 spectrometer (Bruker, Billerica, MA, USA) for newly prepared membranes and for membranes after operation under current; the measurement were made for dry membranes.