Modification of SiO2, ZnO, Fe2O3 and TiN Films by Electronic Excitation under High Energy Ion Impact

It has been known that the modification of non-metallic solid materials (oxides, nitrides, etc.), e.g., the formation of tracks, sputtering representing atomic displacement near the surface and lattice disordering are induced by electronic excitation under high-energy ion impact. We have investigated lattice disordering by the X-ray diffraction (XRD) of SiO2, ZnO, Fe2O3 and TiN films and have also measured the sputtering yields of TiN for a comparison of lattice disordering with sputtering. We find that both the degradation of the XRD intensity per unit ion fluence and the sputtering yields follow the power-law of the electronic stopping power and that these exponents are larger than unity. The exponents for the XRD degradation and sputtering are found to be comparable. These results imply that similar mechanisms are responsible for the lattice disordering and electronic sputtering. A mechanism of electron–lattice coupling, i.e., the energy transfer from the electronic system into the lattice, is discussed based on a crude estimation of atomic displacement due to Coulomb repulsion during the short neutralization time (~fs) in the ionized region. The bandgap scheme or exciton model is examined.

Electrochemical Neutralization of Acidic Industrial Effluents

An electrochemical method for neutralizing "acidic" industrial effluents is presented. The dependences of the electrical conductivity of industrial water on the neutralization time on platinum and steel electrodes are compared.

Process features of neutralization of technical sulfuric acid with natural limestone

The work was devoted to the solution of the environmental problem associated with the disposal of sulfur dioxide emissions from metallurgical production at the Nadezhda Metallurgical Plant (Norilsk, Norilsk Nickel PJSC). For utilization of sulfur dioxide it is planned to build a sulfuric acid plant. Concentrated sulfuric acid produced at plant is planned to be neutralized with natural limestone. This work presents the results of the study on the neutralization of concentrated sulfuric acid with limestone pulp from the Mokulay deposit (Norilsk). The influence of the following parameters was investigated: limestone consumption, acid dosing rate, limestone pulp density. It is established that the process is limited by the internal diffusion of acid through the layer of gypsum. In order to eliminate internal diffusion process it is advisable to carry out neutralization in a periodic mode by introducing a strictly measured amount of acid into an excess amount of limestone pulp. This process allows one to speed up the process of neutralization in 3-3.5 times and achieve a higher value of the final pH of the pulp comparing with continuous process. Carrying out the process in the periodic way also makes it possible to achieve the complete absence of the release of acidic off-gas during neutralization. The optimal values of neutralization parameters were determined as the following: limestone pulp density was 11-12%, acid delivery time was 40 minutes, neutralization time was 20 minutes, and final pH value was at least 6.5, while the limestone feeding was an excessive by 22-28% from stoichiometry. It was shown that an increase in the limestone pulp density is impractical because it will lead to an increase in the duration of neutralization, as well as to a sharp increase in the viscosity of the gypsum pulp. That, in its turn, makes gypsum pulp difficult to flow from the neutralization apparatus. It was recommended to filter the resulting pulp in order to obtain a gypsum cake with a moisture content of about 55%. It was recommended to store cake on a special site. A flowsheet has been developed and process schedules have been implemented for the design of a neutralization plant with a capacity of up to 2 million tons technical sulfuric acid per year.

A DYNAMICAL STATE FEEDBACK CHAOTIFICATION METHOD WITH APPLICATION ON LIQUID MIXING

This paper introduces chaotic reference model-based dynamical state feedback chaotification method which can be applied to any input-state linearizable (nonlinear) system including linear controllable ones as special cases. In the developed method, any chaotic system of arbitrary dimension can be used as the reference model with no need to transform it into a special form, so providing the advantage of exploiting the vast amount of information on chaotic systems and their implementations available in the literature. To demonstrate the potential effective applications of the method, a permanent magnet dc motor is chaotified by the proposed dynamical state feedback as matching the closed loop dynamics to the well-known Chua's chaotic circuit. Then, an impeller mounted on the chaotified dc motor is used for mixing a corn syrup added acid–base mixture. It is observed in a nonintrusive way that mixing actuated by the chaotified dc motor is more efficient than constant and also periodical motor speed cases for the consideration of neutralization time and power consumption together.

Kinetics of Charge Scavenging in γ Irradiated Liquids with Large Free Ion Yields

The extent to which the calculated scavenging yields are affected by the form of the ion–electron special distribution decreases as the free ion yield increases. The increasing free ion yield may be due to larger electron ranges or to a larger dielectric constant. The free ion yields in neopentane and water are respectively 1.0 (due to large electron ranges) and 2.7 (due to large dielectric constant). The scavenging yields in neopentane calculated with three different forms of spacial distribution, using the forced diffusion (FD) approximation, are significantly affected by the form of the spacial distribution. The scavenging yields in water calculated with four different forms of spacial distribution, using the FD approximation, are all within the experimental error of the measured yields. Use of the prescribed diffusion (PD) approximation permits satisfactory yields to be calculated for neopentane, but leads to the unsatisfactory result that all of the secondary electrons in the liquid have the same range (delta function distribution YD). The scavenging yield curves obtained using the PD approximation for water did not have a steep enough slope even when the distribution YD was used; YD leads to a steeper slope than any other form of distribution. The PD approximation gives an overestimate of the breadth of the geminate neutralization time distribution. The calculated time required for half of the geminate neutralization reaction to occur is similar whether the FD or PD approximation is used, but the spread of the neutralization times is an order of magnitude greater from the latter than from the former. Calculations were also done for electron scavenging in methylcyclopentane and in methanol. Methylcyclopentane behaves like cyclohexane and methanol behaves much like water with regard to the kinetics of ion–electron reactions in the spurs.