Among the several steps involved in molecular evolution, molecular preconcentration is the first and most important. If the molecules are not preconcentrated the other steps of molecular evolution cannot occur. There are several ways to preconcentrate molecules: sorption, wetting/drying cycles, freezing/sublimation and sorption/precipitation with minerals. In the present work, the effect of NH4SCN and artificial seawater 4.0 Gy on the synthesis of ferrihydrite was studied. It should be noted that thiocyanate could play the same role as that of CN− in the Strecker reaction. Unlike today's seawater that has high Na+ and Cl− concentrations, the seawater used in this work has high Mg2+, Ca2+ and SO42− concentrations. Two results stand out, first SCN− and NH4+ were preconcentrated by sorption/precipitation in some syntheses and second, in some experiments, a mixture of goethite, hematite and magnetite was obtained. The sorption/precipitation of SCN− is always associated with the synthesis of goethite. This could be an indication that SCN− interacts with Fe3+ through the sulphur group of SCN−. In addition, the synthesis of magnetite could be an indication that the SCN− ion oxidized, forming thiocyanogen-(SCN)2 or trithiocyanate ion-(SCN)−3 and that Fe3+ reduced to Fe2+. Besides the sorption/precipitation of SCN− and NH4+, Fourier-transform infrared spectroscopy also showed that sorption/precipitation of SO42− and CO32− occurred. Ferrihydrite synthesized with artificial seawater presented the highest surface area and pore size. The pHpzc values of the samples were in the range of pHpzc described in the literature. The X-ray photoelectron spectroscopy (XPS) measurements performed show proportions of iron present in different oxidation states, however, the electronic similarities observed in the mixtures of iron oxides and oxy-hydroxides make it difficult to quantify them. Direct comparison between XPS spectra of the Fe2p and O 1s core-levels reveal no significant differences from the effect of artificial seawater 4.0 Gy on the synthesis of ferrihydrite.

中文翻译：

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益生元化学条件下水铁矿形成的研究：人工海水 4.0 Gy 和硫氰酸铵

在涉及分子进化的几个步骤中，分子预浓缩是第一个也是最重要的。如果分子没有预先浓缩，分子进化的其他步骤就不会发生。有几种预浓缩分子的方法：吸附、润湿/干燥循环、冷冻/升华和用矿物质吸附/沉淀。在目前的工作中，NH 的影响4研究了SCN和人工海水4.0 Gy对水铁矿的合成。需要注意的是，硫氰酸盐可以起到与CN相同的作用-在 Strecker 反应中。不像今天的海水含有高 Na+和氯-浓度，这项工作中使用的海水含有高镁2+, 钙2+所以42−浓度。两个结果脱颖而出，第一个SCN-和 NH4+在一些合成中通过吸附/沉淀进行预浓缩，其次，在一些实验中，获得了针铁矿、赤铁矿和磁铁矿的混合物。SCN的吸附/沉淀-总是与针铁矿的合成有关。这可能表明 SCN-与 Fe 相互作用3+通过 SCN 的硫基-. 此外，磁铁矿的合成可能表明 SCN-离子被氧化，形成硫氰-(SCN)2或三硫氰酸根离子-(SCN)-3和那个铁3+还原为铁2+. 除了 SCN 的吸附/沉淀-和 NH4+, 傅里叶变换红外光谱也表明 SO 的吸附/沉淀42−和一氧化碳32−发生了。人工海水合成的水铁矿具有最高的表面积和孔径。酸碱度pzc样品的值在 pH 范围内pzc文献中描述的。进行的 X 射线光电子能谱 (XPS) 测量显示了以不同氧化态存在的铁的比例，然而，在铁氧化物和羟基氧化物的混合物中观察到的电子相似性使其难以量化。直接比较 Fe2p 和 O 1s 核心水平的 XPS 光谱表明，人工海水 4.0 Gy 对水铁矿合成的影响没有显着差异。