8/31/2023 0 Comments Iron sulfide charge![]() ![]() 43 Recently, the crystal structure of (C 2H 8N 2) 0.4Fe 2S 2 was published, which further supports this functionality. reported on intercalation of cationic iron complexes of bipyridine, phenanthroline and other amino bases between mackinawite layers and such processes may also have contributed to condensation reactions on the prebiotic earth. Toxic metal ions like Cu 2+, Pb 2+ and Hg 2+ would have been precipitated in aqueous environments where mackinawite is present. The capability of mackinawite to capture metal ions may have also led to a non-toxic environment in a stage, where biopolymers have formed which is one of “nine requirements” for the origin of earth's life as suggested by Maruyama et al. 41 The adsorption of biopolymer precursors increases their local concentrations and could have enabled polycondensation reactions. Especially, amino acids, carbohydrates and lipids were captured by mackinawite particles and they concluded that “Biogenic iron sulfide minerals represent a potential strong protectant for proteinaceous organic carbon as long as anoxic conditions are preserved in low temperature surface environments”. 39,40 The potential role of the pronounced adsorption ability of mackinawite was covered earlier by Picard and coworkers. showed by DFT calculations that the mackinawite surface is able to activate CO 2 molecules and to promote CO 2 dissociation under certain conditions. The oxidation of mackinawite coupled to the formation of pyrite has been studied extensively, due to its possible relevance as a primordial energy source as well as a very simple mimic of iron–sulfur proteins. The role of mackinawite has been discussed in the context of the origin of life and it could have contributed to crucial steps towards the emergence of the first self-replicating system. ![]() However, corrosion scientists have been more interested in the fate of the corroding metal than in the sulfides produced. ![]() 19–23 Examinations of corrosion processes of iron in sulfide and sulfur containing solutions led to the discovery of mackinawite formation on metal surfaces. As a result, the intercalation chemistry of mackinawite has received some attention and experiments have been carried out to modify the interlayer space and to tune its electrical properties. 16–18 Its intrinsic physical properties like electrical conductivity and superconductivity have been studied by materials scientists. 13–15 Organic chemists have studied its reducing power towards organic nitro and chlorinated compounds that may be useful for wastewater treatment. ![]() 3–12 Related to these studies are the investigations of mackinawite's pronounced capabilities to adsorb heavy and rare earth metalions what is of interest from many points of view. They mainly focused on the solubility and the transformation of precipitated mackinawite. Earth scientists have investigated mackinawite formation in laboratory and field studies to explore its role in natural biogeochemical processes. 2 Inspired from these publications we have intensively investigated the reaction between elemental iron and elemental sulfur at ambient conditions to fill this gap.ĭuring the last 60 years, the formation and characteristics of mackinawite have been studied from different points of view. 1 The reaction was again mentioned 200 years later in a short notice, but no characterization of the products was given. Introduction The fascinating, but almost forgotten reaction of forming iron sulfides from wet elemental iron and elemental sulfur under mild conditions was reported in 1700 AD, but this knowledge has not yet found its way into the inorganic chemistry textbooks. This finding leads us to propose a novel model of charged layers which can be used to explain some of the inconsistencies found in the literature regarding the structure and particle characteristics of nano-mackinawite. We found that the addition of NaCl significantly accelerates the reaction and furthermore influences the Fe 2+ ion content of the formed mackinawite itself. This makes it possible to investigate the influence of any dissolved salts on the mackinawite formation and its properties. In contrast to the conventional preparation of mackinawite by precipitation, the synthesis from the elements can be carried out without additional ions. Though the corrosion of iron in the presence of sulfur has been studied extensively, it has never been used to intentionally synthesize mackinawite. Sulfur-assisted corrosion is a process known to material scientists for many decades now. ![]()
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