Absorbent Material Modified By Ionic Liquids And Adsorption Performance Study Of Re(?)

As a kind of green solvent,ionic liquids have the advantages of high thermal stability and low vapor pressure.Ionic liquids are used in many fields.Such as catalasis,material praperation and adsorption and separation et.al.This paper mainly studies their applications in adsorption and separation.Ionic liquids were used as adsorption functional groups,and three kinds of adsorption materials were prepared by different methods.The recovery and separation performances of Re(?)were studied.The results are as follows:1? First,imidazolium-based ionic liquids with different carbon chain lengths were synthesized by reacting N-methylimidazole,N-ethylimidazole and N-butylimidazole with epichlorohydrin.It was grafted onto the chitosan matrix as an adsorption functional group to obtain modified CS adsorbent by imidazolium-based ionic liquid.When the volume ratio of N-methylimidazole to epichlorohydrin was 1:2 and the mass of CS was 0.3 g,the adsorption rate of Re(?)was the highest when CS-MEIC was used at p H 3.According to R2,it was consistent with the Langmuir adsorption isotherm model.The maximum adsorption capacity at p H 3 was 184.71 mg·g-1.It can be seen from the kinetic experiments that the adsorption conformed to the pseudo-second-order kinetics adsorption model.The adsorption mechanism of CS-MEIC for Re(?)was investigated by FT-IR and XPS characterization methods,mainly chelation and ion exchange.After five cycles experiments,we found that CS-MEIC had good stability and cycling performance.2? In order to improve the adsorption capacity and selectivity of rhenium,So we prepared adsorbents-CS-p[C4Vmir][Cl] and CS-p[C4Da][Cl],which were modified by poly(imidazolium)-based ionic liquid and poly-quaterniums adsorption functional group and chitosan matrix.It was found that poly(imidazolium)-based ionic liquid modified chitosans had higher adsorption efficiency for Re(?)than poly-quaterniums under different acidity conditions.This may be due to the conjugation of the imidazole ring in CS-p[C4Vmir][Cl] and the high content of N.In the multi-system experiments with different acidity,CS-p[C4Vmir][Cl] had higher selectivity factor for Re(?)than CS-p[C4Da][Cl].At p H 3,the isothermal adsorption capacities of CS-p[C4Vmir][Cl] and CS-p[C4Da][Cl] were 219.4 and 155.5 mg·g-1,respectively,which were consistent with the Langmuir adsorption isotherm model.The adsorption mechanism was investigated by FT-IR,XPS and IC.We discovered that the dsorption mechanismthe was chelation and ion exchange.Five adsorption-analysis experiments showed that CS-p[C4Vmir][Cl] had better reusability.3? In order to increase the adsorption capacity,we used poly(ionic liquids)which had superior adsorption performance,as functional groups to prepare a series of poly(imidazolium)ionic liquid adsorbents.During the synthesis,in order to increase the rigidity of the adsorbent,divinylbenzene was added as a crosslinking agent,and Potassium persulfate was added as an initiator to prepare DVB-p[C2Vmir][Cl],DVB-p[C4Vmir][Cl],and DVB-p[C6Vmir][Cl].We can be seen that there were large differences in the microstructure of the three adsorbents by SEM characterization.DVB-p[C2Vmir][Cl] was an agglomerated sheet structure,and DVB-p[C4Vmir][Cl] was obviously a more dispersed sheet structure,while DVB-p[C6Vmir][Cl] showed a more pronounced globular structure.In acidity experiments,it was found that DVB-p[C4Vmir][Cl] and DVB-p[C6Vmir][Cl] had higher adsorption efficiency for Re(?)at different acidity.It also had high adsorption efficiency for Mo(VI).It can be seen that in the acidity experiment of the polybasic system that the adsorption selectivity of DVB-p[C4Vmir][Cl] to Re(?)was better.The isothermal adsorption capacities of DVB-p[C2Vmir][Cl],DVB-p[C4Vmir][Cl],and DVB-p[C6Vmir][Cl] were 264.90,517.61,458.84 mg·g-1,respectively,which were in accordance with Langmuir.The adsorption mechanism of DVB-p[C4Vmir][Cl] for Re(?)was investigated by FT-IR,XPS and IC.The adsorption mechanism was observed as chelation and ion exchange.Four adsorption-analysis experiments shown that the adsorbent DVB-p[C4Vmir][Cl] had good stability and cycle performance,and its practical application was stronger.