Several procedures for hydrothermal synthesis of saponite can be found in the literature. They differ in terms of the preparation conditions of the precursor and of the synthesis temperature. The objective of the present study was to investigate how these two parameters influence the structure of the final synthesis product. The precursor was prepared from Mg(NO3)2, Al(NO3)3, and Na4SiO4 in three different ways: as a gel, a dried gel, and a calcined gel. The influence of the synthesis temperature on the structure of saponite was investigated in the range 90–200°C. The results showed that the use of a calcined precursor yielded a single mineral phase, saponite, with up to 90% aluminum in tetrahedral configuration. In comparison, the use of a gel precursor resulted in a product with only 60% aluminum in the tetrahedral configuration. The synthesis temperature had no significant effect on the saponite structure. The reported synthesis method showed the possibility of obtaining saponite with superior characteristics, in terms of crystallinity, surface acidity, and thermal stability compared to the natural mineral, even at 90°C, and thus with greater potential for industrial application.

中文翻译：

---

前体和合成温度对皂石结构的影响

在文献中可以找到几种水热合成皂石的方法。它们在前体的制备条件和合成温度方面不同。本研究的目的是研究这两个参数如何影响最终合成产物的结构。前体由 Mg(NO3)2、Al(NO3)3 和 Na4SiO4 以三种不同的方式制备：凝胶、干燥凝胶和煅烧凝胶。在90-200°C范围内研究了合成温度对皂石结构的影响。结果表明，使用煅烧前体产生单一矿物相皂石，其中铝含量高达 90%，呈四面体结构。相比之下，凝胶前体的使用导致产品的四面体结构中只有 60% 的铝。合成温度对皂石结构没有显着影响。报道的合成方法表明，与天然矿物相比，即使在 90°C 下，也有可能获得在结晶度、表面酸度和热稳定性方面具有优异特性的皂石，因此具有更大的工业应用潜力。