Study On The Detection And Removal Of Uranium/Iodine By Cyanide Based Charge Transfer Complexes

Radioactive uranium and iodine are common radioactive pollutants in the ecosystem,and their excessive emissions have become important environmental issue,threatening public health and ecosystems worldwide.Therefore,the highly sensitive detection and efficient removal of radioactive elements are of great significance for the protection of human health and the sustainable development of social economy.Charge transfer complex（CTC）is formed based on the interaction or complexation between donor（D）and acceptor（A）through electron transition from the highest occupied molecular orbital（HOMO）of D to the lowest unoccupied molecular orbital（LUMO）of A.Due to the simple and costless synthetic process as well as the unique optical properties,CTC has demonstrated great potential in sensing applications.Selective detection and efficient separation of uranyl ions(UO₂²⁺)in rare earth wastewater was achieved by introducing specific functional groups with strong affinity for UO₂²⁺into CTC.In addition,ternary CTC was designed and synthesized to achieve efficient adsorption of iodine.In this paper,the sensing and adsorption behaviors of radioactive uranium and iodine in different environmental media were studied by preparing two new CTC materials.The main research contents are as follows:1.Separation of uranium from lanthanides is very important to reduce the radioactive hazard caused by the residual solution in rare earth mineral hydrometallurgy.Herein,we use triphenylphosphine（TPP）and7,7,8,8-tetracyanoquinodimethane（TCNQ）as precursors to construct a charge transfer complex（TPP-TCNQ-CTC）as a chemical sensor for detecting UO₂²⁺and a coprecipitation reagent for the separation of uranium/lanthanides.Because P and N elements in TPP-TCNQ-CTC can have strong coordination interaction with UO₂²⁺,which affects the charge transfer process in TPP-TCPQ CTC,the resulting optical property changes can be used for multi-signal detection of UO₂²⁺(including absorbance,fluorescence and light scattering.This strong coordination interaction leads to significant coprecipitation,which can quickly realize the effective separation and removal of UO₂²⁺（90%）without complex procedures.This work proposes a simple synthesis method for CTC,which can selectively detect UO₂²⁺,separate uranium/lanthanides,and endow it with great potential in practical sample applications.2.The release of untreated radioactive iodine(¹²⁹I and ¹³¹I)in nuclear power plants poses a significant threat to humans and the environment,so the development of materials to capture iodine（from aqueous media and vapour）is critical.Here we report the TCNQ-MA CTC with an abundant nitrogen atom andπconjugated system.Due to the synergistic mechanism of benzene ring,triazine ring and cyano binding site,charge transfer interaction and unique I-πinteraction between groups and guest are formed,which makes CTC have up to 2.42 g/g and 800 mg/g adsorption capacity for I₂and I₃^-.TCNQ-MA CTC can capture 92%of I₃^-within 2.5 min,showing extremely fast kinetics,high selectivity and affinity（K_d=8×10⁶m L/g）.In addition,TCNQ-MA successfully removed iodine from seawater with a removal efficiency of 95.80%.The excellent adsorption performance confirms the important application value of this new CTC in the capture of iodine.