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The selected lanthanum-strontium-borate glasses were prepared by a conventional melt-quenching technique. The compositions of the investigated glasses were chosen to be: 5.7, 9.5, 14.3, 19.1 mol % for La2O3, 22.9, 19.1, 14.3, 9.5 for mol % SrO and 71.4 mol % for B2O3. The density, molar volume, oxygen molar volume, oxygen packing density, oxygen/boron ratios and structural transformations in the glass network were investigated according to the substitution of SrO by La2O3. The density and the molar volume increased in parallel with La2O3 content increase. Simultaneously, oxygen molar volume values increased while the oxygen packing density values decreased. A hot stage microscope (HSM) and a differential thermal analysis (DTA) were used to determine the characteristic temperatures. By increasing the content of lanthanum, the glass transition temperatures, changed with the same trend as the molar volume. Glass stability parameters were calculated from the temperatures obtained by DTA and HSM. The HSM results were used to obtain the viscosity curves by applying Vogel-Fulcher-Tamman (VFT) equation. [Projekat Ministarstva nauke Republike Srbije, br. 172004 i br. 34001]

The suitable characteristics of fly ash from thermal power plants make it a proper adsorbent for removing various pollutants from water and aqueous solutions. Valorization and utilization of fly ash can reduce the use of conventional adsorbents. The paper presents an overview of the possibility of using raw and modified fly ash to remove fluorides from water and aqueous solutions, as well as the influence of different process parameters (sorbent dose, contact time, pH value, temperature, etc.) on the value of adsorption capacity and adsorption efficiency of used sorbent. Fly ash can be used as an effective sorbent for the removal of fluoride, both in raw and modified form, with given optimal process parameters. Raw fly ash shows better adsorption properties when performing the experiment in a column, with a higher dose of sorbent and longer contact time, in an acidic environment (pH = 2-3), compared to batch experiments. Various authors have modified fly ash by treatment with certain chemical agents (HCl, Ca (OH)2…) or by synthesis of zeolite based on fly ash. Modification of fly ash improves its adsorption properties, so in slightly acidic conditions (pH = 6), for a relatively short contact time (10-30 min), in batch conditions, significant adsorption efficiency (~ 90%) can be achieved.

In this work, the dissolution behavior of a polyphosphate glass, with the composition 45P2O5?3SiO2?25K2O?15CaO?10MgO?ZnO?MnO (mol %), in simulated body fluid (SBF) at a temperature of 37 ?C for different times was studied. Two powder sizes of the glass (granulation: 0.1?0.3 and 0.3?0.65 mm) and the bulk glass were investigated. The dissolution experiments were conducted under stationary conditions. Changes in the normalized mass release, normalized concentration of ions, pH values, and surface morphology were determined as a function of the dissolution time. The initial rates of glass powder dissolution and leaching of ions, as well as the diffusion coefficient of cations and the releasing rate of ions, during the hydrolysis process of glass were determined. It was shown that the investigated phosphate glass dissolves in SBF incongruently, with neither precipitation nor the formation of newly potentially toxic compounds, in a dissolution period 720 h. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 34001 and Grant no. 172004]

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