The Selective Capture Of SeO₃^2- Anions By Bi/Fe-based Metal Organic Frameworks And The Study Of Its Mechanism

With the rapid development of the energy industry,a large number of industrial wastewater which is harmful to water system has been produced while promoting economic growth.The most typical highly toxic anion in industrial wastewater is radioactive selenite anions.Selenite anions have attracted much attention in the field of water purification because of their high free and high toxicity.In this thesis,two kind of MOFs adsorbent with different channels were prepared and selectivily captured SeO₃^2-anions in the wastewater.The adsorption mechanisms were explained from their unique structural characteristics.Section?:CAU-17?Bi-MOF?on selective capture and mechanism of seleniteA novel bismuth-based metal-organic framework?Bi-MOF,CAU-17?was used as adsorbent to selectively capture SeO₃^2-anions from wastewater.The CAU-17 adsorbent showed a very high uptake capacity of 255.3 mg/g by forming Bi-O-Se bond.The CAU-17 also displayed fast uptake kinetics and could be easily separated from a liquid after used due to its novel morphology.Besides,CAU-17 showed excellent selectivity for SeO₃^2-anions in the presence of large concentrations of 11 competitive anions such as NO₃^-and SO₄^2-,and could work steady in a wide pH range of 4-11.Herein,the mechanism of selenite adsorption is explored to determine the important features that make CAU-17 a superior adsorbent for this application.Section?:MIL-101?Fe-MOF?on selective capture and mechanism of seleniteMIL-101 with more open-framework structures was designed to adsorb SeO₃^2-from aqueous solutions.MIL-101 showns the superior adsorption capacity with a high uptake capacity of 183.7 mg/g for SeO₃^2-,and fastest uptake rates for selenite anions with achieving 76%uptake capacity within 1 min under low concentrations.In addition,In addition,the adsorbent showed excellent selectivity for SeO₃^2-between the coexistence anions(NO₃^-and CO₃^2-et.)with large concentrations and target anions SeO₃^2-.Comparing with other metal oxide adsorbents,the MIL-101 was also able to work relatively steadily in a broad pH range of 4-11.The superior sorption property of MIL-101 is mainly attributed to its unique adsorption sites.