Extraction of diosgenin from the rhizome of Dioscorea by catalytic hydrolysis over recyclable solid acids is one of the most enviromentally friendly ways for the conversion of biomass into chemicals. In this paper, a magnetic solid acid, Fe₃O₄@SiO₂@NH-(CH₂)₂-NH₂@SO₃H with the particle size of about 80 nm, was synthesized by using Fe₃O₄ (~ 20 nm) as a magnetic core and then coated orderly with tetraethyl orthosilicate (TEOS) and N-{3-(Trimethoxysilyl) propyl} ethylenediamine (TMPED) by sol-gel reactions in water/ethanol solution, followed by the sulfonation of chlorosulfonic acid. The solid acid was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). The content of acidic sites on the surface of the solid acid was 1.01 mmol/g, measured by back titration method. The prepared solid acid was used to hydrolyze and extract diosgenin from Dioscorea nipponica Makino (DNM). The results show that the magnetic solid acid has higher hydrolysis activity than 2.5 M hydrochloric acid under same hydrolysis conditions, at 110 °C for 5 h. In addition, the magnetic solid acid can be easily separated from the reaction mixture by the application of a magnet and reused several times without significant activity loss. This work has a potential application value for the extraction of diosgenin from plants.

通过可循环利用的固体酸催化水解从薯os的根茎中提取薯os皂甙元是将生物质转化为化学物质的最环保的方法之一。在本文中，一个磁性固体酸，铁₃ ö ₄ @SiO ₂ @ NH-（CH ₂）₂ -NH ₂ @SO ₃ H带颗粒的约80nm的大小，通过使用合成的Fe ₃ ö ₄（〜20 nm）作为磁芯，然后在水/乙醇溶液中通过溶胶-凝胶反应有序地涂覆原硅酸四乙酯（TEOS）和N- {3-（三甲氧基甲硅烷基）丙基}乙二胺（TMPED），然后磺化氯磺酸。通过傅立叶变换红外光谱（FTIR），热重分析（TGA），扫描电子显微镜（SEM），X射线衍射（XRD），振动样品磁力计（VSM）和X射线光电子能谱（XPS）对固体酸进行表征）。通过反滴定法测定，固体酸表面的酸性部位的含量为1.01mmol / g。所制备的固体酸用于水解和提取薯Di中的薯gen皂苷元牧野（DNM）。结果表明，在相同的水解条件下，在110°C下保持5 h，磁性固体酸的水解活性高于2.5 M盐酸。另外，通过施加磁体，可以容易地从反应混合物中分离出磁性固体酸，并且可以重复使用几次而不会显着降低活性。这项工作对于从植物中提取薯os皂苷元具有潜在的应用价值。