Photoluminescence from the surface of a Nafion polymer membrane upon swelling in isotonic aqueous solutions and Milli-Q water has been studied. Liquid samples were preliminarily processed by electric pulses with a duration of 1 μs and an amplitude of 0.1 V using an antenna in the form of a flat capacitor; experiments on photoluminescent spectroscopy were carried out 20 min after this treatment. A typical dependence of the luminescence intensity, I, on the swelling time, t, obeys an exponentially decaying function. The characteristic decay time of these functions and the stationary level of luminescence intensity depend on the repetition rate of electrical pulses, and the obtained dependences are well reproduced. It transpired that, at certain pulse repetition rates, the dependence, I(t), is a random function, and there is no reproducibility. Stochastic effects are associated with a random external force of an electromagnetic nature that acts on a polymer membrane during swelling. The source of this random force, in our opinion, is low-frequency pulsations of neutron stars or white dwarfs.
A process of phosphorylation for a mercerized cotton kersey fabric was investigated. After wet oxidation, the phosphorus content in each sample was determined by spectrophotometric analysis. The range was 0.179 to 0.950 mmol g–1. A significant decrease in the tensile strength of samples resulted from an increase of phosphoric acid concentration in the phosphorylating solution. The mercerization has a positive impact on the process of phosphorylation, as the phosphorus content was found to be three times higher in the samples that underwent mercerization. The sorption properties of phosphorylated cotton fabric were studied using the Cu2+ sorption process as a reference. The value of the static exchange capacity for the phosphorylated fabric was determined to reach its maximum when the concentration of the H3PO4 in the phosphorylating solution was 1.40 M, and was found to be 1.48 ± 0.11 mmol g–1 with the phosphorus content equal to 0.898 ± 0.090 mmol g–1. The sorption of Cu2+ by a single phosphorus-containing group occurred for samples with phosphorus content not exceeding 0.80 mmol g–1. The preliminary studies of micro-quantities of 241Am, 233U, and 239Pu radionuclide sorption from aqueous solutions with phosphorylated textile demonstrated the high efficiency.
1 November 2017 in Russian Journal of General Chemistry
The oxidation of oxalate ions with ozone in aqueous solution has been studied, and the effects of pH, temperature, and reactant concentrations on the reaction rate and efficiency have been estimated.
Granulated inorganic sorbents based on silica gel of KSKG grade and aluminum oxide and modified with Fe(III) compounds were developed for water treatment to remove As(V). The influence of the particle size of the modifying additive on the ability of silica gel to take up As(V) was examined. The KSKG-based sorbents modified with nanoparticles of Fe(III) compounds exhibit the highest sorption capacity. The capacity of silica gel based sorbents modified with nanoparticles of iron compounds for As(V) is higher than that of analogous sorbents modified with iron oxides prepared by thermal decomposition of Fe(III) nitrate.
In this work, we report on a comparative analysis of the bromine permeability for three separator groups under the operating conditions of a non-flow zinc–bromine battery. A new method for the synthesis of porous heterogeneous membranes based on a cation-exchange resin followed by treatment with tetrabutylammonium bromide is proposed. It was shown that the modified membrane significantly reduced the bromine permeability (crossover) with an acceptable increase in the ionic conductivity of the separator group. Leakage currents not exceeding 10–20 µA/cm2 were achieved, and the Coulomb efficiency was over 90%. The ionic conductivity (at AC) of a membrane soaked with water was compared for different pretreatment conditions. The frequency dependence of the membrane resistance is shown. The features of the conduction mechanism of the modified membrane are discussed.