The Method of Improving the Corrosive Environment in a Reclaimed-Water Pipe using the SA Method
To increase the practical-use value of multi-water-resources, reclaimed water was used as the experimental water because the frequency of reclaimed-water usage has been very high of late. The SA method was then applied to a reclaimed-water pipe as a way of inhibiting its corrosion, and its anticorrosion effect was observed. Corrosion effect by the sacrificial anode method was measured by lab scale experiments, reclaimed water was used as the experimental water, and also tap water was used as a control group. As a result of experiments, efficiency of SA method can be made higher by increasing the amount of SA metal. In addition, anticorrosive effect was not large compared to the reclaimed water condition, and it was determined that efficiency of the SA method increases in a pipeline where high-conductivity water flows. And the corrosive-index (KRWI) trend was not large regardless of the flow time and the degree of corrosion.
Theoretical Study of the Water Exchange Reaction on Divalent Zinc Ion using Density Functional Theory
Recent ab initio studies reported in the literature have challenged the mechanistic assignments made on the basis of volume of activation data [1,2]. In addition to that ab initio molecular orbital calculations on hydrated zinc(II)-ions were used to elucidate the general role of this ion in metalloproteins [3]. Due to our interest in both inorganic reaction mechanisms and enzymatic catalysis we started a systematic investigation of solvent exchange processes on divalent zinc-ion using density functional calculations. Our investigations cover aqua complexes of the general form [Zn(H2O)n]2+·mH20 with n=3-6 and m=0-2, where n and m represent the number of water molecules in the coordination and solvation sphere, respectively.The complexes [Zn(H2O)5]2+·2H2O and [Zn(H2O)4]2+·2H2O turnend out to be the most stable zinc complexes with seven and six water molecules, respectively. This implies that a heptacoordinated zinc(II) complex, where all water molecules are located in the co-ordination sphere, should be energetically highly unfavorable and that [Zn(H2O)6]2+ can quite readily push two coordinated water molecules into the solvation sphere. For the pentaqua complex [Zn(H2O)5]2+ only one water molecule is easily lost to the solvation sphere, which makes the [Zn(H2O)4]2+·H2O complex the most favorable in order to consider the limiting dissociative and associative water exchange process of hexacoordinated zinc(II). The dehydration and hydration energies using the most stable zinc(II) complexes [Zn(H2O)4]2+·2H2O, [Zn(H2O)5]2+·2H2O and [Zn(H2O)4]2+·H2O were calculated to be 24.1 and -21.0 kcal/mol, respectively.
Modeling of chemical reactors—XXIX mixing-cell model for packed bed reactors. Steady state considerations. Problems of multiplicity
Abstract The axial heat and mass transfer in tubular catalytic reactors may be described by mixing-cell model and diffusion model as well. The diffusion description yields for a strong exothermic reaction and adiabatic conditions three steady state profiles, on the other hand the mixing-cell model gives rise to more than three steady states. A simple numerical and graphical analysis for mixing-cell model is presented.