Synthesis And Preparation Of Metal-organic Frameworks And Films With Photocatalytic And Adsorption Properties

The pollution of surface and groundwater with heavy metals is a serious global concern,both environmentally,as well as with respect to human health.Overabundance of these elements poses severe health risks for humans,and also for other life forms through bioaccumulation along food chains.Therefore,steps should be taken to reduce the amount of such elements in water to acceptable levels.Traditional water treatment methods include adsorption,coagulation,membrane separation and so on.The development of a new type of environmental repair materials is a hot spot.Metal-organic frameworks?MOFs?have been widely used in the field of environmental remediation,such as adsorption,separation,and photocatalytic degradation of organic dye pollutant.In this work,several metal-organic frameworks /membranes have been synthesized and characterized by some instruments.Their properties of adsorptive or photocatalytic removal of heveay metals have been investigated.The mechanism of each experiment has been studied.The result are as follows:1.A metal-organic framework material,?4-Hap?₄[Mo₈O₂₆]?4-ap = 4-aminopyridine??BUC-14?,was synthesized via hydrothermal method,and utilized to conduct adsorptive uptake of typical heavy metal ion?Pb????,in which some key parameters on Pb???adsorption and possible mechanism were investigated.In order to test the preferential adsorption of specified heavy metal species from Pb???/Cu???and Pb???/Cd???mixture,the selective adsorption experiments were designed.The BUC-14 resulted in excellent adsorption performance for Pb???from simulated wastewater,and the maximum uptake capacity is 1105.7 mg/g at 298 K.The kinetics behavior and equilibrium isotherm were well described using pseudo-second-order and Langmuir model,respectively.In order to clarify the feasibility,favorability,spontaneity and even the mechanism of the ongoing adsorption process,thermodynamic parameters including standard Gibbs free energy??35?Go<0?,endothermic??Ho>0?and entropy change??So>0?,were calculated with the aid of data obtained from Langmuir adsorption isotherm.The adsorption process was thought to be divided two stages as electrostatic adsorption and ion exchange adsorption,which were proved by various characterization techniques like XRD,SEM-EDS,FTIR,XPS and even Q-TOF-MS.One SPE column including BUC-14 was made by ourselves,which could achieve excellent separation of Pb???/Cu???and Pb???/Cd???from their mixture.2.The metal–organic framework MIL-100?Fe?and g-C₃N₄ hybrids?MG-x,x = 5%,10%,20% and 30%?were fabricated through ball-milling and annealing,and which were characterized by PXRD,FTIR,TEM,TGA,UV-Vis DRS,and PL analysis.It was showed that a certain amount of g-C₃N₄ on the surface of MIL-100?Fe?would improve the separation and migration rate of photo-induced charges,consequently resulting in the improvement of photocatalytic efficiency.Compared with pure MIL-100?Fe?and g-C₃N₄,the composites exhibited more efficient photocatalytic performance for Cr???reduction under UV-Vis light.The optimal MIL-100?Fe?content in MIL-100?Fe?/g-C₃N₄ composite was determined to be 20.0 wt%,whose photocatalytic rate is 2.31 times of g-C₃N₄ and3.08 times of MIL-100?Fe?.Meanwhile,we explored the effects of organic compounds?ethanol,citric acid,oxalic acid and diclofenac sodium?and p H?2,3,4,6 and 8?on the photocatalytic reduction of Cr???by MG-20%.The composite exhibited good reusability and stability in the process of cyclic experiments.3.In this paper,Ui O-66-NH₂ membrane was successfully fabricated on alumina porous supports by a facile reactive seeding method.The structure and morphology of the obtained metal-organic framework membranes were characterized by PXRD,FTIR,SEM,UV-Vis DRS and so on.And the Ui O-66-NH₂ membrane showed a better performance in the adsorption of Cr???and photocatalytic reduction of Cr???under visible-light.After twenty runs,the removal efficiency of Cr???was still up to 94.1% and the crystal structure of Ui O-66-NH₂ membrane was almost intact.Ui O-66-NH₂ membrane has great potential in Cr???wastewater treatment.