Adsorption Of Heavy Metal Ions And Organic Pharmaceuticals By Metal-organic Frameworks

Recently,metal-organic frameworks with good stability and abundant functional groups,have become a new type of adsorbents for capturing various metal ions and organic pharmaceutical polluntants in wastewater.The adsorption of heavy metal ions by PCN-222-PA and UiO-66-Py was systematacially studied in this work,as well as the selective adsorption of antibiotic by PCN-222.The specific work is as follows:(1)In this work,PCN-222 with good biocompatibility was synthesized,and applied to adsorb organic pharmaceuticals.The results show that it has a large adsorption capacity of 370 mg·g-1,which is superior to all other reported adsorbents.Moreover,the adsorption equilibrium can be quickly obtained in a few minutes.Further investigation indicates that the interactions between the functional groups of amitripline and the surface of PCN-222 play an important role on the high-efficiency removal performance.(2)This work prepared a phytic acid(PA)-grafted PCN-222(PCN-222-PA)by solvent-assisted ligand incorporation method successfully,which was applied to U(VI)extraction in aqueous solution under a series of conditions.Due to the large amount of free phosphate groups,the adsorption capacity of PCN-222-PA(401.61 mg·g-1)outperforms most of the reported MOF-based adsorbents,which is 347.75%higher than that of the as-prepared PCN-222.It also shows high removal efficiency and good selectivity with the coexistence of other metal ions and lanthanides.The remarkable performance may be due to the inner-sphere complexation between U(VI)and the phosphate sites modified on PCN-222-PA surface.(3)A metal-organic framework decorated by hydrophilic pyridine group(UiO-66-Py)was prepared,and applied to adsorb Cr(VI)due to the excellent water stability and recyclable property it has.The maximum capacity of 195.31 mg·g-1 was obtained according to Langmuir model at 298 K for Cr(VI),which is 5 times of that of original UiO-66.The characterizions and theoretical analysis reveal that the interaction between the hydrophilic N-heterocycles of UiO-66-Py and Cr(VI)is responsible for the adsorption difference of these two adsorbents.