However, application of ceramic separators to electromembrane processes is limited by an absence of charge selectivity in spite of a nanoporous active layer. This is due to extremely low ion exchange capacity (low surface charge density) of ceramics, since these materials are produced at high temperature [4], which does not provide retention of functional groups. Earlier, we modified Al2O3-ZrO2 ceramics with hydrated zirconium dioxide (HZD), which contains -OH groups. HZD is able to sorb cations (Cat) in alkaline media [5] (1) and anions (An) in acidic solutions: (2) The conditions of thermal treatment of the membranes provided

ion exchange ability of PD173074 HZD. Pores of 190 nm dominated in learn more pristine ceramics. After modification, their size decreased to 80 nm [6, 7] indicating formation of an active layer inside the pores of ceramics, opposite to known inorganic materials for baromembrane separation [1, 2]. This location of the active layer provides

its mechanical durability. Predominant pores of the composite membranes [6, 7] cannot provide overlapping of intraporous diffusion double electric layers. In spite of this, the membranes were shown to possess charge selectivity. They demonstrate membrane potential in rather concentrated acid solutions [6]. When the composite separators are applied to electrodialysis, the ion transport through these separators is due to migration of counter ions and electrolyte diffusion during electrodialysis [7]. At the same time, no migration of co-ions through RG7112 solubility dmso these separators was found. Many types of ceramics contain larger pores (up to several microns) in comparison with the material investigated in [6, 7]. The aims of the work involve

formation of the inner active layer in coarse-pored membranes, ascertainment of the cause of their charge selectivity and application of these materials to electromembrane separation. A method of standard contact porosimetry (SCP) was applied to membrane investigation. The method allows us to obtain pore size distribution in a wide interval of 1 nm to 300 μm as well as total volume of micropores of 0.3 to 1 nm [8–11]. The SCP method is non-destructive, since it does not require high pressure compared to mercury porosimetry. Cobimetinib Thus, small pores can be determined more exactly. Moreover, analysis of integral pore size distribution gives a possibility to determine particle size using geometrical models [12–14]. However, in the case of composites, the particle size of their components can be close to each other; as a result, the constituents cannot be recognized. Thus, the next important task of the work is to develop an approach for analysis of pore size distributions for composite materials. Experimental Synthesis of the composite membranes Planar ceramic membranes (matrix) based on TiO2 (TAMI GmbH, Hermsdorf, Germany), which contain no active layer, were used.