Abstract: As a typical metal‑organic framework MOF material cobalt‑based zeolitic imidazolate framework‑67 ZIF‑67 possesses a high specific surface area abundant active sites and excellent PMS activation capability which enables it to efficiently promote the degradation of dyes such as methylene blue MB . However ZIF‑67 usually exists in powder form and tends to agglomerate and is difficult to settle in practical water treatment systems. This leads to difficulties in catalyst recovery which not only causes resource waste but also may introduce secondary pollution due to cobalt ion leaching severely limiting its engineering application. Therefore the development of ZIF‑67‑based composite support materials with high catalytic performance good dispersibility and easy recoverability has become a critical direction to overcome the aforementioned bottlenecks. In this study sugarcane—an abundant environmentally friendly raw material with a natural highly oriented and hierarchical porous structure—was used as the starting material. Sugarcane cellulose was subjected to selective oxidation using a 2 2 6 6‑tetramethylpiperidin‑1‑oxyl TEMPO oxidation system converting the hydroxyl groups on the cellulose surface into carboxyl groups. Subsequently sugarcane nanocellulose aerogels SNCA with a three‑dimensional porous network structure were prepared via a freeze‑drying process. On this basis ZIF‑67 was introduced into the porous channels of SNCA by an in‑situ growth method. The loading amount and dispersibility of ZIF‑67 in SNCA were regulated by controlling the number of ZIF‑67 assembly cycles 1‑4 cycles and a series of ZIF‑67@SNCA composite aerogels were finally constructed. The microstructure chemical composition and surface properties of the materials were characterized by means of scanning electron microscopy SEM X‑ray photoelectron spectroscopy XPS specific surface area analysis and other techniques. Moreover in the PMS activation system MB was used as the target pollutant to systematically investigate the adsorption performance catalytic degradation efficiency and cyclic stability of the composite aerogels. The results indicate that TEMPO oxidation treatment significantly increases the carboxyl content on the surface of SNCA. The carboxyl groups can form a coordination interaction with Co²⁺ in ZIF‑67 which effectively inhibits the agglomeration of ZIF‑67 nanoparticles and enables the uniform dispersion of ZIF‑67 within the porous network of SNCA. The loading rate of ZIF‑67 in ZIF‑67@ SNCA‑4 reaches as high as 32. 47%. BET tests show that the prepared ZIF‑67@SNCA‑1 composite aerogel has a high specific surface area of 217 m²/ g. Its three‑dimensional porous structure not only provides sufficient adsorption sites for MB molecules with an adsorption capacity of 8. 15 mg / g but also accelerates the mass transfer efficiency of PMS and active free radicals. In a high‑concentration MB solution 50 mg / L the catalytic degradation rate of ZIF‑67@ SNCA‑4 in the PMS activation system remains at 92. 15% and deep degradation of MB can be achieved within 60 min of reaction. Within a wide pH range of 4‑9 there is no significant change in catalytic degradation performance which overcomes the defect of activity attenuation of traditional cobalt‑based catalysts under extreme pH conditions. In addition after 5 adsorption‑desorption cycles the catalytic degradation rate of ZIF‑67@SNCA remains above 90%.

Key words: sugarcane cellulose aerogel, ZIF?67, in?situ growth, dye adsorption, catalytic degradation

摘要： 为了解决钴基沸石咪唑酯骨架材料(ZIF-67)粉末在实际应用中难以回收的问题,利用 2,2,6,6-四甲基哌啶-1-氧基(TEMPO)对具有高取向性和分级多孔结构的甘蔗进行氧化处理,得到甘蔗纳米纤维素气凝胶(SNCA),借助原位生长法在其内部负载 ZIF-67在通过控制组装次数来调控 ZIF-67 的负载量和分散性,制得系列 ZIF-67@SNCA 复合气凝胶,并在 PMS 活化体系中,以亚甲基蓝(MB)为目标污染物探究复合气凝胶的催化降解性能。 结果表明:增加组装次数可有效提升 ZIF-67 在 SNCA 内的负载率和分散性,ZIF-67@SNCA-1具有较高的比表面积( 217 m 2/ g),对 MB 的吸附量可达 8. 15 mg / g,ZIF-67@ SNCA-4 在高浓度 MB 溶液(50 mg / L)中依然保持高催化降解率,在 pH 为 4~ 9 范围内具有良好的催化稳定性,并且经过 5 轮吸附-脱附循环实验,复合气凝胶对 MB 的催化去除效率仍超过 90%。 研究结果可为构建高效、可循环的生物质基复合催化材料提供新思路。

关键词: 甘蔗纳米纤维素气凝胶, 钴基沸石咪唑酯骨架材料(ZIF-67), 原位生长, 染料吸附, 催化降解