| With the rapid development of the world economy,the industries of manufacturing,chemical,electronics,and instrumentation have developed rapidly,and the discharge of solid waste has also increased rapidly.The treatment of wastewater containing heavy metal ions has become a research hots pot.Common methods for removing heavy metal ions from water include adsorption,membrane separation,ion exchange,and electrochemical methods.In contrast,the adsorption method has been successfully applied to various types of pollutant treatment due to its high efficiency,energy saving,recyclability and environmental protection,but traditional commercial adsorption materials?such as activated carbon,zeolite and resin materials?have disadvantages,such as small adsorption capacity,low adsorption efficiency,poor selectivity,and slow removal rate.As a new type of porous material,metal-organic framework materials?MOFs?have great potential in the adsorption and separation of pollutants due to their large specific surface area,strong designability and rich adsorption sites.The crystallinity of MOFs itself makes it mostly in the form of powder,resulting in low processability and operability,which is not conducive to recycling.The growth of MOFs on suitable substrate materials is an effective method for recycling and reusing functionalized MOFs.In this paper,cellulose aerogel?CA?and yeast beads?Yeast?were used as templates to successfully mount MOFs on cellulose aerogels and yeast pellets by in situ growth method to prepare metals.Metal-organic framework materials@cellulose aerogel composites?MOFs@CA?and metal-organic framework materials@yeast pellet composites?MOFs@Yeast?enable the recycling of MOFs.The adsorption properties of heavy metal ions in MOFs@CA and MOFs@Yeast adsorption water were studied.By comparing the equilibrium adsorption of heavy metal ions on pure MOFs and MOFs composites,it is determined that the MOFs are not blocked after being loaded on the cellulose aerogel and yeast pellets,and are still functional.Provides an idea and method for the recycling of MOFs.The research process and results are as follows:?1?Preparation,characterization and performance study of metal-organic framework materials@cellulose aerogel composites?MOFs@CA?.The prepared cellulose aerogel is immersed in a precursor solution containing a zirconium metal source,and then the cellulose aerogel doped with zirconium metal is immersed in a methanol solution of terephthalic acid and diaminoterephthalic acid.In the in situ growth,UiO-66@cellulose aerogel composite?UiO-66@CA?and UiO-66-NH2@cellulose aerogel composite?UiO-66-NH2@CA?were prepared.UiO-66@CA and UiO-66-NH2@CA were characterized by X-ray diffraction?XRD?,field emission scanning electron microscopy?FESEM?and thermogravimetric analysis?TG?.The results show that MOFs@CA composites are recycled.After that,it showed good shape stability,and it was possible to reuse 5 cycles,and the adsorption performance was not significantly lowered.Compared with CA,the compressive stress of UiO-66@CA and UiO-66-NH2@CA increased by 52%and 60%,respectively.After UiO-66-NH2 was grown on the surface of CA aerogel,the thermal stability of CA was improved.The highest decomposition temperature(Tmax)and complete decomposition temperature?Tf?increased by 24.6°C and62.1°C,respectively.The highest decomposition temperature(Tmax)and complete decomposition temperature?Tf?of UiO-66@CA increased by 20.7°C and 60.7°C,respectively.At the same time,the obtained MOFs@CA composite material can be easily separated from the wastewater without any secondary pollution.The equilibrium adsorption capacity of UiO-66-NH2@CA for Pb2+was 89.40 mg/g.This excellent reusability and easy separation properties make MOFs composite aerogels ideal for removing heavy metal ions from wastewater.?2?Preparation,characterization and performance study of metal-organic framework materials@yeast pellet composites?MOFs@Yeast?.The prepared yeast pellets are respectively immersed in a methanol solution containing a cobalt metal source and a zinc metal source,and then the yeast beads doped with the cobalt metal source and the zinc metal source are immersed in a methanol solution of dimethylimidazole.ZIF-67@yeast pellet composite?ZIF-67@Yeast?and ZIF-8@yeast pellet composite?ZIF-8@Yeast?were prepared in situ.ZIF-67@Yeast and ZIF-8@Yeast were characterized by X-ray diffraction?XRD?,field emission scanning electron microscopy?FESEM?and thermogravimetric analysis?TG?.The results showed that ZIF-67 can be evenly distributed on yeast beads.The growth rate can reach 31 wt%.After ZIF-67 was grown on the surface of yeast pellets,the thermal stability of yeast pellets was improved.Compared with pure yeast pellets,the highest decomposition temperature(Tmax)and complete decomposition temperature?Tf?of ZIF-67@Yeast are increased 47.3°C and 37.7°C,respectively.ZIF-67@Yeast has an equilibrium adsorption capacity of 64.7 mg/g for Pb2+.This easy separation provides an idea and method for MOFs to remove heavy metal ions from wastewater. |
PDF Full Text Request