Abstract: A novel sodium alginate hydrogel composite membrane (U-MCM-41@ASA) was successfully prepared using 3-aminopropyltrimethoxysilane functionalized sodium alginate (ASA) with 3-urea-propyltrimethoxysilane functionalized MCM-41 molecular sieve (U-MCM-41) for the highly efficient adsorption of Pb2+. The incorporation of functionalized MCM-41 into the sodium alginate hydrogel network significantly increased the amount of active adsorption sites and enhanced the adsorption performance of the composite membrane. A variety of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS), were used to systematically analyze the microstructure, surface morphology, functional groups, surface chemical states, and thermal stability of the U-MCM-41@ASA composite membrane. The results indicated that U-MCM-41 was uniformly dispersed within the sodium alginate matrix, and the surface was rich in active groups such as amino groups, providing abundant adsorption sites for Pb2+. The removal of Pb2+ from aqueous solution by the U-MCM-41@ASA composite membrane was primarily achieved through coordination and chelation between the organic functional groups on the membrane surface and Pb2+, as well as electrostatic adsorption and ion exchange. Adsorption kinetics and thermodynamics analyses revealed that the adsorption process conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, and it was a spontaneous, endothermic, entropy-increasing behavior. Under the adsorption conditions of 15 mg composite membrane dosage, solution pH of 5.5, adsorption temperature of 45℃, initial Pb2+ concentration of 200 mg/L, and adsorption time of 240 min, the maximum adsorption capacity of the U-MCM-41@ASA composite membrane for Pb2+ reached 266.67 mg/g. Furthermore, the composite membrane exhibited excellent regeneration capability, with only a 10% decrease in adsorption capacity after five consecutive adsorption-desorption cycles. The U-MCM-41@ASA composite membrane not only possesses favorable adsorption performance and remarkable regeneration ability, but also offers advantages such as simple preparation and environmental friendliness, demonstrating potential application prospects in the treatment of lead-containing wastewater.

Key words: sodium alginate, hydrogel, composite membrane, adsorption, lead ions

摘要： 本研究通过将3-氨丙基三甲氧基硅烷功能化海藻酸钠与3-脲丙基三甲氧基硅烷功能化MCM-41分子筛进行复合，成功构建了一种高效吸附铅离子(Pb2+)的海藻酸钠水凝胶复合膜(U-MCM-41@ASA)。功能化MCM-41分子筛嵌入海藻酸钠水凝胶网络中，显著增加了吸附活性位点，提高了海藻酸钠水凝胶复合膜的吸附性能。采用多种表征手段对U-MCM-41@ASA复合膜的微观结构、表面形貌、官能团种类、表面化学状态及其热稳定性进行了系统分析。结果表明，U-MCM-41均匀分散于海藻酸钠基质中，且表面富含氨基等活性基团，为Pb2+的吸附提供了丰富的吸附位点。U-MCM-41@ASA复合膜对水溶液中Pb2+的去除主要依赖于膜表面有机官能团与Pb2+的配位螯合作用、静电吸附作用和离子交换作用。吸附动力学和吸附热力学分析表明，该吸附过程是一种自发、吸热的熵增行为，符合准二级动力学模型与Langmuir吸附等温线模型。当复合膜用量为15 mg、溶液pH为5.5、吸附温度为45℃、Pb2+初始浓度为200 mg/L、吸附时间为240 min时，U-MCM-41@ASA复合膜对Pb2+的最大吸附容量达到266.67 mg/g。此外，该复合膜经过重复使用5次后，其吸附容量仅下降10%。U-MCM-41@ASA复合膜具有较好的吸附性能和优良的再生性能，还具有制备工艺简单、环境友好等优势，在含铅废水处理领域展现出良好的应用前景。

关键词: 海藻酸钠, 水凝胶, 复合膜, 吸附, 铅离子