Synthesis Of Functionalized Metal-organic Frameworks For The Treatment Of Contaminants In Water

Among all resources,the wide availability of water resources makes them more vulnerable to pollution.With the rapid development of industry and modern agriculture,many harmful substances are released into the environment,causing great harm to the environment and organisms.Therefore,it is necessary to separate and remove the contaminants from water.Today,there are more and more means applied to the treatment of water pollution.Among them,adsorption method is widely used for water pollution treatment due to its advantages such as low energy consumption and simple operation.Metal-organic frameworks（MOFs）,a new type of porous crystalline organic-inorganic cluster complexes,are increasingly investigated by scientists due to their high specific surface area,tunable pores and modifiable chemical functional groups.However,the performance of MOFs is limited by insufficient active sites and powder shapes,which restrict their practical application and are not conducive to efficient removal of pollutants from water.However,through the rational selection and functionalization of the structure of MOFs,high performance adsorbents can be constructed.In order to develop the application of MOFs in the field of adsorption and separation,it is necessary to develop strategies for the functionalization of new MOFs.The functionalization of MOFs is mainly divided into two ways:（1）preparation of MOFs composites to facilitate the feasibility of MOFs with use in the actual environment;（2）modification of MOFs to enhance the MOFs’ability to treat water pollutants.Therefore,in this paper,ZIF-90 was compounded with melamine sponge to explore its adsorption performance on heavy metal ions.On this basis,covalent modification was used to change the wettability of the material and to explore the performance of the modified material in the field of oil-water separation.Finally,the ability of MIL-101-NH₂ to remove organic pollutants was explored by grafting 4-formyltriphenylamine to enhanceπ-πstacking.1.Efficient removal of roxarsone by enhancing theπ-πeffect of MIL-101（Fe）.Roxarsone（ROX）is absorbed and transformed by animals at a very low rate,and is prone to release highly toxic inorganic arsenic in nature,which causing harm to the environment.In this study,π-πstacking was enhanced by grafting 4-diphenylaminobenzaldehyde（TPA-CHO）on MIL-101-NH₂.The obtained TPA-MIL-101improved the adsorption of ROX and the removal efficiency of trace ROX from the actual water samples was as high as 99.98%,and the treated water samples all met the international drinking water stand.2.ZIF-90/MS composite with"punctured"microstructure for efficient removal of Pb（Ⅱ）in water.Firstly,the ZIF-90/MS composite with"punctured"microstructure was obtained for Pb（Ⅱ）removal in natural water environment by using the secondary growth method.This method allows ZIF-90 to penetrate uniformly on the melamine sponge fibers like pearls on a pearl chain,which greatly enhances the anchoring force of ZIF-90 on the melamine sponge fibers.According to the adsorption thermodynamics,its maximum adsorption capacity for Pb（Ⅱ）in water could reach 572.4 mg.g^-1.In addition,the selectivity of ZIF-90/MS composite for Pb（Ⅱ）in natural environment was also investigated.This work shows that the prepared ZIF-90/MS composites have the potential to remove Pb（Ⅱ）in real environmental water samples.3.Construction of superhydrophobic ZIF-90/MS with highly stable puncture structure for sustainable removal of oil spills in seawater.The ZIF-90/MS composite with"puncture"microstructure was firstly obtained by secondary growth method.Then,the ZIF-90/MS composite was superhydrophobized by grafting octadecylamine to the aldehyde group of ZIF-90 through Schiff base reaction.The ODA-ZIF-90/MS obtained after the modification exhibited great oil adsorption capacity(24-63 g·g^-1)and excellent recoverability（98.7%absorption retention after 50 cycles）.The physical stability provided by the"puncture"microstructure was also investigated,with the spill rate of ODA-ZIF-90 being less than 1%after 50 squeeze desorption cycles,and the separation rate of the oil spill being less than 1%after 50 cycles.The DLS diagram did not show the spillage of ODA-ZIF-90.This work demonstrates a promising strategy for large-scale oil spill cleanup.