Chemical Review and Letters
Volume:2 Issue: 2, Spring 2019

Drag coefficient independent on bubble diameter is required to ease design sieve trays or bubble column, through simulation of computational fluid dynamic. In this paper, the drag coefficients, independent or dependent on the diameter, are reviewed for gas-liquid system. A number of drag coefficients are used for Computational Fluid Dynamics (CFD). Different forces are entered to the liquid-bubble separation surface in diverse directions. Forces are investigated with mathematical proving for Newtonian fluids and Eulerian coordinate. Finally, the external force as a new force, enter to the drag coefficient equations. Drag coefficient is included force coefficient. Drag force is entered in momentum equations. Drag coefficient is used in two-phase systems which bubbles and liquid are activated as dispersed and continuous phase, respectively. Bubbles and liquid are in contact with each other in separation surface on bubble. Drag force is created slip on separation surface. The drag coefficients are investigated depended on the size and configuration of bubbles. The drag coefficient of Krishna et al is used dependent on bubble diameter. Schiller - Nauman model drag coefficient is estimated with 9% error and dependence on bubble diameter. In this article, the modern drag coefficients are studied independent on the diameter and shape of the bubble. The Drag coefficients are resulted theoretical, mathematical and experimental independent and dependent of diameter bubble. The new Drag coefficient is presented dependent on surface tension and diameter of the tower hole with 6.3 of error approximately.

In the present study, Arundo donax L was used as a low-cost biosorbent for the uptake of basic dye crystal violet (CV) from aqueous media. Systematic batch mode studies of adsorption of crystal violet (CV) on Arundo donax were carried out as a function of process of parameters includes initial CV concentration, dose of adsorbent, pH, contact time and temperature. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D-R) isotherm models. The adsorption of CV followed the Langmuir model with a maximum adsorption capacity (qmax) of 19.60 mg/g and pseudo second-order kinetics under a specified set of conditions. The thermodynamic parameters like free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) changes for the adsorption of CV ions have been evaluated and it has been found that the reaction was spontaneous and exothermic in nature. Owing to its rapid adsorption rate and uptake capacity, stem of Arundo donax L. seems to be a promising biosorbent for removal of toxic dyes from wastewater.

The manuscripts entails the use of plant gum blends prepared with gum Arabic and strawberry gum, to inhibit the corrosion of aluminum immersed in concentrated sulfuric acid solution. The miscibility tests of the blended gums (Arabic and strawberry) were carried out using Ostwald viscometer. Following the ratio of gum Arabic to strawberry gum, the ratio 0.2:0.8 has the highest relative viscosity and thus more viscous than all the other blends prepared in this work, and due to its viscosity strength the 0.2:0.8 ratio was used. In addition, the inhibitive and adsorption properties of Arabic and strawberry gums were studied using gravimetric method. The results obtained indicated that the blend of Arabic and strawberry gums are effective in the corrosion inhibition of aluminum in H2SO4 solutions. The adsorption of the inhibitor on the aluminium surface is spontaneous and supports the Langmuir adsorption model, the data was also subjected to other isotherms and thermodynamic models.

The structural, electronic and optical properties of graphene-like ZnX (X=O, S, Se and Te) are investigated in the framework of the density functional theory. Calculating strain energy exhibits that all compound has an asymmetric behavior with respect to applied biaxial strain. The electronic results indicate that the electronic properties of the considered layered compounds such as energy gap and gap direction can be tuned using exerting biaxial in-plane compressive and tensile strains. It has been shown that both compressive and tensile strains decrease the energy gap of ZnO monolayer. However, for the other compounds, ZnS, ZnSe and ZnTe, the energy gap increases by applying compressive strain while it decreases under tensile strains, respectively. The band gap direction changes by imposing different types strains. The optical results exhibit red shift and blue shift in the optical absorption spectrum for ZnO and ZnS monolayers by exerting tensile and compressive strains, respectively. Our obtained results suggest that these wide gap semiconductors can be good candidate for optoelectronic nano-base device.

The effects and decomposition of ammonium thiosulfate and guanyl thiourea, a nitrification inhibitor, are discussed. When ammonium thiosulfate and guanyl thiourea are used as nitrification inhibitors, leaching of ammonium nitrate from calcium ammonium nitrate in soil is reduced, while the yields and nitrogen intake of the plant are increased. When ammonium thiosulfate and guanyl thiourea are used, labor costs are reduced without any loss of product yield or quality. The use of ammonium nitrate products containing ammonium thiosulfate and guanyl thiourea reduced the nitrogen requirement for maximum efficiency. In this study, the effect of ammonium thiosulfate and guanylthiourea on calcium ammonium nitrate and how it affects nitrogen concentration under fertilization conditions were discussed. however, the results obtained by monitoring the loss of nitrogen concentration and the change in nitrate and ammonium concentrations over a specified time period indicate that the ammonium thiosulfate and guanylthiourea used are the best choice as an inhibitor candidate.

In the present work, a combined theoretical and experimental investigation on the properties of 1-(4-chlorophenyl)-3-(2-ethoxyphenyl)triazene is reported. The optimized geometry was calculated by B3LYP method using 6-311++G(2d,p) as a large basis set. The FT-IR spectrum was calculated at this level of theory, and was interpreted in terms of potential energy distribution (PED) analysis. The scaled theoretical frequencies were in line with the experimental ones. Furthermore, natural bond orbital (NBO) and atoms in molecules (AIM) theories were used to characterize intra-molecular hydrogen bond. The low value of charge transfer and the absence of bond critical point between O···HN show that there is not intra-molecular hydrogen bond.