Experimental Study Onthe Adsorption Of Pollutants In Wastewaterusing Metal-organic Frameworks

Recently,as a class of newly developed porous materials,metal-organic frameworks(MOFs)gradually gain the popularity among the researchers.MOFs which combine high free pore volume,large surface areas,tuneable surface properties and so on are widely used in many fields,such as gas storage,gas or liquid adsorption/separation,drug delivery,catalysis,fluorescence and so on.In this paper,we mainly study the application of MOFs in the field of liquid adsorption/separation,the details are as follows:1.The porphyrin ligands with high purity were synthesized and the structure was confirmed by FT-IR and 1H NMR.PCN-222 was synthesized by solvothermal method.2-Nph and 1-NA were selected as representative of aromatic compounds,and the revalent adsorption performance of PCN-222 was studied,and the adsorption mechanism was explained.2.After a series of characterization,it was confirmed that Al-TCPP(Al-TCPP②)synthesized in DMF has a larger specific surface area(up to 56%),higher crystallinity and yield,comparing with that(Al-TCPP ①)synthesized in water.It shows that the adsorption of Al-TCPP② for 2-Nph and 1-NA was better than Al-TCPP ①,and was more suitable for pseudo-second-order kinetic and Langmuir model.The values of qm were 549.5,571.4 mg·g-1,respectively.The effect of temperature on the adsorption performance of Al-TCPP ② was further studied.The changes of free energy,enthalpy and entropy of the adsorption process were calculated and explained.After five cycles,the adsorption capacity of Al-TCPP ② for 2-Nph and 1-NA remained above 98%.3.The main adsorption mechanism,that is double-sided conjugation effect of Al-TCPP for 2-Nph and 1-NA,was explained in detail.Based on this,BTA and 5-TTA were selected as additional subtances to study.It shows that the adsorption of Al-TCPP ② was more consistent with pseudo-second-order kinetic and Langmuir model.The values of qm were 606.1,675.7 mg·g-1,respectively.And the amount of adsorption decreased as the temperature increased.After five cycles,the adsorption capacity of Al-TCPP ② for BTA and 5-TTA remained above 95%.