ZIF-67@SNCA复合气凝胶的制备及催化降解性能OA

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％.