Preparation Of Metal-organic Framework/graphene Oxide Composites And The Adsorption Properties For Volatile Organic Compounds

Volatile organic compounds(VOCs)are increasingly polluting the environment and harmful for human health.Thus,it is important to determine the composition,source,and elimination methods of VOCs.One of the most useful methods to remove VOCs is adsorption,so developing a new and efficient adsorbent is the key of detecting VOCs.This paper takes advantages of porous Metal-Organic framework——ZIF-8 and graphene oxide(GO)to design and synthesis composites.The synthesis methods and adsorption/desorption performance of ZIF-8?ZIF-8/GO and functionalized GO with ZIF-8(ZIF-8/GO-PTMS)are studied.The method of adsorping and detecting VOCs.on online thermal desorption-gas chromatography(TD-GC)has been developed.The main research contents and conclusions are as follows:1.ZIF-8 was used as matrix to synthesize composites with GO.ZIF-8/GO were synthesized by stirring at room temperature and solvothermal methods.The adsorption and desorption conditions of the composites were optimized.The composite materials were comparatively studied for the adsorption performance of volatile organic compounds(n-hexane,benzene,methylbenzene,butyl acetate,undecane)on thermal desorption-gas chromatography.The results show that ZIF-8/GO prepared by the stirring method at room temperature have a smaller particle size and better morphology.By comparing the adsorption efficiency and the normalized peak area,it is found that the adsorption performance of ZIF-8/GO prepared by the stirring method is better than the solvothermal method,and the recovery and adsorption capacity were high.2.The composites of ZIF-8 and GO with the percentage of 5?10 and 20 were successfully prepared by stirring at room temperature and atmospheric pressure to study the effect of GO content on adsorption performance.The results show that the adsorption of the composites was better than that of ZIF-8.The desorption efficieny was over 98%.Through comparison,it was found that with the increase of the content of GO,the benzene compounds adsorption capacity enhanced due to the interaction of ?-?.The strategy of combining GO and ZIF can effectively solve the shortcomings of low adsorption capacity of ZIF,and improve the adsorption efficiency.3.By propyltrimethylsilane reacting with GO(GO-PTMS),the GO was functionalized with silane and then synthesized with ZIF-8.Through XRD,it was found that the distance between the functionally modified GO layers increased 0.104 nm,which solved its easy aggregation and stacking problem.The GO-PTMS was combined with ZIF-8(ZIF-8/GO-PTMS)to study the adsorption performance to VOCs.The results shows that the larger interlayer spacing of GO-PTMS improved the adsorption performance,and its adsorption capacity is 1.01~2.56 times that of unfunctionalized composite material(ZIF-8/GO).The ZIF-8/GO-PTMS composites were filled in the adsorbent tube and nine kinds of VOCs were determined by on-line thermal desorption-gas chromatography.The average recovery is 89.8%~105.1%,and the detection limit is 0.49~1.84 mg m-3,and has a good linear relationship(R2=0.9931~0.9990).It was found that benzene,toluene and heptanal were detected at concentrations of 7.4,12.3 and 11.6 mg m-3 in the testing room.