We have theoretically studied the stability and reconstruction of (111) surfaces of Au, Pt, and Cu. We have calculated the surface energy, surface stress, interatomic force constants, and other relevant quantities by ab initio electronic structure calculations using the density functional theory (DFT), in a slab geometry with periodic boundary conditions. We have estimated the stability towards a quasi-one-dimensional reconstruction by using the calculated quantities as parameters in a one-dimensional Frenkel-Kontorova model. On all surfaces we have found an intrinsic tensile stress. This stress is large enough on Au and Pt surfaces to lead to a reconstruction in which a denser surface layer is formed, in agreement with experiment. The experimentally observed differences between the dense reconstruction pattern on Au(111) and a sparse structure of stripes on Pt(111) are attributed to the details of the interaction potential between the first layer of atoms and the substrate.

Coal fly ash was modified to zeolitic materials by hydrothermal treatment at 90 oC. The zeolite synthesis was studied as a function of the mole ratio of Na2O/SiO2 in the reaction mixtures. The results showed that NaP1 zeolite is obtained when the Na2O/SiO2 mole ratio was 0.7. Hydroxysodalite is the dominant zeolite phase in modified fly ash treated with a higher Na2O concentration solution (Na2O/SiO2 = 1.3). The IR and XRD methods were used to determine the phases present in the starting sample and in the zeolitic materials.

Sample of nonmagnetic fraction of fly ash "Nikola Tesla-B" power station was used for zeolite synthesis experiment Quartz and amorphous phase as aluminosilicate glass were main phases in this sample. After zeolitization under some hydrothermal conditions in the new product were also detected quartz and new phases A zeolite and some amount of hydroxysodalite. IR and XRD methods were used to determine phases present in the starting and zeolitic material.

The effect of lead ions on the galena and sphalerite surface properties, ethylxanthate adsorption and kinetics of ethylxanthate adsorption in alkaline medium were studied for the possible use of recycled flotation water. The flotation tests and the zeta-potential measurements were carried out and correlated with the results of the infrared attenuated total reflection spectrophotometry (ATR–IR) and UV data. Lead adsorbed on the galena or sphalerite surface as Pb(OH) + and less as Pb 2+ reduces the collectorless galena floatability from pH 7 to 9.5, but has a strong activating effect on natural sphalerite floatability (in pH range 7.6–10.5). After collection of Pb-modified minerals with K-ethylxanthate both forms of lead ethylxanthate, monolayer Pb–EX (chemically adsorbed (EX) – ), and multilayer, physically adsorbed Pb(EX)2, were detected on the mineral surfaces. Sphalerite floated nearly 100% in the examined pH range, but galena floated better only from pH 8 to 9.5 (85–95%). The main surface reaction in pH range 8–9.5 is probably the ion-exchange reaction M–Pb–OH + (EX) – = M–Pb–EX +(OH) – (M – mineral), which contributes to the chemical adsorption of (EX) – as monolayer –Pb–EX, on the surface of either of the mineral. The reaction between Pb-treated mineral and (EX) – ion is the reaction of pseudo-first order (on Pb-modified galena – rate constant is k = 0.711 min –1 ; on Pb-modified sphalerite k = 0.102 min –1 ).