Development and Application of ReaxFF Methodology for Understanding the Chemical Dynamics of Metal Carbonates in Aqueous Solutions

A new ReaxFF reactive force field has been developed for metal carbonate systems including Na+, Ca2+, and Mg2+ cations and the CO32- anion. This force field is fully transferable with...

Formation and Transformation Trends of Metal Carbonates With Cation Ratio and Ion Interaction in Post-treatment Process of Desalination Brine

BackgroundTo address the negative effects of desalination plants, CO2 emissions, and discharge of desalination brine, we studied the carbon capture utilization (CCU) process based on metal carbonation via the reuse of desalination brine. In this study, we converted CO2 and simulated desalination brine into metal carbonate using monoethanolamine as an aqueous absorbent. The produced metal carbonate varied according to the cation component of the simulated desalination brine. We focused on ion interactions in the aqueous system, occurred by cation ratio, and other phenomena caused by the interactions.ResultsWe determined that the common ion effect, which occurred owing to the ion interactions of the system, was the main reason for the various carbonation trends. Ionic atmospheres that were changed by the ionic components significantly affected the trends. The high salinity of the desalination brine also affected the metal carbonation. We further deduced that the variation in the results was derived from interactions between the abovementioned effects. And we also found that Na+, which was overlooked in former studies about polymorph transformation, also affects polymorph transformation.ConclusionsAll the phenomena in the metal carbonation interrupt desalination brine post-treatment because of their unpredictability. However, we suggest ambient estimation of its cation components, which would help future studies and demonstrate desalination brine post-treatment.

The Influence of Silicateins on the Shape and Crystalline Habit of Silica Carbonate Biomorphs of Alkaline Earth Metals (Ca, Ba, Sr)

This contribution presents the effect of two ortholog enzymes from marine sponges called silicateins on the formation of silica carbonate biomorphs of alkaline metals (Ca, Ba, Sr). In vivo, these enzymes participate in the polymerization of silica. Silicateins from Tethya aurantia and Suberitis domuncula were produced recombinantly and presented different degrees of activity, as evidenced by their ability to cleave silyl ether-like bonds in a model compound. Biomorphs are typically inorganic structures that show characteristic shapes resembling those of biological structures such as helices, leaves, flowers, disks or spheres. Irrespective of the concentration or the enzyme used, the presence of silicateins inhibited the formation of classic morphologies of biomorphs, albeit to different extents. Thus, not only the silica condensation activity of the enzyme but also its ability to bind silica compounds is implicated in the inhibition process. The largest effect was observed for the strontium and barium biomorphs, leading to the formation of spheres similar to those observed in diatoms and Radiolaria rather than the classical non-symmetrical forms. Characterization of the samples using Raman spectroscopy showed that silicatein did not affect the crystalline structure of the alkaline earth metal carbonate but did modify the crystalline habit.

Synthesis, characterization, and thermal behavior of amidosulfonates of transition metals in air and nitrogen atmosphere

The amidosulfonates of Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ were prepared by the direct reaction between the metal carbonate and the amidosulfonic acid with heating and stirring. The compounds were characterized by infrared absorption spectroscopy (IRFT), elemental analysis, thermal analysis (TG and DTA) and X-ray diffraction by the powder method. The absorptions observed in IR spectra are associated with N-H and O-H stretching, as well as symmetrical and asymmetric S-O stretching in the sulfonic group. The compounds present X-ray diffraction pattern with well-defined reflections, showing no evidence of isomorphism. The TG-DTA curves allowed to establish the stoichiometry of compounds as M(NH2SO3)2.xH2O, where M = Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ and x ranging from 1 to 4. Dehydration leads to the formation of stable anhydrous. In all cases the respective sulfates are formed as an intermediate. After consecutive steps of decomposition, the respective oxides were obtained: Mn3O4, CoO, NiO, CuO and ZnO. The TG-DTA curves are characteristic for each sample, with thermal events related to dehydration and ligand decomposition.