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Abstract: The influence of lactose on the main transport characteristics of ion-exchange membranes including surface-modified with polyaniline cation-exchange membranes is studied. A pronounced to different extents positive effect of modification of MK-40 and Ralex CMHPES membranes with polyaniline on their biofouling by Bacillussp. or Shewanella oneidensisMR-1 cell cultures is found which is due to the different conductive surface areas of these membranes. It is revealed that the presence of lactose in a solution leads to a decrease in the electrical conductivity of all the studied membranes; however, the effect the most substantially manifests itself for a modified with polyaniline MK-40 membrane: its electrical conductivity decreases by 15–25%. The diffusion permeability of the anion-exchange and initial cation-exchange membranes weakly depends on the presence of lactose in a solution; however, its 2–2.5-fold decrease is observed in the case of modified with polyaniline cation-exchange membranes. A significant effect of lactose on the current–voltage characteristics of the anion-exchange membranes has been found, which indicates significant adsorption of lactose on their surface under the conditions of an external constant electric field. It is shown that ion-exchange membranes remain quite effective for electrodialysis of solutions of lactoserum but their use in underlimiting current modes will be more effective.

Abstract: Surface-modified cation exchange materials are obtained based on industrial MK-40 heterogeneous and MF-4SK homogeneous cation-exchange membranes by in situ oxidative polymerization of aniline under electrodialysis conditions. The conduction and diffusion characteristics of the initial and modified membranes in solutions of sulfuric acid and nickel sulfate are studied. It is shown that the modification of the membranes with polyaniline leads to a decrease in their electrical conductivity and diffusion permeability without sacrificing high selectivity. The diffusion permeability of the cation-exchange membranes is higher in solutions of nickel sulfate in comparison with solutions of sulfuric acid, while an inverse dependence is found for anion-exchange membranes. The competitive transport of sulfuric acid and nickel sulfate during electrodialysis separation and concentration of their mixture using initial commercial and modified cation-exchange membranes paired with an MA-41 anion-exchange membrane is studied. It is shown that applying a layer of polyaniline with positively charged groups onto one of the surfaces of MK-40 or MF-4SK cation-exchange membranes leads to a decrease in the transport of a doubly charged nickel cation both in the separation and concentration modes over the entire range of current densities. The highest repulsion effect is observed in the case of the use of homogeneous modified membranes, where the selective permeability coefficient P(H2SO4/NiSO4) increases from 0.7–1.7 up to 32.5–19.7 depending on the current density. It is found that the use of surface-modified with polyaniline cation-exchange membranes makes it possible to concentrate a solution containing 0.1 mol-equiv/L (4.9 g/L) H2SO4and 0.1 mol-equiv/L (7.7 g/L) NiSO4with simultaneous separation to sulfuric acid with a concentration of about 2.4 mol-equiv/L (120 g/L) and a solution of nickel sulfate. Here, the concentration of nickel sulfate in the concentrate does not exceed 0.13 mol-equiv/L (10 g/L).

Abstract: A series of composite ion-exchange membranes based on an heterogeneous cation-exchange MK‑40 membrane and polyaniline is obtained under the conditions of electrodiffusion of a monomer and an oxidizing agent. The process of polyaniline synthesis on the membrane surface is accompanied by recording of chronopotentiograms and pH of the solution leaving the desalination compartment. The initial cation-exchange MK-40 membrane and obtained composites based on it are studied by voltammetry and chronopotentiometry in solutions of NaCl, CaCl2, and MgCl2in the same flow-type electrodialysis cell, in which the composites are obtained. To calculate the transport numbers of counterions in the membranes in solutions of CaCl2and MgCl2by chronopotentiometry, the apparent fraction of the conductive membrane surface in a solution of NaCl is calculated based on the experimental data on the potentiometric transport numbers of counterions in the membrane. The conditions for the synthesis of polyaniline on the surface of an heterogeneous MK-40 membrane which result in the preparation of samples with selectivity to singly charged ions are found out.

Abstract: Comprehensive characterization of basic MK-40 and Ralex CMH heterogeneous cation-exchange membranes and composite membranes with polyaniline based on them is performed including the determination of specific electrical conductivity and diffusion permeability; measurement of current–voltage curves in solutions of sodium, calcium, and magnesium chlorides and hydrochloric acid and curves of distribution of water with respect to the bond energies and effective pore radii as well as assessment of the transport structural parameters of a microheterogeneous model. The time of synthesis of polyaniline on the surface of cation-exchange membranes for obtaining samples with an anisotropic structure and asymmetric electric transport properties is determined by successive diffusion of a solution of an oxidizing agent and a monomer through the membrane into water. It is shown based on the analysis of the electric transport properties, structural characteristics, and model transport structural parameters of the membranes in solutions of singly and doubly charged ions that the obtained materials are promising for use in the processes of electrodialysis desalination of multicomponent solutions.

Abstract: Based on the analysis of the results of sorption experiments and the study of the influence of the oxidant nature at different stages of the preparation of composites, a method has been developed for modifying anion exchange membranes with sulfonated polyaniline by in situ oxidative polymerization of 2-aminobenzenesulfonic acid. The formation of the modifier in the membranes has been proven by analyzing the ATR IR spectra of the samples. The study of the physicochemical and transport properties of composite membranes has shown that the synthesis of the modifier leads to a significant decrease in the exchange capacity from 3.41 to 1.65 mmol/gdryfor the MA-40 membrane and from 0.87 to 0.21 mmol/gdryfor MA-41. In this case, the electrical conductivity of the composite based on the MA-40 membrane increases by 2 to 3 times in sodium chloride solutions and that of the composite based on the MA-41 membrane decreases by a factor of 1.5–2. The current–voltage characteristics of the composite membranes were found to have asymmetry, which confirms the gradient character of the modifier distribution.

Abstract: Polyaniline has been synthesized on the surface of anion exchange membranes by the successive diffusion of an oxidizer and monomer solutions through a membrane in water. Current–voltage curves of initial and modified membranes in solutions of sodium chloride, calcium chloride, hydrochloric acid, and their equimolar mixtures have been studied. The asymmetry of current–voltage curves of composite membranes due to the polyaniline layer present on their surface have been observed. This effect depends on the nature of ionogenic groups of anion exchange membranes. An increase in the limiting current density as a result of the modification of ion-exchange membranes with polyaniline was found for the first time.

1.It was shown that n-octane is cyclized with formation of propylcyclopentane and trans-1-ethyl-2-methylcyclopentane in almost equal amounts. In the case of n-octane reaction is only one-quarter to one-sixth as fast as in the case of its isomer 2,2,4-trimethylpentane.2.Results were obtained which suggested that cyclopentane homologs can also undergo cyclization with formation of a five-membered ring (octahydropentalene derivatives).3.Very pure preparations of stereoisomeric 1-ethyl-2-methylcyclopentanes were synthesized, and their Raman spectra were determined.

1.A study was made of the effect of temperature on ethylenimine, 1-methylethylenimine, 1-phenyl-ethylenimine and 2-phenylethylenimine.2.Ethylenimine and 1-methylethylenimine are stable when heated up to approximately 400°. Both of the phenyl-substituted ethylenimines undergo rupture of the ring bonds when heated at a lower temperature: the C-N bond in the case of 1-phenylethylenimine and the C-C bond in the case of 2-phenylethylenimine.3.The lower stability of the bonds in the phenyl-substituted ethylenimines is explained by the conjugation of the phenyl ring with the ethylenimine ring in the case of 2-phenylethylenimine and with the free electron pair of nitrogen in the case of 1-phenylethylenimine.

1.In the presence of either platinum or palladium black, both ethylenimine and N-phenylethylenimine add hydrogen across the N-C bond of the ring under mild conditions.2.Palladium black is an especially active catalyst in this reaction.

by Wittig reaction of aldehyde (II) with ylide derived from phosphonium bromide (III)

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