Higher polythionic acids – the precursors for formation of thallium sulphide layers on polyethylene surface

The method of thallium sulphide thin films deposition on low density polyethylene (LDPE), based on applying solutions of higher polythionic acids (H2SnO6, n = 21, 33, 45), was developed and investigated. The concentration of sulphur in the LDPE film increases with the increase of temperature of higher polythionic acid solution and its sulphurity, as well as the duration of retention of LDPE in its solution is prolonged. The sulphur concentration in the PE film under the same duration of sulphurisation and repetition of treatment cycles insignificantly changes. When the sulphurised LDPE was treated with a thallium Tl(I) salt solution, sulphur present in the polymer reacts with thallium ions and the layers of thallium sulphides, TlxSy, of different composition are formed. The stoichiometric composition of the layer changes from Tl0.1S to Tl2.6S. The amount of thallium increases in the sulphide layers when the number of the cycles of LDPE sulphurisation in the H2S33O6 solution and treatment of sulphurised polymer with the Tl(I) salt solution is increased. The stoichiometric composition of TlxSy coats of one treatment cycle samples changes from Tl0.5S to Tl1.1S. The X-ray diffraction analysis of the polyethylene, treated with the solution of higher polythionic acid, H2S33O6, and then with the Tl(I) salt solution, confirmed the premise that on the LDPE surface the layers of thallium sulphides, TlxSy, were formed. Five phases of thallium sulphides were identified: TlS, Tl2S, Tl2S2, Tl4S3 and Tl2S5. The TlS phase prevailed in diffractograms. The chemical and phase composition of the TlxSy layers surface (up to 1 nm depth) is identified by X-ray photo-electronic spectroscopy analysis. The analysis data confirmed that the compounds of TlS, Tl2S, Tl2SO4, Tl(OH)3, S8 and Tl2O3 were formed on the surface of the layers. The morphology of thallium sulphide layers and the mechanism of their formation are determined by means of scanning atomic force and electronic microscopy. Two processes take place during the formation of the layer: desorption of sulphur and reaction of thallium ions from the thallium(I) salt solution with sulphur present on the LDPE surface. The layer of thallium sulphides is formed on the surface of the sulphur layer. Deposition of thallium sulpfide films from the solution of higher polythionic acid on the LDPE films is not homogeneous, it has the separated island type morphology. The identified regularities let purposively choose the conditions for sulphurisation of LDPE films by using the solution of higher polythionic acid as the agent of polymer sulphurisation in order to compose the layers of thallium sulphides, TlxSy, of the desired chemical and phasic composition on the surface of this polymer by means of the sorption–diffusion method.

Electrochemical Deposition and Dissolution of Thallium from Sulfate Solutions

The electrochemical behavior of thallium was studied on glassy carbon electrodes in sulfate solutions. Cyclic voltammetry was used to study the kinetics of the electrode processes and to determine the nature of the limiting step of the cathodic reduction of thallium ions. According to the dependence of current on stirring rate and scan rate, this process is diffusion limited. Chronocoulometry showed that the electrodeposition can be performed with a current efficiency of up to 96% in the absence of oxygen.

Potassium Sulfate Nanoparticles in Water Solutions: Experiment and Quantum Chemistry Simulation

Pure potassium sulfate single crystals are transparent in a wide spectral range up to 155 nm and do not show fluorescence and absorption over a wide spectral range of 200-800 nm before and after X-ray irradiation of the samples. The centers of luminescence in thallium-doped potassium sulfate crystals showed a maximum absorption 216 nm and emission 285 nm at room temperature. These centers are singly charged thallium ions. It is interesting to research the optical properties with decreasing size of crystals (size effects). For this, we used a supersaturated aqueous solution of potassium sulfate, in which the crystallization begins. The results of computer simulations using Scigress quantum chemistry package show that the occurrence of macromolecules in a cooled supersaturated solution should result in an increased absorption. In supercooled saturated aqueous solutions of ionic crystals nucleation occurs. A decrease of transparency of saturated solutions with decreasing temperature is clearly seen. This is due to absorption and scattering in the medium with the growing small crystals in the solution.

Use of styrene–divinylbenzene grafted with aminoethylaminomethyl groups and various ionic liquids in the removal process of thallium and strontium

This work reports the adsorption of thallium and strontium from aqueous solutions onto styrene-divinylbenzene grafted with aminoethylaminomethyl groups which was impregnated with various ionic liquids [trihexyltetradecylphosphonium chloride ionic liquid – (Cyphos IL-101); 1-octyl-3-methylimidazolium tetrafluoroborate – (OmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate – (BmimPF6)]. The impregnation of the solid support with the studied ionic liquids was realized through ultrasonication method. The obtained impregnated materials have been subjected to Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Their adsorption performance in the removal process of thallium and strontium from aqueous solutions was studied as a function of the initial concentration of metal ions. Adsorption isotherms like Langmuir, Freundlich, Dubinin–Radushkevich (D–R) and Temkin were used to analyze the equilibrium data at different concentrations. The studied materials showed a better adsorption performance in the removal process of strontium ions compared to the adsorption performance obtained in case of thallium ions removal process. From the studied ionic liquids, (OmimBF4) presented the most efficient performance for the removal of the studied metal ions.