Effect of hydrogen peroxide on the electrochemical oxidation of thiocyanate-containing solutions was studied.

3 -2 (3) Depending on sulfur content and number of processing cycles, the concentration of thiocyanates in process liquors can vary from several milligrams to several tens grams per liter. Thiocyanate forma- tion results not only in an increase of reagent consumption at cyanation but also provides adverse effect at the stages of sorption and desorption in sorption leaching of gold (2). Moreover, destructive oxidation of excess amount of process water is required prior to disposal to tailing storage, with respective high con- sumption of oxidant for decomposition of thiocyanate complexes. Recently, both in Russia and abroad, there is a growing interest in environmentally safe and straight- forward methods of processing of industrial waste and sewage waters. There are several methods of pro- cessing of cyanide solutions aimed both at decrease of their toxicity by means of complete decomposition of harmful constituents and at cyanide regeneration at incomplete oxidation of thiocyanates. It is a well-known fact that depending on the electrolysis conditions electric oxidation of thiocyanates can be accompanied with formation of cyanide or cyanate ions. In the work (3) it has been demonstrated that the solutions with high concentration of SCN - (>1000-3000 mg/dm 3 ) can be electrochemically treat- ed with formation of CN - . It allows to simultaneously reduce the concentration of harmful substances and decrease the costs of their detoxification by means of reagent regeneration (CN - ). At lower concentrations of thiocyanate ions oxidation can be performed with obtaining of less toxic substances. At cyanide regeneration from thiocyanates simultaneous reduction of carbon and oxidation of sulfur in SCN - complex takes place, accompanied with formation if free cyanide and sulfate:

The dipole moments of neutral water clusters (H2O)n (n ≤ 100) have been simulated using the molecular dynamics method within the framework of the Stillinger-David polarization model. The spectral characteristics of emission from clusters have been calculated. It is shown that water clusters generated by flying vehicles in the Earth’s troposphere can initiate a trigger mechanism that enhances the greenhouse effect via the reactions CO2* + (H2O)n → CO2 + (H2O)n(*) → CO2 + (H2O)n + hv.

Behavior of silver sulfide in the system Ag 2 S-Fe(NO 3 ) 3 -HNO 3 -H 2 O was studied at 25, 55, and 80°C using the method of the simplex-lattice experiment design. The quantitative dependences of Ag 2 S oxidation on the concentrations of the acid and Fe 3+ were determined. The isoconcentration diagrams were obtained.

The molecular dynamics calculations of stable geometries and energy parameters of neutral (H2O)(n) (n <= 100), positively H+(H2O)(n) and negatively HO-(H2O)(n) (n <= 15) charged clusters have been carried out within the framework of the Stillinger-David polarization model. Using the results, the size dependences of the energy of the polar fragmentation (H2O)(n) -> H+(H2O)(i) + HO-(H2O)(j) have been calculated. The dynamics of collisions between (H2O)(27) clusters with the relative velocities of 1, 3, and 10 km/s has been studied. The formation of hydrated ion pairs H+ and OH- was detected, and time dependences of the number of ion pairs, rotational and vibrational temperatures of molecules were obtained. It has been found that both the excitation of molecules in cluster collisions and the dissipation of the hydration energy of ions H+ and OH- have the nonequilibrium character. (c) 2005 Elsevier B.V. All rights reserved.

Solubility of lead nitrate in the system H 2 O-Zn(NO 3 ) 2 -HNO 3 was studied using the simplexlattice design method. The equations describing the effect of nitric acid and zinc nitrate concentrations on the content of lead nitrate in solution at 25 and 55°C were derived.

The behavior of zinc sulfide in the system HNO3-Fe(NO3)3-H2O at 25, 55, and 80°C was studied using the simplex-lattice design method.

Solubility of lead(II) nitrate in the system H2O-Fe(NO3)3-HNO3 was studied using the simplex-lattice method of experiment design.

The structures and energies of small water clusters (H 2 O) n with n ≤10 were calculated based on the results of computer simulation using molecular dynamics method and a polarization model with nonadditive potential. Structures with minimum energies are characterized by the cluster energy as function of the temperature and by the heat capacity, binding energy, and molecular evaporation energy for various n . The most stable structure is that of a ring-shaped (H 2 O) 5 cluster with only one proton of each water molecule involved into the hydrogen bond formation.

We observed a continuous emission spectrum of 60 * and C 60 +* clusters induced by electron impact for wavelengths 300 to 800 nm (the monochromator’s resolution was Δλ = 3.2 rim). The emission spectrum was described by a modified Planck’s formula for the black-body-like radiation. The radiative temperature of clusters, T,(up to 3100 K) and the integral intensity of emission depend on the electron energy E e in a beam. The intensity of emission from C 60 + is higher than that from a neutral cluster. The emissivity coefficient has been found to be ε(C 60 +* ) = 7.6 × 10−3.

We have measured the absolute cross-section, sigma(-,+) of both negative and positive ion formation by the electron-fullerene collision in crossed beams. The cross-section sigma(-) of C-60(-) formation as a function of the electron energy E-e has a resonance-like structure superimposed on a broad continuum-type curve from 0.5 eV to 7 eV. The most intense (similar to 0.9 nm(2)) and narrow peak at the electron energy E-e = 0.20 eV has been found. Unstable anions were formed at the energy E-e greater than or equal to 7.5 eV. The cross-section of C-60 ionization has a maximum (similar to 0.53 nm(2)) at 52 eV. The ionization potential was determined to be 7.6 eV. The delayed (greater than or equal to 150 mu s) ionization (DI) of C-60 has also been observed with the maximum of the DI function at 42 eV. The decay of excited molecules of C-60 into ion and electron was induced by surface collision and an electric field. We assumed that the C-60 molecules in the Rydberg states of C-60 were the main source of delayed ionization.

Nitric acid breakdown of lead concentrate PbS-FeCO3-ZnS-SiO2 obtained from the Gorevskoe deposit was studied. Effects of temperature and acid concentration on the lead transfer into a solution were examined.