Verification Of Lithium Complex System With Crown Ether Coordination And Preparation Of Li~+ Adsorption Resin

Lithium as a strategic resource,lithium and its compounds are particularly widely used.Extraction of lithium ions from brine with high magnesium and lithium has been a problem,which is due to the fact that lithium ions and magnesium ions are a diagonal element in the periodic table.Therefore,from the lithium magnesium co-brine in the extraction of lithium,must solve the separation of lithium and magnesium,which is to say a higher lithium-magnesium selective lithium material need to be synthesized.In this paper,dibenzoyl crown ether was selected as the raw material of lithium,and the crown ether was ring-shaped polygonal ligand.Different metal ions could be selectively complexed according to different cavity diameter.Dibenzo-14-crown-4 and bis?2-ethylhexyl?phosphate have synergistic coordination with lithium ions to meet the optimum coordination number of Li+ 5⁶.However,if the liquid-liquid extraction method is used to extract lithium ions,the toxicity of the small-molecule crown ether and it is expensive,and the loss rate of the extracting agent in the extraction process is high.The synergistic coordination system is an effective choice to solve the inherent shortcomings of the extraction method.However,whether this synergistic coordination system can play a synergistic effect on the polymer skeleton,and the experiment is not enough,need to carry out further experimental verification of this system.The use of crown ether and organic phosphine as a synergistic sensing material of glassy carbon electrode,dissolving it and using the drop coating method to produce sensors,a new type of lithium ion selective electrode was prepared.The use of graphene good conductivity,in the composition of the sensor material by adding graphene composite modified electrode.The selectivity of the two membranes was investigated by cyclic voltammetry.Therefore,it can be concluded that coordination system can also have synergistic effect on the polymer skeleton.In this experiment,the polymer of the crown ether was prepared by inverse suspension polymerization,and the lithium ions adsorption resin was separated.Through the experimental exploration,this topic draws the following results:?1?DB14C4 was synthesized by the improved ultrasonic method,and the yield was 43.8%.The structure of the product was confirmed by Gaussian frequency calculation and the frequency of the functional group in the measured infrared spectrum.The structure of the synthesized product was verified by mass spectrometry and nuclear magnetic resonance spectroscopy.?2?2-ethylhexyl)phosphate?B2EHPA?as synergistic complex was investigated by means of co-extraction method.Using a single extraction method of DB14C4 for lithium ion extraction?14.65?.The extraction efficiency of DB14C4/B2 EHPA was studied and the results showed that the selectivity coefficient was 6.24 and the extraction rate was increased to 24.32.?3?The DB14C4 / B2 EHPA electrode was prepared by dropping method.The results showed that DB14C4: B2 EHPA was 1: 2?molar ratio?,the best amount of drops were 4 ?L,linear scanning interval was 0.5 2.0 V,and the best film forming time was 45 s.Lithium ions have a better selectivity.The common cations in the brine of brine have less interference to the electrode,and the effect of the anion on the electrode is also small.?4?The DB14C4 / B2 EHPA / GR electrode was prepared by adding the graphene on the basis of the excellent conductivity of the graphene.Through the conditional experiment,the results were:The optimal ratio of functional monomer?DB14C4:B2EHPA?was 1:2?molar ratio?.Electrode conductivity improved through the peak height becoming higher;the optimal amount of graphene was 40 ?L;and selectivity has a more obvious improvement.?5?Comparison of the standard curve,linearity and detection limit of the two electrodes: DB14C4/B2 EHPA electrode,under the optimum preparation conditions,the concentration of lithium ions showed a good linearity with the peak current in the range of 1²0 mmol·L^-1?R=0.9943?and the detection limit was 0.002633 mmol·L^-1.DB14C4/B2EHPA/GR electrode,under the optimum preparation conditions,the concentration of lithium ions showed a good linearity with the peak current in the range of 0.8²0 mmol·L^-1?R=0.9966?and the detection limit was 0.0006166 mmol·L^-1.Compared with the linear range of the electrode without graphene,the linear correlation was improved and the detection limit was lower.?6?DB14C4 was achieved chemical modification by chloro-methylation and hydroxyl-methylation.The chemically modified DB14C4,B2 EHPA and toluene diisocynate?TDI?were synthesized by inverse suspension polymerization to synthesize spherical lithium ions adsorption resin.?7?The synthesized lithium ion separation resin was evaluated for structural analysis by infrared spectroscopy?IR?,thermal analysis?TG-DTA?,SEM and particle size analysis.The adsorption conditions of lithium ion were evaluated by adsorption experiments.The optimum conditions were as follows: optimum polymerization time was 8 h,polymerization temperature was 60 ?,pore preparation was lithium chloride solution.?8?The static adsorption experiments were carried out to investigate the optimum conditions for the adsorption of the synthesized spherical lithium ion adsorption resin: the time was 6 h,the adsorption temperature was 25 ? and the pH was 7.Under the optimum conditions,the maximum adsorption capacity was 0.7102 mmol·g^-1.