Preparation And Adsorption Properties Of Cellulose/Carbon Nanotubes Hollow Composite Microspheres

Environmental protection is an important theme of the 21 st century.With the rapid development of mobile internet,online shopping has become an indispensable part of people’s daily life,which is followed by a large number of express junk.Most express boxes are discarded after a single use,with an actual recovery rate of less than 10%.A large amount of waste paper destroys the earth’s ecology,causing serious environmental problems.Therefore,recycling packaging waste paper has become a meaningful and challenging work.As a cellulose rich biomass resource,paper packaging provides a potential source for the production of various green and useful specialty products.The further development and utilization of cellulose resources are of great significance to the development of new energy,new materials and ecological environment.Research and development of cellulose based functional materials is one of the important and effective ways to utilize cellulose resources.In this study,cellulose was used as the raw material.Cellulose was dissolved in alkali/urea system and hollow microspheres were constructed.Their applications in the environmental field were discussed.The main research contents and conclusions are as follows:(1)Preparation of cellulose hollow microspheres.Cellulose mecrospheres were prepared by electrostatic drop method.Liquid nitrogen was used as coagulant,and then freeze-dried to prepare hollow cellulose microspheres with regular shape,uniform size distribution,unique hollow structure and orderly pore structure.The effects of cellulose concentration,applied voltage and precooling temperature on the structure of hollow microspheres were investigated.It was found that the higher concentration of cellulose solution resulted in larger particle size and thicker wall.The higher voltage resulted in smaller particle size and thinner wall.At the same time,the precooling temperature is the key to prepare the hollow structure.When the precooling temperature was-40℃,the microspheres had obvious hollow structure.When the precooling temperature enhanced to-196℃,the microspheres was a solid structure.Therefore,the particle size and wall thickness of microspheres can be easily controlled by simply adjusting the cellulose concentration,the volatge and the pre-cooling temperature.(2)Preparation and characterization of magnetic cellulose/carbon nanotubes hollow composite microspheres(MCCM).By blending the carbon nanotubes and ferroferric oxide nanoparticles with cellulose solution,the mixture was prepared.The MCCM microspheres were prepared by means of electrostatic droplet methods.The hollow structure formed during freeze-drying process,which proved that the electrostatic droplet method can also be used to prepare hollow composite microspheres.This method is simple and green,and the prepared MCCM microspheres have regular shape,uniform size and good magnetic properties.The MCCM microspheres can be easily separated and recycled under magnetic field.Carbon nanotubes were incoprated into the cellulose network to support the high mechanical strength and layered structure.The size of the MCCM microspheres and hollow structure can be controlled by adjusting the concentration of cellulose and carbon nanotubes.(3)The adsorption properties of the MCCM microspheres.The adsorption properties of the MCCM microspheres prepared in previous chapter were studied by using methylene blue as an adsorption model.The effects of reaction time,initial concentration and other parameters on the adsorption process were studied systematically.It was found that the reaction time had an effect on the adsorption process,and the adsorption of methylene blue was fast firstly,then the adsorption became slow and finally tended to be stable.With the increase of the initial concentration of dye,the adsorption amount increases.In addition,the adsorption kinetics,isotherm and adsorption mechanism of the MCCM microspheres were also studied.It was found that the adsorption of methylene blue by the MCCM microspheres was quasi-secondary kinetic model and Langmuir model.In addition,the magnetic properties of t the MCCM microspheres were evaluated and it was found that they presented high magnetic sensitivity under the external magnetic field and could be simply and effectively separated from the aqueous solution.The adsorption-desorption experiments showed that the adsorption performance of the MCCM microspheres were almost the same after 5 cycles’ adsorption-desorption experiments,indicating that the MCCM microspheres had good reusability.The degradation of the MCCM microspheres was preformed in the natural environment.The results indicated that the MCCM microspheres was environmental-friendly one.These properties proved that the MCCM microspheres have potential application in the wastewater treatment field.