巯基膨润土的制备工艺及性能

为了简化巯基膨润土(Bent-SH)的制备工艺、降低制备成本以便于实际应用,用3-巯丙基三甲氧基硅烷(MPS)与硅酸钠协同改性膨润土(Bent)。 优化了Bent-SH的工艺条件、表征了Bent-SH的结构、测定了Bent-SH的性能。 最佳制备工艺为:Bent与MPS的用量比为1∶0.05(g/mL);m(Na₂SiO₃)∶m(Bent)=7.0∶100;固液比为1∶20(g/mL);改性悬浮液的最佳pH值为8.0～10.0;改性时间为5～6 h,反应温度为室温。 Bent-SH较Bent胶质价、膨胀倍和阳离子交换容量均有所下降,但Bent-SH对镉的饱和吸附容量为20.86 mg/g,比Bent提高了20多倍。 硅酸钠和MPS协同改性没有改变Bent层状结构,而显著增强了Bent-SH的疏水性,分散性及对镉的吸附容量和吸附选择性。 Bent-SH是一种具有应用前景的重金属污染土壤的钝化剂。

Preparation and Properties of Mercapto Bentonite

In order to simplify the preparation process and reduce the preparation cost of mercapto bentonite (Bent-SH) for practical application, the bentonite(Bent) was synergistically modified by 3-mercaptopropyltrimethoxysilane (MPS) and sodium silicate. The preparation process of Bent-SH was optimized, the structure of Bent-SH was characterized, and the performance of Bent-SH was measured. The best process is:the solid-liquid ratio of Bent to MPS is 1∶0.05 (g/mL); the mass ratio of Na₂SiO₃ to Bent is 7.0∶100; the solid-liquid ratio is 1∶20 (g/mL); the pH of the modified suspension is 8.0~10.0; the modification time is 5~6 h, and the reaction temperature is room temperature. The gum value, expansion factor and cation exchange capacity of Bent-SH decrease compared with Bent, but the saturated adsorption capacity of Bent-SH for cadmium is 20.86 mg/g, 20 times more than that of Bent. The synergistic modification of sodium silicate and MPS does not change the layer structure of material, but significantly improve the hydrophobicity, dispersity, adsorption capacity and selectivity. The Bent-SH is a promising passivator for heavy metal contaminated soil.