Porous Ordered Composite Aerogels:Fabrication,Photocatalytic And Oil Adsorption Performances

With the rapid development of science and technology and economy,the environmental pollution problems have become increasingly serious.Water pollution,especially the pollution of wastewater containing industrial dyes and pollution caused by oil spills,has gradually become a research hotspot.Aerogels,as a class of materials with light weight,high porosity,and high specific surface area,have a wide range of application potential and prospects in the field of environmental protection.Based on this,this research project intends to use unidirectional freezing technology to prepare porous aerogels with oriented structure and modify them to obtain functional aerogels that can be used in photocatalytic degradation of dyes or oil-water separation fields..This research is specifically carried out in the following two parts:(1)Unidirectional freezing technology was adopted.Chitosan and titania were used as the main materials.At the same time,rectorite and carbon nanotubes were introduced to prepare a composite aerogel material with good orientation.At the initial stage of the experiment,the influence of various parameters(such as the device and the total concentration of the composite suspension)on the morphology of the aerogel was investigated.Finally,alcohol was selected as a stable cold transfer medium,and the total concentration of the composite suspension was determined to be 6%.The composite aerogels have a large number of uniform oriented lamellar structures,and there are "fishbone structures" interconnected between the laminae.This structure enables the aerogels to have a large specific surface area up to 84.59 cm3/g..At the same time,the successful introduction of rectorite and carbon nanotubes enhances the mechanical properties of the composite aerogels,giving it good hardness,elasticity and restorability.At the same time,the photocatalytic degradation efficiency of the composite aerogels for rhodamine B were discussed.The results show that the introduction of rectorite and carbon nanotubes is beneficial to the photocatalytic reaction.When the content of rectorite in the composite aerogel is 4 wt%,the photocatalytic degradation rate is the fastest,and the decolorization rate can reach 95%within 100 minutes.After repeated use three times,the decolorization rate can reach 75%in 80 minutes.(2)Nanofibers with core-shell structure were prepared by using coaxial electrospinning and mixed electrospinning techniques.Alcohol-soaked dissolution method was used to remove core material,and polyacrylonitrile-benzoxazine monomer nanofibers with hollow structure was obtained.Subsequently,homogeneous and stable nanofiber suspensions were obtained using the homogenization method,and unidirectional freezing technology was used to order the nanofibers in the aerogels.Subsequently,the pre-oxidation of polyacrylonitrile and the polymerization of benzoxazine monomer were initiated by calcination at 240℃ to obtain superhydrophobic hollow nanofiber aerogels.The nanofibers in the obtained aerogels are arranged orderly,and at the same time,the fibers are connected with each other,so that the aerogels have a high porosity,low density structure and a certain mechanical strength.The apparent density of the prepared superhydrophobic hollow polyacrylonitrile aerogel is only 12.16±1.43 mg/cm3,and the oil absorption efficiency can reach 75.34±2.49 g/g,which can effectively adsorb the oil.