On-Aluminum and Barrier Anodic Oxide: Meeting the Challenges of Chemical Dissolution Rate in Various Acids and Solutions

The chemical dissolution—in 0.1 M solutions of phosphoric, malonic, citric, sulfosalicylic, and tartaric acids and 0.6 M solutions of sulfuric, oxalic, malonic, phosphoric, tartaric, and citric acids—of aluminum (Al) and its barrier anodic oxide, with thicknesses of 240 and 350 nm, produced during the anodization of Al deposited on a sitall substrate and Al foil, respectively, in a 1% citric acid aqueous solution, was investigated. Signs of chemical dissolution for 0.1 M phosphoric acid solution and 0.6 M concentrations of all the listed solutions were found. It was shown that the dissolution rate and the nature of its change depend on the acid nature, the state of the sample surface, and the classification of the electrolytes according to their degrees of aggressiveness with respect to aluminum.

Geothermal and Mineralogic Analysis of Hot Springs in the Puracé-La Mina Sector in Cauca, Colombia

Thermal waters are natural resources of great value to geothermal sciences, the tourism industry, and health. In this work, geochemical classification of physicochemical results of 17 sources at the Puracé-La Mina (Cauca, Colombia) sector was implemented in order to strengthen and determine their potential applications and enhance the continental tourism in Colombia. The analyzed parameters were developed following the Standard Methods 22nd edition, at Universidad Nacional de Colombia-Manizales. According to the results obtained by means of a geochemical classification, it was found that most of the sources have a sulfated-acid nature which makes them heated vapor waters and volcanic waters. Likewise, it was observed that all the sources are immature waters and still do not reach chemical equilibrium. On the other hand, mineralogical and chemical characterization by means of XRD and XRF showed a high content of silica isomorphous minerals with a low concentration. In addition, the presence of Fe2O3 was observed, which is insoluble at pH > 5 and remains in the rock. Nevertheless, considering that mine sources possess pH ± 2 and temperatures of 40°C, leaching is possible for iron justifying its presence in the water. Instead, elements like Na+, K+, Mg2+, and Ca2+ have high mobility at the conditions of mine sources (low pH) as a consequence of hydrolysis processes, which produce variations in water composition.

Unique reactivity of B in B[Ge9Y3]3 (Y = H, CH3, BO, CN): formation of a Lewis base

Boron compounds usually exhibit Lewis acidity at the boron center due to the presence of vacant p-orbitals. But using Zintl-ion based groups (Ge9Y3, Y = H, CH3, BO, CN), we can alter Lewis acid nature of B to a Lewis base.

Ultra-low density metallic foams synthesized by contact glow discharge electrolysis (CGDE) for laser experiments

The goal of this work is to realize metallic foams synthesized by contact glow discharge electrolysis with specific characteristics. In this paper, we show the results of our studies, consisting in investigating parameters that influence the foams characteristics. Thus, the morphology of metallic foams is examined through scanning electron microscopy (SEM) observations with the acid nature. Moreover, the evolution of the mass and the volume of metallic foams with two experimental parameters (overvoltage and gold concentration) is also investigated. The acid nature affects the foams microscopic structure highlighted by the SEM observations, but for now no valid explanation to this behaviour was found. We prove that the mass deposited on the electrode is dependent on the ionic salt concentration, whereas the overvoltage only affects the foam overall density.

Extraction of actinides by tertiary amines in room temperature ionic liquids: evidence for anion exchange as a major process at high acidity and impact of acid nature

The extraction of U(vi) and Pu(iv) by tri-alkyl amines in room temperature ionic liquids, [Cnmim][Tf2N] (where, n = 4, 6 or 8) follow anion exchange mechanism.

Synthesis and Characterization of Fe,Cr or Sn-MSU-X and Catalytic Applications

Iron, chromium or tin containing mesoporous materials MSU-X were synthesized using Pluronic F127 as templating agent under the neutral pH condition by one-step method. The samples were characterized by XRD, N2 adsorption, TEM, FT-IR, UV-Vis. The surface acid nature of Sn-MSU-X was investigated by FT-IR of pyridine adsorption. The results indicate that Fe, Cr and Sn have been successfully incorprated into the framework of the MSU-X samples. And these samples have an uniform pore size distribution. Fe-MSU-X and Cr-MSU-X exhibit disordered worm-like mesostructure. However, Sn-MSU-X exhibits highly ordered hexagonal-pores mesostructure. The Fe-MSU-X and Cr-MSU-X catalysts are more active for the selective oxidation of phenol and cyclooctane, respectively.There are both Lewis and Brönsted acid sites on the surface of Sn-MSU-X.