Study On 3D Printing For Preparing Composite Electrodes And Adsorption Behavior Of Li~+/Cl~-

With the development of science and technology,the demand for lithium in the fields of electronics,aviation and medical treatment is becoming more and more important,and chlorine is also in a very important position in the fields of industry,agriculture and medical treatment.At present,the adsorption of lithium chloride is generally adsorbed by adsorbent powder,and the adsorbent will be lost in the process of adsorption recovery.In this paper,3D printing technology is used to prepare the compound electrodes,and extracting lithium and chlorine elements aim for lithium and chloride resources in Xinjiang salt lake brine,researched in three aspects:the preparation of electrodes precursor,3D printing preparation of composite electrodes materials,and electrodes mainly extracting lithium and chlorine.Characterized and analyzed by electrochemistry,XPS,TEM,BET,FTIR,and so on,investigated the behavior of the kinetics of adsorption process,the main contents and results are as follows:?1?Firstly,for the preparation of electrode precursors,ion sieve spinel and hydrotalcite with high adsorption capacity were selected as precursors for electrodes.For the cathode precursors,in the process of synthetic lithium ion sieve,carbon quantum dots nanomaterials were put in the modified treatment.The study shows that the adsorption capacity of PG-CQDs@HMS?Carbon quantum dots doped lithium ion sieve?on lithium ion is greater than HMS?Pure lithium ion sieve?at pH=7.0.Further research found that with the increase of temperature,the adsorption capacity of PG-CQDs@HMS increased.The results of XRD and FTIR tests show that the crystal lattice distortion of the spinel is caused by the doping of carbon quantum dots,and the number of protons in the lithium hydrogen exchange is obviously increased.The BET and Zeta potential tests show that the PG-CQDs@HMS has a larger specific surface area,which is transformed from micropore distribution to micropore distribution,and the absolute value of Zeta potential of the adsorbed lithium is reduced.In the process of lithium ion attachment,the number of lithium ions entered the double layer increases.Through further analysis of AAS,XPS,thermogravimetry and EDS,the bond of C-O-Mn is found in the material.According to the measured components,the molecular formula of PG-CQDs@HMS can be expressed as H _2.05Mn _1.86C _0.43O ₄,and the lithium capture performance of the material is further increased under the synergistic effect of the C-O-Mn bond.In this paper,the Lithium ion sieve doped by carbon quantum dots was chosen as the precursor of cathode materials.For the precursor of the anode materials,this paper selected from magnesium aluminum hydrotalcite,calcium aluminum hydrotalcite,and the hydrotalcite doped by quantum dots,than studied the adsorption performance of the pure hydrotalcite and the hydrotalcite doped by quantum dots for anions such as chloride ions and so on.However,it has been shown that the adsorption capacity of chlorine ions on the magnesium aluminum hydrotalcite and calcium aluminum hydrotalcite doped carbon quantum dots have reduced,but the adsorption capacity for borate ions of magnesium aluminum hydrotalcite modified by carbon quantum dots shows higher adsorption capacity.But pure calcium aluminate hydrotalcite Ca-LDHs has high adsorption capacity for chloride and borate ions.Therefore,Ca-LDHs is chosen as the precursor of anodic materials.?2?Secondly,in this study,bio-gels have been chosen as the loading agent for electrode precursors,the conductivity has increased by doping polyaniline.For the cathode and anode,the doping content of polyaniline were 25 wt.%and 45 wt.%show higher conductivity,respectively.In the process of precursors doped into gel,PG-CQDs@HMS and Ca-LDHs were doped 20 wt.%and 15 wt.%,respectively.The inner diameter of the negative and anode spray heads chosen as 0.44 mm and 1.54 mm respectively.The control printing speed chosen as 4 mm/s and the injection flow rate contoled as 0.36 mL/min.According to the printing conditions,the synthesized electrode was prepared by 3D printing,and finally the heteromorphic porous electrode was obtained.?3?Finally,the 3D printed electrodes have been used for electroadsorption,The adsorption properties of the electrode materials were investigated from voltage,initial concentration,cycle adsorption and other aspects.Results show that the adsorption capacity of electrodes increased with the increase of adsorption voltages,and when the adsorption voltage below 0.8 V,the electrodes are more stable and the adsorption capacity of lithium and chloride ions increased with the increase of initial concentration.When the initial concentration of lithium and chloride ions is 150 mg/L and 2000 mg/L respectively,the adsorption and desorption experiments of five cycles show that the adsorption of lithium and chloride ions on the electrodes is kept near 15 mg/g and 50 mg/g,respectively.In this paper,composite electrodes simultaneous extracted lithium and chlorine in salt lake brine have been studied.The adsorption kinetics of lithium ion,chloride ion and borate ion on the electrodes trend to the pseudo-second-order kinetic model,which shows that the adsorption of lithium ion,chloride ion and borate ion on the electrodes is controlled by diffusion control and reaction control,provide a reference method for salt lake resources development.