Coating of ion exchange membranes used in electrodialysis with layers of polyelectrolytes is a proven approach that allows for the increasing of the limiting current, the suppressing of sedimentation, the controlling of the intensity of generation of H⁺ and OH⁻ ions, and also the improving of monovalent selectivity. However, in the case when two materials with the opposite sign of the charge of fixed groups come in contact, a bipolar boundary is created that can cause undesirable changes in the membrane properties. In this work, we used a MK-40 heterogeneous membrane on the surface of which a layer of polyethyleneimine was applied by adsorption from a solution as a model of heterogeneous membranes modified with oppositely charged polyelectrolyte. It was found that, on one hand, the properties of modified membrane were beneficial for electrodialysis, its limiting current did not decrease and the membrane even acquired a barrier to non-selective electrolyte transport. At the same time, the generation of H⁺ and OH⁻ ions of low intensity arose, even in underlimiting current modes. It was also shown that despite the presence of a layer of polyethyleneimine, the surface charge of the modified membrane remained negative, which we associate with low protonation of polyethyleneimine at neutral pH.

Ion exchange membranes covered with layers of polyelectrolytes of alternating charges are characterized by very high monovalent selectivity. This allows the use of such membranes for electrodialytic fractionation of multicomponent solutions. However, the very existence of the boundary at which differently charged layers come in contact can hinder a membrane’s effectiveness by limiting its ion permeability, raising levels of H⁺ and OH⁻ ions (thus shifting the pH) and increasing the electrical resistance of the membrane, which leads to increased energy consumption. To test how these properties would be changed, we created cheap layer-by-layer-modified membranes based on the heterogeneous MK-40 membrane, on which we adsorbed layers of polyallylamine and sulfonated polystyrene. We created samples with 3, 4, and 5 layers of polyelectrolytes and characterized them. We showed that the application of layers did not decrease the efficiency of the membrane, since the electrical resistance of the modified samples, which increased after application of the first oppositely charged layer, declined with the application of the following layers and became comparable to that of the substrate, while their limiting current density was higher and the shift of pH of treated solution was low in magnitude and comparable with that of the substrate membrane.

The creation of monovalent selective ion exchange membranes benefits the desalination of surface waters by removing interfering monovalent ions while preserving polyvalent ionic nutrients. Studies of a promising method of layer-by-layer adsorption of polymers for the creation of monovalent selective coatings note a significant effect of the number of formed layers and of the nature of the external layer on the properties of the resulting membranes. This article reports the changes in properties of layer-by-layer coated heterogeneous membranes occurring at increasing numbers of layers that are attributed to the supposed intermixing of polymers between the layers, namely dependence of limiting current densities determined from i-V curve, enhanced electroconvection that was attributed to the appearing electrical heterogeneity of the surface, and the decreasing monovalent selectivity in electrodialysis of mixed NaCl + CaCl₂ solution (from 1.33 to about 1) between the samples with five and six to eight layers of polymers.

Electrodialysis with layer-by-layer coated membranes is a promising method for the separation of monovalent and polyvalent ions. Since the separation selectivity is significantly reduced in the presence of defects in the multilayer system, the stability of the modifiers becomes an important issue. This article reports the i-V curves of layer-by-layer coated membranes based on the heterogeneous MK-40 membrane before and after 50 h long electrodialysis of a solution containing sodium and calcium ions at an underlimiting current density, and the values of concentrations of cations in the desalination chamber during electrodialysis. It is shown that the transport of bivalent ions through the modified membranes is reduced throughout the electrodialysis by about 50%, but the operation results in decreased resistance of the membrane modified with polyethylenimine, which may suggest damage to the modifying layer. Even after electrodialysis, the modified membrane demonstrated experimental limiting current densities higher than that of the substrate, and in case of the membrane modified with polyallylamine, the limiting current density 10% higher than that of the substrate membrane.

The transition to renewable energy is strongly affected by legal regulation. To increase the efficiency of the introduction of renewable energy into the energy systems of component states of federations and accelerate the energy transition, it is necessary to carry out systematic work to improve regional legislation in this area. The purpose of this study was to analyze the current regulatory legal acts on the renewable energy of the regions of a number of countries such as the USA, Germany, India, Switzerland and Russia in order to form a universal list of issues that need regulation at the regional level. The main methods for achieving the objectives set in this study were the comparative legal method and the method of analysis and synthesis. As a result, a number of recommendations were developed describing how legal relations primarily need to be regulated by regional legislation, and examples of different approaches to their settlement were presented. The issues in need of legal regulation were divided into three groups according to the degree of importance of their regulation by the legislation of the component state of the federation. Further development of this study will be aimed at identifying the most effective industrial practices for resolving each of the issues included in the compiled list which will help improve the efficiency of regional legal regulation of renewable energy.

Layer-by-layer adsorption of polyelectrolytes with alternating charges of polar groups makes it possible to create functional coatings to increase the monovalent selectivity of ion exchange membranes. In this work the chronopotentiograms of MK-40 heterogeneous ion exchange membrane layer-by-layer coated with polyallylamine and with sodium polystyrene sulfonate are studied. It is shown that chronopotentiometry allows detecting a more pronounced second transition time, a decrease in the stationary potential drop and an increase in the amplitude of the oscillations of potential drop in the stationary sections of the chronopotentiograms of modified membranes, indicating the differences in the counterions transport between the supporting and the modified membranes that can be attributed to “expansion of the funnel” for the entry of electric current lines into the heterogeneous membrane after the application of the homogenizing layer and to enhancement of the development of electroconvection. An increase in the number of modifying layers from two to five does not lead to significant changes in the form of chronopotentiograms.