Ionic Liquids Are Used For The Study Of Cellulose Dissolution, Radioactive Iodine Trapping And Distillation Of Ionic Liquids

As a green solvent ionic liquid(IL)has many excellent characteristics and is widely used in many fields in recent years.Studies on the unique properties of IL have far-reaching significance in developing its potential application prospect.In this paper,the properties and applications of ILs in cellulose dissolution and radioactive iodine storage and the reversibility and distillability of IL are studied by theoretical and experimental methods.Cellobiose is used as a model system to revealing cellulose dissolution mechanism in acetate-based ILs in computational and experimental methods.The geometric and electronic potential(ESP)analyses are performed to study the features of stable complexes formed by cellobiose and ILs.Many computational methods based on wavefunctions,such as atoms in molecules(AIM)theory,reduced density gradient(RDG)theory,natural bond orbital(NBO)theory,indicate that the solubility of cellobiose in ILs are related to the strength of hydrogen bonding interactions and van der Waals interaction between cellobiose and ILs in the complexes.Thermodynamic analysis suggests that increasing temperature can distinctly enhance the cellulose dissolution in [Bmim][OAc].NMR spectrum shows that the formation of hydrogen bonds between cellulose and ILs and the rupture of intrinsic hydrogen bond in cel obiose are the driving force of the dissolution.The reaction mechanism of radioactive iodine capture by 1-butyl-3-imidazolium based ILs is studied in theoretical method.The structure design and optimization of the complexes are based on the distribution of electrostatic potential on the molecular surface.The interaction energy is an indicator of halogen bonding interactions between radioactive iodine and ILs.The halogen bonds in the system are characterized by natural bond orbital(NBO)theory and atoms in molecules(AIM)theory.Computational and experimental results show that radioiodine can be captured by ILs with a 1:1 mol stoichiometry.Among them,the capture efficiency of [Bmim][Br],[Bmim][I] and [Bmim][Cl] reaches 80% within 5 hour,implying its good application prospect and developmental potential.Based on N-C=X(N,O and S)fragment,a series of reversible ILs are designed and studied in theoretical and experimental methods.Electrostatic potential on van der Waals surfaces of structure suggests that the high nucleophilic activity of X atoms on N-C=X makes methyl transferring becomes easier.The results of energy barriers for the studied ILs are chosen as an indicator for experimental synthesis.Seven ILs are chosen and synthesized to study their thermal stabilities in thermogravimetry.The results show that the initial decomposition temperature of ILs based on N-C=O is around 250?,which implies the reversible reaction of these ILs are easily to occur.The weight loss of [MMU][TfO] at 270? is less than 20% after 6 hours,indicating that it has high thermal stability.Theoretical methods,such as atoms in molecules(AIM),reduced density gradient(RDG),natural bond orbital(N BO),indicate that non-covalent interaction is the driving force for methyl transfer.