In the present study, a magnetically separable potent solid acid nanocatalyst with a facile preparation technique was fabricated via incorporation of fibroin as a natural polymer with Fe₃O₄ nanoparticles. In fact, the Fe₃O₄ nanoparticles were thoroughly covered by the fibroin protein, followed by treating with chlorosulfuric acid for surface sulfonation. Next, physicochemical properties were characterized using FT-IR, XRD, TGA, SEM, EDX, and TEM techniques to elucidate the Fe₃O₄@fibroin-SO₃H structure. The analyses proved the core–shell structure and the presence of sulfonyl on the surface. The Fe₃O₄@fibroin-SO₃H showed significant activity in the tetrazole derivatives synthesis reactions under solvent-free and relatively mild conditions. The structure of the products was validated using ¹H-NMR and ¹³C-NMR. The prepared catalyst showed good stability and reusability even after easy separation by an external magnet for four consecutive reaction rounds. Considering the crucial importance of sulfuric acid catalysis, we believe that Fe₃O₄@fibroin-SO₃H will find wide applications as a separable, green, and potent solid acid nanocatalyst.

在本研究中，通过将作为天然聚合物的丝素蛋白与Fe ₃ O ₄纳米粒子结合在一起，制备了一种具有简便制备技术的磁性可分离强效固体酸纳米催化剂。实际上，Fe ₃ O ₄纳米颗粒被纤维蛋白蛋白完全覆盖，然后用氯硫酸处理以进行表面磺化。接下来，使用FT-IR，XRD，TGA，SEM，EDX和TEM技术表征理化性质，以阐明Fe ₃ O ₄纤维蛋白素SO ₃ H的结构。分析证明了核-壳结构以及表面上存在磺酰基。铁₃ O ₄丝素蛋白SO ₃ H在无溶剂和相对温和的条件下在四唑衍生物合成反应中显示出显着的活性。使用¹ H-NMR和¹³ C-NMR验证产物的结构。所制备的催化剂即使在通过外部磁体容易地分离连续四轮反应后仍显示出良好的稳定性和可重复使用性。考虑到硫酸催化的至关重要性，我们认为Fe ₃ O ₄ @丝素蛋白SO ₃ H将作为可分离，绿色且有效的固体酸纳米催化剂得到广泛的应用。