| In the past 20 years,metal organic frameworks（MOFs）have been widely used in the prevention and control of air pollution and water pollution due to their excellent properties.UiO-66 and its derivatives are regarded as a potential MOFs material because of their excellent stability and adjustability.The pore size and functionality of UiO-66 are designed by selecting organic ligands,functional groups,metal ion activation and other methods,thus giving UiO-66special chemical and physical properties to meet the needs of different scenes.As an important component of VOCs,oil vapor is composed of alkanes,alcohols and aromatics.At present,adsorption method is mainly used to treat oil vapor pollution,in which n-hexane is generally regarded as the key component of oil vapor and becomes the substitute object of oil vapor research.Due to its high specific surface area and adjustability,UiO-66 is being widely studied and applied in oil vapor adsorption.At present,there is still room for improvement in the synthesis and application of oil vapor adsorption material UiO-66:First,the specific surface area and pore size need to be adjusted for better adsorption,and the adsorption capacity decreases differently at different temperatures;Second,the adsorption performance of water containing oil vapor is not good,and the pore channel is easy to be blocked by water molecules;Third,the circulation of use is limited,and the economy is not strong;Fourth,the adsorption performance of UiO-66 is poor;Fifth,synthesis consumes a lot of energy and uses toxic and harmful organic solvents.In order to solve the above problems,a series of modification and synthesis methods were adopted.（1）UiO-66 was synthesized by solvothermal method.Zirconium tetrachloride（Zr Cl4）:terephthalic acid（H2BDC）mole ratio=1:1,1:1.5,1:2was synthesized at 90℃,120℃,150℃,180℃,210℃and 240℃.It was found that the maximum BET specific surface area was 1353.8 m2·g-1 at 120℃,1:1.5.（2）Different concentrations of benzoic acid were used to modify UiO-66and UiO-66-NH2.The highest BET specific surface area of UiO-66 was1688.57 m2·g-1,and the highest BET specific surface area of UiO-66-NH2 was1257.51 m2·g-1.The adsorption of n-hexane was carried out at 30℃,80℃and120℃.At low temperature,the adsorption capacity was positively correlated with the specific surface area.At high temperature,the amino group played an important role in the adsorption capacity.UiO-66 modified by benzoic acid has good recycling property.（3）Graphite（NGr）was compounded with the molar ratio of NGr:Zr Cl4 of1:4,1:2,1:1 and 2:1 by hydrothermal method,and the composite was obtained NGr@UiO-66.The BET specific surface area reached 1392.55 m2·g-1.The addition of NGr improved the specific surface area of UiO-66 and enhanced the adsorption of n-hexane.At the same time,because of the hydrophobicity of NGr,the properties of the composites are improved NGr@UiO-66 The adsorption capacity of water vapor is only half of the original.The optimal ratio of 1:4 and different concentrations of glacial acetic acid were selected to further increase the specific surface area and decrease the water absorption capacity.The high specific surface area and high hydrophobicity polymer was successfully prepared HAC@UiO-66@NGr The BET specific surface area of the composite is 1679.62 m2·g-1,and the water absorption saturation is only9.04%of UiO-66.（4）Mesoporous UiO-66 was synthesized by solvothermal modification using surfactant and soft template P123.By adding a certain concentration of P123 and using different concentrations of hydrochloric acid,UiO-66 with different mesopores was successfully synthesized and n-hexane and cyclohexane with different molecular dynamics diameters were adsorbed.With mesoporous,the adsorption rate of n-hexane and cyclohexane is greatly increased,and the recycling efficiency is also greatly improved.The mass of n-hexane was increased from 17.35%to 22.17%,and the mass of cyclohexane was increased from 17.18%to 24.28%.（5）UiO-66-NH2 was successfully synthesized by adding different concentrations of acetic acid at room temperature without using toxic and harmful solvents.The BET specific surface area of UiO-66-NH2 was much higher than that of the sample synthesized by solvothermal method,and the maximum was 1401.72 m2·g-1,which was more than twice of that of the sample synthesized by solvothermal method.The adsorption capacity has also been greatly improved.Due to the current environmental protection and energy saving policy,the samples synthesized by the green synthesis method at room temperature adsorb n-hexane and ethanol vapor respectively,and the adsorption rates are as high as 25.47%and 40.33%. |
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