Controlled Fabrication Of UiO-66 And UiO-66-derived Composites For Removal Of Pollutants From Water

With the rapid development of economic,people's living standards are improving gradually.However,various types of industry produced the corresponding products to support human life and also made a large amount of persistent organic pollutants at the same time,such as organic dyes and organic wastewater,which are toxic and refractory,long residence time of pops.It may directly lead to an increase in the contents of heavy metals and drugs and personal care products?PPCPs?in groundwater and drinking water that disposing of industrial wastewater and discharge of domestic waste in random places.And a significant drop in the quality of surface water,which will pose a great threat to the ecological environment and human health.Adsorption method because of its high effect and low secondary pollution and other characteristics,stand out from many traditional processing technology emerged as researchers'research hot spot.In this paper,a metal-organic framework UiO-66 was selected as the research object.Carbamazepine,tetracycline,and antimony ions were taken as target pollutants,to examined the adsorption properties of deal with these pollutants by synthesized metal organic framework UiO-66 and the nano porous composite materials based on the metal organic framework UiO-66 as adsorbents,and analysis adsorption mechanism of it.In order to be able to use in the actual wastewater treatment well,we also explored the stability and ion interference ability of the material.The content is as follows:?1?The metal-organic framework UiO-66 was prepared by a facile and simple one-step solvothermal method and then we used UiO-66 as an adsorbent to remove organic micro-contaminants carbamazepine and tetracycline in water.We have investigated adsorption capacity of the effect of temperature,time,pH,and cationic interference and the competitive adsorption between carbamazepine and tetracycline and the reuse of sorbent.The maximum adsorption capacities of CBZ and TC on the UiO-66 were 37.2 and 23.1 mg·g^-1 at 25?,respectively.The adsorption isotherms and kinetics of CBZ and TC were well described by using the Langmuir model and pseudo-second-order model,respectively,and the adsorptions on UiO-66 are endothermic reactions.The adsorption capacities of CBZ and TC on UiO-66 were decreased with the increase of solution pH.The presence of humic acid could improve the adsorption of CBZ and TC on UiO-66,but K⁺ion inhibited their adsorption obviously.In addition,Ca²⁺,and Al³⁺ions also suppressed the adsorption of TC on UiO-66.The competitive adsorption suggested the adsorption sites for CBZ on UiO-66 were different from those for TC.At the same time,we have proved that tetracycline and carbamazepine do adsorb onto surface of UiO-66 by SEM,XRD,Fourier transform infrared spectroscopy.We have explored the adsorption mechanism of CBZ and TC on UiO-66,the results showed that the adsorption of CBZ on UiO-66is mainly a physisorption,and the hydrophobic effect played a crucial role during the adsorption of CBZ,meanwhile weak?–?electron donor-acceptor interaction and electrostatic attraction also existed.However,the adsorption of TC on UiO-66 is mainly a chemisorption,in addition to the strong electrostatic attraction and?–?electron donor-acceptor interaction forces,the nitrogenous groups of TC played an important role,which can replace the carboxylic groups coordinated with Zr-O clusters.This is evidenced by the reuse of sorbent.The recycled UiO-66 still showed good adsorption affinity for CBZ,while tetracycline does not desorb the second time.However,because of the strong adsorption force between TC and UiO-66,the adsorbed TC on UiO-66 could not be desorbed by chloroform.?2?Herein,zirconium metal–organic framework UiO-66 is used as precursor and template to prepare ZrO_x/porous carbon nanocomposites with tunable specific surface area and pore volume.The morphology and structure of the as-prepared ZrO_x/porous carbon nanocomposites have been well characterized by using SEM,TEM,N₂adsorption isotherms,XRD,Raman spectroscopy,FT-IR,and XPS methods.The results show that the tetragonal Zr O₂ nanoparticles in carbon matrix gradually grow up and transform into monoclinic ZrO₂ and ZrO as well as escape from the porous carbon nanocubes resulting in the increase of their specific surface area and pore volume with the increase of calcination temperature.The as-prepared ZrO_x/porous carbon nanocomposites at 1200?exhibited a high specific surface area up to 468.9m² g^-1.As adsorbent,the nanocomposites show excellent adsorption performance with high adsorption capacity(up to190 mg·g^-1)and fast adsorption equilibrium?60 min?for the removal of carbamazepine?CBZ?from the water in a wide pH range of 2-12.?3?UiO-66 were used as precursors to fabricate five different porous ZrO₂nanomaterials by one-step method and two-step method with changing the calcination temperature and retention time.The adsorption properties of five porous ZrO₂nanomaterials for Sb?III?in water were investigated.The results show that the two-step calcination method can significantly increase the specific surface area and pore volume of the material.And the maxium specific surface area and pore volume of the porous ZrO₂ nanomaterial were obtained by the two-step method with calcination temperature at 400°C and retention time for 2 hours in an air atmosphere at second step.The maximum surface area and pore volume are 136.1 m²·g^-1,0.170cm^-3·g^-1,respectively.Meanwhile,this porous ZrO₂ nanomaterials has the best adsorption performance for Sb?III?in water,the maximum adsorption capacity is 120mg·g^-1.This factor can be attributed to the larger specific surface area that provide more adsorption sites.