Research On Preparation Of Functionalized Poplar Catkins Aerogels And Its Application To Removal Of Heavy Metals From Wastewater

In this paper,poplar catkins aerogels were prepared from forestry waste poplar fiber,and two kinds of functionalized poplar fiber aerogels were prepared.The purification of poplar cellulose,the preparation of poplar cellulose-chitosan magnetic aerogel and ZIF-8functionalized poplar cellulose aerogel,the adsorption properties of two aerogels for Cu（II）and Pb（II）in wastewater and the removal of methylene blue by poplar cellulose-chitosan magnetic aerogel were mainly studied.The surface morphology and internal structure of two aerogels were studied by various characterization methods,In the main adsorption experiments,the effects of various factors on the adsorption capacity of aerogels were studied,and the adsorption mechanism of Cu（II）and Pb（II）by two aerogels and the adsorption performance of magnetic poplar cellulose-chitosan aerogels on methylene blue were further studied.The main research contents and results are as follows:（1）Poplar cellulose was extracted by alkali bleaching treatment,and the optimum reaction conditions of cellulose purification were obtained by single factor experiment.Under these conditions,the yield of cellulose was 83.5%.Poplar cellulose-chitosan magnetic aerogel was prepared by sol-gel method,and the SEM showed that the aerogel had a 3D network structure.The XRD spectrum showed the successful loading of Fe₃O₄.FTIR characterization showed that chitosan and poplar cellulose had been successfully combined by hydrogen bonding.ZIF-8 can be directly supported on poplar cellulose aerogel by in-situ growth,and its surface morphology and internal structure are analyzed by SEM,XRD and FTIR,which shows that ZIF-8 and poplar cellulose aerogel are successfully combined.（2）The adsorption properties of poplar cellulose-chitosan magnetic aerogel for Cu（II）and Pb（II）were studied.The maximum adsorption capacities of the aerogel for Cu（II）and Pb（II）were 81.3 mg/g and 112.3 mg/g,respectively.The adsorption process conformed to Langmuir isotherm and quasi-second order kinetic model.FTIR and XPS analysis showed that the main functional groups of magnetic poplar cellulose-chitosan aerogel were-NH₂and-OH.After five adsorption-desorption cycles,the adsorption capacity of the aerogel for Cu（II）and Pb（II）could still reach 85%and 80%of the initial adsorption capacity.（3）The wastewater containing Cu（II）and Pb（II）was adsorbed by ZIF-8functionalized poplar cellulose aerogel.Under the optimum adsorption conditions,the rapid adsorption of Cu（II）and Pb（II）could be realized,that is,the adsorption balance could be reached within 120 min,and the adsorption capacity of the aerogel for Cu（II）and Pb（II）was 241.7 mg/g and 266.8 mg/g,respectively The adsorption process accords with Langmuir and Quasi-second order kinetic model.The fast adsorption and large adsorption capacity are attributed to the high specific surface area of ZIF-8 and the porous structure of poplar cellulose aerogel.（4）The adsorption performance of poplar cellulose-chitosan magnetic aerogel on wastewater containing methylene blue was studied.The adsorption effect was the best when p H was 9.0 and initial temperature was 30℃,the maximum adsorption capacity was234.74 mg/g.The action mechanism was mainly studied by FTIR,which showed that the aerogel and methylene blue could be combined by electrostatic attraction and hydrogen bonding.